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Cardona GI, Escobar MC, Acosta-González A, Díaz-Ruíz N, Niño-García JP, Vasquez Y, Marrugo-Negrete J, Marqués S. Microbial diversity and abundance of Hg related genes from water, sediment and soil the Colombian amazon ecosystems impacted by artisanal and small-scale gold mining. Chemosphere 2024; 352:141348. [PMID: 38340998 DOI: 10.1016/j.chemosphere.2024.141348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/12/2024]
Abstract
The Amazon region abounds in precious mineral resources including gold, copper, iron, and coltan. Artisanal and small-scale gold mining (ASGM) poses a severe risk in this area due to considerable mercury release into the surrounding ecosystems. Nonetheless, the impact of mercury on both the overall microbiota and the microbial populations involved in mercury transformation is not well understood. In this study we evaluated microbial diversity in samples of soil, sediment and water potentially associated with mercury contamination in two localities (Taraira and Tarapacá) in the Colombian Amazon Forest. To this end, we characterized the bacterial community structure and mercury-related functions in samples from sites with a chronic history of mercury contamination which today have different levels of total mercury content. We also determined mercury bioavailability and mobility in the samples with the highest THg and MeHg levels (up to 43.34 and 0.049 mg kg-1, respectively, in Taraira). Our analysis of mercury speciation showed that the immobile form of mercury predominated in soils and sediments, probably rendering it unavailable to microorganisms. Despite its long-term presence, mercury did not appear to alter the microbial community structure or composition, which was primarily shaped by environmental and physicochemical factors. However, an increase in the relative abundance of merA genes was detected in polluted sediments from Taraira. Several Hg-responsive taxa in soil and sediments were detected in sites with high levels of THg, including members of the Proteobacteria, Acidobacteria, Actinobacteria, Firmicutes and Chloroflexi phyla. The results suggest that mercury contamination at the two locations sampled may select mercury-adapted bacteria carrying the merA gene that could be used in bioremediation processes for the region.
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Affiliation(s)
- Gladys Inés Cardona
- Instituto Amazónico de Investigaciones Científicas SINCHI. Laboratorio de Biotecnología y Recursos Genéticos, Bogotá, Colombia.
| | - Maria Camila Escobar
- Instituto Amazónico de Investigaciones Científicas SINCHI. Laboratorio de Biotecnología y Recursos Genéticos, Bogotá, Colombia; Escuela de Microbiología. Universidad de Antioquia, Medellín, Colombia
| | | | - Natalie Díaz-Ruíz
- Escuela de Microbiología. Universidad de Antioquia, Medellín, Colombia
| | | | - Yaneth Vasquez
- Chemistry Department, Universidad de Córdoba, Montería, Colombia
| | - José Marrugo-Negrete
- Convergence Science and Technology Cluster, Universidad Central, Bogotá, Colombia
| | - Silvia Marqués
- Department of Biotechnology and Environmental Protection. Estación Experimental Del Zaidín. Consejo Superior de Investigaciones Científicas, Granada, Spain
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2
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He R, Hu S, Li Q, Zhao D, Wu QL, Zeng J. Greater transmission capacities and small-world characteristics of bacterial communities in the above- than those in the below- ground niches of a typical submerged macrophyte, Vallisneria natans. Sci Total Environ 2023; 903:166229. [PMID: 37586539 DOI: 10.1016/j.scitotenv.2023.166229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/06/2023] [Accepted: 08/09/2023] [Indexed: 08/18/2023]
Abstract
Leaves and roots of submerged macrophytes provide extended surfaces and stable internal tissues for distinct microorganisms to rest, but how these microorganisms interact with each other across different niches and ultimately drive the distribution through horizontal and vertical transmissions remains largely undetermined. Knowledge of the mechanisms of assemblage and transmission in aquatic macrophytes-associated microbial communities will help to better understanding their important roles in plant fitness and benefit ecological functions. Here, we conducted a microcosmic experiment based on in situ lake samples to investigate the bacterial community assemblage, transmission, and co-occurrence patterns in different niches of a typical submerged macrophyte, Vallisneria natans (V. natans), including seed endosphere, as well as environmental (water and bulk sediment), epiphytic (phyllosphere and rhizosphere), and endophytic (leaf and root endosphere) microhabitats of both leaves and roots representatives of the above- and below- ground niches (AGNs and BGNs), respectively. We found the bacterial communities colonized in epiphytic niches not only exhibited the highest diversity compared to adjacent environmental and endophytic niches, but also dominated the interactions between those bacterial members of neighboring niches in both AGNs and BGNs. The host plants promoted niche specificity at bacterial community-level, as confirmed by the proportion of bacterial specialists increased with plant proximity, especially in the BGNs. Furthermore, the bacterial taxa colonized in the AGNs exhibited higher horizontal and vertical transmission capacities than those in the BGNs, especially in the vertical transmission from seeds to leaves (41.38 %) than roots (0.42 %). Meanwhile, the bacterial co-occurrence network in AGNs was shown to have stronger small-world characteristics but weaker stability than those in the BGNs. Overall, this study cast new light on the plant microbiome in the aquatic environment, thus better promoting the potential development of strategies for breeding aquatic macrophyte holobiont with enhanced water purification and pollutant removal capabilities in the future.
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Affiliation(s)
- Rujia He
- State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Joint International Research Laboratory of Global Change and Water Cycle, Hohai University, Nanjing 210098, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Siwen Hu
- State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Joint International Research Laboratory of Global Change and Water Cycle, Hohai University, Nanjing 210098, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Qisheng Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Dayong Zhao
- State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Joint International Research Laboratory of Global Change and Water Cycle, Hohai University, Nanjing 210098, China
| | - Qinglong L Wu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; Center for Evolution and Conservation Biology, Southern Marine Sciences and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China; Sino-Danish Centre for Education and Research, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Jin Zeng
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; Sino-Danish Centre for Education and Research, University of Chinese Academy of Sciences, Beijing 100039, China.
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3
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Harrow-Lyle TJ, Lam WY, Emilson EJS, Mackereth RW, Mitchell CPJ, Melles SJ. Watershed characteristics and chemical properties govern methyl mercury concentrations within headwater streams of boreal forests in Ontario, Canada. J Environ Manage 2023; 345:118526. [PMID: 37418824 DOI: 10.1016/j.jenvman.2023.118526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/21/2023] [Accepted: 06/25/2023] [Indexed: 07/09/2023]
Abstract
Methyl mercury (MeHg) concentrations in boreal headwater streams are influenced by complex natural processes and disturbances such as forestry management. Understanding drivers of MeHg within boreal streams in Ontario, Canada, is of particular interest as there are legacy MeHg concerns. However, models accounting for the complexity of underlying processes have not yet been developed. We assessed how catchment characteristics and stream water chemistry influence MeHg concentrations within 19 watersheds of the Dryden - Wabigoon Forest in Ontario, Canada, using a structural equation modelling (SEM) approach. Despite the study area encompassing a large variation of boreal forest watersheds in the Canadian Shield, our SEM had substantial explanatory power across the region (χ251 = 45.37, p-value = 0.70, R2 = 0.75). Nitrate concentrations (p-value <0.001), water temperature (p-value = 0.002), and the latent watershed characteristic (p-value <0.001) had a positive influence on MeHg concentrations once variable interactions were accounted. Due to the inherent strengths of applying an SEM approach, we describe two plausible pathways driving MeHg concentrations: 1) indirect effect of forest-derived nutrients increases in-situ MeHg production in Dryden - Wabigoon Forest streams, and 2) direct supply of MeHg from inundated soils following consistent precipitation and inundation events (i.e., fill, sit, and spill).
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Affiliation(s)
- Tyler J Harrow-Lyle
- Department of Chemistry and Biology, Toronto Metropolitan University, 43 Gerrard St, Toronto, Ontario, M5B 2K, Canada.
| | - Wai Ying Lam
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada.
| | - Erik J S Emilson
- Natural Resources Canada, Canadian Forest Service, 1219 Queen Street E., Sault Ste. Marie, Ontario, P6A 2E5, Canada.
| | - Robert W Mackereth
- Ministry Natural Resources and Forestry, 421 James St., Thunder Bay, Ontario, P7E 2V6, Canada.
| | - Carl P J Mitchell
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada.
| | - Stephanie J Melles
- Department of Chemistry and Biology, Toronto Metropolitan University, 43 Gerrard St, Toronto, Ontario, M5B 2K, Canada.
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Brooks SC, Riscassi AL, Miller CL, Lowe KA, Yin X, Mehlhorn TL. Diel mercury concentration variations in a mercury-impacted stream. Environ Sci Process Impacts 2022; 24:1195-1211. [PMID: 35829655 DOI: 10.1039/d2em00142j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Filtered and particulate mercury (Hg) and methylmercury (MMHg), and associated water chemistry parameters, were evaluated bi-hourly for several 30 h periods during the summer and winter seasons at several distinct locations (downstream forested, midstream urban/suburban, upstream industrial) along a creek contaminated with high levels of inorganic Hg to determine if biogeochemical Hg and MMHg cycles respond to the daily photocycle. In summer particulate Hg and MMHg concentrations doubled overnight (excluding the upstream industrial site) concurrent with increases in turbidity and total suspended sediment; no such pattern was evident in winter. Seasonal and diel changes in the activity of macrobiota affecting the suspension of contaminated sediments are likely responsible for these patterns as other potential explanatory variables (e.g., instrument drift, pH, discharge) could not account for the range and timing of our observations. Diel patterns in filtered Hg (HgD) were significant only at locations and times of the year when channel shading was not present and daytime concentrations increased 22-89% above nighttime minima likely caused by direct and indirect photochemical reactions. Relationships between HgD and dissolved organic carbon (DOC) concentration or character were inconsistent between sites. Unlike HgD, there were significant diel patterns in filtered MMHg (MMHgD) at all sites and times of year, with summer concentrations peaking in mid to late afternoon while the timing differed in winter, with concentrations peaking after sunset. Daily variability in MMHgD concentration ranged between 25 and 75%. The results imply key controls on net methylation occur within the stream or on the stream bed and include factors such as small-scale temperature changes in the water column and photosynthetic activity of stream biofilm. With respect to stream monitoring, results from this study indicate (1) consistent timing in stream Hg and MMHg sampling is required for accurate assessment of long-term trends, (2) in situ measurements of turbidity can be used to quantify diel dynamics of both particulate Hg and MMHg concentrations, and (3) in situ fluorescing dissolved organic matter (FDOM), a potential proxy for DOC, was not capable of resolving diel dynamics of filtered Hg or MMHg.
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Affiliation(s)
- Scott C Brooks
- Oak Ridge National Laboratory, Environmental Sciences Division, PO Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, USA.
| | - Ami L Riscassi
- University of Virginia, Environmental Sciences Department, 291 McCormick Rd., Charlottesville, VA, USA
| | - Carrie L Miller
- Theoretical and Applied Science, Ramapo College of New Jersey, Mahwah, New Jersey, USA
| | - Kenneth A Lowe
- Oak Ridge National Laboratory, Environmental Sciences Division, PO Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, USA.
| | - Xiangping Yin
- Oak Ridge National Laboratory, Environmental Sciences Division, PO Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, USA.
| | - Tonia L Mehlhorn
- Oak Ridge National Laboratory, Environmental Sciences Division, PO Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, USA.
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Nyholt K, Jardine TD, Villamarín F, Jacobi CM, Hawes JE, Campos-Silva JV, Srayko S, Magnusson WE. High rates of mercury biomagnification in fish from Amazonian floodplain-lake food webs. Sci Total Environ 2022; 833:155161. [PMID: 35421468 DOI: 10.1016/j.scitotenv.2022.155161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 06/14/2023]
Abstract
Despite a global phase out of some point sources, mercury (Hg) remains elevated in aquatic food webs, posing health risks for fish-eating consumers. Many tropical regions have fast growing organisms, potentially short food chains, and few industrial point sources, suggesting low Hg baselines and low rates of trophic magnification with limited risk to people. Nevertheless, insufficient work on food-web Hg has been undertaken in the tropics and fish consumption is high in some regions. We studied Hg concentrations in fishes from floodplain lakes of the Juruá River, Amazonas, Brazil with three objectives: 1) determine rates of Hg trophic magnification, 2) assess whether Hg concentrations are high enough to impact humans eating fish, and 3) determine whether there are seasonal differences in fish Hg concentrations. A total of 377 fish-muscle samples were collected from 12 floodplain lakes during the low-water (September 2018) and falling-water (June 2019) seasons and analysed for total Hg and stable nitrogen (N) isotopes. The average trophic magnification factor (increase per trophic level) was 10.1 in the low-water season and 5.4 in the falling-water season, both well above the global average for freshwaters. This high rate of trophic magnification, coupled with higher-than-expected Hg concentrations in herbivorous species, led to high concentrations (up to 17.6 ng/g dry weight) in predatory pirarucu and piranha. Nearly 70% of all samples had Hg concentrations above the recommended human-consumption guidelines. Average concentrations were 42% higher in the low-water season than the falling-water season, but differences varied by species. Since Hg concentrations are higher than expected and fish consumption in this region is high, future research should focus on Hg exposure for human populations here and in other tropical-rainforest regions, even in the absence of local point sources of Hg.
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Affiliation(s)
- Kelsey Nyholt
- Toxicology Centre and School of Environment and Sustainability, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada
| | - Timothy D Jardine
- Toxicology Centre and School of Environment and Sustainability, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada.
| | - Francisco Villamarín
- Grupo de Biogeografía y Ecología Espacial (BioGeoE(2)), Universidad Regional Amazónica Ikiam, km7 vía Muyuna, Tena, Ecuador
| | - Cristina M Jacobi
- Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Petrópolis, Manaus, Amazonas 69067-375, Brazil; Institute of Biosciences, São Paulo State University (UNESP), Avenida 24 A 1515, Rio Claro, São Paulo 13506-900, Brazil
| | - Joseph E Hawes
- Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences, Universitetstunet 3, 1433 Ås, Norway; Applied Ecology Research Group, School of Life Sciences, Anglia Ruskin University, Cambridge CB1 1PT, UK; Instituto Juruá, Manaus, Amazonas 69083-300, Brazil
| | - João V Campos-Silva
- Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences, Universitetstunet 3, 1433 Ås, Norway; Instituto Juruá, Manaus, Amazonas 69083-300, Brazil
| | - Stephen Srayko
- Toxicology Centre and School of Environment and Sustainability, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada
| | - William E Magnusson
- Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Petrópolis, Manaus, Amazonas 69067-375, Brazil
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Liu J, Li Y, Duan D, Peng G, Li P, Lei P, Zhong H, Tsui MTK, Pan K. Effects and mechanisms of organic matter regulating the methylmercury dynamics in mangrove sediments. J Hazard Mater 2022; 432:128690. [PMID: 35325865 DOI: 10.1016/j.jhazmat.2022.128690] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/09/2022] [Accepted: 03/09/2022] [Indexed: 06/14/2023]
Abstract
Mangrove ecosystems serve as an important carbon sink but also could be a hotspot that produces neurotoxic methylmercury (MeHg). Although many studies have focused on mercury (Hg) contamination in this carbon-rich ecosystem, our understanding of the effects and mechanisms of the organic matter (OM) regulation of MeHg production in mangrove sediments is still limited. Here, we examined the effects of Hg contamination and OM enrichment on MeHg production in anoxic mangrove sediments and identified the major microbial guilds attending this process. The mangrove sediments possessed a high potential for producing MeHg, but this was counterbalanced by its rapid degradation. Sulfate-reducing bacteria (SRB) such as Desulfobacterales, Desulfovibrionales, and Syntrophobacterales were the major methylators. OM diagenesis significantly changed the biogeochemical conditions, accelerating MeHg degradation in the sediments. The enhanced MeHg degradation could be attributed to the abundant sulfide produced during OM decomposition, which could potentially inhibit the Hg methylation by immobilization of inorganic Hg, abiotically degrade MeHg, and favor the non-mer-mediated degradation of MeHg by SRB. Our study provides both geochemical and microbial clues that can partly explain the low MeHg levels widely observed in mangrove sediments.
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Affiliation(s)
- Jingli Liu
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yanping Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Dandan Duan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Guogan Peng
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Ping Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Pei Lei
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Martin Tsz-Ki Tsui
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Ke Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
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7
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Ghezzi L, Arrighi S, Giannecchini R, Bini M, Valerio M, Petrini R. The Legacy of Mercury Contamination from a Past Leather Manufacturer and Health Risk Assessment in an Urban Area (Pisa Municipality, Italy). Sustainability 2022; 14:4367. [DOI: 10.3390/su14074367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
An abandoned open green space in the urban setting of the Municipality of Pisa (Tuscany, Italy) has been designed for renewal to foster the development of recreational activities and improve the lives of the surrounding communities. However, the geochemical site characterization revealed Pb, Cu, Zn and Hg concentrations in the soil exceeding the thresholds imposed by Italian regulations for residential use. Pb, Cu and Zn contents likely reflect the effects of urban vehicle traffic, while Hg contamination represents the legacy of a past artisanal tannery that used Hg(II)-chloride in leather processing in the mid-1900s. Mercury is widely distributed in the area, with the highest concentration in the uppermost soil layer, and reaching about 170 mg/kg in the common dandelion rhizosphere. Chemical extractions and thermal desorption experiments have indicated that most Hg is in the elemental free and matrix-bound fraction, with a possible minor amount (less than 4 wt%) of HgS and negligible methylated forms (0.1 wt%). The data suggest that soil processes could reduce Hg2+ to volatile Hg0. Mercury in groundwater, hosted in a shallow aquitard in the area, was below 0.2 µg/L. However, the presence of chloride in groundwater might result in the formation of Hg stable aqueous complexes, increasing Hg release from solids. Future water quality monitoring is hence recommended. The risk assessment highlighted that mercury in soil carries a risk of non-cancerous effects, in particular for children, posing the basis for management planning.
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Wang J, Dai J, Chen G, Jiang F. Role of sulfur biogeochemical cycle in mercury methylation in estuarine sediments: A review. J Hazard Mater 2022; 423:126964. [PMID: 34523493 DOI: 10.1016/j.jhazmat.2021.126964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 07/26/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Estuaries are sinks for mercury, in which the most toxic mercury form, neurotoxic methylmercury (MeHg), is produced by mercury methylators and accumulates in estuarine sediments. In the same area, the microbial sulfur cycle is triggered by sulfate-reducing bacteria (SRB), which is considered as the main mercury methylator. In this review, we analyzed the sulfur and mercury speciation in sediments from 70 estuaries globally. Abundant mercury and sulfur species were found in the global estuarine sediments. Up to 727 μg THg/g dw and 880 ng MeHg/g dw were found in estuarine sediments, showing the serious risk of mercury to aquatic ecological systems. Significant correlations between sulfur and MeHg concentrations were discovered. Especially, the porewater sulfate concentration positively correlated to MeHg production. The sulfur cycle affects MeHg formation via activating mercury methylator activities and limiting mercury bioavailability, leading to promote or inhibit MeHg formation at different sulfur speciation concentrations. These results suggest that sulfur biogeochemical cycle plays an important role in mercury methylation in estuarine sediments, and the effect of the sulfur cycle on mercury methylation deserves to be further explored in future research.
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Affiliation(s)
- Jinting Wang
- Department of Civil and Environmental Engineering, Water Technology Lab, Hong Kong Branch of Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ji Dai
- Department of Civil and Environmental Engineering, Water Technology Lab, Hong Kong Branch of Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
| | - Guanghao Chen
- Department of Civil and Environmental Engineering, Water Technology Lab, Hong Kong Branch of Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Feng Jiang
- Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science & Engineering, Sun Yat-sen University, Guangzhou, China.
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Barbosa MS, Carvalho DP, Gravena W, de Almeida R, Mussy MH, Sousa EA, Holanda IBB, de Sousa-Filho IF, Bastos WR. Total mercury and methylmercury in river dolphins (Cetacea: Iniidae: Inia spp.) in the Madeira River Basin, Western Amazon. Environ Sci Pollut Res Int 2021; 28:45121-45133. [PMID: 33861423 DOI: 10.1007/s11356-021-13953-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
In the Amazon, mercury (Hg) contamination comes from ASGM operations along with soil remobilization processes associated with deforestation. The objective of this study was to evaluate the exposure to methylmercury (MeHg) and total mercury (THg) in 88 samples of skin and blubber tissue obtained from live captured river dolphins (Inia boliviensis, Inia geoffrensis, and Inia spp.) in the Madeira River Basin. THg and MeHg measurements were performed by CV-AAS and GC-AFS, respectively. We also calculated the daily intake rate (DIR) of THg (wet weight) by Inia spp. THg levels in blubber tissue of adult river dolphins (Inia spp.) ranged from 0.015 to 3.804 mg kg-1, while MeHg concentrations in blubber tissue varied from 0.04 to 2.65 mg kg-1 and in skin tissue from 0.09 to 0.66 mg kg-1. There were no significant differences in MeHg concentration in blubber (p = 0.616) and skin (p = 0.498) tissue samples between adult males and females in the different sampling locations. The adult animals showed differences in THg and MeHg concentrations significantly higher than in the calves. The estimate of the DIR of the genus Inia ranged from 1.17 to 12.35 μg kg-1 day-1 (bw), from the consumption of fish species with herbivorous to piscivorous habits, respectively. More biological and ecological data, such as the precise determination of age, mediated length, weight, and diet of river dolphins, are necessary to verify the Hg biomagnification. However, our data indicate that bioaccumulation is an active process in the dolphins of the Madeira River Basin.
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Affiliation(s)
- Melissa S Barbosa
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
| | - Dario P Carvalho
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
- Santo Antônio Energia, Porto Velho, RO, Brazil
| | - Waleska Gravena
- Instituto de Saúde e Biotecnologia, Universidade Federal do Amazonas, Manaus, AM, Brazil
- Laboratório de Mamíferos Aquáticos, Instituto Nacional de Pesquisas da Amazônia, Manaus, AM, Brazil
| | - Ronaldo de Almeida
- Departamento de Ciências Sociais e Ambientais, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
| | - Marília H Mussy
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
| | - Eduardo A Sousa
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
| | - Igor B B Holanda
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
| | - Izidro F de Sousa-Filho
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Wanderley R Bastos
- Laboratório de Biogeoquímica Ambiental WCP, Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brazil.
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10
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Xiang Y, Liu G, Yin Y, Cai Y. Periphyton as an important source of methylmercury in Everglades water and food web. J Hazard Mater 2021; 410:124551. [PMID: 33223320 DOI: 10.1016/j.jhazmat.2020.124551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/23/2020] [Accepted: 11/10/2020] [Indexed: 06/11/2023]
Abstract
Periphyton is ubiquitous in Florida Everglades and has a profound effect on mercury (Hg) cycling. Enhanced methylmercury (MeHg) production in periphyton has been well documented, but the re-distribution of MeHg from periphyton remains unknown. In this study, periphyton, sediments, surface water, periphyton overlying water, and periphyton porewater were collected from Everglades for analyzing the distribution of MeHg and total Hg (THg). Results showed that there were no significant differences in THg and MeHg in different types of periphyton, but they all displayed higher MeHg levels than sediments. MeHg distribution coefficients (logkd) in periphyton were lower than in sediments, suggesting that periphyton MeHg could be more labile entering aquatic cycling and bioaccumulation. In water, the more the distance of water samples taken from periphyton, the lower the MeHg and dissolved organic carbon concentrations were detected. In extracellular polymeric substances of periphyton, MeHg in colloidal fractions was significantly higher than that in capsular fractions. It was estimated that approximately 10% (or 1.35 kg) of periphyton MeHg were passed on to mosquitofish entering the food web during wet season, contributing 73% of total Hg stocked in mosquitofish. These results revealed the importance of periphyton on water MeHg distribution and MeHg bioaccumulation in Everglades.
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Affiliation(s)
- Yuping Xiang
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Guangliang Liu
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Cai
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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11
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Carrell AA, Schwartz GE, Cregger MA, Gionfriddo CM, Elias DA, Wilpiszeski RL, Klingeman DM, Wymore AM, Muller KA, Brooks SC. Nutrient Exposure Alters Microbial Composition, Structure, and Mercury Methylating Activity in Periphyton in a Contaminated Watershed. Front Microbiol 2021; 12:647861. [PMID: 33815336 PMCID: PMC8017159 DOI: 10.3389/fmicb.2021.647861] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/22/2021] [Indexed: 01/04/2023] Open
Abstract
The conversion of mercury (Hg) to monomethylmercury (MMHg) is a critical area of concern in global Hg cycling. Periphyton biofilms may harbor significant amounts of MMHg but little is known about the Hg-methylating potential of the periphyton microbiome. Therefore, we used high-throughput amplicon sequencing of the 16S rRNA gene, ITS2 region, and Hg methylation gene pair (hgcAB) to characterize the archaea/bacteria, fungi, and Hg-methylating microorganisms in periphyton communities grown in a contaminated watershed in East Tennessee (United States). Furthermore, we examined how nutrient amendments (nitrate and/or phosphate) altered periphyton community structure and function. We found that bacterial/archaeal richness in experimental conditions decreased in summer and increased in autumn relative to control treatments, while fungal diversity generally increased in summer and decreased in autumn relative to control treatments. Interestingly, the Hg-methylating communities were dominated by Proteobacteria followed by Candidatus Atribacteria across both seasons. Surprisingly, Hg methylation potential correlated with numerous bacterial families that do not contain hgcAB, suggesting that the overall microbiome structure of periphyton communities influences rates of Hg transformation within these microbial mats. To further explore these complex community interactions, we performed a microbial network analysis and found that the nitrate-amended treatment resulted in the highest number of hub taxa that also corresponded with enhanced Hg methylation potential. This work provides insight into community interactions within the periphyton microbiome that may contribute to Hg cycling and will inform future research that will focus on establishing mixed microbial consortia to uncover mechanisms driving shifts in Hg cycling within periphyton habitats.
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Affiliation(s)
- Alyssa A Carrell
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Grace E Schwartz
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States.,Department of Chemistry, Wofford College, Spartanburg, SC, United States
| | - Melissa A Cregger
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Caitlin M Gionfriddo
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.,Smithsonian Environmental Research Center, Edgewater, MD, United States
| | - Dwayne A Elias
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Regina L Wilpiszeski
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Dawn M Klingeman
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Ann M Wymore
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Katherine A Muller
- Pacific Northwest National Laboratory, Earth Systems Science Division, Richland, WA, United States
| | - Scott C Brooks
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States
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12
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Quiroga-Flores R, Guédron S, Achá D. High methylmercury uptake by green algae in Lake Titicaca: Potential implications for remediation. Ecotoxicol Environ Saf 2021; 207:111256. [PMID: 32920312 DOI: 10.1016/j.ecoenv.2020.111256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 04/20/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
Anthropogenic pressure in the high altitude lakes such as Titicaca and Uru (Bolivia) may favor the production of methylmercury (MeHg) known to accumulate in trophic chains. Periphyton associated with emerged aquatic plants (totoras) from the lake shores accumulates and demethylates MeHg providing a potential cost-effective water treatment technique. In this laboratory study, we measured the MeHg uptake kinetics of a consortium of green algae isolated from Lake Titicaca totora's periphyton. The most abundant algal consortium, composed of Oedogonium spp., Chlorella spp., Scenedesmus spp., was exposed to rising MeHg concentrations (from 5 to 200 ng·L-1) to assess their maximum potential capacity for MeHg accumulation. Various algal biomass concentrations were tested to choose the optimal one. Results provided a net MeHg uptake rate by this algal consortium of 2.38 amol ng-1·h-1·nM-1 (the total uptake was 2863 ng MeHg·g-1) for an initial concentration of 200 ng MeHg·L-1 with an algal biomass concentration of 0.02 g·L-1. This initial MeHg concentration is 1000 times higher than the one measured in the eutrophic Cohana Bay of Lake Titicaca, which shows the high accumulation potential of these green algae. Our data suggest that periphyton has a high potential for the treatment of Hg contaminated waters in constructing wetlands in the Andean Altiplano.
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Affiliation(s)
- Roxana Quiroga-Flores
- Instituto de Investigaciones Fármaco Bioquímicas, Universidad Mayor de San Andrés, La Paz, Bolivia; Division of Biotechnology, Department of Chemistry, P.O. Box 124, Lund University, SE-223 62, Lund, Sweden.
| | - Stéphane Guédron
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000, Grenoble, France
| | - Dario Achá
- Laboratorio de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla, 3161, La Paz, Bolivia
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13
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Branfireun BA, Cosio C, Poulain AJ, Riise G, Bravo AG. Mercury cycling in freshwater systems - An updated conceptual model. Sci Total Environ 2020; 745:140906. [PMID: 32758756 DOI: 10.1016/j.scitotenv.2020.140906] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
The widely accepted conceptual model of mercury (Hg) cycling in freshwater lakes (atmospheric deposition and runoff of inorganic Hg, methylation in bottom sediments and subsequent bioaccumulation and biomagnification in biota) is practically accepted as common knowledge. There is mounting evidence that the dominant processes that regulate inputs, transformations, and bioavailability of Hg in many lakes may be missing from this picture, and the fixation on the temperate stratified lake archetype is impeding our exploration of understudied, but potentially important sources of methylmercury to freshwater lakes. In this review, the importance of understudied biogeochemical processes and sites of methylmercury production are highlighted, including the complexity of redox transformations of Hg within the lake system itself, the complex assemblage of microbes found in biofilms and periphyton (two vastly understudied important sources of methylmercury in many freshwater ecosystems), and the critical role of autochthonous and allochthonous dissolved organic matter which mediates the net supply of methylmercury from the cellular to catchment scale. A conceptual model of lake Hg in contrasting lakes and catchments is presented, highlighting the importance of the autochthonous and allochthonous supply of dissolved organic matter, bioavailable inorganic mercury and methylmercury and providing a framework for future convergent research at the lab and field scales to establish more mechanistic process-based relationships within and among critical compartments that regulate methylmercury concentrations in freshwater ecosystems.
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Affiliation(s)
- Brian A Branfireun
- Department of Biology and Centre for Environment & Sustainability, The University of Western Ontario, London, Canada.
| | - Claudia Cosio
- Université de Reims Champagne-Ardenne, UMR I-02 SEBIO, Reims, France
| | | | - Gunnhild Riise
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Andrea G Bravo
- Spanish National Research Council | CSIC, Institut de Ciències del Mar, Barcelona, Spain.
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14
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Shanley JB, Marvin-DiPasquale M, Lane O, Arendt W, Hall S, McDowell WH. Resolving a paradox-high mercury deposition, but low bioaccumulation in northeastern Puerto Rico. Ecotoxicology 2020; 29:1207-1220. [PMID: 31643013 DOI: 10.1007/s10646-019-02108-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
At a "clean air" trade winds site in northeastern Puerto Rico, we found an apparent paradox: atmospheric total mercury (THg) deposition was highest of any site in the USA Mercury Deposition Network, but assimilation into the local food web was quite low. Avian blood THg concentrations (n = 31, from eight species in five foraging guilds) ranged widely from 0.2 to 32 ng g-1 (median of 4.3 ng g-1). Within this population, THg was significantly greater at a low-elevation site near a wetland compared to an upland montane site, even when the comparison was limited to a single species. Overall, however, THg concentrations were approximately an order of magnitude lower than comparable populations in the continental U.S. In surface soil and sediment, potential rates of demethylation were 3 to 9-fold greater than those for Hg(II)-methylation (based on six radiotracer amendment incubations), but rates of change of ambient MeHg pools showed a slight net positive Hg(II)-methylation. Thus, the resolution of the paradox is that MeHg degradation approximately keeps pace with MeHg production in this landscape. Further, any net production of MeHg is subject to frequent flushing by high rainfall on chronically wet soils. The interplay of these microbial processes and hydrology appears to shield the local food web from adverse effects of high atmospheric mercury loading. This scenario may play out in other humid tropical ecosystems as well, but it is difficult to evaluate because coordinated studies of Hg deposition, methylation, and trophic uptake have not been conducted at other tropical sites.
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Affiliation(s)
- James B Shanley
- U.S. Geological Survey, P.O. Box 628, Montpelier, VT, 05601, USA.
| | | | - Oksana Lane
- Biodiversity Research Institute, Portland, ME, USA
| | - Wayne Arendt
- USFS, International Institute of Tropical Forestry, Luquillo, PR, USA
| | - Steven Hall
- Department of Ecology and Evolutionary Biology, Iowa State University, Ames, IA, USA
| | - William H McDowell
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA
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15
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Bravo AG, Cosio C. Biotic formation of methylmercury: A bio-physico-chemical conundrum. Limnol Oceanogr 2020; 65:1010-1027. [PMID: 32612306 PMCID: PMC7319479 DOI: 10.1002/lno.11366] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 09/17/2019] [Accepted: 10/02/2019] [Indexed: 05/11/2023]
Abstract
Mercury (Hg) is a natural and widespread trace metal, but is considered a priority pollutant, particularly its organic form methylmercury (MMHg), because of human's exposure to MMHg through fish consumption. Pioneering studies showed the methylation of divalent Hg (HgII) to MMHg to occur under oxygen-limited conditions and to depend on the activity of anaerobic microorganisms. Recent studies identified the hgcAB gene cluster in microorganisms with the capacity to methylate HgII and unveiled a much wider range of species and environmental conditions producing MMHg than previously expected. Here, we review the recent knowledge and approaches used to understand HgII-methylation, microbial biodiversity and activity involved in these processes, and we highlight the current limits for predicting MMHg concentrations in the environment. The available data unveil the fact that HgII methylation is a bio-physico-chemical conundrum in which the efficiency of biological HgII methylation appears to depend chiefly on HgII and nutrients availability, the abundance of electron acceptors such as sulfate or iron, the abundance and composition of organic matter as well as the activity and structure of the microbial community. An increased knowledge of the relationship between microbial community composition, physico-chemical conditions, MMHg production, and demethylation is necessary to predict variability in MMHg concentrations across environments.
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Affiliation(s)
- Andrea G. Bravo
- Department of Marine Biology and Oceanography, Institute of Marine SciencesSpanish National Research Council (CSIC)BarcelonaSpain
| | - Claudia Cosio
- Université de Reims Champagne Ardennes, UMR‐I 02 INERIS‐URCA‐ULH SEBIO, Unité Stress Environnementaux et BIOsurveillance des milieux aquatiquesReimsFrance
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16
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Tang WL, Liu YR, Guan WY, Zhong H, Qu XM, Zhang T. Understanding mercury methylation in the changing environment: Recent advances in assessing microbial methylators and mercury bioavailability. Sci Total Environ 2020; 714:136827. [PMID: 32018974 DOI: 10.1016/j.scitotenv.2020.136827] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/17/2020] [Accepted: 01/18/2020] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) is a neurotoxin, mainly derived from microbial mercury methylation in natural aquatic environments, and poses threats to human health. Polar regions and paddy soils are potential hotspots of mercury methylation and represent environmental settings that are susceptible to natural and anthropogenic perturbations. The effects of changing environmental conditions on the methylating microorganisms and mercury speciation due to global climate change and farming practices aimed for sustainable agriculture were discussed for polar regions and paddy soils, respectively. To better understand and predict microbial mercury methylation in the changing environment, we synthesized current understanding of how to effectively identify active mercury methylators and assess the bioavailability of different mercury species for methylation. The application of biomarkers based on the hgcAB genes have demonstrated the occurrence of potential mercury methylators, such as sulfate-reducing bacteria, iron-reducing bacteria, methanogen and syntrophs, in a diverse variety of microbial habitats. Advanced techniques, such as enriched stable isotope tracers, whole-cell biosensor and diffusive gradient thin film (DGT) have shown great promises in quantitatively assessing mercury availability to microbial methylators. Improved understanding of the complex structure of microbial communities consisting mercury methylators and non-methylators, chemical speciation of inorganic mercury under geochemically relevant conditions, and the pathway of cellular mercury uptake will undoubtedly facilitate accurate assessment and prediction of in situ microbial mercury methylation.
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Affiliation(s)
- Wen-Li Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Yu-Rong Liu
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Wen-Yu Guan
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario K9L 0G2, Canada
| | - Xiao-Min Qu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China.
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17
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Haris H, Aris AZ, Mokhtar MB, Looi LJ. The accumulation of metals and methylmercury in Nerita lineata and the relation to intertidal surface sediment concentrations. Chemosphere 2020; 245:125590. [PMID: 31874324 DOI: 10.1016/j.chemosphere.2019.125590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 12/02/2019] [Accepted: 12/08/2019] [Indexed: 06/10/2023]
Abstract
This study was conducted to assess the reliability of Nerita lineata as a bioindicator for metals in sediment and the factors influencing the accumulation of metals and methylmercury in its soft tissue. The two matrices were analyzed for Co, Cr, Cu, THg, MeHg, Mn, Ni, Pb, and Zn. The metal concentrations in N. lineata were comparable to previously reported results with the exception of Ni which was higher. Cu, Mn, and Pb in N. lineata were significantly (p < 0.05) positively correlated with the respective elements in the sediment, while the biota-sediment accumulation factor showed that Cu, THg, MeHg, and Ni were bioconcentrated in N. lineata. This suggests that N. lineata has the potential to be a bioindicator for Cu, THg, MeHg, Mn, Ni, and Pb. The results also suggest an indirect relationship between THg in the sediment and the MeHg concentration in N. lineata in which periphyton might play a role. The affinity of Cr, Cu, Pb, and Zn with Mn (oxides) in sediment was also found to be a factor influencing their accumulation in N. lineata.
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Affiliation(s)
- Hazzeman Haris
- School of Biological Sciences, Universiti Sains Malaysia, 11800, USM, Penang, Malaysia; Faculty of Environmental Studies, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia.
| | - Ahmad Zaharin Aris
- Faculty of Environmental Studies, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia.
| | - Mazlin Bin Mokhtar
- Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, 43600, UKM Bangi, Selangor, Malaysia.
| | - Ley Juen Looi
- Department of Environmental Sciences, Faculty of Environmental Studies, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia.
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18
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Gao Z, Cai L, Liu M, Zhang Z, Gao B, Zhao W, Cizdziel JV, Chen L. Total mercury and methylmercury migration and transformation in an A 2/O wastewater treatment plant. Sci Total Environ 2020; 710:136384. [PMID: 31927291 DOI: 10.1016/j.scitotenv.2019.136384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/05/2019] [Accepted: 12/26/2019] [Indexed: 06/10/2023]
Abstract
Municipal wastewater treatment plants (MWTPs) serve an essential role in reducing mercury (Hg) pollution. However, few studies quantified the transport and transformation of Hg through MWTPs, particularly plants based on the anaerobic-anoxic-aerobic (A2/O) process. Here, we present a mass balance for total mercury (THg) and total methylmercury (TMeHg) at the plant, and investigate the influence of pH, temperature, and dissolved oxygen on the occurrence and fate of methylmercury (MeHg) in the system. The concentrations of the THg and TMeHg in the raw sewage were 40.3 ± 26.6 ng/L (4.3 ± 2.7 g/day) and 1.9 ± 0.6 ng/L (193 ± 58 mg/day), respectively. Their concentrations in the plant's effluent water were 7.4 ± 1.5 ng/L (0.74 ± 0.2 g/day) and 0.04 ± 0.01 ng/L (3.9 ± 1.0 mg/day), corresponding to decreases of ~82% for THg and ~98% for TMeHg. Within the plant, only ~10% of the THg was removed with primary sedimentation, as Hg in the raw sewage was predominately in dissolved form. In contrast, a significant portion of TMeHg (~43%) was associated with incoming particulate matter. Much of the remaining Hg was removed in subsequent A2/O process and secondary clarifiers, with a ~78% of the THg entering the plant transferring to the dewatered sludge (concentration 1.05 ± 0.28 μg/g; 3.2 ± 0.8 g/day). These same steps decreased TMeHg in the water by ~95%, with <10% of that reduction being TMeHg transferred to the sludge (concentration 2.1 ± 1.1 ng/g; 6.2 ± 3.3 mg/day), suggesting >90% TMeHg degradation. In addition, the most important factor that impacted the variation of TMeHg concentrations was pH, then was temperature. Dissolved oxygen showed no relationship with TMeHg and DMeHg. Overall, this study demonstrates that A2/O MWTPs effectively remove MeHg from wastewater, however, sludge remains an important potential source of Hg to the environment.
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Affiliation(s)
- Zhiqiang Gao
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China; Department of Chemistry and Biochemistry, University of Mississippi, MS 38677, United States
| | - Limei Cai
- College of Resources and Environment, Yangtze University, Wuhan 430100, China
| | - Ming Liu
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China
| | - Zuo Zhang
- Qingyuan Environmental Monitoring station, Qingyuan 511515, China
| | - Bo Gao
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China
| | - Wei Zhao
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China
| | - James V Cizdziel
- Department of Chemistry and Biochemistry, University of Mississippi, MS 38677, United States
| | - Laiguo Chen
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China.
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19
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Liu C, Chen L, Liang S, Li Y. Distribution of total mercury and methylmercury and their controlling factors in the East China Sea. Environ Pollut 2020; 258:113667. [PMID: 31810718 DOI: 10.1016/j.envpol.2019.113667] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 11/13/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) is among contaminants of public concern due to its prevalent existence, high toxicity, and bioaccumulation through food chains. Elevated Hg has been detected in seafood from the East China Sea (ECS), which is one of the largest marginal seas and an important fishing region in the northwestern Pacific Ocean. However, there is still a lack of knowledge on the distribution of Hg species and their controlling factors in the ECS water column, thus preventing the understanding of Hg cycling and the assessment of Hg risks in the ECS. In this study, two cruises were conducted in October 2014 and June 2015 in order to investigate the distribution of total Hg (THg) and methylmercury (MeHg) and their controlling factors in the ECS. The concentrations of THg and MeHg were determined to be 4.2 ± 2.8 ng/L (THg) and 0.25 ± 0.13 ng/L (MeHg) in water from the ECS. The level of Hg in the ECS occupied the higher rank among the marginal seas, thus indicating significant Hg contamination in this system. Both the THg and MeHg presented complicated spatial distribution patterns in the ECS, with high concentration areas located in both the nearshore and offshore areas. Statistical analyses suggest that temperature (T) and Hg in sediment may be the controlling factors for THg distribution, while dissolved organic matter (DOM), T, and MeHg in the sediment may be the controlling factors for MeHg distribution in the seawater of the ECS. The relative importance of these environmental factors in Hg distribution depends on the water depth. T-salinity (S) diagram analyses showed that water mass mixing may also play an important role in controlling THg and MeHg distribution in the coastal ECS.
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Affiliation(s)
- Chang Liu
- Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao, 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
| | - Lufeng Chen
- Institute of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Shengkang Liang
- Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao, 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
| | - Yanbin Li
- Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao, 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China.
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20
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Gentès S, Monperrus M, Legeay A, Gassie C, Maury-brachet R, André J, Guyoneaud R. Influence of Macrophyte and Gut Microbiota on Mercury Contamination in Fish: A Microcosms Study. Applied Sciences 2020; 10:1500. [DOI: 10.3390/app10041500] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The freshwater lakes of southwestern France are subject to the development of invasive macrophytes which are associated with mercury (Hg) contamination of the food web. The aim of this study was to determine the bioavailability of methylmercury (MeHg) produced by plant roots in aquatic ecosystems. A microcosm experiment was performed using isotopically enriched inorganic Hg at environmental concentrations (1 µg 199IHg·L−1). For all conditions, total Hg in fish as well as Hg species associated with different compartments (water, sediments, plant roots, fish) were analyzed by gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). In addition, sediment, plants, and fish gut microbiota were studied by MiSEQ sequencing. Some strains were isolated and tested for their ability to methylate Hg. The results revealed 199MeHg production in plant roots and the presence of this form in fish (tissues and gut), highlighting a MeHg trophic transfer. Moreover, methylator bacteria were identified from the gut contents of the fish when they were in the presence of plants. Some of them were related to bacteria found in the plant roots. On the basis of these results, the transfer of MeHg and bacteria from plants to fish is highlighted; in addition, Hg methylation is strongly suspected in the fish gut, potentially increasing the Hg bioaccumulation.
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Sharma Ghimire P, Tripathee L, Zhang Q, Guo J, Ram K, Huang J, Sharma CM, Kang S. Microbial mercury methylation in the cryosphere: Progress and prospects. Sci Total Environ 2019; 697:134150. [PMID: 32380618 DOI: 10.1016/j.scitotenv.2019.134150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/20/2019] [Accepted: 08/26/2019] [Indexed: 06/11/2023]
Abstract
Mercury (Hg) is one of the most toxic heavy metals, and its cycle is mainly controlled by oxidation-reduction reactions carried out by photochemical or microbial process under suitable conditions. The deposition and accumulation of methylmercury (MeHg) in various ecosystems, including the cryospheric components such as snow, meltwater, glaciers, and ice sheet, and subsequently in the food chain pose serious health concerns for living beings. Unlike the abundance of knowledge about the processes of MeHg production over land and oceans, little is known about the sources and production/degradation rate of MeHg in cryosphere systems. In addition, processes controlling the concentration of Hg and MeHg in the cryosphere remains poorly understood, and filling this scientific gap has been challenging. Therefore, it is essential to study and review the deposition and accumulation by biological, physical, and chemical mechanisms involved in Hg methylation in the cryosphere. This review attempts to address knowledge gaps in understanding processes, especially biotic and abiotic, applicable for Hg methylation in the cryosphere. First, we focus on the variability in Hg concentration and mechanisms of Hg methylation, including physical, chemical, microbial, and biological processes, and transportation in the cryosphere. Then, we elaborate on the mechanism of redox reactions and biotic and abiotic factors controlling Hg methylation and biogeochemistry of Hg in the cryosphere. We also present possible mechanisms of Hg methylation with an emphasis on microbial transformation and molecular function to understand variability in Hg concentration in the cryosphere. Recent advancements in the genetic and physicochemical mechanisms of Hg methylation are also presented. Finally, we summarize and propose a method to study the unsolved issues of Hg methylation in the cryosphere.
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Affiliation(s)
- Prakriti Sharma Ghimire
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; Himalayan Environment Research Institute (HERI), Kathmandu, Nepal
| | - Lekhendra Tripathee
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; Himalayan Environment Research Institute (HERI), Kathmandu, Nepal.
| | - Qianggong Zhang
- Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China
| | - Junming Guo
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China
| | - Kirpa Ram
- Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India
| | - Jie Huang
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China; Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Chhatra Mani Sharma
- Himalayan Environment Research Institute (HERI), Kathmandu, Nepal; Central Department of Environmental Science, Tribhuvan University, Kathmandu, Nepal
| | - Shichang Kang
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China.
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Schwartz GE, Olsen TA, Muller KA, Brooks SC. Ecosystem Controls on Methylmercury Production by Periphyton Biofilms in a Contaminated Stream: Implications for Predictive Modeling. Environ Toxicol Chem 2019; 38:2426-2435. [PMID: 31365146 DOI: 10.1002/etc.4551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/12/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
Periphyton biofilms produce a substantial fraction of the overall monomethylmercury (MMHg) flux in East Fork Poplar Creek, an industrially contaminated, freshwater creek in Oak Ridge, Tennessee. We examined periphyton MMHg production across seasons, locations, and light conditions using mercury stable isotopes. Methylation and demethylation rate potentials (km, trans av and kd, trans av , respectively) were calculated using a transient availability kinetic model. Light exposure and season were significant predictors of km, trans av , with greater values in full light exposure and in the summer. Season, light exposure, and location were significant predictors of kd, trans av , which was highest in dark conditions, in the spring, and at the upstream location. Light exposure was the controlling factor for net MMHg production, with positive production for periphyton grown under full light exposure and net demethylation for periphyton grown in the dark. Ambient MMHg and km, trans av were significantly correlated. Transient availability rate potentials were 15 times higher for km and 9 times higher for kd compared to full availability rate potentials (km, full av and kd, full av ) calculated at 1 d. No significant model for the prediction of km, full av or kd, full av could be constructed using light, season, and location. In addition, there were no significant differences among treatments for the full availability km, full av , kd, full av , or net MMHg calculated using the full availability rate potentials. km, full av was not correlated with ambient MMHg concentrations. The present results underscore the importance of applying transient availability kinetics to MMHg production data when estimating MMHg production potential and flux. Environ Toxicol Chem 2019;38:2426-2435. © 2019 SETAC.
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Affiliation(s)
- Grace E Schwartz
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Todd A Olsen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Katherine A Muller
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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Ávila MP, Oliveira-Junior ES, Reis MP, Hester ER, Diamantino C, Veraart AJ, Lamers LPM, Kosten S, Nascimento AMA. The Water Hyacinth Microbiome: Link Between Carbon Turnover and Nutrient Cycling. Microb Ecol 2019; 78:575-588. [PMID: 30706113 DOI: 10.1007/s00248-019-01331-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
Water hyacinth (WH), a large floating plant, plays an important role in the biogeochemistry and ecology of many freshwaters globally. Its biogeochemical impact on wetland functioning is strongly mediated by the microbiome associated with its roots. However, little is known about the structure and function of this WH rhizobiome and its relation to wetland ecosystem functioning. Here, we unveil the core and transient rhizobiomes of WH and their key biogeochemical functions in two of the world's largest wetlands: the Amazon and the Pantanal. WH hosts a highly diverse microbial community shaped by spatiotemporal changes. Proteobacteria lineages were most common, followed by Actinobacteria and Planctomycetes. Deltaproteobacteria and Sphingobacteriia predominated in the core microbiome, potentially associated with polysaccharide degradation and fermentation of plant-derived carbon. Conversely, a plethora of lineages were transient, including highly abundant Acinetobacter, Acidobacteria subgroup 6, and methanotrophs, thus assuring diverse taxonomic signatures in the two different wetlands. Our findings point out that methanogenesis is a key driver of, and proxy for, community structure, especially during seasonal plant decline. We provide ecologically relevant insights into the WH microbiome, which is a key element linking plant-associated carbon turnover with other biogeochemical fluxes in tropical wetlands.
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Affiliation(s)
- Marcelo P Ávila
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, MG, 31270-901, Brazil
| | - Ernandes S Oliveira-Junior
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Mariana P Reis
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, MG, 31270-901, Brazil
| | - Eric R Hester
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Cristiane Diamantino
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, MG, 31270-901, Brazil
| | - Annelies J Veraart
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Leon P M Lamers
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Sarian Kosten
- Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Andréa M A Nascimento
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, MG, 31270-901, Brazil.
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Lázaro WL, Díez S, Bravo AG, da Silva CJ, Ignácio ÁRA, Guimaraes JRD. Cyanobacteria as regulators of methylmercury production in periphyton. Sci Total Environ 2019; 668:723-729. [PMID: 30861408 DOI: 10.1016/j.scitotenv.2019.02.233] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/18/2019] [Accepted: 02/15/2019] [Indexed: 06/09/2023]
Abstract
Biotic mercury (Hg) methylation appears to depend on factors such as microbial activity and the concentration and bioavailability of Hg2+ to the Hg-methylating organisms. Recently, the presence of cyanobacteria has been linked with high methylmercury (MeHg) concentrations. The aim of this work was to test MeHg production in microcosms, in relation to the amount of periphytic cyanobacteria, dissolved organic matter (DOM) and phosphorus concentrations, as well as periphytic primary production rates. Water and periphyton samples were collected for cultivation and isolation of cyanobacteria from the Guaporé River floodplain, Brazil. We cultivated the periphyton in microcosms with different concentrations of cyanobacteria, total phosphorus and DOM. The highest net MeHg production (6.8 to 24.6% of added Hg d-1) occurred in the microcosm with added cyanobacteria, followed by microcosms with added phosphorus (6.1 to 11.4%) and added DOM (6.4 to 9.1%). Positive correlations were found between MeHg production, addition of cyanobacteria, phosphorus and DOM and periphytic primary productivity. Our results bring the first direct experimental evidence of the relevance of cyanobacteria and primary production as regulators of MeHg production in periphyton. These findings have numerous implications for the management of natural and engineered wetlands.
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Affiliation(s)
- Wilkinson L Lázaro
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil. Avenida Santos Dummont, Cidade Universitária, 78200-000 Cáceres, MT, Brazil.
| | - Sergi Díez
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research (IDAEA-CSIC). C/Jordi Girona, 18-26, 08034 Barcelona, Spain.
| | - Andrea G Bravo
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research (IDAEA-CSIC). C/Jordi Girona, 18-26, 08034 Barcelona, Spain.
| | - Carolina J da Silva
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil. Avenida Santos Dummont, Cidade Universitária, 78200-000 Cáceres, MT, Brazil; Rede Bionorte, Doutorado em Biodiversidade e Biotecnologia da Amazônia Legal. Avenida Fernando Correa da Costa, 2.367, Boa Esperança, 78060-900, Cuiabá, Brazil.
| | - Áurea R A Ignácio
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil. Avenida Santos Dummont, Cidade Universitária, 78200-000 Cáceres, MT, Brazil.
| | - Jean R D Guimaraes
- Laboratório de Traçadores, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ). Av. Carlos Chagas Filho 373 Bloco G, CCS, Cidade Universitária, 21941-902, Rio de Janeiro, RJ, Brazil.
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Hakim JA, Schram JB, Galloway AWE, Morrow CD, Crowley MR, Watts SA, Bej AK. The Purple Sea Urchin Strongylocentrotus purpuratus Demonstrates a Compartmentalization of Gut Bacterial Microbiota, Predictive Functional Attributes, and Taxonomic Co-Occurrence. Microorganisms 2019; 7:E35. [PMID: 30691133 PMCID: PMC6406795 DOI: 10.3390/microorganisms7020035] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/13/2019] [Accepted: 01/21/2019] [Indexed: 12/13/2022] Open
Abstract
The sea urchin Strongylocentrotus purpuratus (order Camarodonta, family Strongylocentrotidae) can be found dominating low intertidal pool biomass on the southern coast of Oregon, USA. In this case study, three adult sea urchins were collected from their shared intertidal pool, and the bacteriome of their pharynx, gut tissue, and gut digesta, including their tide pool water and algae, was determined using targeted high-throughput sequencing (HTS) of the 16S rRNA genes and bioinformatics tools. Overall, the gut tissue demonstrated Arcobacter and Sulfurimonas (Epsilonproteobacteria) to be abundant, whereas the gut digesta was dominated by Psychromonas (Gammaproteobacteria), Propionigenium (Fusobacteria), and Flavobacteriales (Bacteroidetes). Alpha and beta diversity analyses indicated low species richness and distinct microbial communities comprising the gut tissue and digesta, while the pharynx tissue had higher richness, more closely resembling the water microbiota. Predicted functional profiles showed Kyoto Encyclopedia of Genes and Genomes (KEGG) Level-2 categories of energy metabolism, membrane transport, cell motility, and signal transduction in the gut tissue, and the gut digesta represented amino acid, carbohydrate, vitamin and cofactor metabolisms, and replication and repair. Co-occurrence network analysis showed the potential relationships and key taxa, such as the highly abundant Arcobacter and Propionigenium, influencing population patterns and taxonomic organization between the gut tissue and digesta. These results demonstrate a trend of microbial community integration, allocation, predicted metabolic roles, and taxonomic co-occurrence patterns in the S. purpuratus gut ecosystem.
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Affiliation(s)
- Joseph A Hakim
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294, USA.
| | - Julie B Schram
- Oregon Institute of Marine Biology, University of Oregon, 63466 Boat Basin Rd, Charleston, OR 97420, USA.
| | - Aaron W E Galloway
- Oregon Institute of Marine Biology, University of Oregon, 63466 Boat Basin Rd, Charleston, OR 97420, USA.
| | - Casey D Morrow
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Blvd., Birmingham, AL 35294, USA.
| | - Michael R Crowley
- Department of Genetics, Heflin Center Genomics Core, School of Medicine, University of Alabama at Birmingham, 705 South 20th Street, Birmingham, AL 35294, USA.
| | - Stephen A Watts
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294, USA.
| | - Asim K Bej
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294, USA.
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Bravo AG, Peura S, Buck M, Ahmed O, Mateos-Rivera A, Herrero Ortega S, Schaefer JK, Bouchet S, Tolu J, Björn E, Bertilsson S. Methanogens and Iron-Reducing Bacteria: the Overlooked Members of Mercury-Methylating Microbial Communities in Boreal Lakes. Appl Environ Microbiol 2018; 84:e01774-18. [PMID: 30242005 DOI: 10.1128/AEM.01774-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 09/15/2018] [Indexed: 12/28/2022] Open
Abstract
Despite the global awareness that mercury, and methylmercury in particular, is a neurotoxin to which millions of people continue to be exposed, there are sizable gaps in the understanding of the processes and organisms involved in methylmercury formation in aquatic ecosystems. In the present study, we shed light on the diversity of the microorganisms responsible for methylmercury formation in boreal lake sediments. All the microorganisms identified are associated with the processing of organic matter in aquatic systems. Moreover, our results show that the well-known mercury-methylating sulfate-reducing bacteria constituted only a minor portion of the potential mercury methylators. In contrast, methanogens and iron-reducing bacteria were important contributors to methylmercury formation, highlighting their role in mercury cycling in the environment. Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38% and 45% of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes. IMPORTANCE Despite the global awareness that mercury, and methylmercury in particular, is a neurotoxin to which millions of people continue to be exposed, there are sizable gaps in the understanding of the processes and organisms involved in methylmercury formation in aquatic ecosystems. In the present study, we shed light on the diversity of the microorganisms responsible for methylmercury formation in boreal lake sediments. All the microorganisms identified are associated with the processing of organic matter in aquatic systems. Moreover, our results show that the well-known mercury-methylating sulfate-reducing bacteria constituted only a minor portion of the potential mercury methylators. In contrast, methanogens and iron-reducing bacteria were important contributors to methylmercury formation, highlighting their role in mercury cycling in the environment.
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Lázaro WL, Díez S, da Silva CJ, Ignácio ÁRA, Guimarães JRD. Seasonal changes in peryphytic microbial metabolism determining mercury methylation in a tropical wetland. Sci Total Environ 2018; 627:1345-1352. [PMID: 30857098 DOI: 10.1016/j.scitotenv.2018.01.186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/08/2018] [Accepted: 01/18/2018] [Indexed: 06/09/2023]
Abstract
Mercury (Hg) methylation, a key process in the biogeochemical cycle of Hg, is mainly attributed to sulfate-reducing bacteria and methanogenic Archaea. However, environmental regulation by these groups has not yet been ascertained in tropical environments, especially in respect to the seasonal flood flooding. This work evaluated the variation of net methylmercury production potential in relation to biological characteristics of the periphyton, environmental factors, and flood pulse seasons. Our results indicate that there is a seasonal change between metabolic groups as main Hg methylators, sulfate-reducing bacteria in the dry season and methanogenic Archaea in the flood season. In addition, there was a positive relationship between dissolved organic carbon (DOC), phosphorus, cyanobacteria biovolume, and periphytic Hg methylation potential. These results shed a new light on MeHg production plasticity, mediated by landscape and flood pulses in tropical wetlands, as well as on ecological relationships within the periphyton.
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Affiliation(s)
- Wilkinson L Lázaro
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brazil.
| | - Sergi Díez
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain.
| | - Carolina J da Silva
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brazil; Rede Bionorte, Doutorado em Biodiversidade e Biotecnologia da Amazônia Legal, Brazil
| | - Áurea R A Ignácio
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brazil
| | - Jean R D Guimarães
- Laboratório de Traçadores. Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Brazil
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Maia PD, Maurice L, Tessier E, Amouroux D, Cossa D, Moreira-Turcq P, Etcheber H. Role of the floodplain lakes in the methylmercury distribution and exchanges with the Amazon River, Brazil. J Environ Sci (China) 2018; 68:24-40. [PMID: 29908742 DOI: 10.1016/j.jes.2018.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 12/19/2017] [Accepted: 02/07/2018] [Indexed: 06/08/2023]
Abstract
Seasonal variability of dissolved and particulate methylmercury (F-MeHg, P-MeHg) concentrations was studied in the waters of the Amazon River and its associated Curuai floodplain during hydrological year 2005-2006, to understand the MeHg exchanges between these aquatic systems. In the oxic white water lakes, with neutral pH, high F-MeHg and P-MeHg concentrations were measured during the rising water stage (0.70±0.37pmol/L, n=26) and flood peak (14.19±9.32pmol/g, n=7) respectively, when the Amazon River water discharge into the lakes was at its maximum. The lowest mean values were reported during the dry season (0.18±0.07pmol/L F-MeHg, n=10 and 1.35±1.24pmol/g P-MeHg, n=8), when water and suspended sediments were outflowing from the lakes into the River. In these lakes, the MeHg concentrations were associated to the aluminium and organic carbon/nitrogen changes. In the black water lakes, with acidic pH and reducing conditions, elevated MeHg concentrations were recorded (0.58±0.32pmol/L F-MeHg, n=16 and 19.82±15.13pmol/g P-MeHg, n=6), and correlated with the organic carbon and manganese concentrations. Elevated values of MeHg partition coefficient (4.87<Kd<5.08log (L/kg) indicate that MeHg is mainly transported associated with the particulate phase. The P-MeHg enrichment detected in all lakes suggests autochthonous MeHg inputs from the sediments into the water column. The MeHg mass balance showed that the Curuai floodplain is not the source of P-MeHg for the Amazon River.
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Affiliation(s)
- Poliana Dutra Maia
- Universidade de Brasília-Faculdade UnB Planaltina, Area Universitaria n. 1-Vila Nossa Senhora de Fátima Planaltina, 73300-000 Brasília, DF, Brazil.
| | - Laurence Maurice
- Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue Edouard Belin, F-31400 Toulouse, France
| | - Emmanuel Tessier
- CNRS/Univ Pau & Pays Adour, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR5254, F-64000 Pau, France
| | - David Amouroux
- CNRS/Univ Pau & Pays Adour, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR5254, F-64000 Pau, France
| | - Daniel Cossa
- Université Grenoble Alpes, CP 40700, F-38058 Grenoble Cedex 9, France
| | - Patricia Moreira-Turcq
- Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue Edouard Belin, F-31400 Toulouse, France
| | - Henri Etcheber
- EPOC UMR 5805, Université de Bordeaux I, Av. des Facultés, F-33405 Talence, France
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Hsu-Kim H, Eckley CS, Achá D, Feng X, Gilmour CC, Jonsson S, Mitchell CPJ. Challenges and opportunities for managing aquatic mercury pollution in altered landscapes. Ambio 2018; 47:141-169. [PMID: 29388127 PMCID: PMC5794684 DOI: 10.1007/s13280-017-1006-7] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The environmental cycling of mercury (Hg) can be affected by natural and anthropogenic perturbations. Of particular concern is how these disruptions increase mobilization of Hg from sites and alter the formation of monomethylmercury (MeHg), a bioaccumulative form of Hg for humans and wildlife. The scientific community has made significant advances in recent years in understanding the processes contributing to the risk of MeHg in the environment. The objective of this paper is to synthesize the scientific understanding of how Hg cycling in the aquatic environment is influenced by landscape perturbations at the local scale, perturbations that include watershed loadings, deforestation, reservoir and wetland creation, rice production, urbanization, mining and industrial point source pollution, and remediation. We focus on the major challenges associated with each type of alteration, as well as management opportunities that could lessen both MeHg levels in biota and exposure to humans. For example, our understanding of approximate response times to changes in Hg inputs from various sources or landscape alterations could lead to policies that prioritize the avoidance of certain activities in the most vulnerable systems and sequestration of Hg in deep soil and sediment pools. The remediation of Hg pollution from historical mining and other industries is shifting towards in situ technologies that could be less disruptive and less costly than conventional approaches. Contemporary artisanal gold mining has well-documented impacts with respect to Hg; however, significant social and political challenges remain in implementing effective policies to minimize Hg use. Much remains to be learned as we strive towards the meaningful application of our understanding for stakeholders, including communities living near Hg-polluted sites, environmental policy makers, and scientists and engineers tasked with developing watershed management solutions. Site-specific assessments of MeHg exposure risk will require new methods to predict the impacts of anthropogenic perturbations and an understanding of the complexity of Hg cycling at the local scale.
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Affiliation(s)
- Heileen Hsu-Kim
- Department of Civil & Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, NC 27708 USA
| | - Chris S. Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101 USA
| | - Dario Achá
- Unidad de Calidad Ambiental, Instituto de Ecología, Carrera de Biología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China
| | - Cynthia C. Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037-0028 USA
| | - Sofi Jonsson
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Svante Arrhenius väg 8, 11418 Stockholm, Sweden
| | - Carl P. J. Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
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da Penha Rhodes V, de Lena JC, Santolin CVA, da Silva Pinto T, Mendes LA, Windmöller CC. Speciation and quantification of Hg in sediments contaminated by artisanal gold mining in the Gualaxo do Norte River, Minas Gerais, SE, Brazil. Environ Monit Assess 2017; 190:49. [PMID: 29285676 DOI: 10.1007/s10661-017-6394-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 12/05/2017] [Indexed: 06/07/2023]
Abstract
The Iron Quadrangle in SE Brazil was, in the eighteenth century, one of the most important Au producing regions of Brazil. In this region, gold is produced, even today, by artisanal methods that use Hg to increase the extraction efficiency with no control of Hg release to water systems and the atmosphere. In this context, the Gualaxo do Norte River is of particular interest; its springs are located in the Doce River basin, an important Brazilian basin that supplies water for 3.5 million people. The main goal of this work was to quantify and speciate the Hg in the sediments of the Gualaxo do Norte River using a direct mercury analyzer and gas chromatography-pyrolysis-atomic fluorescence detection system. Statistical analyses consisted of principal component analysis, aiming to assess interactions among elements and species and to group the variables in factors affecting the properties of sediment. The results show that total Hg (THg) and methylmercury (CH3Hg+) concentrations in samples ranged from 209 to 1207 μg kg-1 and from 0.07 to 1.00 μg kg-1, respectively (methylation percentages from 0.01 to 0.27%). Thermal desorption analysis showed that mercury is mainly present in the oxidized form, and correlation analyses pointed to a relationship between THg and MnO, indicating that manganese can oxidize and/or adsorb Hg. Together, MO and CH3Hg+ are important parameters in the third principal component, indicating the influence of OM on the methylation process. This first investigation on Hg methylation in this small-scale gold mining area points to the possibility of Hg bioaccumulation and to the need of better understanding the biogeochemical cycle of Hg in this area. Samples were collected in 2012, prior to the 2015 Fundão Dam disaster. The results are also a record of the characteristics of the sediment prior to that event.
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Affiliation(s)
- Valdilene da Penha Rhodes
- Departamento de Geologia, Escola de Minas, Campus Morro do Cruzeiro, Universidade Federal de Ouro Preto, Ouro Preto, MG, 35400-000, Brazil
| | - Jorge Carvalho de Lena
- Departamento de Geologia, Escola de Minas, Campus Morro do Cruzeiro, Universidade Federal de Ouro Preto, Ouro Preto, MG, 35400-000, Brazil.
| | - Camila Vidal Alves Santolin
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil
| | - Thais da Silva Pinto
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil
| | - Louise Aparecida Mendes
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil
| | - Cláudia Carvalhinho Windmöller
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil
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Dranguet P, Le Faucheur S, Slaveykova VI. Mercury bioavailability, transformations, and effects on freshwater biofilms. Environ Toxicol Chem 2017; 36:3194-3205. [PMID: 28771825 DOI: 10.1002/etc.3934] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 10/10/2016] [Accepted: 08/01/2017] [Indexed: 05/16/2023]
Abstract
Mercury (Hg) compounds represent an important risk to aquatic ecosystems because of their persistence, bioaccumulation, and biomagnification potential. In the present review, we critically examine state-of-the-art studies on the interactions of Hg compounds with freshwater biofilms, with an emphasis on Hg accumulation, transformations, and effects. Freshwater biofilms contain both primary producers (e.g., algae) and decomposers (e.g., bacteria and fungi), which contribute to both aquatic food webs and the microbial loop. Hence they play a central role in shallow water and streams, and also contribute to Hg trophic transfer through their consumption. Both inorganic and methylated mercury compounds accumulate in biofilms, which could transform them mainly by methylation, demethylation, and reduction. Accumulated Hg compounds could induce diverse metabolic and physiological perturbations in the microorganisms embedded in the biofilm matrix and affect their community composition. The bioavailability of Hg compounds, their transformations, and their effects depend on their concentrations and speciation, ambient water characteristics, biofilm matrix composition, and microorganism-specific characteristics. The basic processes governing the interactions of Hg compounds with biofilm constituents are understudied. The development of novel conceptual and methodological approaches allowing an understanding of the chemo- and biodynamic aspects is necessary to improve the knowledge on Hg cycling in shallow water as well as to enable improved use of freshwater biofilms as potential indicators of water quality and to support better informed risk assessment. Environ Toxicol Chem 2017;36:3194-3205. © 2017 SETAC.
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Affiliation(s)
- Perrine Dranguet
- Faculty of Sciences, School of Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, Switzerland
| | - Séverine Le Faucheur
- Faculty of Sciences, School of Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, Switzerland
| | - Vera I Slaveykova
- Faculty of Sciences, School of Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, Switzerland
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Guédron S, Point D, Acha D, Bouchet S, Baya PA, Tessier E, Monperrus M, Molina CI, Groleau A, Chauvaud L, Thebault J, Amice E, Alanoca L, Duwig C, Uzu G, Lazzaro X, Bertrand A, Bertrand S, Barbraud C, Delord K, Gibon FM, Ibanez C, Flores M, Fernandez Saavedra P, Ezpinoza ME, Heredia C, Rocha F, Zepita C, Amouroux D. Mercury contamination level and speciation inventory in Lakes Titicaca & Uru-Uru (Bolivia): Current status and future trends. Environ Pollut 2017; 231:262-270. [PMID: 28806691 DOI: 10.1016/j.envpol.2017.08.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/27/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3-10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota.
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Affiliation(s)
- S Guédron
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, France; Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, Casilla 3161, La Paz, Bolivia.
| | - D Point
- Géosciences Environnement Toulouse, UMR5563 - IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin 31400 Toulouse, France; Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia.
| | - D Acha
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia.
| | - S Bouchet
- CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France
| | - P A Baya
- Géosciences Environnement Toulouse, UMR5563 - IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin 31400 Toulouse, France
| | - E Tessier
- CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France
| | - M Monperrus
- CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France
| | - C I Molina
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - A Groleau
- Institut de Physique du Globe de Paris (IPGP), 1, rue Jussieu, 75238 Paris Cedex 05, France
| | - L Chauvaud
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539, IUEM Technopôle Brest-Iroise, rue Dumont d'Urville, 29280 Plouzané, France
| | - J Thebault
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539, IUEM Technopôle Brest-Iroise, rue Dumont d'Urville, 29280 Plouzané, France
| | - E Amice
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539, IUEM Technopôle Brest-Iroise, rue Dumont d'Urville, 29280 Plouzané, France
| | - L Alanoca
- Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, Casilla 3161, La Paz, Bolivia
| | - C Duwig
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, IGE, 38000 Grenoble, France
| | - G Uzu
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, IGE, 38000 Grenoble, France
| | - X Lazzaro
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia; Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Institut de Recherche pour le Développement (IRD), UMR 7208, Paris, France
| | - A Bertrand
- MARine Biodiversity, Exploitation and Conservation (MARBEC), Institut de Recherche pour le Développement (IRD), Univ. Montpellier, Place Eugène Bataillon, bât 24, CC093 34 095 Montpellier Cedex 5, France
| | - S Bertrand
- MARine Biodiversity, Exploitation and Conservation (MARBEC), Institut de Recherche pour le Développement (IRD), Univ. Montpellier, Place Eugène Bataillon, bât 24, CC093 34 095 Montpellier Cedex 5, France
| | - C Barbraud
- Laboratoire du Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372, CNRS, Université de La Rochelle 405 Route de La Canauderie, 79360 Villiers-en-Bois, France
| | - K Delord
- Laboratoire du Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372, CNRS, Université de La Rochelle 405 Route de La Canauderie, 79360 Villiers-en-Bois, France
| | - F M Gibon
- Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Institut de Recherche pour le Développement (IRD), UMR 7208, Paris, France
| | - C Ibanez
- UPA, Universidad Pública de El Alto, Ecología y Recursos Naturales, El Alto, Bolivia
| | - M Flores
- Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, Casilla 3161, La Paz, Bolivia; Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - P Fernandez Saavedra
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - M E Ezpinoza
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - C Heredia
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - F Rocha
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - C Zepita
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - D Amouroux
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia; CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France.
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Wang P, Yao Y, Wang C, Hou J, Qian J, Miao L. Impact of macrozoobenthic bioturbation and wind fluctuation interactions on net methylmercury in freshwater lakes. Water Res 2017; 124:320-330. [PMID: 28780357 DOI: 10.1016/j.watres.2017.07.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/05/2017] [Accepted: 07/29/2017] [Indexed: 06/07/2023]
Abstract
The methylmercury (MeHg) as the toxic fractions has presented significant threats to biota in freshwater ecosystems. Hg methylation process is demonstrated to be manipulated by biota process (benthic disturbance and algae bloom existence) as well as the abiotic influence (wind fluctuation and illumination intensity) in freshwater ecosystems. However, the mechanisms influencing Hg methylation are still unclear, and the coupled influences of the biotic and abiotic process with the shifts in variation on methylmercury remain unexplored. Accordingly, an annular flume experiment which simulated the freshwater ecosystem, was conducted for 108 days to examine the influences of typical disturbance by chironomid larvae and wind fluctuations on MeHg variation in sediment profiles. The in-situ, passive sampler technique of revealing diffusive gradients in thin films (DGT) encompassed the special resin, based on referenced extraction and coloration-computer imaging densitometry, were employed to obtain labile MeHg, Fe, and S concentrations at high resolution. The results indicate that larval bioturbation during the initial period of the experiment could diminish bioavailable MeHg concentrations and change the diffusion direction of MeHg fluxes. However, this inhibitive effect on MeHg concentrations ceased with larvae eclosion. Compared to bioturbation, wind fluctuation exerted slow but sustained inhibition on MeHg release. Furthermore, the eight parameters (dissolved organic carbon (DOC), DO, labile Fe and S concentrations, pH, sulfate-reducing bacteria (SRB) abundance in sediment, oxidation-reduction potential (ORP) and EC) could explain more of variation in MeHg concentrations which indicated by the canonical correspondence analysis. And these eight parameters manifest higher explanatory power for MeHg distributed in newly formed sediment. More notably, the comparison results of the multiple and simple regression directly demonstrated the DOC was the fundamental and robust factor to control the MeHg variation in the freshwater ecosystem.
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Affiliation(s)
- Peifang Wang
- Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
| | - Yu Yao
- Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
| | - Chao Wang
- Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| | - Jun Hou
- Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| | - Jin Qian
- Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| | - Lingzhan Miao
- Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
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Zhou J, Smith MD, Cooper CJ, Cheng X, Smith JC, Parks JM. Modeling of the Passive Permeation of Mercury and Methylmercury Complexes Through a Bacterial Cytoplasmic Membrane. Environ Sci Technol 2017; 51:10595-10604. [PMID: 28806072 DOI: 10.1021/acs.est.7b02204] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Cellular uptake and export are important steps in the biotransformation of mercury (Hg) by microorganisms. However, the mechanisms of transport across biological membranes remain unclear. Membrane-bound transporters are known to be relevant, but passive permeation may also be involved. Inorganic HgII and methylmercury ([CH3HgII]+) are commonly complexed with thiolate ligands. Here, we have performed extensive molecular dynamics simulations of the passive permeation of HgII and [CH3HgII]+ complexes with thiolate ligands through a model bacterial cytoplasmic membrane. We find that the differences in free energy between the individual complexes in bulk water and at their most favorable position within the membrane are ∼2 kcal mol-1. We provide a detailed description of the molecular interactions that drive the membrane crossing process. Favorable interactions with carbonyl and tail groups of phospholipids stabilize Hg-containing solutes in the tail-head interface region of the membrane. The calculated permeability coefficients for the neutral compounds CH3S-HgII-SCH3 and CH3HgII-SCH3 are on the order of 10-5 cm s-1. We conclude that small, nonionized Hg-containing species can permeate readily through cytoplasmic membranes.
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Affiliation(s)
- Jing Zhou
- Graduate School of Genome Science and Technology, University of Tennessee , Knoxville, Tennessee 37996, United States
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
| | - Micholas Dean Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States
| | - Connor J Cooper
- Graduate School of Genome Science and Technology, University of Tennessee , Knoxville, Tennessee 37996, United States
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
| | - Xiaolin Cheng
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States
| | - Jeremy C Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States
| | - Jerry M Parks
- Graduate School of Genome Science and Technology, University of Tennessee , Knoxville, Tennessee 37996, United States
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
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Zhu S, Zhang Z, Liu X. Enhanced Two Dimensional Hydrodynamic and Water Quality Model (CE-QUAL-W2) for Simulating Mercury Transport and Cycling in Water Bodies. Water 2017; 9:643. [DOI: 10.3390/w9090643] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Gentès S, Taupiac J, Colin Y, André JM, Guyoneaud R. Bacterial periphytic communities related to mercury methylation within aquatic plant roots from a temperate freshwater lake (South-Western France). Environ Sci Pollut Res Int 2017; 24:19223-19233. [PMID: 28664497 DOI: 10.1007/s11356-017-9597-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/20/2017] [Indexed: 06/07/2023]
Abstract
Macrophyte floating roots are considered as hotspots for methylmercury (MeHg) production in aquatic ecosystems through microbial activity. Nevertheless, very little is known about periphyton bacterial communities and mercury (Hg) methylators in such ecological niches. The ability to methylate inorganic Hg is broadly distributed among prokaryotes; however, sulfate-reducers have been reported to be the most important MeHg producers in macrophyte floating roots. In the present work, the periphyton bacterial communities colonizing Ludwigia sp. floating roots were investigated through molecular methods. Among the 244 clones investigated, anaerobic microorganisms associated with the sulfur biogeochemical cycle were identified. Notably, members of the sulfur-oxidizing prokaryotes and the anoxygenic, purple non-sulfur bacteria (Rhodobacteraceae, Comamonadaceae, Rhodocyclaceae, Hyphomicrobiaceae) and the sulfate reducers (Desulfobacteraceae, Syntrophobacteraceae, and Desulfobulbaceae) were detected. In addition, 15 sulfate-reducing strains related to the Desulfovibrionaceae family were isolated and their Hg-methylation capacity was tested using a biosensor. The overall results confirmed that Hg methylation is a strain-specific process since the four strains identified as new Hg-methylators were closely related to non-methylating isolates. This study highlights the potential involvement of periphytic bacteria in Hg methylation when favorable environmental conditions are present in such ecological micro-niches.
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Affiliation(s)
- Sophie Gentès
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France.
- Université de Bordeaux, EPOC, UMR CNRS 5805, 33120, Arcachon, France.
| | - Julie Taupiac
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - Yannick Colin
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - Jean-Marc André
- Equipe CIH, IMS UMR 5218, Ecole Nationale Supérieure de Cognitique, 109 Avenue Roul, 33400, Talence, France
| | - Rémy Guyoneaud
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
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Abstract
With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity, it has become imperative to examine how mercury may enter biotic systems through its methylation to bioavailable forms in aquatic environments. Recent development of stable isotope-based methods in methylation studies has enabled a better understanding of the factors controlling methylation in aquatic systems. In addition, the identification and tracking of the hgcAB gene cluster, which is necessary for methylation, has broadened the range of known methylators and methylation-conducive environments. Study of abiotic factors in methylation with new molecular methods (the use of stable isotopes and genomic methods) has helped elucidate the confounding influences of many environmental factors, as these methods enable the examination of their direct effects instead of merely correlative observations. Such developments will be helpful in the finer characterization of mercury biogeochemical cycles, which will enable better predictions of the potential effects of climate change on mercury methylation in aquatic systems and, by extension, the threat this may pose to biota.
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Affiliation(s)
- Avnee R. Paranjape
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| | - Britt D. Hall
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
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Du H, Ma M, Sun T, Dai X, Yang C, Luo F, Wang D, Igarashi Y. Mercury-methylating genes dsrB and hgcA in soils/sediments of the Three Gorges Reservoir. Environ Sci Pollut Res Int 2017; 24:5001-5011. [PMID: 28000068 DOI: 10.1007/s11356-016-8213-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/06/2016] [Indexed: 05/04/2023]
Abstract
Previous research found that the water-level fluctuating zone (WLFZ) of the Three Gorges Reservoir (TGR) was an Hg-sensitive area. However, little research has been conducted on the distribution of Hg-methylating microorganisms in this area. The goal of this research was to provide an initial description of the distribution of the dsrB (for sulfate-reducing bacteria) and hgcA (one gene confirmed for Hg methylation) genes. Different types of soil were selected to analyze the abundance of the dsrB and hgcA in different periods, in inundated soil (SI, ≤155 m, which becomes sediment during the wet period, SS) and in non-inundated soil (≥175 m, SN) from Shibao, a typical WLFZ of the TGR. A significant positive correlation was observed between dsrB and hgcA abundance and MeHg concentrations, suggesting that microorganisms with these genes contribute to Hg methylation. Principal component analysis (PCA) indicated that dsrB diversity was highest in SI, followed by SS; SS had the highest diversity of hcgA. Six phylogenetic trees were constructed and showed that more strains were present in SI than in SS. HgcA sequences in SS were confined to three evolutionarily distant clades, δ-Proteobacteria, a methanogen group, and a Clostridia group, which was relatively rare among most clades.
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Affiliation(s)
- Hongxia Du
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China
- Research Center of Bioenergy and Bioremediation, Southwest University, Chongqing, 400715, China
| | - Ming Ma
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China
- Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing, 400715, China
| | - Tao Sun
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China
- Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing, 400715, China
| | - Xianzhu Dai
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China
- Research Center of Bioenergy and Bioremediation, Southwest University, Chongqing, 400715, China
| | - Caiyun Yang
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China
- Research Center of Bioenergy and Bioremediation, Southwest University, Chongqing, 400715, China
| | - Feng Luo
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China
- Research Center of Bioenergy and Bioremediation, Southwest University, Chongqing, 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China.
- Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing, 400715, China.
| | - Yasuo Igarashi
- College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing, 400715, People's Republic of China.
- Research Center of Bioenergy and Bioremediation, Southwest University, Chongqing, 400715, China.
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Dranguet P, Le Faucheur S, Cosio C, Slaveykova VI. Influence of chemical speciation and biofilm composition on mercury accumulation by freshwater biofilms. Environ Sci Process Impacts 2017; 19:38-49. [PMID: 27942649 DOI: 10.1039/c6em00493h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Mercury (Hg) is a pollutant of high concern for aquatic systems due to the biomagnification of its methylated form along the food chain. However, in contrast to other metals, gaining knowledge of its bioavailable forms for aquatic microorganisms remains challenging, making Hg risk assessment difficult. Ubiquitous and sessile freshwater biofilms are well known to accumulate and to transform Hg present in their ambient environment. The present study thus aims to evaluate whether non-extractable (proxy of intracellular) Hg accumulated by biofilms could be a good indicator of Hg bioavailability for microorganisms in freshwater. To that end, the link between Hg concentration and speciation, as well as biofilm composition (percentage of abiotic, biotic, chlorophyll and phycocyanin-fractions and abundance of dsrA, gcs, merA and hgcA bacterial genes) and biofilm Hg accumulation was examined. The studied biofilms were grown on artificial substrata in four reservoirs along the Olt River (Romania), which was contaminated by Hg coming from chlor-alkali plant effluents. The 0.45 μm-filterable Hg concentrations in ambient waters were measured and inorganic IHg speciation was modelled. Biofilms were analyzed for their non-extractable IHg and methylmercury (MeHg) contents as well as for their composition. The non-extractable IHg content was related, but not significantly, to the concentration of total IHg (r2 = 0.88, p = 0.061) whereas a significant correlation was found with the predicted IHg concentration that is not bound to dissolved organic matter (r2 = 0.95, p = 0.027), despite its extremely low concentrations (10-25 M), showing a limitation of the thermodynamic Hg modelling to predict Hg bioavailability. The studied biofilms were different in biomass and composition and a principal component analysis showed that the non-extractable IHg content correlated with the abundance of the merA and hgcA genes, while MeHg accumulation was only linked with the abundance of the rRNA 16S gene. The present study suggests that non-extractable IHg concentrations in biofilms are a useful proxy of IHg bioavailable forms in waters whereas the hgcA and merA genes are good biomarkers of both biofilm IHg exposure and bioavailability.
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Affiliation(s)
- P Dranguet
- University of Geneva, Faculty of Science, Earth and Environmental Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Uni Carl Vogt, 66 Bvd. Carl Vogt, CH-1211 Geneva, Switzerland.
| | - S Le Faucheur
- University of Geneva, Faculty of Science, Earth and Environmental Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Uni Carl Vogt, 66 Bvd. Carl Vogt, CH-1211 Geneva, Switzerland.
| | - C Cosio
- University of Geneva, Faculty of Science, Earth and Environmental Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Uni Carl Vogt, 66 Bvd. Carl Vogt, CH-1211 Geneva, Switzerland.
| | - V I Slaveykova
- University of Geneva, Faculty of Science, Earth and Environmental Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Uni Carl Vogt, 66 Bvd. Carl Vogt, CH-1211 Geneva, Switzerland.
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Lanza WG, Achá D, Point D, Masbou J, Alanoca L, Amouroux D, Lazzaro X. Association of a Specific Algal Group with Methylmercury Accumulation in Periphyton of a Tropical High-Altitude Andean Lake. Arch Environ Contam Toxicol 2017; 72:1-10. [PMID: 27822581 DOI: 10.1007/s00244-016-0324-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 10/21/2016] [Indexed: 06/06/2023]
Abstract
Periphyton relevance for methylmercury (MeHg) production and accumulation are now well known in aquatic ecosystems. Sulfate-reducing bacteria and other microbial groups were identified as the main MeHg producers, but the effect of periphyton algae on the accumulation and transfer of MeHg to the food web remains little studied. Here we investigated the role of specific groups of algae on MeHg accumulation in the periphyton of Schoenoplectus californicus ssp. (Totora) and Myriophyllum sp. in Uru Uru, a tropical high-altitude Bolivian lake with substantial fishing and mining activities accruing around it. MeHg concentrations were most strongly related to the cell abundance of the Chlorophyte genus Oedogonium (r 2 = 0.783, p = 0.0126) and to no other specific genus despite the presence of other 34 genera identified. MeHg was also related to total chlorophyll-a (total algae) (r 2 = 0.675, p = 0.0459), but relations were more significant with chlorophyte cell numbers, chlorophyll-b (chlorophytes), and chlorophyll-c (diatoms and dinoflagellates) (r 2 = 0.72, p = 0.028, r 2 = 0.744, p = 0.0214, and r 2 = 0.766, p = 0.0161 respectively). However, Oedogonium explains most variability of chlorophytes and chlorophyll-c (r 2 = 0.856, p = < 0.001 and r 2 = 0.619, p = 0.002, respectively), suggesting it is the most influential group for MeHg accumulation and periphyton algae composition at this particular location and given time.
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Affiliation(s)
- William G Lanza
- Carrera de Biología, Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, La Paz, Bolivia
| | - Darío Achá
- Carrera de Biología, Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, La Paz, Bolivia.
| | - David Point
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
| | - Jeremy Masbou
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
| | - Lucia Alanoca
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
- LCABIE-IPREM, UMR 5254 - CNRS, Université de Pau et des Pays de l'Adour, 64053, Pau, France
| | - David Amouroux
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
- LCABIE-IPREM, UMR 5254 - CNRS, Université de Pau et des Pays de l'Adour, 64053, Pau, France
| | - Xavier Lazzaro
- Unité Mixte de Recherche Biologie des Organismes et Ecosystèmes Aquatiques (BOREA UMR 7208), Muséum National d'Histoire Naturelle, Université Pierre et Marie Curie, Université de Caen Basse-Normandie, Centre National de la Recherche Scientifique, Institut de Recherche pour le Développement-207; CP53, 61 rue Buffon, 75005, Paris, France
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Mahbub KR, Subashchandrabose SR, Krishnan K, Naidu R, Megharaj M. Mercury alters the bacterial community structure and diversity in soil even at concentrations lower than the guideline values. Appl Microbiol Biotechnol 2017; 101:2163-75. [PMID: 27873000 DOI: 10.1007/s00253-016-7965-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 10/26/2016] [Accepted: 10/31/2016] [Indexed: 12/13/2022]
Abstract
This study evaluated the effect of inorganic mercury (Hg) on bacterial community and diversity in different soils. Three soils-neutral, alkaline and acidic-were spiked with six different concentrations of Hg ranging from 0 to 200 mg kg-1 and aged for 90 days. At the end of the ageing period, 18 samples from three different soils were investigated for bacterial community structure and soil physicochemical properties. Illumina MiSeq-based 16s ribosomal RNA (rRNA) amplicon sequencing revealed the alteration in the bacterial community between un-spiked control soils and Hg-spiked soils. Among the bacterial groups, Actinobacteria (22.65%) were the most abundant phyla in all samples followed by Proteobacteria (21.95%), Bacteroidetes (4.15%), Firmicutes (2.9%) and Acidobacteria (2.04%). However, the largest group showing increased abundance with higher Hg doses was the unclassified group (45.86%), followed by Proteobacteria. Mercury had a considerable negative impact on key soil functional bacteria such as ammonium oxidizers and nitrifiers. Canonical correspondence analysis (CCA) indicated that among the measured soil properties, Hg had a major influence on bacterial community structure. Furthermore, nonlinear regression analysis confirmed that Hg significantly decreased soil bacterial alpha diversity in lower organic carbon containing neutral and alkaline soils, whereas in acidic soil with higher organic carbon there was no significant correlation. EC20 values obtained by a nonlinear regression analysis indicated that Hg significantly decreased soil bacterial diversity in concentrations lower than several guideline values.
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Rivera SJ, Pacheco LF, Achá D, Molina CI, Miranda-Chumacero G. Low total mercury in Caiman yacare (Alligatoridae) as compared to carnivorous, and non-carnivorous fish consumed by Amazonian indigenous communities. Environ Pollut 2016; 218:366-371. [PMID: 27427172 DOI: 10.1016/j.envpol.2016.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 07/04/2016] [Accepted: 07/04/2016] [Indexed: 06/06/2023]
Abstract
Mercury contamination in the River Beni basin is an important health risk factor, primarily for indigenous communities that live along the river. Among them are the Tacana, living in their original territory with sustainable use of their natural resources, consuming fish, Caiman yacare, and other riverine resources as their main source of protein. To assess mercury exposure to Tacana people, total mercury (THg) was evaluated in the muscle of seven commercial fish, and Caiman yacare (yacare caiman) during 2007 and 2008. THg was extracted by acid digestion and concentrations were determined by atomic absorption spectrometry. Mean mercury concentrations in C. yacare was 0.21 ± 0.22 μg g-1Hg w.w. (wet weight), which is lower than expected given its high trophic level, and its long life-span. It is possible that mercury in C. yacare is accumulated in other organs, not included in this study; but it is also possible that physiological mechanisms are involved that help caimans get rid of ingested mercury, or simply that C. yacare's diverse diet reduces THg accumulation. Carnivorous fishes (Pygocentrus nattereri, Pseudoplatystoma tigrinum, Zungaro zungaro, Plagioscion squamosissimus, and Leiarius marmoratus) had the highest total mercury concentrations, ranging from 0.35 to 1.27 μg g-1Hg w.w. moreover, most were above the limit recommended by WHO (0.5 μg g-1Hg w.w.); except for Leiarius marmuratus, which presented a mean of 0.353 ± 0.322 μg g-1Hg w.w. The two non-carnivorous fish species (Prochilodus nigricans, and Piaractus brachypomus) present mean concentrations of 0.099 ± 0.027, and 0.041 ± 0.019 μg g-1Hg w.w., respectively. Finally, recommendations on the consumption habits of Tacana communities are discussed.
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Affiliation(s)
- S J Rivera
- Wildlife Conservation Society, Greater Madidi-Tambopata Landscape Conservation Program, La Paz, Bolivia
| | - L F Pacheco
- Colección Boliviana de Fauna, Instituto de Ecología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia
| | - D Achá
- Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia.
| | - C I Molina
- Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia; Instituto de Ecología, Unidad de Limnología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia
| | - G Miranda-Chumacero
- Wildlife Conservation Society, Greater Madidi-Tambopata Landscape Conservation Program, La Paz, Bolivia; Instituto de Ecología, Unidad de Limnología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia
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Gascón Díez E, Loizeau JL, Cosio C, Bouchet S, Adatte T, Amouroux D, Bravo AG. Role of Settling Particles on Mercury Methylation in the Oxic Water Column of Freshwater Systems. Environ Sci Technol 2016; 50:11672-11679. [PMID: 27670225 DOI: 10.1021/acs.est.6b03260] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
As the methylation of inorganic mercury to neurotoxic methylmercury has been attributed to the activity of anaerobic bacteria, the formation of methylmercury in the oxic water column of marine ecosystems has puzzled scientists over the past years. Here we show for the first time that methylmercury can be produced in particles sinking through oxygenated water column of lakes. Total mercury and methylmercury concentrations were measured in the settling particles and in surface sediments of the largest freshwater lake in Western Europe (Lake Geneva). While total mercury concentration differences between sediments and settling particles were not significant, methylmercury concentrations were about ten-fold greater in settling particles. Methylmercury demethylation rate constants (kd) were of similar magnitude in both compartments. In contrast, mercury methylation rate constants (km) were one order of magnitude greater in settling particles. The net potential for methylmercury formation, assessed by the ratio between the two rate constants (km kd-1), was therefore up to ten fold greater in settling particles, denoting that in situ transformations likely contributed to the high methylmercury concentration found in settling particles. Mercury methylation was inhibited (∼80%) in settling particles amended with molybdate, demonstrating the prominent role of biological sulfate-reduction in the process.
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Affiliation(s)
- Elena Gascón Díez
- Department F.-A. Forel for Environmental and Water Sciences, University of Geneva , Boulevard Carl-Vogt 66, 1211 Geneva 4, Switzerland
| | - Jean-Luc Loizeau
- Department F.-A. Forel for Environmental and Water Sciences, University of Geneva , Boulevard Carl-Vogt 66, 1211 Geneva 4, Switzerland
| | - Claudia Cosio
- Department F.-A. Forel for Environmental and Water Sciences, University of Geneva , Boulevard Carl-Vogt 66, 1211 Geneva 4, Switzerland
| | - Sylvain Bouchet
- Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Hélioparc , 64053 Pau, France
| | - Thierry Adatte
- Institute of Earth Sciences (ISTE), University of Lausanne , 1015 Lausanne, Switzerland
| | - David Amouroux
- Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Hélioparc , 64053 Pau, France
| | - Andrea G Bravo
- Limnology Department, Evolutionary Biology Centre, EBC, Norbyvägen 18D, 75236 Uppsala, Sweden
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Olsen TA, Brandt CC, Brooks SC. Periphyton Biofilms Influence Net Methylmercury Production in an Industrially Contaminated System. Environ Sci Technol 2016; 50:10843-10850. [PMID: 27617484 DOI: 10.1021/acs.est.6b01538] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Mercury (Hg) methylation and methylmercury (MMHg) demethylation activity of periphyton biofilms from the industrially contaminated East Fork Poplar Creek, Tennessee (EFPC) were measured during 2014-2016 using stable Hg isotopic rate assays. 201HgII and MM202Hg were added to intact periphyton samples in ambient streamwater and the formation of MM201Hg and loss of MM202Hg were monitored over time and used to calculate first-order rate potentials for methylation and demethylation. The influences of location, temperature/season, light exposure and biofilm structure on methylation and demethylation potentials were examined. Between-site differences in net methylation for samples collected from an upstream versus downstream location were driven by differences in the demethylation rate potential (kd). In contrast, the within-site temperature-dependent difference in net methylation was driven by changes in the methylation rate potential (km). Samples incubated in the dark had lower net methylation due to lower km values than those incubated in the light. Disrupting the biofilm structure decreased km and resulted in lower net methylation. Overall, the measured rates resulted in a net excess of MMHg generated which could account for 3.71-7.88 mg d-1 MMHg flux in EFPC and suggests intact, actively photosynthesizing periphyton biofilms harbor zones of MMHg production.
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Affiliation(s)
- Todd A Olsen
- Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008 MS 6038, Oak Ridge, Tennessee 37831-6038, United States
| | - Craig C Brandt
- Biosciences Division, Oak Ridge National Laboratory, P.O. Box 2008 MS 6038, Oak Ridge, Tennessee 37831-6038, United States
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008 MS 6038, Oak Ridge, Tennessee 37831-6038, United States
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Lázaro WL, Díez S, da Silva CJ, Ignácio ÁRA, Guimarães JRD. Waterscape determinants of net mercury methylation in a tropical wetland. Environ Res 2016; 150:438-445. [PMID: 27376931 DOI: 10.1016/j.envres.2016.06.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/30/2016] [Accepted: 06/17/2016] [Indexed: 06/06/2023]
Abstract
The periphyton associated with freshwater macrophyte roots is the main site of Hg methylation in different wetland environments in the world. The aim of this study was to test the use of connectivity metrics of water bodies, in the context of patches, in a tropical waterscape wetland (Guapore River, Amazonia, Brazil) as a predictor of potential net methylmercury (MeHg) production by periphyton communities. We sampled 15 lakes with different patterns of lateral connectivity with the main river channel, performing net mercury methylation potential tests in incubations with local water and Eichhornia crassipes root-periphyton samples, using (203)HgCl2 as a tracer. Physico-chemical variables, landscape data (morphological characteristics, land use, and lateral connection type of water bodies) using GIS resources and field data were analyzed with Generalized Additive Models (GAM). The net Me(203)Hg production (as % of total added (203)Hg) was expressive (6.2-25.6%) showing that periphyton is an important matrix in MeHg production. The model that best explained the variation in the net Me(203)Hg production (76%) was built by the variables: connection type, total phosphorus and dissolved organic carbon (DOC) in water (AICc=48.324, p=0.001). Connection type factor was the best factor to model fit (r(2)=0.32; p=0.008) and temporarily connected lakes had higher rates of net mercury methylation. Both DOC and total phosphorus showed positive significant covariation with the net methylation rates (r(2)=0.26; p=0.008 and r(2)=0.21; p=0.012 respectively). Our study suggests a strong relationship between rates of net MeHg production in this tropical area and the type of water body and its hydrological connectivity within the waterscape.
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Affiliation(s)
- Wilkinson L Lázaro
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil; Programa de Pós Graduação em Ecologia, Universidade Federal do Rio de Janeiro (UFRJ), Brasil.
| | - Sergi Díez
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain
| | - Carolina J da Silva
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil; Rede Bionorte, Doutorado em Biodiversidade e Biotecnologia da Amazônia Legal, Brasil
| | - Áurea R A Ignácio
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil
| | - Jean R D Guimarães
- Laboratório de Traçadores. Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Brasil
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Souza-Araujo J, Giarrizzo T, Lima MO, Souza MBG. Mercury and methyl mercury in fishes from Bacajá River (Brazilian Amazon): evidence for bioaccumulation and biomagnification. J Fish Biol 2016; 89:249-263. [PMID: 27241551 DOI: 10.1111/jfb.13027] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 04/18/2016] [Indexed: 06/05/2023]
Abstract
This study assessed total mercury (THg) and methyl mercury (MeHg) concentrations, bioaccumulation and biomagnification of THg through the food web in fishes consumed by indigenous communities of Bacajá River, the largest tributary of the right bank of Xingu River. In total, 496 fish (22 species) were sampled. Nine species had THg concentrations above the limit recommended by the World Health Organisation (0·5 µg g(-1) wet mass), and one exceeded the recommended level for Hg in predatory fishes by Brazilian law (1·0 µg g(-1) ). The average concentration of THg increased significantly with trophic guild (herbivorous to piscivorous) and trophic level, with higher accumulation in fishes with greater total length. Ninety-six per cent of all mercury was methylated. These results suggest that feeding habits determine THg concentrations in fishes and that Hg elimination rate is slow during growth, which allows greater accumulation. These findings show that fishes in the Bacajá River contain high concentrations of THg and MeHg.
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Affiliation(s)
- J Souza-Araujo
- Aquatic Ecology Group, Federal University of Pará, Avenida Perimetral 2651, Terra Firme, 66040170, Belém, PA, Brazil
| | - T Giarrizzo
- Aquatic Ecology Group, Federal University of Pará, Avenida Perimetral 2651, Terra Firme, 66040170, Belém, PA, Brazil
| | - M O Lima
- Evandro Chagas Institute, Environment Section, Rodovia BR-316, km 7, S/N, Levilândia, 67030000, Ananindeua, PA, Brazil
| | - M B G Souza
- Tractebel Engineering-LEME Engineering, Avenida dos Andradas 3000, Santa Efigênia, 30260070, Belo Horizonte, MG, Brazil
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Bravo AG, Loizeau JL, Dranguet P, Makri S, Björn E, Ungureanu VG, Slaveykova VI, Cosio C. Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania). Environ Sci Pollut Res Int 2016; 23:10529-10541. [PMID: 26662302 DOI: 10.1007/s11356-015-5906-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 11/30/2015] [Indexed: 05/16/2023]
Abstract
Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl(-) concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.
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Affiliation(s)
- Andrea G Bravo
- Limnology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Jean-Luc Loizeau
- Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland
| | - Perrine Dranguet
- Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland
| | - Stamatina Makri
- Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland
| | - Erik Björn
- Department of Chemistry, Umeå University, SE-90187, Umeå, Sweden
| | - Viorel Gh Ungureanu
- Faculty of Geology and Geophysics, University of Bucharest, Bucharest, Romania
- GeoEcoMar, National Research and Development Institute for Marine Geology and Geoecology, Bucharest, Romania
| | - Vera I Slaveykova
- Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland
| | - Claudia Cosio
- Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland.
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Lee SW, Lowry GV, Hsu-Kim H. Biogeochemical transformations of mercury in solid waste landfills and pathways for release. Environ Sci Process Impacts 2016; 18:176-189. [PMID: 26745831 DOI: 10.1039/c5em00561b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Mercury (Hg) is present in a variety of solid wastes including industrial wastes, household products, consumer electronics, and medical wastes, some of which can be disposed in conventional landfills. The presence of this neurotoxic metal in landfills is a concern due to the potential for it to leach or volatilize from the landfill and impact local ecosystems. The objective of this review is to describe general practices for the disposal of mercury-bearing solid wastes, summarize previous studies on the release of mercury from landfills, and delineate the expected transformations of Hg within landfill environments that would influence transport of Hg via landfill gas and leachate. A few studies have documented the emissions of Hg as landfill gas, primarily as gaseous elemental Hg(0) and smaller amounts as methylated Hg species. Much less is known regarding the release of Hg in leachate. Landfill conditions are unique from other subsurface environments in that they can contain water with very high conductivity and organic carbon concentration. Landfills also experience large changes in redox potential (and the associated microbial community) that greatly influence Hg speciation, transformations, and mobilization potential. Generally, Hg is not likely to persist in large quantities as dissolved species, since Hg(0) tends to evolve in the gas phase and divalent Hg(ii) sorbs strongly to particulate phases including organic carbon and sulfides. However, Hg(ii) has the potential to associate with or form colloidal particles that can be mobilized in porous media under high organic carbon conditions. Moreover, the anaerobic conditions within landfills can foster the growth of microorganisms that produced monomethyl- and dimethyl-Hg species, the forms of mercury with high potential for bioaccumulation. Much advancement has recently been made in the mercury biogeochemistry research field, and this study seeks to incorporate these findings for landfill settings.
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Affiliation(s)
- Sung-Woo Lee
- Department of Civil & Environmental Engineering, Duke University, Durham, North Carolina 27708, USA.
| | - Gregory V Lowry
- Department of Civil & Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Heileen Hsu-Kim
- Department of Civil & Environmental Engineering, Duke University, Durham, North Carolina 27708, USA.
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Li D, Hu N, Ding D, Li S, Li G, Wang Y. An experimental study on the inhibitory effect of high concentration bicarbonate on the reduction of U(VI) in groundwater by functionalized indigenous microbial communities. J Radioanal Nucl Chem 2015. [DOI: 10.1007/s10967-015-4427-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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de Oliveira DCM, Correia RRS, Marinho CC, Guimarães JRD. Mercury methylation in sediments of a Brazilian mangrove under different vegetation covers and salinities. Chemosphere 2015; 127:214-221. [PMID: 25732633 DOI: 10.1016/j.chemosphere.2015.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 01/22/2015] [Accepted: 02/03/2015] [Indexed: 06/04/2023]
Abstract
The presence and formation of methylmercury (MMHg), a highly toxic form of Hg, in mangrove ecosystems is poorly studied. Therefore the aim of this study was to evaluate mercury methylation potentials in sediment, litter and root samples (Avicennia shaueriana and Spartina alterniflora) from different regions of a mangrove ecosystem, as well as the influence of salinity on methylation. Sediment was sampled under different depths and in mangrove regions with different plant covers and salinities. All samples were incubated with (203)Hg and MM(203)Hg was extracted and measured by liquid scintillation. MMHg was formed in all samples and sites tested including plant roots and litter. Higher Hg methylation was found in the superficial fraction of sediments (0.47-7.82%). Infralittoral sandy sediment had low MMHg formation (0.44-1.61%). Sediment under Rhizophora mangle had lower MMHg formation (0.018-2.23%) than under A. shaueriana (0.2-4.63%) and Laguncularia racemosa (0.08-7.82). MMHg formation in sediment tended to increase with salinity but the differences were not significant. Therefore, MMHg formation occurs in different sites of mangrove ecosystems and may be an important threat that requires further study.
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Affiliation(s)
- Diana Ciannella Martins de Oliveira
- Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil.
| | - Raquel Rose Silva Correia
- Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil.
| | - Claudio Cardoso Marinho
- Laboratório de Limnologia, Departamento de Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Bloco A/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil.
| | - Jean Remy Davée Guimarães
- Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil.
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