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Anjuman A, Xiang Y, Liu G, Cai Y. Compositional and spectroscopic analysis of dissolved organic matter samples from Everglades periphyton and water. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:106502-106513. [PMID: 37730981 DOI: 10.1007/s11356-023-29461-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/18/2023] [Indexed: 09/22/2023]
Abstract
Periphyton is a ubiquitous niche in aquatic environments and can be a significant source of dissolved organic matter (DOM) production and leaching, especially in such environment as the Everglades, a slow-water flow wetland in Florida, USA. We employed an array of methods, including compositional analysis, 3-dimensional excitation emission matrix (3-D EEM) fluorescence spectroscopy, and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, to perform quantitative and qualitative analyses on the DOM produced by periphyton and DOM in surrounding surface water and periphyton overlying water for comparison purposes. Higher dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) contents in periphyton pore water than surface water and periphyton overlying water indicated the remarkable contribution from periphyton-produced DOM. Higher total protein, carbohydrate, and thiol contents in periphyton pore water than in surface water and periphyton overlying water underscored the possibility of periphyton pore water DOM leached from periphyton. These results agreed with 3-D EEM and ATR-FTIR analyses that showed the prevalence of possible microbial source of periphyton pore water DOM as indicated by higher fluorescence index (FI) than surface water and periphyton overlying water. Similarly, the size-fractionated DOM from surface water demonstrated terrestrial sources, and periphyton pore water demonstrated microbial sources regardless of their differences in size based on their FI values. The types of periphyton affect the production and composition of DOM, as evidenced by higher total protein, carbohydrate, and chlorophyll-a (Chl-a) contents in floating mat on the water surface than in epiphyton attached to submerged phytoplankton, probably because the former is photo-synthetically more productive than the latter due to different light availability. This study provided fundamental information on periphyton DOM that is essential for further investigating its role in carbon cycle and its biogeochemistry.
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Affiliation(s)
- Afia Anjuman
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th ST, Miami, FL, 33199, USA
| | - Yuping Xiang
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th ST, Miami, FL, 33199, USA
| | - Guangliang Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th ST, Miami, FL, 33199, USA
| | - Yong Cai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th ST, Miami, FL, 33199, USA.
- Southeast Environmental Research Center, Florida International University, 11200 SW 8Th ST, Miami, FL, 33199, USA.
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Wang K, Liu G, Cai Y. Effects of natural particles on photo-reduction of divalent mercury in everglades waters. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 323:121327. [PMID: 36822309 DOI: 10.1016/j.envpol.2023.121327] [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: 08/15/2022] [Revised: 02/17/2023] [Accepted: 02/19/2023] [Indexed: 06/18/2023]
Abstract
Photo-reduction of divalent mercury (Hg(II)) in waters plays an important role in the air-water exchange of Hg and biogeochemical cycle of Hg in general. As previous studies on photo-reduction of Hg(II) have mainly focused on dissolved Hg species, the effects of natural particles on photo-reduction of Hg(II) remain largely unknown, except the presumed light attenuating effect through light absorption and scattering. Considering the prevalence of particulate Hg due to adsorption of divalent and elemental Hg species on aquatic particles that are often photochemically active, natural particles may play a more direct role in Hg photo-reduction. By using incubation experiments with Everglades waters and additions of isotopically labelled Hg(II), we studied the effects of particles on photo-reduction of Hg(II) in natural waters. The effect of natural particles on Hg(II) photo-reduction was not observed between filtered or unfiltered Everglades waters, probably because of the low particle concentrations (<3 mg/L). When suspended particles isolated from original water was used to amend its concentration to 6.9 times the ambient Everglades waters, photo-reduction of Hg(II) was significantly enhanced. Given that the particles in Everglades waters are often semiconducting in nature, particulate Hg(II) may undergo heterogenous photo-reduction and lead to higher Hg(II) photo-reduction. However, in Everglades waters with both suspended and settling particles, high concentrations (∼100 mg/L) of particles did not result in enhanced Hg(II) photo-reduction. In this case, the enhancing effects of particles on Hg(II) photo-reduction were likely offset by inhibiting effects due to the higher irradiation attenuation and lower Hg(II) partition coefficients of the settling particles with larger sizes. This study highlights the direct involvements of particles in photoreaction of Hg species in natural waters and calls for more mechanistic research on heterogenous photo-reduction of Hg species on particles' surfaces.
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Affiliation(s)
- Kang Wang
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA
| | - Guangliang Liu
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA
| | - Yong Cai
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA.
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Janssen SE, Tate MT, Poulin BA, Krabbenhoft DP, DeWild JF, Ogorek JM, Varonka MS, Orem WH, Kline JL. Decadal trends of mercury cycling and bioaccumulation within Everglades National Park. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156031. [PMID: 35595135 DOI: 10.1016/j.scitotenv.2022.156031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) contamination has been a persistent concern in the Florida Everglades for over three decades due to elevated atmospheric deposition and the system's propensity for methylation and rapid bioaccumulation. Given declines in atmospheric Hg concentrations in the conterminous United States and efforts to mitigate nutrient release to the greater Everglades ecosystem, it was vital to assess how Hg dynamics responded on temporal and spatial scales. This study used a multimedia approach (water and biota) to examine Hg and methylmercury (MeHg) dynamics across a 76-site network within the southernmost portion of the region, Everglades National Park (ENP), from 2008 to 2018. Hg concentrations across matrices showed that air, water, and biota from the system were inextricably linked. Temporal patterns across matrices were driven primarily by hydrologic and climatic changes in the park and no evidence of a decline in atmospheric Hg deposition from 2008 to 2018 was observed, unlike other regions of the United States. In the Shark River Slough (SRS), excess dissolved organic carbon and sulfate were also consistently delivered from upgradient canals and showed no evidence of decline over the study period. Within the SRS a strong positive correlation was observed between MeHg concentrations in surface water and resident fish. Within distinct geographic regions of ENP (SRS, Marsh, Coastal), the geochemical controls on MeHg dynamics differed and highlighted regions susceptible to higher MeHg bioaccumulation, particularly in the SRS and Coastal regions. This study demonstrates the strong influence that dissolved organic carbon and sulfate loads have on spatial and temporal distributions of MeHg across ENP. Importantly, improved water quality and flow rates are two key restoration targets of the nearly 30-year Everglades restoration program, which if achieved, this study suggests would lead to reduced MeHg production and exposure.
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Affiliation(s)
- Sarah E Janssen
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA.
| | - Michael T Tate
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - Brett A Poulin
- University of California-Davis, Department of Environmental Toxicology, Davis, CA, USA
| | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - John F DeWild
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - Jacob M Ogorek
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - Matthew S Varonka
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, USA
| | - William H Orem
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, USA
| | - Jeffrey L Kline
- South Florida Natural Resources Center, Everglades National Park, Homestead, FL, USA
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Rabadjieva D, Kovacheva A, Tepavitcharova S, Ilieva R, Gergulova R, Vladov I, Karavoltsos S. Modelling of chemical species of Al, Mn, Zn, and Pb in river body waters of industrial areas of West Rhodope Mountain, Bulgaria. ENVIRONMENTAL MONITORING AND ASSESSMENT 2021; 193:430. [PMID: 34151379 DOI: 10.1007/s10661-021-09193-w] [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: 05/18/2020] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
The assessment of the ecological status of natural surface water, in terms of dominant trace metals, within an area subject to various sources of pollution including a non-ferrous metal ore mining, such as the West Rhodope Mountain, Bulgaria, is significant. The present study estimates the ecological status of river body waters at industrial areas of the West Rhodope Mountain, Bulgaria, simultaneously evaluating the possibility of state forecasting, together with assessing the potential risks, through the study of scenarios focusing on (i) possible variations of physicochemical parameters such as pH, concentration levels of trace metals, sulphates, and dissolved organic carbon (DOC) of surface water and (ii) consideration of potential spontaneous precipitation reactions in the studied waters. The ecological status of river body waters was assessed through a combination of experimental field, laboratory, and computational techniques. Al, Mn, Zn, and Pb were found to be the dominant pollutants with a variety of chemical species and distribution. The most significant difference characterizing the chemical species distribution in light of total spontaneous crystallization in the systems was found for Pb, followed by Zn and Mn, with the differences being more significant at lower trace metal levels. The calculated species were discussed on the basis of HSAB (hard and soft acids and bases) principle.
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Affiliation(s)
- Diana Rabadjieva
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str, Bl. 11, 1113, Sofia, Bulgaria.
| | - Antonina Kovacheva
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str, Bl. 11, 1113, Sofia, Bulgaria
| | - Stefka Tepavitcharova
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str, Bl. 11, 1113, Sofia, Bulgaria
| | - Radost Ilieva
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str, Bl. 11, 1113, Sofia, Bulgaria
| | - Rumiana Gergulova
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str, Bl. 11, 1113, Sofia, Bulgaria
| | - Ivelin Vladov
- Institute of Experimental Morphology, Pathology and Anthropology With Museum, Bulgarian Academy of Sciences, Acad. G. Bonchev Str, Bl. 25, 1113, Sofia, Bulgaria
| | - Sotirios Karavoltsos
- Department of Chemistry, Laboratory of Environmental Chemistry, National and Kapodistrian University of Athens, 15784, Panepistimiopolis, Athens, Greece
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Ratanawimarnwong N, Ruckchang P, Yooram S, Songsrirote K, Uraisin K, Cerdà V. Development of a microfluidic membraneless vaporization flow system for trace analysis of arsenic. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:202-211. [PMID: 33331839 DOI: 10.1039/d0ay01970d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A new design of a membraneless vaporization (MBL-VP) unit coupled with a specific flow system is presented for the determination of arsenic at trace levels using a hydride generation process. The MBL-VP unit contains two concentric conical reservoirs, with the outer cone selected as the donor reservoir. The volume of the outer donor reservoir is thereby greater than the acceptor volume, necessary for holding sufficient sample and reagents for the generation of arsine gas by reaction between As(iii) and sodium borohydride under acidic conditions. The arsine gas diffuses into the narrow headspace and is absorbed by an aliquot of 150 μL of mercuric chloride acceptor solution. The resulting reaction produces hydronium ions which is monitored by the absorbance change at 530 nm of the methyl orange indicator added in the acceptor solution. To decrease the detection limit, the aspiration and removal of the donor plug, comprising the sample, borohydride and acid, into and out of the donor cone are repeated several times, while the acceptor solution is kept unchanged. As a result, analysis of arsenic was achieved in the range of 10 to 100 μg L-1 with a detection limit of 8 μg L-1. Application to surface water was investigated. Percent recoveries of spiked surface water samples were in the range of 94-110%. For comparison of total arsenic (As(iii) and As(v)), the results obtained from the developed method are not statistically different from the ICP-OES method.
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Affiliation(s)
- Nuanlaor Ratanawimarnwong
- Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Bangkok 10110, Thailand. and Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand
| | - Patcharat Ruckchang
- Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Bangkok 10110, Thailand.
| | - Supattra Yooram
- Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Bangkok 10110, Thailand.
| | - Kriangsak Songsrirote
- Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Bangkok 10110, Thailand.
| | - Kanchana Uraisin
- Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand and Department of Chemistry, Center of the Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Victor Cerdà
- Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca, Spain
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Mercury oxidation coupled to autotrophic denitrifying branched sulfur oxidation and sulfur disproportionation for simultaneous removal of Hg0 and NO. Appl Microbiol Biotechnol 2020; 104:8489-8504. [DOI: 10.1007/s00253-020-10827-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/10/2020] [Accepted: 08/11/2020] [Indexed: 01/18/2023]
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Singh S, Kumar V. Mercury detoxification by absorption, mercuric ion reductase, and exopolysaccharides: a comprehensive study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:27181-27201. [PMID: 31001776 DOI: 10.1007/s11356-019-04974-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/22/2019] [Indexed: 06/09/2023]
Abstract
Mercury (Hg), the environmental toxicant, is present in the soil, water, and air as it is substantially distributed throughout the environment. Being extremely toxic even at low concentration, its remediation is utterly important. Therefore, it is necessary to detoxify the contaminant within the acceptable limits before threatening the environment. Although various conventional methods are being used, irrespective of high cost, it produces intermediate toxic by-product too. Biological methods are eco-friendly, clean, greener, and safer for the remediation of heavy metals corresponding to the conventional remediation due to their economic and high-tech constraints. Bioremediation is now being used for Hg (II) removal, which involves biosorption and bioaccumulation mechanisms or both, also mercuric ion reductase, exopolysaccharide play significant role in detoxification of mercury by acting a potential instrument for the remediation of heavy metals. In this review paper, we shed light on problems caused by mercury pollution, mercury cycle, and its global scenario and detoxification approaches by biological methods and result found in the literature.
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Affiliation(s)
- Shalini Singh
- Laboratory of Applied Microbiology, Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand, 826 004, India
| | - Vipin Kumar
- Laboratory of Applied Microbiology, Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand, 826 004, India.
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Huang ZS, Wei ZS, Xiao XL, Li BL, Ming S, Cheng XL, Jiao HY. Bioconversion of Hg 0 into HA-Hg for simultaneous removal of Hg 0 and NO in a denitrifying membrane biofilm reactor. CHEMOSPHERE 2020; 244:125544. [PMID: 32050341 DOI: 10.1016/j.chemosphere.2019.125544] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 12/01/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
Bacterial mercury oxidation coupled to denitrification offers great potential for simultaneous removal of elemental mercury (Hg0) and nitric oxide (NO) in a denitrifying membrane biofilm reactor (MBfR). Four potentially contributory mechanisms tested separately, namely, membrane gas separation, medium absorption, biosorption and biotransformation, which contributed 4.9%/7.2%, 8.1%/8.9%, 38.8%/9.5% and 48.2%/84.9% of overall Hg0/NO removal in MBfR. Herein, Hg0 bio-oxidation, oxidative Hg0 biosorption and denitrification played leading roles in simultaneous removal of Hg0 and NO. Living microbes performed simultaneous Hg0 bio-oxidation and denitrification, in which Hg0 as electron donor was biologically oxidized to oxidized mercury (Hg2+), while NO as the terminal electron acceptor was denitrified to N2. The Hg2+ further complexed with humic acids in extracellular polymeric substances via functional groups (-SH, -OH, -NH- and -COO-) and formed humic acids bound mercury (HA-Hg). Non-living microbial matrix performed oxidative Hg0 biosorption, in which Hg0 may be physically adsorbed by cellular matrix, then non-metabolically oxidized to Hg2+ via oxidative complexation with -SH in humic acids and finally cleavage of S-H bond and surface charge transfer led to formation of HA-Hg. Therefore, bioconversion of Hg0 to HA-Hg by Hg0 bio-oxidation and oxidative Hg0 biosorption coupled with NO denitrification to N2 dynamically cooperated to accomplish simultaneous removal of Hg0 and NO in MBfR.
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Affiliation(s)
- Z S Huang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
| | - Z S Wei
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China.
| | - X L Xiao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
| | - B L Li
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
| | - S Ming
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
| | - X L Cheng
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
| | - H Y Jiao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
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Eckley CS, Gilmour CC, Janssen S, Luxton TP, Randall PM, Whalin L, Austin C. The assessment and remediation of mercury contaminated sites: A review of current approaches. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 707:136031. [PMID: 31869604 PMCID: PMC6980986 DOI: 10.1016/j.scitotenv.2019.136031] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/07/2019] [Accepted: 12/07/2019] [Indexed: 04/13/2023]
Abstract
Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial extent of contamination, Hg stable isotope fractionation to identify sources and transformation processes, and solid-phase characterization (XAFS) to evaluate Hg forms. The understanding of Hg bioavailability for methylation has been improved by methods such as sequential chemical extractions and porewater measurements, including the use of diffuse gradient in thin-film (DGT) samplers. These approaches have shown varying success in identifying bioavailable Hg fractions and further study and field applications are needed. The downstream accumulation of methylmercury (MeHg) in biota is a concern at many contaminated sites. Identifying the variables limiting/controlling MeHg production-such as bioavailable inorganic Hg, organic carbon, and/or terminal electron acceptors (e.g. sulfate, iron) is critical. Mercury can be released from contaminated sites to the air and water, both of which are influenced by meteorological and hydrological conditions. Mercury mobilized from contaminated sites is predominantly bound to particles, highly correlated with total sediment solids (TSS), and elevated during stormflow. Remediation techniques to address Hg contamination can include the removal or containment of Hg contaminated materials, the application of amendments to reduce mobility and bioavailability, landscape/waterbody manipulations to reduce MeHg production, and food web manipulations through stocking or extirpation to reduce MeHg accumulated in desired species. These approaches often rely on knowledge of the Hg forms/speciation at the site, and utilize physical, chemical, thermal and biological methods to achieve remediation goals. Overall, the complexity of Hg cycling allows many different opportunities to reduce/mitigate impacts, which creates flexibility in determining suitable and logistically feasible remedies.
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Affiliation(s)
- Chris S Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101, USA.
| | - Cynthia C Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 21037-0028, USA.
| | - Sarah Janssen
- USGS Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA.
| | - Todd P Luxton
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Paul M Randall
- US Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA.
| | - Lindsay Whalin
- San Francisco Bay Water Board, 1515 Clay St., Ste. 1400, Oakland, CA 94612, USA.
| | - Carrie Austin
- San Francisco Bay Water Board, 1515 Clay St., Ste. 1400, Oakland, CA 94612, USA.
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Huang Z, Wei Z, Xiao X, Tang M, Li B, Ming S, Cheng X. Bio-oxidation of Elemental Mercury into Mercury Sulfide and Humic Acid-Bound Mercury by Sulfate Reduction for Hg 0 Removal in Flue Gas. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12923-12934. [PMID: 31589025 DOI: 10.1021/acs.est.9b04029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bioconversion of elemental mercury (Hg0) into immobile, nontoxic, and less bioavailable species is of vital environmental significance. Here, we investigated bioconversion of Hg0 in a sulfate-reducing membrane biofilm reactor (MBfR). The MBfR achieved effective Hg0 removal by sulfate bioreduction. 16 S rDNA sequencing and metagenomic sequencing revealed that diverse groups of mercury-oxidizing/sulfate-reducing bacteria (Desulfobulbus, Desulfuromonas, Desulfomicrobium, etc.) utilized Hg0 as the initial electron donor and sulfate as the terminal electron acceptor to form the overall redox. These microorganisms coupled Hg0 bio-oxidation to sulfate bioreduction. Analysis on mercury speciation in biofilm by sequential extraction processes (SEPs) and inductively coupled mass spectrometry (ICP-MS) and by mercury temperature programmed desorption (Hg-TPD) showed that mercury sulfide (HgS) and humic acid-bound mercury (HA-Hg) were two major products of Hg0 bio-oxidation. With HgS and HA-Hg comprehensively characterized by X-ray diffraction (XRD), excitation-emission matrix spectra (EEM), scanning electron microscopy-energy disperse spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), it was proposed that biologically oxidized mercury (Hg2+) further reacted with biogenic sulfides to form cubically crystallized metacinnabar (β-HgS) extracellular particles. Hg2+ was also complexed with functional groups -SH, -OH, -NH-, and -COO- in humic acids from extracellular polymeric substances (EPS) to form HA-Hg. HA-Hg may further react with biogenic sulfides to form HgS. Bioconversion of Hg0 into HgS was therefore achieved and can be a feasible biotechnique for flue gas demercuration.
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Affiliation(s)
- Zhenshan Huang
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
| | - Zaishan Wei
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
| | - Xiaoliang Xiao
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
| | - Meiru Tang
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
| | - Bailong Li
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
| | - Song Ming
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
| | - Xiangling Cheng
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology , Sun Yat-sen University , Guangzhou 510275 , China
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