1
|
Wang YL, Ikuma K, Brooks SC, Varonka MS, Deonarine A. Non-mercury methylating microbial taxa are integral to understanding links between mercury methylation and elemental cycles in marine and freshwater sediments. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123573. [PMID: 38365074 DOI: 10.1016/j.envpol.2024.123573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/09/2024] [Accepted: 02/13/2024] [Indexed: 02/18/2024]
Abstract
The goal of this study was to explore the role of non-mercury (Hg) methylating taxa in mercury methylation and to identify potential links between elemental cycles and Hg methylation. Statistical approaches were utilized to investigate the microbial community and biochemical functions in relation to methylmercury (MeHg) concentrations in marine and freshwater sediments. Sediments were collected from the methylation zone (top 15 cm) in four Hg-contaminated sites. Both abiotic (e.g., sulfate, sulfide, iron, salinity, total organic matter, etc.) and biotic factors (e.g., hgcA, abundances of methylating and non-methylating taxa) were quantified. Random forest and stepwise regression were performed to assess whether non-methylating taxa were significantly associated with MeHg concentration. Co-occurrence and functional network analyses were constructed to explore associations between taxa by examining microbial community structure, composition, and biochemical functions across sites. Regression analysis showed that approximately 80% of the variability in sediment MeHg concentration was predicted by total mercury concentration, the abundances of Hg methylating taxa, and the abundances of the non-Hg methylating taxa. The co-occurrence networks identified Paludibacteraceae and Syntrophorhabdaceae as keystone non Hg methylating taxa in multiple sites, indicating the potential for syntrophic interactions with Hg methylators. Strong associations were also observed between methanogens and sulfate-reducing bacteria, which were likely symbiotic associations. The functional network results suggested that non-Hg methylating taxa play important roles in sulfur respiration, nitrogen respiration, and the carbon metabolism-related functions methylotrophy, methanotrophy, and chemoheterotrophy. Interestingly, keystone functions varied by site and did not involve carbon- and sulfur-related functions only. Our findings highlight associations between methylating and non-methylating taxa and sulfur, carbon, and nitrogen cycles in sediment methylation zones, with implications for predicting and understanding the impact of climate and land/sea use changes on Hg methylation.
Collapse
Affiliation(s)
- Yong-Li Wang
- Department of Civil, Environmental & Construction Engineering, Texas Tech University, Lubbock, TX, United States
| | - Kaoru Ikuma
- Department of Civil, Construction & Environmental Engineering, Iowa State University, Ames, IA, United States
| | - Scott C Brooks
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States
| | - Matthew S Varonka
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, United States
| | - Amrika Deonarine
- Department of Civil, Environmental & Construction Engineering, Texas Tech University, Lubbock, TX, United States.
| |
Collapse
|
2
|
Kim YG, Kwon SY, Washburn SJ, Hong Y, Han SH, Lee M, Park JH. Environmental forensics approach to source investigation in a mercury contaminated river: Insights from mercury stable isotopes. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132559. [PMID: 37729710 DOI: 10.1016/j.jhazmat.2023.132559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/10/2023] [Accepted: 09/12/2023] [Indexed: 09/22/2023]
Abstract
Environmental forensics approach was applied to assess the efficacy of mercury (Hg) stable isotopes for source screening and decision-making in the Hyeongsan River, South Korea. Four Hg contamination scenarios were identified- atmospheric Hg emissions from a steel manufacturing industry, upstream riverine Hg transport, and industrial Hg releases and historical landfill collapse from Gumu Creek. The absence of significant Hg isotope difference between the Hyeongsan River sediments (δ202Hg; -0.46 ± 0.17‰, Δ199Hg; -0.04 ± 0.06‰) and the Gumu Creek sediment (δ202Hg; -0.39 ± 0.26‰, Δ199Hg; -0.04 ± 0.03‰) confirm that Hg source is originated from Gumu Creek. The heterogeneous Hg distribution throughout Gumu Creek and statistically similar Hg isotope ratios between Gumu Creek and solid waste cores from the landfill suggests that the landfill collapse is the dominant source to the Hyeongsan-Gumu system. Present Hg releases is also possible given the elevated and matching Δ199Hg between some riverine sediments and wastewater sampled from the landfill. The ternary mixing model estimates that the landfill collapse and wastewater releases contribute 61 ± 25 % and 22 ± 11 %, and the regional background, reflecting terrestrial runoff using deep sediment cores, explain 17 ± 24 % of Hg to the riverine sediment. We suggest that Hg isotopes can be used for routine source screening in areas where Hg sources are unknown.
Collapse
Affiliation(s)
- Young Gwang Kim
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, South Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, South Korea; Institute for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, South Korea.
| | - Spencer J Washburn
- Geosyntec Consultants, Inc., 100 Washington Ave. S, Suite 1590, Minneapolis, MN 55401, USA
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-Ro, Sejong City 30019, South Korea
| | - Seung Hee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Buk-Gu, Gwangju 61005, South Korea
| | - Mikyung Lee
- Water Environmental Engineering Research Division, National Institute of Environmental Research, 42 Hwangyeong-Ro, Seo-Gu, Incheon 22689, South Korea
| | - Ji Hyoung Park
- Water Environmental Engineering Research Division, National Institute of Environmental Research, 42 Hwangyeong-Ro, Seo-Gu, Incheon 22689, South Korea
| |
Collapse
|
3
|
Kim YG, Kwon SY, Washburn SJ, Brooks SC, Yoon JW, Besnard L. Reconsidering mercury sources and exposure pathways to bivalves: Insights from mercury stable isotopes. WATER RESEARCH 2024; 248:120843. [PMID: 37976947 DOI: 10.1016/j.watres.2023.120843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/03/2023] [Accepted: 11/05/2023] [Indexed: 11/19/2023]
Abstract
Identifying mercury (Hg) sources and exposure pathways to bivalves, particularly in relation to sediment, is important for expanding the utility of bivalves as a monitoring organism for sediment quality. Here we use Hg isotope ratios to decipher Hg sources accumulated into bivalves by conducting field studies and in situ experiments. In the first part of this study, we characterized Hg isotope ratios in individual geochemical fractions of riverine sediment, contaminated by liquid Hg in South Korea (Hyeongsan River; HS). Asian clams (Corbicula fluminea) were then deployed at the contaminated sites to evaluate the isotopic turnover. Over the two-month period, the isotope ratios of the clams shifted toward the labile/exchangeable Hg pools (F1, F2 fractions) of the sediment. Conversely, in the control site where sediment Hg is low, we observed similar Hg isotope ratios between Asian clams and the samples of precipitation and dissolved phase of water column. In East Fork Poplar Creek, (Oak Ridge) U.S., Asian clams also displayed similar Hg isotope ratios with the dissolved phase of water column, which have undergone substantial in-stream processing or input from Hg-contaminated groundwater from the hyporheic zones and riparian tributary during high hydrologic flow seasons. Our study demonstrates that the dissolved Hg phases within the water column, whether originating via sediment diffusion or derived externally, act as the primary source and exposure pathways to bivalves. The results of our study also shed new light to the prior Hg isotope measurement in bivalves collected from estuarine, lake, and coastal systems, which showed significant isotopic deviation from bulk sediment. The fact that bivalves are sensitive to in situ and external dissolved Hg phases provides additional insight into the existing biomonitoring program, which uses bivalves as a bioindicator for sediment quality.
Collapse
Affiliation(s)
- Young Gwang Kim
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Republic of Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Republic of Korea; Institute for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, Republic of Korea.
| | - Spencer J Washburn
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, United States
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, United States
| | - Ji Won Yoon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Republic of Korea
| | - Lucien Besnard
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Republic of Korea
| |
Collapse
|
4
|
Wang Y, Liu G, Fang Y, Liu P, Liu Y, Guo Y, Shi J, Hu L, Cai Y, Yin Y, Jiang G. Dark oxidation of mercury droplet: Mercurous [Hg(I)] species controls transformation kinetics. WATER RESEARCH 2023; 244:120472. [PMID: 37619304 DOI: 10.1016/j.watres.2023.120472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/05/2023] [Accepted: 08/08/2023] [Indexed: 08/26/2023]
Abstract
Liquid elemental mercury droplet (Hg(0)l) is an important species in heavy Hg-contaminated environments. The oxidation processes of Hg(0)l and its related mechanisms are still poorly understood. Herein, for the first time, it was verified that mercurous species [Hg(I)] was an important species in natural water contaminated by Hg(0)l as well as in the simulated dark oxidation of Hg(0)l. The formation and further transformation of Hg(I) controlled the overall oxidation process of Hg(0)l and were affected by different environmental factors. Through kinetic modeling using ACUCHEM program, oxidation of Hg(0) to Hg(I) (Hg(0) → Hg(I)) was determined to be the rate-limiting step in Hg(0)l oxidation because its k value ((8.7 ± 0.21) × 10-11s-1) is seven orders of magnitude lower than that of Hg(I) oxidation (Hg(I) → Hg(II), (4.7 ± 0.15) × 10-4s-1). Ligands like OH-, Cl-, and natural organic matter enhanced the formation of Hg(I) via promoting the constants of comproportionation (up to (9.5 ± 0.78) × 10-4s-1). These findings highlight the importance of Hg(I) in Hg(0)l oxidation process by controlling the transformation kinetics of Hg species, facilitating an improved understanding of the environmental redox cycles of Hg.
Collapse
Affiliation(s)
- Ying Wang
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China; 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; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guangliang Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Yingying Fang
- 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; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Liu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Yanwei Liu
- 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; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingying Guo
- 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; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Cai
- 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; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongguang Yin
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China; 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; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
5
|
Koenigsmark F, Rivera NA, Pierce EM, Hsu-Kim H. Dissolution Potential of Elemental Mercury in the Presence of Bisulfide and Implications for Mobilization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:12388-12397. [PMID: 37561589 DOI: 10.1021/acs.est.3c00694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Liquid elemental mercury (Hg0L) pollution can remain in soils for decades and, over time, will undergo corrosion, a process in which the droplet surface oxidizes soil constituents to form more reactive phases, such as mercury oxide (HgO). While these reactive coatings may enhance Hg migration in the subsurface, little is known about the transformation potential of corroded Hg0L in the presence of reduced inorganic sulfur species to form sparingly soluble HgS particles, a process that enables the long-term sequestration of mercury in soils and generally reduces its mobility and bioavailability. In this study, we investigated the dissolution of corroded Hg0L in the presence of sulfide by quantifying rates of aqueous Hg release from corroded Hg0L droplets under different sulfide concentrations (expressed as the S:Hg molar ratio). For droplets corroded in ambient air, no differences in soluble Hg release were observed among all sulfide exposure levels (S:Hg mole ratios ranging from 10-4 to 10). However, for droplets oxidized in the presence of a more reactive oxidant (hydrogen peroxide, H2O2), we observed a 10- to 25-fold increase in dissolved Hg when the oxidized droplets were exposed to low sulfide concentrations (S:Hg ratios from 10-4 to 10-1) relative to droplets exposed to high sulfide concentrations. These results suggest two critical factors that dictate the release of soluble Hg from Hg0L in the presence of sulfide: the extent of surface corrosion of the Hg0L droplet and sufficient sulfide concentration for the formation of HgS solids. The mobilization of Hg0L in porous media, therefore, largely depends on aging conditions in the subsurface and chemical reactivity at the Hg0L droplet interface.
Collapse
Affiliation(s)
- Faye Koenigsmark
- Civil and Environmental Engineering, Duke University ,118A Hudson Hall, Box 90287,Durham, North Carolina 27708, United States
| | - Nelson A Rivera
- Civil and Environmental Engineering, Duke University ,118A Hudson Hall, Box 90287,Durham, North Carolina 27708, United States
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Heileen Hsu-Kim
- Civil and Environmental Engineering, Duke University ,118A Hudson Hall, Box 90287,Durham, North Carolina 27708, United States
| |
Collapse
|
6
|
Koenigsmark F, Chiu M, Rivera N, Johs A, Eskelsen J, Leonard D, Robertson BK, Szynkiewicz A, Derolph C, Zhao L, Gu B, Hsu-Kim H, Pierce EM. Crystal lattice defects in nanocrystalline metacinnabar in contaminated streambank soils suggest a role for biogenic sulfides in the formation of mercury sulfide phases. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:445-460. [PMID: 36692344 DOI: 10.1039/d1em00549a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
At mercury (Hg)-contaminated sites, streambank erosion can act as a main mobilizer of Hg into nearby waterbodies. Once deposited into the waters, mercury from these soils can be transformed to MeHg by microorganisms. It is therefore important to understand the solid-phase speciation of Hg in streambanks as differences in Hg speciation will have implications for Hg transport and bioavailability. In this study, we characterized Hg solid phases in Hg-contaminated soils (100-1100 mg per kg Hg) collected from the incised bank of the East Fork Poplar Creek (EFPC) in Oak Ridge, TN (USA). The analysis of the soil samples by scanning electron microscopy-energy dispersive spectroscopy indicated numerous microenvironments where Hg and sulfur (S) are co-located. According to bulk soil analyses by extended X-ray absorption fine structure spectroscopy (EXAFS), the near-neighbor Hg molecular coordination in the soils closely resembled freshly precipitated Hg sulfide (metacinnabar, HgS); however, EXAFS fits indicated the Hg in the HgS structure was undercoordinated with respect to crystalline metacinnabar. This undercoordination of Hg-S observed by spectroscopy is consistent with transmission electron microspy images showing the presence of nanocrystallites with structural defects (twinning, stacking faults, dislocations) in individual HgS-bearing particles. Although the soils were collected from exposed parts of the stream bank (i.e., open to the atmosphere), the presence of reduced forms of S and sulfate-reducing microbes suggests that biogenic sulfides promote the formation of HgS nanoparticles in these soils. Altogether, these data demonstrate the predominance of nanoparticulate HgS with crystal lattice defects in the bank soils of an industrially impacted stream. Efforts to predict the mobilization and bioavailability of Hg associated with nano-HgS forms should consider the impact of nanocrystalline lattice defects on particle surface reactivity, including Hg dissolution rates and bioavailability on Hg fate and transformations.
Collapse
Affiliation(s)
- Faye Koenigsmark
- Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Michelle Chiu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Nelson Rivera
- Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Jeremy Eskelsen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Donovan Leonard
- Manufacturing Demonstration Facility Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Boakai K Robertson
- Department of Biological Sciences, Alabama State University, Montgomery, AL 36104, USA
| | - Anna Szynkiewicz
- Department of Earth and Planetary Sciences, University of Tennessee at Knoxville, Knoxville, TN 37996, USA
| | - Christopher Derolph
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Linduo Zhao
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Heileen Hsu-Kim
- Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| |
Collapse
|
7
|
Du H, Gu X, Johs A, Yin X, Spano T, Wang D, Pierce EM, Gu B. Sonochemical oxidation and stabilization of liquid elemental mercury in water and soil. JOURNAL OF HAZARDOUS MATERIALS 2023; 445:130589. [PMID: 37055993 DOI: 10.1016/j.jhazmat.2022.130589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/23/2022] [Accepted: 12/08/2022] [Indexed: 06/19/2023]
Abstract
Over 3000 mercury (Hg)-contaminated sites worldwide contain liquid metallic Hg [Hg(0)l] representing a continuous source of elemental Hg(0) in the environment through volatilization and solubilization in water. Currently, there are few effective treatment technologies available to remove or sequester Hg(0)l in situ. We investigated sonochemical treatments coupled with complexing agents, polysulfide and sulfide, in oxidizing Hg(0)l and stabilizing Hg in water, soil and quartz sand. Results indicate that sonication is highly effective in breaking up and oxidizing liquid Hg(0)l beads via acoustic cavitation, particularly in the presence of polysulfide. Without complexing agents, sonication caused only minor oxidation of Hg(0)l but increased headspace gaseous Hg(0)g and dissolved Hg(0)aq in water. However, the presence of polysulfide essentially stopped Hg(0) volatilization and solubilization. As a charged polymer, polysulfide was more effective than sulfide in oxidizing Hg(0)l and subsequently stabilizing the precipitated metacinnabar (β-HgS) nanocrystals. Sonochemical treatments with sulfide yielded incomplete oxidation of Hg(0)l, likely resulting from the formation of HgS coatings on the dispersed µm-size Hg(0)l bead surfaces. Sonication with polysulfide also resulted in rapid oxidation of Hg(0)l and precipitation of HgS in quartz sand and in the Hg(0)l-contaminated soil. This research indicates that sonochemical treatment with polysulfide could be an effective means in rapidly converting Hg(0)l to insoluble HgS precipitates in water and sediments, thereby preventing its further emission and release to the environment. We suggest that future studies are performed to confirm its technical feasibility and treatment efficacy for remediation applications.
Collapse
Affiliation(s)
- Hongxia Du
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China; Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Xin Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Xiangping Yin
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Tyler Spano
- Nuclear Nonproliferation Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN 37996, United States.
| |
Collapse
|
8
|
Schwartz GE, Muller KA, Rathore SS, Wilpiszeski RL, Carrell AA, Cregger MA, Elias DA, Podar M, Painter SL, Brooks SC. Incorporating concentration-dependent sediment microbial activity into methylmercury production kinetics modeling. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:1392-1405. [PMID: 34727150 DOI: 10.1039/d1em00287b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In anoxic environments, anaerobic microorganisms carrying the hgcAB gene cluster can mediate the transformation of inorganic mercury (Hg(II)) to monomethylmercury (MMHg). The kinetics of Hg(II) transformation to MMHg in periphyton from East Fork Poplar Creek (EFPC) in Oak Ridge, TN have previously been modeled using a transient availability model (TAM). The TAM for Hg(II) methylation combines methylation/demethylation kinetics with kinetic expressions for processes that decrease Hg(II) and MMHg availability for methylation and demethylation (multisite sorption of Hg(II) and MMHg, Hg(II) reduction/Hg(0) oxidation). In this study, the TAM is used for the first time to describe MMHg production in sediment. We assessed MMHg production in sediment microcosms using two different sediment types from EFPC: a relatively anoxic, carbon-rich sediment with higher microbial activity (higher CO2 production from sediment) and a relatively oxic, sandy, carbon-poor sediment with lower microbial activity (lower CO2 production from sediment). Based on 16s rRNA sequencing, the overall microbial community structure in the two sediments was retained during the incubations. However, the hgcA containing methanogenic Euryarchaeota communities differed between sediment types and their growth followed different trajectories over the course of incubations, potentially contributing to the distinct patterns of MMHg production observed. The general TAM paradigm performed well in describing MMHg production in the sediments. However, the MMHg production and ancillary data suggested the need to revise the model structure to incorporate terms for concentration-dependent microbial activity over the course of the incubations. We modified the TAM to include Monod-type kinetics for methylation and demethylation and observed an improved fit for the carbon-rich, microbially active sediment. Overall our work shows that the TAM can be applied to describe Hg(II) methylation in sediments and that including expressions accounting for concentration-dependent microbial activity can improve the accuracy of the model description of the data in some cases.
Collapse
Affiliation(s)
- Grace E Schwartz
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| | - Katherine A Muller
- Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Saubhagya S Rathore
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| | - Regina L Wilpiszeski
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Alyssa A Carrell
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Melissa A Cregger
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Scott L Painter
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| |
Collapse
|
9
|
Brooks SC, Riscassi AL, Miller CL, Lowe KA, Yin X, Mehlhorn TL. Diel mercury concentration variations in a mercury-impacted stream. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:1195-1211. [PMID: 35829655 DOI: 10.1039/d2em00142j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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.
Collapse
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.
| |
Collapse
|
10
|
Yin X, Wang L, Liang X, Zhang L, Zhao J, Gu B. Contrary effects of phytoplankton Chlorella vulgaris and its exudates on mercury methylation by iron- and sulfate-reducing bacteria. JOURNAL OF HAZARDOUS MATERIALS 2022; 433:128835. [PMID: 35398798 DOI: 10.1016/j.jhazmat.2022.128835] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Mercury (Hg) is a pervasive environmental pollutant and poses serious health concerns as inorganic Hg(II) can be converted to the neurotoxin methylmercury (MeHg), which bioaccumulates and biomagnifies in food webs. Phytoplankton, representing the base of aquatic food webs, can take up Hg(II) and influence MeHg production, but currently little is known about how and to what extent phytoplankton may impact Hg(II) methylation by itself or by methylating bacteria it harbors. This study investigated whether some species of phytoplankton could produce MeHg and how the live or dead phytoplankton cells and excreted algal organic matter (AOM) impact Hg(II) methylation by several known methylators, including iron-reducing bacteria (FeRB), Geobacter anodireducens SD-1 and Geobacter sulfurreducens PCA, and the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans ND132 (or Pseudodesulfovibrio mercurii). Our results indicate that, among the 4 phytoplankton species studied, none were capable of methylating Hg(II). However, the presence of phytoplankton cells (either live or dead) from Chlorella vulgaris (CV) generally inhibited Hg(II) methylation by FeRB but substantially enhanced methylation by SRB D. desulfuricans ND132. Enhanced methylation was attributed in part to CV-excreted AOM, which increased Hg(II) complexation and methylation by ND132 cells. In contrast, inhibition of methylation by FeRB was attributed to these bacteria incapable of competing with phytoplankton for Hg(II) binding and uptake. These observations suggest that phytoplankton could play different roles in affecting Hg(II) methylation by the two groups of anaerobic bacteria, FeRB and SRB, and thus shed additional light on how phytoplankton blooms may modulate MeHg production and bioaccumulation in the aquatic environment.
Collapse
Affiliation(s)
- Xixiang Yin
- Shandong Jinan Eco-environmental Monitoring Center, Jinan 250014, China; Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Lihong Wang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States; Qilu University of Technology (Shandong Academy of Sciences), Shandong Analysis and Test Center, Jinan 250014, China
| | - Xujun Liang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Lijie Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Jiating Zhao
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States; Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Ten 37996, United States.
| |
Collapse
|
11
|
Experimental and theoretical investigations of lithium isotopes separation using 10-hydroxybenzoquinoline. J Radioanal Nucl Chem 2022. [DOI: 10.1007/s10967-022-08378-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
12
|
Pouil S, Stevenson LM, Goñez-Rodríguez L, Mathews TJ. Stannous chloride as a tool for mercury stripping in contaminated streams: Experimental assessment of toxicity in an invertebrate model species. CHEMOSPHERE 2022; 296:133762. [PMID: 35093417 DOI: 10.1016/j.chemosphere.2022.133762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 01/05/2022] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
The chronic toxicity of an innovative Hg water treatment system using tin (Sn) (II) chloride (SnCl2) followed by air stripping was assessed through measurements of survival, growth, and reproduction rate in the freshwater cladoceran Ceriodaphnia dubia, a model species for toxicity testing. We first calculated the concentrations of Hg causing 25% reduction in survival and reproduction (Lethal or Inhibition Concentrations, or LC25 and IC25, for survival and reproduction, respectively) through exposure to aqueous Hg at concentrations ranging from 0 to 25,000 ng L-1. Then, we treated media (DMW and natural stream water) contaminated with Hg at LC25 and IC25 concentrations with SnCl2 at a Sn:Hg stoichiometric ratio of 8:1 and air stripping and exposed C. dubia to this Sn-amended media. Our results showed that Hg significantly affected survival, reproduction rates and impaired growth. SnCl2-treatment removed 100% of the Hg from the media at all concentrations tested with no deleterious effects on survival, growth and reproduction. Our results confirmed the efficacy of SnCl2 in removing aqueous Hg from stream water and showed that the added Sn did not impact C. dubia at the concentrations tested, supporting the suitability of SnCl2-based treatments in appropriate Hg-contaminated environments.
Collapse
Affiliation(s)
- Simon Pouil
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Louise M Stevenson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Leroy Goñez-Rodríguez
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Teresa J Mathews
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.
| |
Collapse
|
13
|
Nair SS, DeRolph C, Peterson MJ, McManamay RA, Mathews T. Integrated watershed process model for evaluating mercury sources, transport, and future remediation scenarios in an industrially contaminated site. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:127049. [PMID: 34517300 DOI: 10.1016/j.jhazmat.2021.127049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
We used the Soil Water Assessment Tool (SWAT) as a framework to develop an empirical Hg flux model for Upper East Fork Poplar Creek (UEFPC), a Hg-contaminated watershed in Oak Ridge, Tennessee. By integrating long-term Hg monitoring data with simulated flow and suspended solid loads in a site-specific empirical Hg transport model, we (1) quantified the spatial, temporal, and flow regime controls on daily Hg flux (adjusted R2 = 0.82) and (2) made predictions about Hg flux under future climate, land use, and management scenarios. We found that 62.79% of the average daily Hg flux in the watershed is currently driven by base flow, whereas variability in Hg flux is driven by storm and extreme flow. We estimate an average annual Hg flux of 28.82 g day-1 leaving the watershed under baseline precipitation, with an estimated 43.73% reduction in daily Hg flux under drought conditions and a 296% increase in daily Hg flux in extreme precipitation scenarios. We estimated that a new mercury treatment facility would result in a 24.7% reduction in Hg flux under baseline conditions and a 33.4% reduction under extreme precipitation scenarios. The study demonstrated the merit of this approach, which can be replicated for sites where information on flow, suspended solids, and Hg concentrations is available.
Collapse
Affiliation(s)
| | - Christopher DeRolph
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Mark J Peterson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Ryan A McManamay
- Department of Environmental Science, Baylor University, Waco, TX 76798, USA
| | - Teresa Mathews
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| |
Collapse
|
14
|
Yusupov DV, Lyapina EE, Tursunalieva EM, Osipova NA, Baranovskaya NV. Poplar tree (Populus balsamifera L.) as indicator of mercury emission from a point source. CHEMOSPHERE 2022; 287:132157. [PMID: 34560495 DOI: 10.1016/j.chemosphere.2021.132157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/31/2021] [Accepted: 09/02/2021] [Indexed: 06/13/2023]
Abstract
The article provides original data on the ecological and geochemical characteristics of the distribution of Hg in the leaves and annual rings of balsam poplar (P. balsamifera L.) in the zone of influence of lithium production (Novosibirsk). In 2017 high Hg concentration (1300 ng/g) in the poplar leaves was recorded in the northeastern part of the city near the industrial facility of the lithium plant. The investigation showed a clear trend of increased Hg accumulation in the poplar leaves during the growing season. The maximum average Hg content was detected in the leaf litter in 2006 (1153-2425 ng/g). However, the average Hg content in the soil is 294 ng/g, which is significantly lower than the threshold limit value (2100 ng/g). Studies of changes in the content of Hg with the height of the crown of the tree revealed an increase in the upwind side of the emission source, the concentration of Hg in the leaves is on average 1.5 times higher than on the side of the "wind shadow". Hg in poplar leaves, leaf litter, and soils is mainly found in free and physically bonded forms - the most mobile, prone to increased migration, transformation and methylation under environmental conditions. According to the Hg content in the poplar cores, an increase in the Hg input near the source was established with the beginning of Li production - in the period 1967-1985 years (441 ng/g) with a subsequent decrease to 6 ng/g in 2000-2017.
Collapse
Affiliation(s)
- D V Yusupov
- National Research Tomsk Polytechnic University, Lenin Ave., 30, Tomsk, 634050, Russia; Amur State University, Ignatyevskoe highway, 21, Blagoveshchensk, Amur Region, 675027, Russia
| | - E E Lyapina
- Institute of Monitoring of Climatic and Ecological Systems Siberian Branch of Russian Academy of Sciences, Akademichesky Ave., 10/3, Tomsk, 634055, Russia.
| | - E M Tursunalieva
- National Research Tomsk Polytechnic University, Lenin Ave., 30, Tomsk, 634050, Russia; National Research Tomsk State University, Lenin Ave., 36, Tomsk, 634050, Russia
| | - N A Osipova
- National Research Tomsk Polytechnic University, Lenin Ave., 30, Tomsk, 634050, Russia
| | - N V Baranovskaya
- National Research Tomsk Polytechnic University, Lenin Ave., 30, Tomsk, 634050, Russia
| |
Collapse
|
15
|
Liu B, Jia Y, Zhang Z, Sun H, Yao Y, Jing Y, Qi M, Zhang Q. Separation of lithium isotopes by crown ether-room temperature ionic liquid-anisole friendly solvent system. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
16
|
Li R, Qi L, Ibeanusi V, Badisa V, Brooks S, Chen G. Reduction and bacterial adsorption of dissolved mercuric ion by indigenous bacteria at the Oak Ridge Reservation site. CHEMOSPHERE 2021; 280:130629. [PMID: 33940452 DOI: 10.1016/j.chemosphere.2021.130629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/04/2021] [Accepted: 04/18/2021] [Indexed: 06/12/2023]
Abstract
Mercury exists in various forms in the environment and the indigenous bacteria mediated processes have the potential to be used for mercury remediation. In this study, two mixed cultures of indigenous bacteria at the Oak Ridge Reservation site (i.e., ORR soil culture and ORR sediment culture) were selected to study the microbial mediated mercuric reduction under an aerobic condition as well as mercury adsorption onto bacterial surfaces. PCR analysis was performed to provide insights into the microbial community. The mercuric volatilizing experiment demonstrated the mercuric reducing capacity for both ORR cultures, in which the Pseudomonas genus was the dominating Hg0 producer. The investigation of the impact of the sole carbon source revealed the energy-dependent characteristics of the mercuric reduction in this study. Namely, the mercuric reduction was nearly not impacted by the type of carbon source but positively related to the energy that a unit amount of substrate could provide. The study also indicated that the mercury adsorption competed with the reduction. According to the fitting of the Langmuir isotherm, the ORR soil culture was found to have a higher mercury adsorption capacity (i.e., 67.5 mg Hg/g dry biomass) than the ORR sediment culture (i.e., 53.1 mg Hg/g dry biomass). The negative correlation between the reduced mercury mass and adsorbed mercury mass was identified for both ORR cultures.
Collapse
Affiliation(s)
- Runwei Li
- School of the Environment, Florida A&M University, Tallahassee, FL, 32307, USA.
| | - Lin Qi
- Department of Civil and Environmental Engineering at FAMU-FSU College of Engineering, Florida State University, Tallahassee, FL, 32310, USA
| | - Victor Ibeanusi
- School of the Environment, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Veera Badisa
- School of the Environment, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Scott Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Gang Chen
- Department of Civil and Environmental Engineering at FAMU-FSU College of Engineering, Florida State University, Tallahassee, FL, 32310, USA
| |
Collapse
|
17
|
Isokpehi RD, McInnis DS, Destefano AM, Johnson GS, Walker AD, Hall YA, Mapp BW, Johnson MO, Simmons SS. Bioinformatics Investigations of Universal Stress Proteins from Mercury-Methylating Desulfovibrionaceae. Microorganisms 2021; 9:microorganisms9081780. [PMID: 34442859 PMCID: PMC8401546 DOI: 10.3390/microorganisms9081780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/30/2021] [Accepted: 08/06/2021] [Indexed: 11/26/2022] Open
Abstract
The presence of methylmercury in aquatic environments and marine food sources is of global concern. The chemical reaction for the addition of a methyl group to inorganic mercury occurs in diverse bacterial taxonomic groups including the Gram-negative, sulfate-reducing Desulfovibrionaceae family that inhabit extreme aquatic environments. The availability of whole-genome sequence datasets for members of the Desulfovibrionaceae presents opportunities to understand the microbial mechanisms that contribute to methylmercury production in extreme aquatic environments. We have applied bioinformatics resources and developed visual analytics resources to categorize a collection of 719 putative universal stress protein (USP) sequences predicted from 93 genomes of Desulfovibrionaceae. We have focused our bioinformatics investigations on protein sequence analytics by developing interactive visualizations to categorize Desulfovibrionaceae universal stress proteins by protein domain composition and functionally important amino acids. We identified 651 Desulfovibrionaceae universal stress protein sequences, of which 488 sequences had only one USP domain and 163 had two USP domains. The 488 single USP domain sequences were further categorized into 340 sequences with ATP-binding motif and 148 sequences without ATP-binding motif. The 163 double USP domain sequences were categorized into (1) both USP domains with ATP-binding motif (3 sequences); (2) both USP domains without ATP-binding motif (138 sequences); and (3) one USP domain with ATP-binding motif (21 sequences). We developed visual analytics resources to facilitate the investigation of these categories of datasets in the presence or absence of the mercury-methylating gene pair (hgcAB). Future research could utilize these functional categories to investigate the participation of universal stress proteins in the bacterial cellular uptake of inorganic mercury and methylmercury production, especially in anaerobic aquatic environments.
Collapse
Affiliation(s)
- Raphael D. Isokpehi
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
- Correspondence:
| | - Dominique S. McInnis
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
| | - Antoinette M. Destefano
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
| | - Gabrielle S. Johnson
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
| | - Akimio D. Walker
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
| | - Yessenia A. Hall
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
| | - Baraka W. Mapp
- College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL 32114, USA; (D.S.M.); (A.M.D.); (G.S.J.); (A.D.W.); (Y.A.H.); (B.W.M.)
| | - Matilda O. Johnson
- College of Nursing and Health Sciences, Bethune-Cookman University, Daytona Beach, FL 32114, USA;
| | - Shaneka S. Simmons
- Department of Science and Mathematics, Jarvis Christian College, Hawkins, TX 75765, USA;
| |
Collapse
|
18
|
The Upcoming 6Li Isotope Requirements Might Be Supplied by a Microalgal Enrichment Process. Microorganisms 2021; 9:microorganisms9081753. [PMID: 34442832 PMCID: PMC8401424 DOI: 10.3390/microorganisms9081753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 11/16/2022] Open
Abstract
Lithium isotopes are essential for nuclear energy, but new enrichment methods are required. In this study, we considered biotechnology as a possibility. We assessed the Li fractionation capabilities of three Chlorophyte strains: Chlamydomonas reinhardtii, Tetraselmis mediterranea, and a freshwater Chlorophyte, Desmodesmus sp. These species were cultured in Li containing media and were analysed just after inoculation and after 3, 12, and 27 days. Li mass was determined using a Inductively Coupled Plasma Mass Spectrometer, and the isotope compositions were measured on a Thermo Element XR Inductively Coupled Plasma Mass Spectrometer. The maximum Li capture was observed at day 27 with C. reinhardtii (31.66 µg/g). Desmodesmus sp. reached the greatest Li fractionation, (δ6 = 85.4‰). All strains fractionated preferentially towards 6Li. More studies are required to find fitter species and to establish the optimal conditions for Li capture and fractionation. Nevertheless, this is the first step for a microalgal nuclear biotechnology.
Collapse
|
19
|
Klaß L, Ritz P, Hirsch M, Kettler J, Havenith A, Wilden A, Modolo G. Gamma-spectrometric measurement procedure for a clearance concept of radioactively contaminated mercury from nuclear facilities. J Radioanal Nucl Chem 2021. [DOI: 10.1007/s10967-021-07840-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractRadioactive mercury waste constitutes a significant challenge, as no approved disposal concept yet exists for such waste in Germany. This work describes a decontamination and measurement procedure for a possible clearance of mercury from nuclear facilities and release into reuse or conventional hazardous waste disposal to reduce the amount of mercury in a nuclear repository. The measurement setup and procedure were developed and evaluated including Monte-Carlo N-Particle® Transport Code (MCNP® and Monte Carlo N-Particle® are registered trademarks owned by Los Alamos National Security, LLC, manager and operator of Los Alamos National Laboratory, (Werner 2018, Werner 2017)), simulations to ensure conservative assumptions during the measurements. Results from decontaminated mercury samples show that a clearance pursuant to the German regulations would be feasible.
Collapse
|
20
|
Crowther ER, Demers JD, Blum JD, Brooks SC, Johnson MW. Use of sequential extraction and mercury stable isotope analysis to assess remobilization of sediment-bound legacy mercury. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:756-775. [PMID: 33970175 DOI: 10.1039/d1em00019e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The goal of this project was to assess how anthropogenic legacy mercury (Hg) retained in streambed sediment may be remobilized to stream water. To do this, we performed sequential extractions and Hg isotope analyses on streambed sediment collected along the length of East Fork Poplar Creek, a point-source contaminated stream in Oak Ridge, Tennessee, USA. Legacy Hg within streambed sediment appears to have been isotopically fractionated by equilibrium isotope effects driven by isotope exchange between co-existing Hg(0) and Hg(ii) species, potentially over-printing fractionation patterns that would have been imparted by kinetic redox reactions. Weakly-bound and recalcitrant sediment Hg pools were isotopically similar to one another, suggesting that small amounts of recalcitrant Hg may be released and then rapidly and weakly re-adsorbed onto the sediment. This weakly-bound Hg pool appears to contribute dissolved Hg to the hyporheic pore water, which may subsequently enter the surface flow. The isotopic composition of the organically-bound sediment Hg pools, as well as biofilm and suspended particulates, converged with that of the weakly-bound and recalcitrant sediment Hg pools along the flow path. This appears to be indicative of both physical mixing with streambed sediment and the transfer of weakly-bound sediment Hg into biofilm and suspended particulates, followed by re-incorporation into the organically-bound sediment Hg pool. Overall, these results provide evidence that legacy Hg in the streambed is remobilized, enters the stream water as dissolved Hg, and may be incorporated into streambed biofilm, which constitutes a basal resource within the stream ecosystem.
Collapse
Affiliation(s)
- Elizabeth R Crowther
- Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave., Ann Arbor, MI 48109-1005, USA.
| | - Jason D Demers
- Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave., Ann Arbor, MI 48109-1005, USA.
| | - Joel D Blum
- Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave., Ann Arbor, MI 48109-1005, USA.
| | - Scott C Brooks
- Environmental Science Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6038, USA
| | - Marcus W Johnson
- Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave., Ann Arbor, MI 48109-1005, USA.
| |
Collapse
|
21
|
Goñez-Rodríguez L, Johs A, Lowe KA, Carter KE, Löffler FE, Mayes MA. Evaluation of engineered sorbents for the sorption of mercury from contaminated bank soils: a column study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:22651-22663. [PMID: 33420931 PMCID: PMC8113147 DOI: 10.1007/s11356-020-12073-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 12/13/2020] [Indexed: 06/12/2023]
Abstract
As a global environmental pollutant, mercury (Hg) threatens our water resources and presents a substantial risk to human health. The rate and extent of immobilization of Hg2+ (hereafter, Hg) on engineered sorbents (Thiol-SAMMS®, pine biochar, SediMite™, Organoclay™ PM-199, and quartz sand as a control) was evaluated using flow-through column experiments. The effectiveness of the sorbents was based on (1) the percentage of Hg removed in relation to the total amount of Hg passing the sorbent column, and (2) the rate of Hg uptake compared to the nonreactive tracer bromide (Br-). All sorbents removed Hg to a certain extent, but none of the sorbents removed all the Hg introduced to the columns. Thiol-SAMMS showed the highest mean percentage of Hg removed (87% ± 2.9%), followed by Organoclay PM-199 (71% ± 0.4%), pine biochar (57% ± 22.3%), SediMite (61% ± 0.8%), and the control quartz sand (11% ± 5.6%). Thiol-SAMMS was the only sorbent to exhibit retardation of Hg in comparison to the conservative tracer Br-. For the remaining sorbents, Br- along with low concentrations of Hg were eluted within the first 3 pore volumes, indicating limited retardation of Hg. Overall, removal of Hg by sorbents was substantial, suggesting that sorbents might be suitable for deployment in contaminated environments. High concentrations of DOM leaching from the soil columns likely influenced the speciation of Hg and inhibited sorption to the sorbents. Incomplete removal of Hg by any sorbent suggests that additional optimization is needed to increase efficiency.
Collapse
Affiliation(s)
- Leroy Goñez-Rodríguez
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA
| | - Kenneth A Lowe
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA
| | - Kimberly E Carter
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Frank E Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, 37996, USA
- Department of Microbiology, University of Tennessee, Knoxville, TN, 37996, USA
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, 37996, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Melanie A Mayes
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA.
| |
Collapse
|
22
|
|
23
|
Metagenome-Assembled Genome Sequences of Novel Prokaryotic Species from the Mercury-Contaminated East Fork Poplar Creek, Oak Ridge, Tennessee, USA. Microbiol Resour Announc 2021; 10:10/17/e00153-21. [PMID: 33927032 PMCID: PMC8086206 DOI: 10.1128/mra.00153-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
We sequenced two metagenomes of sediments from the East Fork Poplar Creek in the Oak Ridge Reservation (Oak Ridge, TN), a natural stream that has been contaminated with Hg from upstream sources, and we reconstructed 28 metagenome-assembled genomes of novel prokaryotic species. We sequenced two metagenomes of sediments from the East Fork Poplar Creek in the Oak Ridge Reservation (Oak Ridge, TN), a natural stream that has been contaminated with Hg from upstream sources, and we reconstructed 28 metagenome-assembled genomes of novel prokaryotic species.
Collapse
|
24
|
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] [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.
Collapse
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
| |
Collapse
|
25
|
Wang Y, Roth S, Schaefer JK, Reinfelder JR, Yee N. Production of methylmercury by methanogens in mercury contaminated estuarine sediments. FEMS Microbiol Lett 2020; 367:6006876. [PMID: 33242089 DOI: 10.1093/femsle/fnaa196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/24/2020] [Indexed: 11/14/2022] Open
Abstract
Anaerobic bacteria are known to produce neurotoxic methylmercury [MeHg] when elemental mercury [Hg(0)] is provided as the sole mercury source. In this study, we examined the formation of MeHg in anaerobic incubations of sediment collected from the San Jacinto River estuary (Texas, USA) amended with aqueous Hg(0) to investigate the microbial communities involved in the conversion of Hg(0) to MeHg. The results show that the addition of the methanogen inhibitor 2-bromoethanesulfonate (BES) significantly decreased MeHg production. The mercury methylation gene, hgcA, was detected in these sediments using archaeal specific primers, and 16S rRNA sequencing showed that a member of the Methanosarcinaceae family of methanogens was active. These results suggest that methanogenic archaea play an underappreciated role in the production of MeHg in estuarine sediments contaminated with Hg(0).
Collapse
Affiliation(s)
- Yuwei Wang
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| | - Spencer Roth
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA.,Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, 76 Lipman Drive, NJ 08901, USA
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| | - Nathan Yee
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| |
Collapse
|
26
|
Wang Q, Zhang L, Liang X, Yin X, Zhang Y, Zheng W, Pierce EM, Gu B. Rates and Dynamics of Mercury Isotope Exchange between Dissolved Elemental Hg(0) and Hg(II) Bound to Organic and Inorganic Ligands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15534-15545. [PMID: 33196184 DOI: 10.1021/acs.est.0c06229] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mercury (Hg) isotope exchange is a common process in biogeochemical transformations of Hg in the environment, but it is unclear whether and at what rates dissolved elemental Hg(0)aq may exchange with divalent Hg(II) bound to various organic and inorganic ligands in water. Using enriched stable isotopes, we investigated the rates and dynamics of isotope exchange between 202Hg(0)aq and 201Hg(II) bound to organic and inorganic ligands with varying chemical structures and binding affinities. Time-dependent exchange reactions were followed by isotope compositional changes using both inductively coupled plasma mass spectrometry and Zeeman cold vapor atomic absorption spectrometry. Rapid, spontaneous isotope exchange (<1 h) was observed between 202Hg(0)aq and 201Hg(II) bound to chloride (Cl-), ethylenediaminetetraacetate (EDTA), and thiols, such as cysteine (CYS), glutathione (GSH), and 2,3-dimercaptopropanesulfonic acid (DMPS) at a thiol ligand-to-Hg(II) molar ratio of 1:1. Without external reductants or oxidants, the exchange resulted in transfer of two electrons and redistribution of Hg isotopes bound to the ligand but no net changes of chemical species in the system. However, an increase in the ligand-to-Hg(II) ratio decreased the exchange rates due to the formation of 2:1 or higher thiol:Hg(II) chelated complexes, but had no effects on exchange rates with 201Hg(II) bound to EDTA or Cl-. The exchange between 202Hg(0)aq and 201Hg(II) bound to dissolved organic matter (DOM) showed an initially rapid followed by a slower exchange rate, likely resulting from Hg(II) complexation with both low- and high-affinity binding functional groups on DOM (e.g., carboxylates vs bidentate thiolates). These results demonstrate that Hg(0)aq readily exchanges with Hg(II) bound to various ligands and highlight the importance of considering exchange reactions in experimental enriched Hg isotope tracer studies or in natural abundance Hg isotope studies in environmental matrices.
Collapse
Affiliation(s)
- Quanying Wang
- Key Laboratory of Wet Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Lijie Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Xujun Liang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Xiangping Yin
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Yaoling Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Wang Zheng
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
- Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee 37996, United States
| |
Collapse
|
27
|
Zhang Z, Murali A, Sarswat PK, Free ML. High-efficiency lithium isotope separation in an electrochemical system with 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and diethyl carbonate as the solvents. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.117539] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
28
|
Pouil S, Jones NJ, Smith JG, Mandal S, Griffiths NA, Mathews TJ. Comparing Trace Element Bioaccumulation and Depuration in Snails and Mayfly Nymphs at a Coal Ash-Contaminated Site. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2020; 39:2437-2449. [PMID: 32833245 DOI: 10.1002/etc.4857] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/20/2020] [Accepted: 08/18/2020] [Indexed: 06/11/2023]
Abstract
We examined the bioaccumulation of essential (Cu, Fe, Se, and Zn) and nonessential (As and Hg) trace elements in 2 aquatic invertebrate species (adult snails and mayfly nymphs) with different feeding habits at the site of a coal ash spill. Differences in food web pathway, exposure concentrations, and biological processing affected bioaccumulation patterns in these species. Mayflies had higher body burdens, but snails had higher retention of most elements studied. Environ Toxicol Chem 2020;39:2437-2449. © 2020 SETAC.
Collapse
Affiliation(s)
- Simon Pouil
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Nikki J Jones
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - John G Smith
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Shovon Mandal
- The Energy and Resources Institute (TERI), TERI-Deakin Nanobiotechnology Centre, New Delhi, India
| | - Natalie A Griffiths
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Teresa J Mathews
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| |
Collapse
|
29
|
Zhang Z, Murali A, Sarswat PK, Free ML. High-efficiency lithium isotope separation by electrochemical deposition and intercalation with electrochemical isotope effect in propylene carbonate and [BMIM][DCA] ionic liquid. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.137060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
30
|
Gionfriddo CM, Wymore AM, Jones DS, Wilpiszeski RL, Lynes MM, Christensen GA, Soren A, Gilmour CC, Podar M, Elias DA. An Improved hgcAB Primer Set and Direct High-Throughput Sequencing Expand Hg-Methylator Diversity in Nature. Front Microbiol 2020; 11:541554. [PMID: 33123100 PMCID: PMC7573106 DOI: 10.3389/fmicb.2020.541554] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 08/25/2020] [Indexed: 01/27/2023] Open
Abstract
The gene pair hgcAB is essential for microbial mercury methylation. Our understanding of its abundance and diversity in nature is rapidly evolving. In this study we developed a new broad-range primer set for hgcAB, plus an expanded hgcAB reference library, and used these to characterize Hg-methylating communities from diverse environments. We applied this new Hg-methylator database to assign taxonomy to hgcA sequences from clone, amplicon, and metagenomic datasets. We evaluated potential biases introduced in primer design, sequence length, and classification, and suggest best practices for studying Hg-methylator diversity. Our study confirms the emerging picture of an expanded diversity of HgcAB-encoding microbes in many types of ecosystems, with abundant putative mercury methylators Nitrospirae and Chloroflexi in several new environments including salt marsh and peat soils. Other common microbes encoding HgcAB included Phycisphaerae, Aminicenantes, Spirochaetes, and Elusimicrobia. Combined with high-throughput amplicon specific sequencing, the new primer set also indentified novel hgcAB sequences similar to Lentisphaerae, Bacteroidetes, Atribacteria, and candidate phyla WOR-3 and KSB1 bacteria. Gene abundance data also corroborate the important role of two "classic" groups of methylators (Deltaproteobacteria and Methanomicrobia) in many environments, but generally show a scarcity of hgcAB+ Firmicutes. The new primer set was developed to specifically target hgcAB sequences found in nature, reducing degeneracy and providing increased sensitivity while maintaining broad diversity capture. We evaluated mock communities to confirm primer improvements, including culture spikes to environmental samples with variable DNA extraction and PCR amplification efficiencies. For select sites, this new workflow was combined with direct high-throughput hgcAB sequencing. The hgcAB diversity generated by direct amplicon sequencing confirmed the potential for novel Hg-methylators previously identified using metagenomic screens. A new phylogenetic analysis using sequences from freshwater, saline, and terrestrial environments showed Deltaproteobacteria HgcA sequences generally clustered among themselves, while metagenome-resolved HgcA sequences in other phyla tended to cluster by environment, suggesting horizontal gene transfer into many clades. HgcA from marine metagenomes often formed distinct subtrees from those sequenced from freshwater ecosystems. Overall the majority of HgcA sequences branch from a cluster of HgcAB fused proteins related to Thermococci, Atribacteria (candidate division OP9), Aminicenantes (OP8), and Chloroflexi. The improved primer set and library, combined with direct amplicon sequencing, provide a significantly improved assessment of the abundance and diversity of hgcAB+ microbes in nature.
Collapse
Affiliation(s)
- Caitlin M Gionfriddo
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ann M Wymore
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Daniel S Jones
- BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.,Department of Earth Sciences, Minneapolis, MN, United States
| | - Regina L Wilpiszeski
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Mackenzie M Lynes
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Geoff A Christensen
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ally Soren
- Smithsonian Environmental Research Center, Edgewater, MD, United States
| | | | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| |
Collapse
|
31
|
Pathak A, Jaswal R, Xu X, White JR, Edwards B, Hunt J, Brooks S, Rathore RS, Agarwal M, Chauhan A. Characterization of Bacterial and Fungal Assemblages From Historically Contaminated Metalliferous Soils Using Metagenomics Coupled With Diffusion Chambers and Microbial Traps. Front Microbiol 2020; 11:1024. [PMID: 32655505 PMCID: PMC7325934 DOI: 10.3389/fmicb.2020.01024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 04/27/2020] [Indexed: 01/05/2023] Open
Abstract
The majority of environmental microbiomes are not amenable to cultivation under standard laboratory growth conditions and hence remain uncharacterized. For environmental applications, such as bioremediation, it is necessary to isolate microbes performing the desired function, which may not necessarily be the fast growing or the copiotroph microbiota. Toward this end, cultivation and isolation of microbial strains using diffusion chambers (DC) and/or microbial traps (MT) have both been recently demonstrated to be effective strategies because microbial enrichment is facilitated by soil nutrients and not by synthetically defined media, thus simulating their native habitat. In this study, DC/MT chambers were established using soils collected from two US Department of Energy (DOE) sites with long-term history of heavy metal contamination, including mercury (Hg). To characterize the contamination levels and nutrient status, soils were first analyzed for total mercury (THg), methylmercury (MeHg), total carbon (TC), total nitrogen (TN), and total phosphorus (TP). Multivariate statistical analysis on these measurements facilitated binning of soils under high, medium and low levels of contamination. Bacterial and fungal microbiomes that developed within the DC and MT chambers were evaluated using comparative metagenomics, revealing Chthoniobacter, Burkholderia and Bradyrhizobium spp., as the predominant bacteria while Penicillium, Thielavia, and Trichoderma predominated among fungi. Many of these core microbiomes were also retrieved as axenic isolates. Furthermore, canonical correspondence analysis (CCA) of biogeochemical measurements, metal concentrations and bacterial communities revealed a positive correlation of Chthoniobacter/Bradyrhizobium spp., to THg whereas Burkholderia spp., correlated with MeHg. Penicillium spp., correlated with THg whereas Trichoderma spp., and Aspergillus spp., correlated with MeHg, from the MT approach. This is the first metagenomics-based assessment, isolation and characterization of soil-borne bacterial and fungal communities colonizing the diffusion chambers (DC) and microbial traps (MT) established with long-term metal contaminated soils. Overall, this study provides proof-of-concept for the successful application of DC/MT based assessment of mercury resistant (HgR) microbiomes in legacy metal-contaminated soils, having complex contamination issues. Overall, this study brings out the significance of microbial communities and their relevance in context to heavy metal cycling for better stewardship and restoration of such historically contaminated systems.
Collapse
Affiliation(s)
- Ashish Pathak
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Rajneesh Jaswal
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Xiaoyu Xu
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, United States
| | - John R White
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, United States
| | - Bobby Edwards
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Jaden Hunt
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Scott Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Rajesh Singh Rathore
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Meenakshi Agarwal
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Ashvini Chauhan
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| |
Collapse
|
32
|
Bezdomnikov AA, Demin SV, Tsivadze AY. Effect of Salt Anion on Lithium Extraction in Systems LiX–H2O–Benzo-15-Crown-5–CHCl3, Where X– Is Br–, $${\mathbf{ClO}}_{{\mathbf{4}}}^{ - },$$ and SCN–. RUSS J INORG CHEM+ 2020. [DOI: 10.1134/s0036023620070025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
33
|
Draft Genome Sequence of Mercury-Resistant Serratia sp. Strain SRS-8-S-2018. Microbiol Resour Announc 2020; 9:9/15/e00136-20. [PMID: 32273355 PMCID: PMC7380528 DOI: 10.1128/mra.00136-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A mercury (Hg)-resistant Serratia sp. strain, SRS-8-S-2018, was isolated, followed by generation of its draft genome sequence, which indicated a genomic size of 5,323,630 bp composed of 5,261 coding sequences. A suite of genomic functions in strain SRS-8-S-2018 was identified, and these likely facilitate survival in a metalliferous soil habitat. A mercury (Hg)-resistant Serratia sp. strain, SRS-8-S-2018, was isolated, followed by generation of its draft genome sequence, which indicated a genomic size of 5,323,630 bp composed of 5,261 coding sequences. A suite of genomic functions in strain SRS-8-S-2018 was identified, and these likely facilitate survival in a metalliferous soil habitat.
Collapse
|
34
|
Johs A, Eller VA, Mehlhorn TL, Brooks SC, Harper DP, Mayes MA, Pierce EM, Peterson MJ. Dissolved organic matter reduces the effectiveness of sorbents for mercury removal. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 690:410-416. [PMID: 31299573 DOI: 10.1016/j.scitotenv.2019.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 06/27/2019] [Accepted: 07/01/2019] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) contamination of soils and sediments impacts numerous environments worldwide and constitutes a challenging remediation problem. In this study, we evaluate the impact of dissolved organic matter (DOM) on the effectiveness of eight sorbent materials considered for Hg remediation in soils and sediments. The materials include both engineered and unmodified materials based on carbon, clays, mesoporous silica and a copper alloy. Initially, we investigated the kinetics of Hg(II) complexation with DOM for a series of Hg:DOM ratios. Steady-state Hg-DOM complexation occurred within 48 to 120 h, taking longer time at higher Hg:DOC (dissolved organic carbon) molar ratios. In subsequent equilibrium experiments, Hg(II) was equilibrated with DOM at a defined Hg:DOC molar ratio (2.4 · 10-6) for 170 h and used in batch experiments to determine the effect of DOM on Hg partition coefficients and sorption isotherms by comparing Hg(II) and Hg-DOM. Hg sorption capacities of all sorbents were severely limited in the presence of DOM as a competing ligand. Thiol-SAMMS®, SediMite™ and pine biochar were most effective in reducing Hg concentrations. While pine biochar and lignin-derived carbon processed at high temperatures released negligible amounts of anions into solution, leaching of sulfate and chloride was observed for most engineered sorbent materials. Sulfate may stimulate microbial communities harboring sulfate reducing bacteria, which are considered one of the primary drivers of microbial mercury methylation in the environment. The results highlight potential challenges arising from the application of sorbents for Hg remediation in the field.
Collapse
Affiliation(s)
- Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA.
| | - Virginia A Eller
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
| | - Tonia L Mehlhorn
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
| | - David P Harper
- Center for Renewable Carbon, University of Tennessee, 2506 Jacob Drive, Knoxville, TN 37996, USA
| | - Melanie A Mayes
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
| | - Mark J Peterson
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
| |
Collapse
|
35
|
Schwartz GE, Olsen TA, Muller KA, Brooks SC. Ecosystem Controls on Methylmercury Production by Periphyton Biofilms in a Contaminated Stream: Implications for Predictive Modeling. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 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] [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.
Collapse
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
| |
Collapse
|
36
|
Measurements and simulations of Li isotope enrichment by diffusion and electrochemical migration using gel-based electrolyte. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2019.05.094] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
37
|
Lian P, Guo L, Devarajan D, Parks JM, Painter SL, Brooks SC, Smith JC. The AQUA-MER databases and aqueous speciation server: A web resource for multiscale modeling of mercury speciation. J Comput Chem 2019; 41:147-155. [PMID: 31603259 DOI: 10.1002/jcc.26081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 02/06/2023]
Abstract
To assess the chemical reactivity, toxicity, and mobility of pollutants in the environment, knowledge of their species distributions is critical. Because their direct measurement is often infeasible, speciation modeling is widely adopted. Mercury (Hg) is a representative pollutant for which study of its speciation benefits from modeling. However, Hg speciation modeling is often hindered by a lack of reliable thermodynamic constants. Although computational chemistry (e.g., density functional theory [DFT]) can generate these constants, methods for directly coupling DFT and speciation modeling are not available. Here, we combine computational chemistry and continuum-scale modeling with curated online databases to ameliorate the problem of unreliable inputs to Hg speciation modeling. Our AQUA-MER databases and web server (https://aquamer.ornl.gov) provides direct speciation results by combining web-based interfaces to a speciation calculator, databases of thermodynamic constants, and a computational chemistry toolkit to estimate missing constants. Although Hg is presented as a concrete use case, AQUA-MER can also be readily applied to other elements. © 2019 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Peng Lian
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee, 37831.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, 37996
| | - Luanjing Guo
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee, 37831.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, 37996
| | - Deepa Devarajan
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee, 37831.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, 37996
| | - Jerry M Parks
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee, 37831
| | - Scott L Painter
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831
| | - Jeremy C Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee, 37831.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, 37996
| |
Collapse
|
38
|
Muller KA, Brandt CC, Mathews TJ, Brooks SC. Methylmercury sorption onto engineered materials. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 245:481-488. [PMID: 31170637 DOI: 10.1016/j.jenvman.2019.05.100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 06/09/2023]
Abstract
Four commercially available sorbents (BioChar (BC), ThiolSAMMS® (TS), SediMite (SM), and Organoclay™ PM-199 (OC-199)) were tested for their ability to sorb methylmercury (MeHg) and MeHg complexed with dissolved organic matter (DOM). Testing sorption behavior with DOM is more representative of the environmental conditions and mercury speciation expected during in-situ remediation efforts. Isotherms were fit using a robust, iterative re-weighting scheme. This fitting approach improves upon the traditionally used indirect sorption method by removing the dependence between aqueous and solid phase concentrations in isotherm fitting. Developed isotherms show that without DOM, BC, TS, and SM adsorbed similar amounts of MeHg while OC-199 sorbed substantially less MeHg. Below an equilibrium concentration of 5.6 ng L-1 BC was the best performing sorbent, between 5.6 and 20.9 ng L-1 SM sorbed the most MeHg, and above an equilibrium concentration of 20.9 ng L-1 TS outperformed the other sorbents. BC and OC-199 showed indication of MeHg sorption saturation over the tested concentration range of 3.5-680 ng L-1. With DOM, SM outperformed the other sorbents at equilibrium concentrations less than 0.98 ng L-1 and TS was the superior MeHg:DOM sorbent at higher concentrations. MeHg:DOM sorption was controlled by DOM-sorbent interactions. DOM decreased MeHg sorption onto BC and SM whereas TS exhibited similar sorption with and without DOM. OC-199 had slightly higher MeHg uptake with DOM. East Fork Poplar Creek (EFPC), an industrially Hg contaminated site, was used as a case study example to build a relationship between aqueous and fish MeHg concentrations and subsequently compare the cost of sorbent materials required to meet regulatory objectives. For this case study, SM provided the most cost-effective sorbent option for in-situ remediation efforts to reduce aqueous MeHg concentrations.
Collapse
Affiliation(s)
- Katherine A Muller
- Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, United States
| | - Craig C Brandt
- Biosciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, United States
| | - Teresa J Mathews
- Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, United States
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6038, Oak Ridge, TN, 37831-6038, United States.
| |
Collapse
|
39
|
Gene Determinants for Mercury Bioremediation as Revealed by Draft Genome Sequence Analysis of Stenotrophomonas sp. Strain MA5. Microbiol Resour Announc 2019; 8:8/17/e00130-19. [PMID: 31023812 PMCID: PMC6486241 DOI: 10.1128/mra.00130-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A soilborne Stenotrophomonas sp. strain (MA5) that is resistant to mercury was isolated. A draft genome sequence-based analysis revealed a suite of gene determinants to resist mercury and other heavy metals, multidrug efflux, stress response, and membrane transport, and these provide cues to a suite of mechanisms that underpin cellular survival in contaminated soil. A soilborne Stenotrophomonas sp. strain (MA5) that is resistant to mercury was isolated. A draft genome sequence-based analysis revealed a suite of gene determinants to resist mercury and other heavy metals, multidrug efflux, stress response, and membrane transport, and these provide cues to a suite of mechanisms that underpin cellular survival in contaminated soil.
Collapse
|
40
|
Multiple Lines of Evidences Reveal Mechanisms Underpinning Mercury Resistance and Volatilization by Stenotrophomonas sp. MA5 Isolated from the Savannah River Site (SRS), USA. Cells 2019; 8:cells8040309. [PMID: 30987227 PMCID: PMC6523443 DOI: 10.3390/cells8040309] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/29/2019] [Accepted: 03/30/2019] [Indexed: 11/17/2022] Open
Abstract
A largely understudied microbially mediated mercury (Hg) bioremediative pathway includes the volatilization of Hg2+ to Hg0. Therefore, studies on Hg resistant bacteria (HgR), isolated from historically long-term contaminated environments, can serve as models to understand mechanisms underpinning Hg cycling. Towards this end, a mercury resistant bacterial strain, identified as Stenotrophomonas sp., strain MA5, was isolated from Mill Branch on the Savannah River Site (SRS); an Hg-impacted ecosystem. Minimum inhibitory concentration (MIC) analysis showed Hg resistance of up to 20 µg/mL by MA5 with 95% of cells retaining viability. Microcosm studies showed that the strain depleted more than 90% of spiked Hg2+ within the first 24 h of growth and the detection of volatilized mercury indicated that the strain was able to reduce Hg2+ to Hg0. To understand molecular mechanisms of Hg volatilization, a draft whole genome sequence was obtained, annotated and analyzed, which revealed the presence of a transposon-derived mer operon (merRTPADE) in MA5, known to transport and reduce Hg2+ into Hg0. Based on the whole genome sequence of strain MA5, qRT-PCR assays were designed on merRTPADE, we found a ~40-fold higher transcription of mer T, P, A, D and E when cells were exposed to 5 µg/mL Hg2+. Interestingly, strain MA5 increased cellular size as a function of increasing Hg concentrations, which is likely an evolutionary response mechanism to cope with Hg stress. Moreover, metal contaminated environments are shown to co-select for antibiotic resistance. When MA5 was screened for antibiotic resistance, broad resistance against penicillin, streptomycin, tetracycline, ampicillin, rifampicin, and erythromycin was found; this correlated with the presence of multiple gene determinants for antibiotic resistance within the whole genome sequence of MA5. Overall, this study provides an in-depth understanding of the underpinnings of Stenotrophomonas-mercury interactions that facilitate cellular survival in a contaminated soil habitat.
Collapse
|
41
|
Zhang L, Wu S, Zhao L, Lu X, Pierce EM, Gu B. Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:2426-2433. [PMID: 30702880 DOI: 10.1021/acs.est.8b06020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In natural freshwater and sediments, mercuric mercury (Hg(II)) is largely associated with particulate minerals and organics, but it remains unclear under what conditions particulates may become a sink or a source for Hg(II) and whether the particulate-bound Hg(II) is bioavailable for microbial uptake and methylation. In this study, we investigated Hg(II) sorption-desorption characteristics on three organo-coated hematite particulates and a Hg-contaminated natural sediment and evaluated the potential of particulate-bound Hg(II) for microbial methylation. Mercury rapidly sorbed onto particulates, especially the cysteine-coated hematite and sediment, with little desorption observed (0.1-4%). However, the presence of Hg-binding ligands, such as low-molecular-weight thiols and humic acids, resulted in up to 60% of Hg(II) desorption from the Hg-laden hematite particulates but <6% from the sediment. Importantly, the particulate-bound Hg(II) was bioavailable for uptake and methylation by a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 under anaerobic incubations, and the methylation rate was 4-10 times higher than the desorption rate of Hg(II). These observations suggest direct contacts and interactions between bacterial cells and the particulate-bound Hg(II), resulting in rapid exchange or uptake of Hg(II) by the bacteria. The results highlight the importance of Hg(II) partitioning at particulate-water interfaces and the role of particulates as a significant source of Hg(II) for methylation in the environment.
Collapse
Affiliation(s)
- Lijie Zhang
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Shan Wu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- School of Resource, Environmental and Chemical Engineering , Nanchang University , Nanchang 330031 , China
| | - Linduo Zhao
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Xia Lu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Eric M Pierce
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Baohua Gu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Department of Biosystems Engineering and Soil Science , University of Tennessee , Knoxville , Tennessee 37996 , United States
| |
Collapse
|
42
|
D'Aniello A, Hartog N, Sweijen T, Pianese D. The impact of water saturation on the infiltration behaviour of elemental mercury DNAPL in heterogeneous porous media. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 216:1-9. [PMID: 30031575 DOI: 10.1016/j.jconhyd.2018.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 07/03/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
Industrial use has led to the presence of liquid elemental mercury (Hg0) worldwide in the subsurface as Dense NonAqueous Phase Liquid (DNAPL), resulting in long lasting sources of contamination, which cause harmful effects on human health and detrimental consequences on ecosystems. However, to date, insight into the infiltration behaviour of elemental mercury DNAPL is lacking. In this study, a two-stage flow container experiment of elemental mercury DNAPL infiltration into a variably water saturated stratified sand is described. During the first stage of the experiment, 16.3 ml of liquid Hg0 infiltrated and distributed into an initially partially water saturated system. Afterwards, during the second stage of the experiment, consisting of the simulation of a "rain event" to assess whether the elemental mercury already infiltrated could be mobilized due to local increases in water saturation, a significant additional infiltration of 4.7 ml of liquid mercury occurred from the remaining DNAPL source. The experiment showed that, under conditions similar to those found in the field, Hg0 DNAPL infiltration is likely to occur via fingers and is strongly controlled by porous medium structure and water saturation. Heterogeneities within the porous medium likely determined preferential pathways for liquid Hg0 infiltration and distribution, as also suggested by dual gamma ray measurements. Overall, this study highlights that the infiltration behaviour of mercury DNAPL is strongly impacted by water saturation. In the field, this may result in a preferential infiltration of Hg0 DNAPL in wetter areas or in its mobilization due to wetting during a rain event, as indicated by this study, or a groundwater table rise. This should be considered when assessing the likely distribution pathways of historic mercury DNAPL contamination as well as the remediation efforts.
Collapse
Affiliation(s)
- Andrea D'Aniello
- University of Naples Federico II, Department of Civil, Architectural and Environmental Engineering, via Claudio 21, 80125 Napoli, Italy.
| | - Niels Hartog
- KWR Watercycle Research Institute, Groningenhaven 7, Nieuwegein, The Netherlands; Utrecht University, Department of Earth Sciences, Environmental Hydrogeology Group, Princetonplein 9, 3584 CC, Utrecht, The Netherlands
| | - Thomas Sweijen
- Utrecht University, Department of Earth Sciences, Environmental Hydrogeology Group, Princetonplein 9, 3584 CC, Utrecht, The Netherlands
| | - Domenico Pianese
- University of Naples Federico II, Department of Civil, Architectural and Environmental Engineering, via Claudio 21, 80125 Napoli, Italy
| |
Collapse
|
43
|
Denmark IS, Begu E, Arslan Z, Han FX, Seiter-Moser JM, Pierce EM. Removal of inorganic mercury by selective extraction and coprecipitation for determination of methylmercury in mercury-contaminated soils by chemical vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS). Anal Chim Acta 2018; 1041:68-77. [PMID: 30340692 DOI: 10.1016/j.aca.2018.08.049] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/15/2018] [Accepted: 08/25/2018] [Indexed: 12/19/2022]
Abstract
A procedure is developed for selective extraction of methylmercury (CH3Hg+) from heavily Hg-contaminated soils and sediments for determination by chemical vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS). Soils artificially contaminated with 40 μg g-1 inorganic mercury (Hg2+) or methylmercury chloride (CH3HgCl) were agitated by shaking or exposing to ultrasounds in dilute hydrochloric acid (HCl) or nitric acid (HNO3) solutions at room temperature. Extractions in HCl (5 or 10% v/v) resulted in substantial leaching of Hg2+ from soils, whereas 5% (v/v) HNO3 provided selectivity for quantitative extraction of CH3Hg+ with minimum Hg2+ leaching. Agitation with ultrasounds in 5% (v/v) HNO3 for about 3 min was sufficient for extraction of all CH3Hg+ from soils. Coprecipitations with Fe(OH)3, Bi(OH)3 and HgS were investigated for removal of residual Hg2+ in soil extracts. Hydroxide precipitations were not effective. Thiourea or l-cysteine added to soil extracts prior to hydroxide precipitation improved precipitation of Hg2+, but also resulted in removal of CH3Hg+. HgS precipitation was made with dilute ammonium sulfide solution, (NH4)2S. Adding 30 μL of 0.35 mol L-1 (NH4)2S to soil extracts in 5% (v/v) HNO3 resulted in removal of all residual Hg2+ without impacting CH3Hg+ levels. Vapor generation was carried out by reacting Hg2+-free soil extracts with 1% (m/v) NaBH4. No significant interferences were observed from (NH4)2S on the vapor generation from CH3Hg+. The slopes of the calibration curves for CH3HgCl standard solutions in 5% (v/v) HNO3 with and without (NH4)2S were similar. Limits of detection (LOD, 3s method) were around 0.08 μg L-1 for 5% (v/v) HNO3 blanks (n = 10) and 0.10 μg L-1 for 5% (v/v) HNO3 + 0.005 mol L-1 (NH4)2S blanks (n = 10). Percent relative standard deviation (%RSD) for five replicate measurements varied between 3.1% and 6.4% at 1.0 CH3HgCl level. The method is validated by analysis of two certified reference materials (CRM); purely Methylmercury sediment (SQC1238, 10.00 ± 0.291 ng g-1 CH3Hg+) and Hg-contaminated Estuarine sediment (ERM - CC580, 75 ± 4 ng g-1 CH3Hg+ and 132 ± 3 μg g-1 total Hg). CH3Hg+ values for SQC1238 were between 13.0 and 13.2 ng g-1, and 79 and 81 ng g-1 for ERM - CC580. Hg-contaminated soils (57-96 μg g-1 total Hg) collected from the floodplains of Oak Ridge, TN were analyzed for CH3Hg+ using the procedure by CVG-ICPMS. CH3Hg+ levels ranged from 30 to 51 ng g-1 and did not correlate with total Hg levels (R2 = 0.01).
Collapse
Affiliation(s)
- Iris S Denmark
- Jackson State University, Department of Chemistry, Physics and Atmospheric Sciences, Jackson, MS, 39217, USA
| | - Ermira Begu
- Jackson State University, Department of Chemistry, Physics and Atmospheric Sciences, Jackson, MS, 39217, USA
| | - Zikri Arslan
- Jackson State University, Department of Chemistry, Physics and Atmospheric Sciences, Jackson, MS, 39217, USA.
| | - Fengxiang X Han
- Jackson State University, Department of Chemistry, Physics and Atmospheric Sciences, Jackson, MS, 39217, USA
| | - Jennifer M Seiter-Moser
- Environmental Laboratory, Engineer Research and Development Center (ERDC), Vicksburg, MS, 39180, USA
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| |
Collapse
|
44
|
Acosta LN, Flexer V. A First Assessment on the Scale-Up Possibilities of Different Electrochemical Techniques for Lithium Isotopic Enrichment. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b01640] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lautaro N. Acosta
- Centro de Investigación y Desarrollo en Materiales Avanzados y Almacenamiento de Energía de Jujuy (CIDMEJu), CONICET, Universidad Nacional de Jujuy, Centro de Desarrollo Tecnológico General Savio, Av. Martijena s/n, 4612 Palpalá, Jujuy, Argentina
| | - Victoria Flexer
- Centro de Investigación y Desarrollo en Materiales Avanzados y Almacenamiento de Energía de Jujuy (CIDMEJu), CONICET, Universidad Nacional de Jujuy, Centro de Desarrollo Tecnológico General Savio, Av. Martijena s/n, 4612 Palpalá, Jujuy, Argentina
| |
Collapse
|
45
|
Draft Genome Sequence of Pseudomonas sp. Strain B1, Isolated from a Contaminated Sediment. GENOME ANNOUNCEMENTS 2018; 6:6/25/e00518-18. [PMID: 29930041 PMCID: PMC6013641 DOI: 10.1128/genomea.00518-18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The draft genome sequence of Pseudomonas sp. strain B1, isolated from a contaminated soil, is reported. The genome comprises 6,706,934 bases, 6,059 coding sequences, and 70 RNAs and has a G+C content of 60.3%. A suite of biodegradative genes, many located on genomic islands, were identified from strain B1, further enhancing our understanding of the versatile pseudomonads.
Collapse
|
46
|
McManamay RA, Smith JG, Jett RT, Mathews TJ, Peterson MJ. Identifying non-reference sites to guide stream restoration and long-term monitoring. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 621:1208-1223. [PMID: 29074249 DOI: 10.1016/j.scitotenv.2017.10.107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/11/2017] [Accepted: 10/12/2017] [Indexed: 06/07/2023]
Abstract
The reference condition paradigm has served as the standard for assessing the outcomes of restoration projects, particularly their success in meeting project objectives. One limitation of relying solely on the reference condition in designing and monitoring restoration projects is that reference conditions do not necessarily elucidate impairments to effective restoration, especially diagnosing the causal mechanisms behind unsuccessful outcomes. We provide a spatial framework to select both reference and non-reference streams to guide restoration planning and long-term monitoring through reliance on anthropogenically altered ecosystems to understand processes that govern ecosystem biophysical properties and ecosystem responses to restoration practices. We then applied the spatial framework to East Fork Poplar Creek (EFPC), Tennessee (USA), a system receiving 30years of remediation and pollution abatement actions from industrialization, pollution, and urbanization. Out of >13,000 stream reaches, we identified anywhere from 4 to 48 reaches, depending on the scenario, that could be used in restoration planning and monitoring for specific sites. Preliminary comparison of fish species composition at these sites compared to EFPC sites were used to identify potential mechanisms limiting the ecological recovery following remediation. We suggest that understanding the relative role of anthropogenic pressures in governing ecosystem responses is required to successful, process-driven restoration.
Collapse
Affiliation(s)
- Ryan A McManamay
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
| | - John G Smith
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Robert T Jett
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Teresa J Mathews
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Mark J Peterson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| |
Collapse
|
47
|
D'Aniello A, Hartog N, Sweijen T, Pianese D. Infiltration behaviour of elemental mercury DNAPL in fully and partially water saturated porous media. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 209:14-23. [PMID: 29338881 DOI: 10.1016/j.jconhyd.2018.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 12/07/2017] [Accepted: 01/03/2018] [Indexed: 06/07/2023]
Abstract
Mercury is a contaminant of global concern due to its harmful effects on human health and for the detrimental consequences of its release in the environment. Sources of liquid elemental mercury are usually anthropogenic, such as chlor-alkali plants. To date insight into the infiltration behaviour of liquid elemental mercury in the subsurface is lacking, although this is critical for assessing both characterization and remediation approaches for mercury DNAPL contaminated sites. Therefore, in this study the infiltration behaviour of elemental mercury in fully and partially water saturated systems was investigated using column experiments. The properties affecting the constitutive relations governing the infiltration behaviour of liquid Hg0, and PCE for comparison, were determined using Pc(S) experiments with different granular porous media (glass beads and sands) for different two- and three-phase configurations. Results showed that, in water saturated porous media, elemental mercury, as PCE, acted as a non-wetting fluid. The required entry head for elemental mercury was higher (from about 5 to 7 times). However, due to the almost tenfold higher density of mercury, the required NAPL entry heads of 6.19cm and 12.51cm for mercury to infiltrate were 37.5% to 20.7% lower than for PCE for the same porous media. Although Leverett scaling was able to reproduce the natural tendency of Hg0 to be more prone than PCE to infiltrate in water saturated porous media, it considerably underestimated Hg0 infiltration capacity in comparison with the experimental results. In the partially water saturated system, in contrast with PCE, elemental mercury also acted as a nonwetting fluid, therefore having to overcome an entry head to infiltrate. The required Hg0 entry heads (10.45 and 15.74cm) were considerably higher (68.9% and 25.8%) than for the water saturated porous systems. Furthermore, in the partially water saturated systems, experiments showed that elemental mercury displaced both air and water, depending on the initial water distribution within the pores. This indicates that the conventional wettability hierarchy, in which the NAPL has an intermediate wetting state between the air and the water phases, is not valid for liquid elemental mercury. Therefore, for future modelling of elemental mercury DNAPL infiltration behaviour in variably water saturated porous media, a different formulation of the governing constitutive relations will be required.
Collapse
Affiliation(s)
- Andrea D'Aniello
- University of Naples Federico II, Department of Civil, Architectural and Environmental Engineering, via Claudio 21, 80125 Napoli, Italy.
| | - Niels Hartog
- KWR Watercycle Research Institute, Groningenhaven 7, Nieuwegein, The Netherlands; Utrecht University, Department of Earth Sciences, Environmental Hydrogeology Group, Princetonplein 9, 3584 CC, Utrecht, The Netherlands
| | - Thomas Sweijen
- Utrecht University, Department of Earth Sciences, Environmental Hydrogeology Group, Princetonplein 9, 3584 CC, Utrecht, The Netherlands
| | - Domenico Pianese
- University of Naples Federico II, Department of Civil, Architectural and Environmental Engineering, via Claudio 21, 80125 Napoli, Italy
| |
Collapse
|
48
|
Carbon Amendments Alter Microbial Community Structure and Net Mercury Methylation Potential in Sediments. Appl Environ Microbiol 2018; 84:AEM.01049-17. [PMID: 29150503 PMCID: PMC5772229 DOI: 10.1128/aem.01049-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/28/2017] [Indexed: 01/08/2023] Open
Abstract
Neurotoxic methylmercury (MeHg) is produced by anaerobic Bacteria and Archaea possessing the genes hgcAB, but it is unknown how organic substrate and electron acceptor availability impacts the distribution and abundance of these organisms. We evaluated the impact of organic substrate amendments on mercury (Hg) methylation rates, microbial community structure, and the distribution of hgcAB+ microbes with sediments. Sediment slurries were amended with short-chain fatty acids, alcohols, or a polysaccharide. Minimal increases in MeHg were observed following lactate, ethanol, and methanol amendments, while a significant decrease (∼70%) was observed with cellobiose incubations. Postincubation, microbial diversity was assessed via 16S rRNA amplicon sequencing. The presence of hgcAB+ organisms was assessed with a broad-range degenerate PCR primer set for both genes, while the presence of microbes in each of the three dominant clades of methylators (Deltaproteobacteria, Firmicutes, and methanogenic Archaea) was measured with clade-specific degenerate hgcA quantitative PCR (qPCR) primer sets. The predominant microorganisms in unamended sediments consisted of Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria Clade-specific qPCR identified hgcA+Deltaproteobacteria and Archaea in all sites but failed to detect hgcA+Firmicutes Cellobiose shifted the communities in all samples to ∼90% non-hgcAB-containing Firmicutes (mainly Bacillus spp. and Clostridium spp.). These results suggest that either expression of hgcAB is downregulated or, more likely given the lack of 16S rRNA gene presence after cellobiose incubation, Hg-methylating organisms are largely outcompeted by cellobiose degraders or degradation products of cellobiose. These results represent a step toward understanding and exploring simple methodologies for controlling MeHg production in the environment.IMPORTANCE Methylmercury (MeHg) is a neurotoxin produced by microorganisms that bioacummulates in the food web and poses a serious health risk to humans. Currently, the impact that organic substrate or electron acceptor availability has on the mercury (Hg)-methylating microorganisms is unclear. To study this, we set up microcosm experiments exposed to different organic substrates and electron acceptors and assayed for Hg methylation rates, for microbial community structure, and for distribution of Hg methylators. The sediment and groundwater was collected from East Fork Poplar Creek in Oak Ridge, TN. Amendment with cellobiose (a lignocellulosic degradation by-product) led to a drastic decrease in the Hg methylation rate compared to that in an unamended control, with an associated shift in the microbial community to mostly nonmethylating Firmicutes This, along with previous Hg-methylating microorganism identification methods, will be important for identifying strategies to control MeHg production and inform future remediation strategies.
Collapse
|
49
|
Sugiyama T, Sugiura K. Preparation of Benzo-15-Crown-5 Adsorbents for the Separation of Lithium Isotopes by Displacement Chromatography. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.1080/15361055.2017.1293424] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - Kei Sugiura
- Nagoya University , Fro-cho, Chikusa-ku, Nagoya 464-8603, Japan
| |
Collapse
|
50
|
Bigham GN, Murray KJ, Masue-Slowey Y, Henry EA. Biogeochemical controls on methylmercury in soils and sediments: Implications for site management. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2017; 13:249-263. [PMID: 27427265 DOI: 10.1002/ieam.1822] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 05/10/2016] [Accepted: 06/28/2016] [Indexed: 05/25/2023]
Abstract
Management of Hg-contaminated sites poses particular challenges because methylmercury (MeHg), a potent bio-accumulative neurotoxin, is formed in the environment, and concentrations are not generally predictable based solely on total Hg (THg) concentrations. In this review, we examine the state of knowledge regarding the chemical, biological, and physical controls on MeHg production and identify those most critical for contaminated site assessment and management. We provide a list of parameters to assess Hg-contaminated soils and sediments with regard to their potential to be a source of MeHg to biota and therefore a risk to humans and ecological receptors. Because some measurable geochemical parameters (e.g., DOC) can have opposing effects on Hg methylation, we recommend focusing first on factors that describe the potential for Hg bio-accumulation: site characteristics, Hg and MeHg concentrations, Hg availability, and microbial activity, where practical. At some sites, more detailed assessment of biogeochemistry may be required to develop a conceptual site model for remedial decision making. Integr Environ Assess Manag 2017;13:249-263. © 2016 SETAC.
Collapse
|