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Zhou Y, Li S, Hintelmann H, Tang W, Zhong H. New insights into HgSe antagonism: Minor impact on inorganic Hg mobility while potential impacts on microorganisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 913:169705. [PMID: 38160847 DOI: 10.1016/j.scitotenv.2023.169705] [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: 10/27/2023] [Revised: 12/13/2023] [Accepted: 12/25/2023] [Indexed: 01/03/2024]
Abstract
Selenium (Se) is a crucial antagonistic factor of mercury (Hg) methylation in soil, with the transformation of inorganic Hg (IHg) to inert mercury selenide (HgSe) being the key mechanism. However, little evidence has been provided of the reduced Hg mobility at environmentally relevant doses of Hg and Se, and the potential impacts of Se on the activities of microbial methylators have been largely ignored. This knowledge gap hinders effective mitigation for methylmercury (MeHg) risks, considering that Hg supply and microbial methylators serve as materials and workers for MeHg production in soils. By monitoring the mobility of IHg and microbial activities after Se spike, we reported that 1) active methylation might be the premise of HgSe antagonism, as higher decreases in MeHg net production were found in soils with higher constants of Hg methylation rate; 2) IHg mobility did not significantly change upon Se addition in soils with high DOC concentrations, challenging the long-held view of Hg immobilization by Se; and 3) the activities of iron-reducing bacteria (FeRB), an important group of microbial methylators, might be potentially regulated by Se addition at a dose of 4 mg/kg. These findings provide empirical evidence that IHg mobility may not be the limiting factor under Se amendment and suggest the potential impacts of Se on microbial activities.
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Affiliation(s)
- Yang Zhou
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Holger Hintelmann
- Department of Chemistry, Trent University, Peterborough, ON, Canada; Water Quality Centre, Trent University, Peterborough, ON, Canada
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
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Wang T, Yang X, Li Z, Chen W, Wen X, He Y, Ma C, Yang Z, Zhang C. MeHg production in eutrophic lakes: Focusing on the roles of algal organic matter and iron-sulfur-phosphorus dynamics. JOURNAL OF HAZARDOUS MATERIALS 2023; 457:131682. [PMID: 37270963 DOI: 10.1016/j.jhazmat.2023.131682] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/20/2023] [Accepted: 05/21/2023] [Indexed: 06/06/2023]
Abstract
The mechanisms by which eutrophication affects methylmercury (MeHg) production have not been comprehensively summarized, which hinders accurately predicting the MeHg risk in eutrophic lakes. In this review, we first discussed the effects of eutrophication on biogeochemical cycle of mercury (Hg). Special attentions were paid to the roles of algal organic matter (AOM) and iron (Fe)-sulfur (S)-phosphorus (P) dynamics in MeHg production. Finally, the suggestions for risk control of MeHg in eutrophic lakes were proposed. AOM can affect in situ Hg methylation by stimulating the abundance and activities of Hg methylating microorganisms and regulating Hg bioavailability, which are dependent on bacteria-strain and algae species, the molecular weight and composition of AOM as well as environmental conditions (e.g., light). Fe-S-P dynamics under eutrophication including sulfate reduction, FeS formation and P release could also play crucial but complicated roles in MeHg production, in which AOM may participate through influencing the dissolution and aggregation processes, structural order and surface properties of HgS nanoparticles (HgSNP). Future studies should pay more attention to the dynamics of AOM in responses to the changing environmental conditions (e.g., light penetration and redox fluctuations) and how such variations will subsequently affect MeHg production. The effects of Fe-S-P dynamics on MeHg production under eutrophication also deserve further investigations, especially the interactions between AOM and HgSNP. Remediation strategies with lower disturbance, greater stability and less cost like the technology of interfacial O2 nanobubbles are urgent to be explored. This review will deepen our understanding of the mechanisms of MeHg production in eutrophic lakes and provide theoretical guidance for its risk control.
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Affiliation(s)
- Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Chi Ma
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zhongzhu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
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Chen W, Yu Z, Yang X, Wang T, Li Z, Wen X, He Y, Zhang C. Unveiling the Role of Dissolved Organic Matter on the Hg Phytoavailability in Biochar-Amended Soils. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:3761. [PMID: 36834455 PMCID: PMC9963283 DOI: 10.3390/ijerph20043761] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 06/13/2023]
Abstract
Biochar can effectively reduce the phytoavailability of mercury (Hg) in soil, but the mechanisms are not fully understood. In this study, the dynamic changes in Hg content adsorbed by the biochar (BC-Hg), Hg phytoavailability in the soil (P-Hg), and soil dissolved organic matter (DOM) characteristics were determined over a 60-day treatment period. Biochar obtained at 300 °C, 500 °C and 700 °C reduced the P-Hg concentration assessed by MgCl2 extraction by 9.4%, 23.5% and 32.7%, respectively. However, biochar showed a very limited adsorption on Hg, with the maximum BC-Hg content only accounting for 1.1% of the total amount. High-resolution scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) results showed that the proportion of Hg atoms in biochar after 60 d was barely detectable. Biochar treatment can shift soil DOM toward higher aromatic content and molecular weight. Additionally, the addition of high-temperature biochar increased more humus-like components, but low-temperature biochar increased more protein-like components. Correlation analysis and partial least squares path modeling (PLS-PM) showed that biochar promoted humus-like fractions formation to reduce the Hg phytoavailability. This research has deepened the understanding of the mechanisms by which biochar stabilizes Hg in agricultural soils.
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Affiliation(s)
- Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zhigang Yu
- Australian Centre for Water and Environmental Biotechnology (Formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
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Hu H, Gao Y, Yu H, Xiao H, Chen S, Tan W, Tang J, Xi B. Mechanisms and biological effects of organic amendments on mercury speciation in soil-rice systems: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 251:114516. [PMID: 36628877 DOI: 10.1016/j.ecoenv.2023.114516] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and biomagnification effects. As the largest global Hg reservoir, the Hg cumulatively stored in soils has reached as high as 250-1000 Gg. Even more concerning is that global soil-rice systems distributed in many countries have become central to the global Hg cycle because they are both a major food source for more than 3 billion people worldwide and the central bridge linking atmospheric and soil Hg circulation. In this review, we discuss the form distribution, transformation, and bioavailability of Hg in soil-rice systems by focusing on the Hg methylation and demethylation pathways and distribution, uptake, and accumulation in rice plants and the effects of Hg on the community structure and ecological functions of microorganisms in soil-rice systems. In addition, we clarify the mechanisms through which commonly used humus and biochar organic amendments influence Hg and its environmental effects in soil-rice systems. The review also elaborates on the advantages of sulfur-modified biochars and their critical role in controlling Hg migration and bioavailability in soils. Finally, we provide key information about Hg pollution in soil-rice systems, which is of great significance for developing appropriate strategies and mitigation planning to limit Hg bioconcentration in rice crops and achieving key global sustainable development goals, such as the guarantee of food security and the promotion of sustainable agriculture.
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Affiliation(s)
- Hualing Hu
- Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Yiman Gao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Hanxia Yu
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Haoyan Xiao
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Shuhe Chen
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Wenbing Tan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Jun Tang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Beidou Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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Li HH, Tsui MTK, Ku P, Chen H, Yin Z, Dahlgren RA, Parikh SJ, Wei J, Hoang TC, Chow AT, Cheng Z, Zhu XM. Impacts of Forest Fire Ash on Aquatic Mercury Cycling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11835-11844. [PMID: 35905396 DOI: 10.1021/acs.est.2c01591] [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: 06/15/2023]
Abstract
Mercury (Hg) is a ubiquitous contaminant in the environment and its methylated form, methylmercury (MeHg), poses a worldwide health concern for humans and wildlife, primarily through fish consumption. Global production of forest fire ash, derived from wildfires and prescribed burns, is rapidly increasing due to a warming climate, but their interactions with aqueous and sedimentary Hg are poorly understood. Herein, we compared the differences of wildfire ash with activated carbon and biochar on the sorption of aqueous inorganic Hg and sedimentary Hg methylation. Sorption of aqueous inorganic Hg was greatest for wildfire ash materials (up to 0.21 μg g-1 or 2.2 μg g-1 C) among all of the solid sorbents evaluated. A similar Hg adsorption mechanism for activated carbon, biochar made of walnut, and wildfire ash was found that involves the formation of complexes between Hg and oxygen-containing functional groups, especially the -COO group. Notably, increasing dissolved organic matter from 2.4 to 70 mg C L-1 remarkably reduced Hg sorption (up to 40% reduction) and increased the time required to reach Hg-sorbent pseudo-equilibrium. Surprisingly, biochar and wildfire ash, but not activated carbon, stimulated MeHg production during anoxic sediment incubation, possibly due to the release of labile organic matter. Overall, our study indicates that while wildfire ash can sequester aqueous Hg, the leaching of its labile organic matter may promote production of toxic MeHg in anoxic sediments, which has an important implication for potential MeHg contamination in downstream aquatic ecosystems after wildfires.
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Affiliation(s)
- Han-Han Li
- College of Environmental Science, Sichuan Agricultural University, Chengdu 611130, China
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Martin Tsz-Ki Tsui
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, NT , Hong Kong SAR, China
| | - Peijia Ku
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Huan Chen
- Biogeochemistry & Environmental Quality Research Group, Clemson University, Georgetown, South Carolina 29442, United States
| | - Ziyu Yin
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro, Greensboro, North Carolina 27401, United States
| | - Randy A Dahlgren
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, United States
| | - Sanjai J Parikh
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, United States
| | - Jianjun Wei
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro, Greensboro, North Carolina 27401, United States
| | - Tham C Hoang
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama 36849, United States
| | - Alex T Chow
- Biogeochemistry & Environmental Quality Research Group, Clemson University, Georgetown, South Carolina 29442, United States
| | - Zhang Cheng
- College of Environmental Science, Sichuan Agricultural University, Chengdu 611130, China
| | - Xue-Mei Zhu
- College of Environmental Science, Sichuan Agricultural University, Chengdu 611130, China
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Hu H, Xi B, Tan W. Effects of sulfur-rich biochar amendment on microbial methylation of mercury in rhizosphere paddy soil and methylmercury accumulation in rice. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 286:117290. [PMID: 33984776 DOI: 10.1016/j.envpol.2021.117290] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 04/12/2021] [Accepted: 04/29/2021] [Indexed: 06/12/2023]
Abstract
Biochar amendment has the potential to reduce methylmercury (MeHg) uptake by rice grains in soil-rice ecosystem. Considering that sulfur can strongly bind Hg and thus reduce its bioavailability, S-modified biochar has been used to immobilize Hg in soils. However, whether natural S-enriched biochar can further reduce Hg and MeHg phytoavailability remains unknown. Moreover, the rhizosphere is one of the most important microbial hotspots regulating the pollutant dynamics in terrestrial ecosystems. Therefore, it is of greater practical significance to examine the impact of biochar amendment on MeHg production and phytoavailability in the rhizosphere versus nonrhizosphere. Here, by conducting a pot experiment, we evaluated the efficacy of biochar derived from sulfur-enriched oilseed rape straw to reduce MeHg accumulation in rice. The results demonstrated that: (1) biochar-induced enhancement of chloride ion and sulfate levels in the overlying water and pore water facilitate microbial methylation of Hg and thus MeHg production in rhizosphere soil. (2) biochar amendment increased rhizosphere soil sulfur content and humic acid-like substances, strengthening MeHg binding to soil, and thus reducing grain MeHg levels by 47%-75%. Our results highlight the necessity to applying natural sulfur-rich biochar accompanied with exogenous sulfur to further reduce MeHg phytoavailability.
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Affiliation(s)
- Hualing Hu
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300350, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Beidou Xi
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300350, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
| | - Wenbing Tan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
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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.
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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.
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Wang AO, Ptacek CJ, Mack EE, Blowes DW. Impact of multiple drying and rewetting events on biochar amendments for Hg stabilization in floodplain soil from South River, VA. CHEMOSPHERE 2021; 262:127794. [PMID: 32771706 DOI: 10.1016/j.chemosphere.2020.127794] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 05/07/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
Frequent drying and rewetting due to flooding/precipitation and drainage events in floodplains induces changes in biogeochemical conditions that may influence the effectiveness of in situ Hg stabilization using biochars as soil amendments. This study evaluated two selected biochars anaerobic digestate (DIG) and sulfurized hardwood (MOAK)) as potential amendment materials in moderately reduced floodplain soil under repeated drying and rewetting events using a modified humidity cell protocol. Enhanced release of filter-passing (0.45-μm) total Hg (THg) and MeHg was observed at early times. Elevated concentrations of 0.45-μm THg were associated with DOC and Mn in sediment control and biochar-amended systems. Elevated concentrations of MeHg were associated with Mn in the MOAK-amended system. Thereafter, decreases in 0.45-μm (up to 57%) and unfiltered THg (up to 93%) were observed. As wetting and drying events continued, decreases in pH and alkalinity as well as increases in SO42- (up to 796 mg L-1) and Ca (up to 215 mg L-1) were observed in the MOAK-amended systems with the microbial community shifted towards sulfur-oxidizing bacteria, indicating microbially-driven oxidation of MOAK. Although results of S K-edge X-ray absorption near edge structure (XANES) analysis suggest polysulfur is the predominant S phase in both MOAK- and DIG-amended systems, microbially-driven oxidation of DIG was not observed. Polysulfur in MOAK from the sulfurization process is more bioavailable to sulfur oxidizing communities than in DIG under the repeated drying and wetting conditions. Results of this study suggest biogeochemical conditions as well as biochar properties should be considered when planning full-scale field applications.
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Affiliation(s)
- Alana O Wang
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada
| | - Carol J Ptacek
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada.
| | - E Erin Mack
- Formerly at E. I. Du Pont de Nemours and Company, 974 Centre Road, Wilmington, DE, 19805, USA
| | - David W Blowes
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada
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Liu Z, Chen B, Wang LA, Urbanovich O, Nagorskaya L, Li X, Tang L. A review on phytoremediation of mercury contaminated soils. JOURNAL OF HAZARDOUS MATERIALS 2020; 400:123138. [PMID: 32947735 DOI: 10.1016/j.jhazmat.2020.123138] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 05/28/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
Mercury (Hg) and its compounds are one of the most dangerous environmental pollutants and Hg pollution exists in soils in different degrees over the world. Phytoremediation of Hg-contaminated soils has attracted increasing attention for the advantages of low investment, in-situ remediation, potential economic benefits and so on. Searching for the hyperaccumulator of Hg and its application in practice become a research hotspot. In this context, we review the current literatures that introduce various experimental plant species for accumulating Hg and aided techniques improving the phytoremediation of Hg-contaminated soils. Experimental plant species for accumulating Hg and accumulation or translocation factor of Hg are listed in detail. The translocation factor (TF) is greater than 1.0 for some plant species, however, the bioaccumulation factor (BAF) is greater than 1.0 for Axonopus compressus only. Plant species, soil properties, weather condition, and the bioavailability and heterogeneity of Hg in soils are the main factors affecting the phytoremediation of Hg-contaminated soils. Chemical accelerator kinds and promoting effect of chemical accelerators for accumulating and transferring Hg by various plant species are also discussed. Potassium iodide, compost, ammonium sulphate, ammonium thiosulfate, sodium sulfite, sodium thiosulfate, hydrochloric acid and sulfur fertilizer may be selected to promote the absorption of Hg by plants. The review introduces transgenic gene kinds and promoting effect of transgenic plants for accumulating and transferring Hg in detail. Some transgenic plants can accumulate more Hg than non-transgenic plants. The composition of rhizosphere microorganisms of remediation plants and the effect of rhizosphere microorganisms on the phytoremediation of Hg-contaminated soils are also introduced. Some rhizosphere microorganisms can increase the mobility of Hg in soils and are beneficial for the phytoremediation.
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Affiliation(s)
- Zhongchuang Liu
- Green Intelligence Environmental School, Yangtze Normal University, 16 Juxian Rd. Lidu, Fuling District of Chongqing, China; Chongqing Multiple-source Technology Engineering Research Center for Ecological Environment Monitoring, Yangtze Normal University, 16 Juxian Rd. Lidu, Fuling District of Chongqing, China.
| | - Boning Chen
- Fuling Environmental Monitoring Center, 3 Taibai Rd, Fuling New District of Chongqing, China
| | - Li-Ao Wang
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing, China; College of Resources and Environmental Science, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing, China
| | - Oksana Urbanovich
- Institute of Genetics and Cytology, National Academy of Sciences of Belarus, Minsk, 220072, Belarus
| | - Liubov Nagorskaya
- Applied Science Center for Bioresources of the National Academy of Sciences of Belarus, Minsk, 220072, Belarus
| | - Xiang Li
- International Policy, Faculty of Law and Economics, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
| | - Li Tang
- School of Chemistry and Chemical Engineering, Southwest University, 2 Tiansheng Road, Beibei District, Chongqing, China
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Wang AO, Ptacek CJ, Paktunc D, Mack EE, Blowes DW. Application of biochar prepared from ethanol refinery by-products for Hg stabilization in floodplain soil: Impacts of drying and rewetting. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115396. [PMID: 32882459 DOI: 10.1016/j.envpol.2020.115396] [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: 01/22/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
This study evaluated three biochars derived from bioenergy by-products - manure-based anaerobic digestate (DIG), distillers' grains (DIS), and a mixture thereof (75G25S) - as amendments to stabilize Hg in contaminated floodplain soil under long-term saturated (up to 200 d) and cyclic drying and rewetting conditions. Greater total Hg (THg) removal (72 to nearly 100%) and limited MeHg production (<65 ng L-1) were observed in digestate-based biochar-amended systems under initial saturated conditions. Drying and rewetting resulted in limited THg release, increased aqueous MeHg, and decreased solid MeHg in digestate-based biochar-amended systems. Changes in Fe and S chemistry as well as microbial communities during drying and rewetting potentially affected MeHg production. Digestate-based biochars may be more effective as amendments to control Hg release and minimize MeHg production in floodplain soils under long-term saturated and drying and rewetting conditions compared to distillers' grains biochar.
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Affiliation(s)
- Alana O Wang
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada
| | - Carol J Ptacek
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada.
| | - Dogan Paktunc
- CanmetMINING, Natural Resource Canada, Ottawa, ON, K1A 0G1, Canada
| | - E Erin Mack
- Formerly E. I. du Pont de Nemours and Company, 974 Centre Road, Wilmington, DE, 19805, USA
| | - David W Blowes
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada
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11
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Tang Z, Fan F, Deng S, Wang D. Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 202:110950. [PMID: 32800226 DOI: 10.1016/j.ecoenv.2020.110950] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.
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Affiliation(s)
- Zhenya Tang
- Faculty of Environmental Science & Engineering, Kunming University of Science &Technology, Kunming, China; Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China.
| | - Fangling Fan
- School of Energy and Environment Science, Yunnan Normal University, Kunming, China.
| | - Shiping Deng
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK, USA.
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China; State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing, China.
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12
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Gustin MS, Bank MS, Bishop K, Bowman K, Branfireun B, Chételat J, Eckley CS, Hammerschmidt CR, Lamborg C, Lyman S, Martínez-Cortizas A, Sommar J, Tsui MTK, Zhang T. Mercury biogeochemical cycling: A synthesis of recent scientific advances. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 737:139619. [PMID: 32783819 PMCID: PMC7430064 DOI: 10.1016/j.scitotenv.2020.139619] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 05/23/2023]
Abstract
The focus of this paper is to briefly discuss the major advances in scientific thinking regarding: a) processes governing the fate and transport of mercury in the environment; b) advances in measurement methods; and c) how these advances in knowledge fit in within the context of the Minamata Convention on Mercury. Details regarding the information summarized here can be found in the papers associated with this Virtual Special Issue of STOTEN.
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Affiliation(s)
- Mae Sexauer Gustin
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV 89439, USA.
| | - Michael S Bank
- Department of Contaminants and Biohazards, Institute of Marine Research, Bergen, Norway; Department of Environmental Conservation, University of Massachusetts, Amherst, MA 01255, USA
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden
| | - Katlin Bowman
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA; University of California Santa Cruz, Ocean Sciences Department, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Brian Branfireun
- Department of Biology and Centre for Environment and Sustainability, Western University, London, Canada
| | - John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada
| | - Chris S Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101, USA
| | - Chad R Hammerschmidt
- Wright State University, Department of Earth and Environmental Sciences, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA
| | - Carl Lamborg
- University of California Santa Cruz, Ocean Sciences Department, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Seth Lyman
- Bingham Research Center, Utah State University, 320 N Aggie Blvd., Vernal, UT, USA
| | - Antonio Martínez-Cortizas
- EcoPast (GI-1553), Facultade de Bioloxía, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Jonas Sommar
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Martin Tsz-Ki Tsui
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China
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13
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Ji X, Liu C, Zhang M, Yin Y, Pan G. Mitigation of methylmercury production in eutrophic waters by interfacial oxygen nanobubbles. WATER RESEARCH 2020; 173:115563. [PMID: 32059129 DOI: 10.1016/j.watres.2020.115563] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/17/2020] [Accepted: 01/28/2020] [Indexed: 06/10/2023]
Abstract
In mercury (Hg)-polluted eutrophic waters, algal blooms are likely to aggravate methylmercury (MeHg) production by causing intensified hypoxia and enriching organic matter at the sediment-water interface. The technology of interfacial oxygen (O2) nanobubbles is proven to alleviate hypoxia and may have potential to mitigate the risks of MeHg formation. In this study, incubation column experiments were performed using sediment and overlying water samples collected from the Baihua Reservoir (China), which is currently suffering from co-contamination of Hg and eutrophication. The results indicated that after the application of O2 nanobubbles, the %MeHg (ratio of MeHg to total Hg) in the overlying water and surface sediment decreased by up to 76% and 56% respectively. In addition, the MeHg concentrations decreased from 0.54 ± 0.15 to 0.17 ± 0.01 ng L-1 in the overlying water and from 56.61 ± 9.23 to 25.48 ± 4.08 ng g-1 in the surface sediment. The decline could be attributed to the alleviation of anoxia and the decrease of labile organic matter and bioavailable Hg. In addition, hgcA gene abundances in the overlying water and surface sediment decreased by up to 69% and 44% after the addition of O2 nanobubbles, as is consistent with MeHg occurrence in such areas. Accordingly, this work proposed a promising strategy of using interfacial oxygen nanobubbles to alleviate the potentially enhanced MeHg production during algal bloom outbreaks in Hg-polluted eutrophic waters.
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Affiliation(s)
- Xiaonan Ji
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Chengbin Liu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, PR China
| | - Meiyi Zhang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China.
| | - Yongguang Yin
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China
| | - Gang Pan
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China; Beijing Advanced Science and Innovation Center, Chinese Academy of Sciences, Beijing, 101407, PR China; Center of Integrated Water-Energy-Food Studies (iWEF), School of Animal, Rural, and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, NG25 0QF, UK.
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14
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Wang AO, Ptacek CJ, Blowes DW, Finfrock YZ, Paktunc D, Mack EE. Use of hardwood and sulfurized-hardwood biochars as amendments to floodplain soil from South River, VA, USA: Impacts of drying-rewetting on Hg removal. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 712:136018. [PMID: 32050399 DOI: 10.1016/j.scitotenv.2019.136018] [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: 09/09/2019] [Revised: 11/24/2019] [Accepted: 12/07/2019] [Indexed: 06/10/2023]
Abstract
Periodic flooding and drying conditions in floodplains affect the mobility and bioavailability of Hg in aquatic sediments and surrounding soils. Sulfurized materials have been recently proposed as Hg sorbents due to their high affinity to bind Hg, while sulfurizing organic matter may enhance methylmercury (MeHg) production, offsetting the beneficial aspects of these materials. This study evaluated hardwood biochar (OAK) and sulfurized-hardwood biochar (MOAK) as soil amendments for controlling Hg release in a contaminated floodplain soil under conditions representative of periodic flooding and drying in microcosm experiments in three stages: (1) wet biochar amended-systems with river water in an anoxic environment up to 200 d; (2) dry selected reaction vessels in an oxic environment for 90 d; (3) rewet such vessels with river water in an anoxic environment for 90 d. In Stage 1, greater Hg removal (17-98% for unfiltered total Hg (THg) and 47-99% for 0.45-μm THg) and lower MeHg concentrations (<20 ng L-1) were observed in MOAK-amended systems (10%MOAKs). In Stage 3, release of Hg in 10%MOAKs was eight-fold lower than in soil controls (SedCTRs), while increases in aqueous (up to 21 ng L-1) and solid (up to 88 ng g-1) MeHg concentrations were observed. The increases in MeHg corresponded to elevated aqueous concentrations of Mn, Fe, SO42-, and HS- in Stage 3. Results of S K-edge X-ray absorption near edge structure (XANES) analysis suggest oxidation of S in Stage 2 and formation of polysulfur in Stage 3. Results of pyrosequencing analysis indicate sulfate-reducing bacteria (SRB) became abundant in Stage 3 in 10%MOAKs. The shifts in biogeochemical conditions in 10%MOAKs in Stage 3 may increase the bioavailability of Hg to methylating bacteria. The results suggest limited impacts on Hg removal during drying and rewetting, while changes in biogeochemical conditions may affect MeHg production in sulfurized biochar-amended systems.
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Affiliation(s)
- Alana O Wang
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W, Waterloo, ON N2L 3G1, Canada
| | - Carol J Ptacek
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W, Waterloo, ON N2L 3G1, Canada.
| | - David W Blowes
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W, Waterloo, ON N2L 3G1, Canada
| | - Y Zou Finfrock
- CLS@APS, Sector 20, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA; Science Division, Canadian Light Source Inc., Saskatoon, SK S7N 2V3, Canada
| | - Dogan Paktunc
- CanmetMINING, Natural Resource Canada, Ottawa, ON K1A 0G1, Canada
| | - E Erin Mack
- Formerly E. I. du Pont de Nemours and Company, 974 Centre Road, Wilmington, DE 19805, USA
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15
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Ting Y, Ch'ng BL, Chen C, Ou MY, Cheng YH, Hsu CJ, Hsi HC. A simulation study of mercury immobilization in estuary sediment microcosm by activated carbon/clay-based thin-layer capping under artificial flow and turbation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 708:135068. [PMID: 31780157 DOI: 10.1016/j.scitotenv.2019.135068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/10/2019] [Accepted: 10/18/2019] [Indexed: 06/10/2023]
Abstract
In-situ thin layer capping (TLC) is a promising sediment remediation approach that has been shown effective in immobilizing contaminants from releasing to natural biotas and human beings. This research intended to comprehend the effectiveness of Hg immobilization by TLC under turbation condition via a microcosm study. Three TLC caps with different activated carbon (AC)/clay combinations were applied to actual Hg-contaminated estuary sediment (76.0 ± 2.6 mg-Hg/kg). The caps with AC (3%) + bentonite (3%) and AC (3%) + kaolin (3%) were efficient in reducing both total mercury (THg) and methylmercury (MeHg) concentrations in overlying water by 75-95% and 64-98%, respectively, in the later stage of 75-d operation. In contrast, the AC (3%) + montmorillonite (3%) cap did not show a significant reduction on THg and MeHg in the overlying water, probably due to the unstable, suspension property of montmorillonite. The stable caps showed higher resistance to Hg breakthrough under occasional turbation events; however, a labile cap appeared to have dramatic Hg breakthrough when turbation occurred. It is therefore essential to note that with unstable caps, turbation events may result in unwanted secondary resuspension of contaminants.
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Affiliation(s)
- Yu Ting
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Boon-Lek Ch'ng
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Chi Chen
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Meng-Yuan Ou
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Yung-Hua Cheng
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Che-Jung Hsu
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan
| | - Hsing-Cheng Hsi
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan.
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16
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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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17
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Jiao Y, Xu L, Li Q, Gu S. Thin-layer fine-sand capping of polluted sediments decreases nutrients in overlying water of Wuhan Donghu Lake in China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:7156-7165. [PMID: 31879889 DOI: 10.1007/s11356-019-07297-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Capping water body sediments with a thin layer of sand is an effective technique to decrease nutrient concentrations in the water column and accelerate ecological restoration of eutrophic water bodies. However, long-term effects of thin-layer sand capping in shallow lakes are reported less often. Using clean fine sand and geotextile mats as capping materials for sediments collected from Wuhan Donghu Lake in China, we designed a 290-day tank experiment with 3 cm of sand capping at four percentages of sediment coverage from 25 to 100% and a control (no capping). We monitored total nitrogen (TN), total phosphorus (TP), nitrate (NO3-), ammonia (NH4+), and soluble reactive phosphorus (SRP) in the overlying water every 7 days. Mean TN and NO3- concentrations were significantly the lowest (P < 0.05) at 50% coverage. Further increase in coverage kept them slightly fluctuating. NH4+ concentration was significantly lowest (P < 0.05) at 75% coverage. The relation between coverage and mean TP and SRP concentrations indicated that 75% coverage significantly decreased (P < 0.05) them, and increasing coverage to 100% decreased them even more. The fluxes of TN and TP estimated between sediments and overlying water showed that the thin fine-sand layer significantly increased the function of sediments as a sink of TN from overlying water and the potential of a sand layer to block release of TP from sediments (P < 0.05). Our results suggested that if thin-layer sand capping were applied to Wuhan Donghu Lake, more than 50% coverage is required to decrease nutrients in the lake's water.
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Affiliation(s)
- Yang Jiao
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, 430072, China
| | - Lei Xu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Qingman Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, 430072, China.
| | - Sen Gu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, 430072, China
- Univ. Rennes, CNRS, OSUR, Géosciences - UMR 6118, F-35000, Rennes, France
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18
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Ji X, Liu C, Pan G. Interfacial oxygen nanobubbles reduce methylmercury production ability of sediments in eutrophic waters. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 188:109888. [PMID: 31706242 DOI: 10.1016/j.ecoenv.2019.109888] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 10/23/2019] [Accepted: 10/27/2019] [Indexed: 06/10/2023]
Abstract
Eutrophication can induce hypoxia/anoxia and rich organic matter at the sediment-water interface in surface waters. When eutrophic waters are impacted with mercury (Hg) pollution, methylmercury (MeHg) production ability (MPA) of surface sediment would increase and more MeHg might be produced. To tackle this risk, this study firstly collected samples of surface sediment and overlying water from a typical eutrophic lake-Taihu Lake. Then from a sediment-water simulation system, we demonstrated that eutrophic waters were able to methylate Hg spontaneously, and that sediment is the major Hg sink in the system. After the addition of HgCl2 solution (approximately 1 mg L-1 in the slurry), MeHg concentrations in the sediment increased by 11.7 times after 48 h. The subsequent column experiments proved that O2 nanobubbles could significantly decrease the MPA of surface sediment, by up to 48%. Furthermore, we found that O2 nanobubbles could remediate anoxia mainly by increasing dissolved oxygen (from 0 to 2.1 mg L-1), oxidation-reduction potentials (by 37% on average), and sulfate (by 31% on average) in the overlying water. In addition, O2 nanobubbles could also help decrease organic matter concentration, as was revealed by the decline of dissolved organic carbon in the overlying water (by up to 57%) and total organic carbon in surface sediment (by up to 37%). The remediation of anoxia and reduction of organic matter could contribute to the decrease of hgcA gene abundance (by up to 86%), and thus result in the reduction of MPA after the addition of O2 nanobubbles. This study revealed the risk of MeHg production in case Hg pollution occurs in eutrophic waters and proposed a feasible solution for MeHg remediation.
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Affiliation(s)
- Xiaonan Ji
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Chengbin Liu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, PR China
| | - Gang Pan
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China; Beijing Advanced Science and Innovation Center, Chinese Academy of Sciences, Beijing, 101407, PR China; Center of Integrated Water-Energy-Food Studies (iWEF), School of Animal, Rural, and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, NG25 0QF, UK.
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19
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Wang L, Hou D, Cao Y, Ok YS, Tack FMG, Rinklebe J, O'Connor D. Remediation of mercury contaminated soil, water, and air: A review of emerging materials and innovative technologies. ENVIRONMENT INTERNATIONAL 2020; 134:105281. [PMID: 31726360 DOI: 10.1016/j.envint.2019.105281] [Citation(s) in RCA: 150] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/23/2019] [Accepted: 10/20/2019] [Indexed: 05/24/2023]
Abstract
Mercury contamination in soil, water and air is associated with potential toxicity to humans and ecosystems. Industrial activities such as coal combustion have led to increased mercury (Hg) concentrations in different environmental media. This review critically evaluates recent developments in technological approaches for the remediation of Hg contaminated soil, water and air, with a focus on emerging materials and innovative technologies. Extensive research on various nanomaterials, such as carbon nanotubes (CNTs), nanosheets and magnetic nanocomposites, for mercury removal are investigated. This paper also examines other emerging materials and their characteristics, including graphene, biochar, metal organic frameworks (MOFs), covalent organic frameworks (COFs), layered double hydroxides (LDHs) as well as other materials such as clay minerals and manganese oxides. Based on approaches including adsorption/desorption, oxidation/reduction and stabilization/containment, the performances of innovative technologies with the aid of these materials were examined. In addition, technologies involving organisms, such as phytoremediation, algae-based mercury removal, microbial reduction and constructed wetlands, were also reviewed, and the role of organisms, especially microorganisms, in these techniques are illustrated.
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Affiliation(s)
- Liuwei Wang
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Deyi Hou
- School of Environment, Tsinghua University, Beijing 100084, China.
| | - Yining Cao
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Yong Sik Ok
- Korea Biochar Research Center & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Filip M G Tack
- Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, Wuppertal 42285, Germany; Department of Environment, Energy and Geoinformatics, Sejong University, 98 Gunja-Dong, Seoul, Republic of Korea
| | - David O'Connor
- School of Environment, Tsinghua University, Beijing 100084, China
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20
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Taylor VF, Buckman KL, Burgess RM. Preliminary investigation of polymer-based in situ passive samplers for mercury and methylmercury. CHEMOSPHERE 2019; 234:806-814. [PMID: 31247490 PMCID: PMC6742538 DOI: 10.1016/j.chemosphere.2019.06.093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 06/05/2019] [Accepted: 06/12/2019] [Indexed: 05/24/2023]
Abstract
Development of an in situ passive sampler for mercury (Hg), and its toxic form, methylmercury (MeHg), using simple polymer films, was explored for the potential to make an efficient and environmentally relevant monitoring tool for this widespread aquatic pollutant. The sulfur-containing polymers polysulfone (PS), and polyphenylene sulfide (PPS), were found to accumulate both MeHg and inorganic Hg (iHg), whereas polyethylene (PE) sorbed iHg but not MeHg, and polyoxymethylene (POM) and polyethersulfone (PES) films had low affinity for both Hg species. Uptake rates of Hg species into polymers were linear over two weeks, and dissolved organic matter at natural levels had no effect on partitioning of MeHg or iHg to the polymers. Sorption of MeHg to PS and PPS from three estuarine sediments correlated with uptake into diffusive gel-type samplers over time, and in PPS, with accumulation by the estuarine amphipod, Leptocheirus plumulosus. These polymers had lower MeHg adsorption rates, but are simpler to assemble, than diffusive gel-type samplers. Higher contaminant concentrations in polymer and gel-type samplers corresponded with porewater concentrations across sediments, suggesting they sample the dissolved MeHg pool, whereas MeHg levels in amphipods were more elevated with higher bulk sediment MeHg, which may reflect feeding strategy. While polymers with higher affinity for MeHg and iHg are needed for some environmental applications, this work suggests a simple sampling approach has potential for time-integrated, environmentally-meaningful MeHg monitoring in contaminated sediments.
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Affiliation(s)
- Vivien F Taylor
- Department of Earth Science, Dartmouth College, Hanover, NH, USA.
| | - Kate L Buckman
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - Robert M Burgess
- U.S. Environmental Protection Agency, Office of Research and Development, Atlantic Ecology Division, Narragansett, RI, USA
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21
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Christensen GA, Gionfriddo CM, King AJ, Moberly JG, Miller CL, Somenahally AC, Callister SJ, Brewer H, Podar M, Brown SD, Palumbo AV, Brandt CC, Wymore AM, Brooks SC, Hwang C, Fields MW, Wall JD, Gilmour CC, Elias DA. Determining the Reliability of Measuring Mercury Cycling Gene Abundance with Correlations with Mercury and Methylmercury Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8649-8663. [PMID: 31260289 DOI: 10.1021/acs.est.8b06389] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Methylmercury (MeHg) is a bioaccumulative toxic contaminant in many ecosystems, but factors governing its production are poorly understood. Recent work has shown that the anaerobic microbial conversion of mercury (Hg) to MeHg requires the Hg-methylation genes hgcAB and that these genes can be used as biomarkers in PCR-based estimators of Hg-methylator abundance. In an effort to determine reliable methods for assessing hgcA abundance and diversity and linking them to MeHg concentrations, multiple approaches were compared including metagenomic shotgun sequencing, 16S rRNA gene pyrosequencing and cloning/sequencing hgcAB gene products. Hg-methylator abundance was also determined by quantitative hgcA qPCR amplification and metaproteomics for comparison to the above measurements. Samples from eight sites were examined covering a range of total Hg (HgT; 0.03-14 mg kg-1 dry wt. soil) and MeHg (0.05-27 μg kg-1 dry wt. soil) concentrations. In the metagenome and amplicon sequencing of hgcAB diversity, the Deltaproteobacteria were the dominant Hg-methylators while Firmicutes and methanogenic Archaea were typically ∼50% less abundant. This was consistent with metaproteomics estimates where the Deltaproteobacteria were steadily higher. The 16S rRNA gene pyrosequencing did not have sufficient resolution to identify hgcAB+ species. Metagenomic and hgcAB results were similar for Hg-methylator diversity and clade-specific qPCR-based approaches for hgcA are only appropriate when comparing the abundance of a particular clade across various samples. Weak correlations between Hg-methylating bacteria and soil Hg concentrations were observed for similar environmental samples, but overall total Hg and MeHg concentrations poorly correlated with Hg-cycling genes.
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Affiliation(s)
- Geoff A Christensen
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Caitlin M Gionfriddo
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Andrew J King
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - James G Moberly
- College of Engineering , University of Idaho , Moscow , Idaho 83844 , United States
| | - Carrie L Miller
- School of Theoretical and Applied Science , Ramapo College of New Jersey , Mahwah , New Jersey 07430 , United States
| | - Anil C Somenahally
- Department of Soil and Crop Sciences , Texas A&M University , Overton , Texas 77843-2474 , United States
| | - Stephen J Callister
- Biological Sciences Division , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Heather Brewer
- Biological Sciences Division , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Mircea Podar
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Steven D Brown
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Anthony V Palumbo
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Craig C Brandt
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Ann M Wymore
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Scott C Brooks
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37830 , United States
| | - Chiachi Hwang
- Center for Biofilm Engineering , Montana State University , Bozeman , Montana 59717 , United States
| | - Matthew W Fields
- Department of Microbiology and Immunology , Montana State University , Bozeman , Montana 59717 , United States
- Center for Biofilm Engineering , Montana State University , Bozeman , Montana 59717 , United States
| | - Judy D Wall
- Department of Biochemistry , University of Missouri , Columbia , Missouri 65211 , United States
| | - Cynthia C Gilmour
- Smithsonian Environmental Research Center , Edgewater , Maryland 21037 , United States
| | - Dwayne A Elias
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
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22
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Turull M, Fontàs C, Díez S. Conventional and novel techniques for the determination of Hg uptake by lettuce in amended agricultural peri-urban soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:40-46. [PMID: 30851683 DOI: 10.1016/j.scitotenv.2019.02.244] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 06/09/2023]
Abstract
Peri-urban agriculture provides environmental benefits to the nearby urban areas. However, domestic and industrial infrastructures can be sources of pollution that can affect agricultural production. In this work, the diffusive gradient in thin film (DGT) technique was used to assess the bioavailability of mercury (Hg) in organic-amended agricultural soils, and uptake by lettuce. Two different amendments were studied individually in three different sets using a wood-based biochar at two rates (3% and 6%, w/w), and compost at one rate (30% w/w). The effect of the amendments on Hg bioavailability, mobility and uptake was investigated by means of both DGT analyses and accumulation of Hg by lettuce. DGT manufactured in-house devices with polyacrylamide gel using both open and restricted diffusive layers (ODL and RDL, respectively) were used to determine organic and inorganic Hg labile species in soils, respectively. The Hg concentration in lettuce leaves and roots were analyzed and compared with DGT measurements to predict the uptake of Hg from the different organic-amended soils and the non-amended soils. Results show that the application of biochar reduces the bioavailability of Hg in soil and, in consequence, the Hg uptake by lettuce. Inorganic Hg species were predominant in all the different sets of the experiment (62-97%), although the addition of the different amendments reduced the free ionic species in soil.
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Affiliation(s)
- Marta Turull
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research, IDÆA-CSIC, E-08034 Barcelona, Spain
| | - Clàudia Fontàs
- Department of Chemistry, University of Girona, C/Maria Aurèlia Capmany 69,17003 Girona, Spain
| | - Sergi Díez
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research, IDÆA-CSIC, E-08034 Barcelona, Spain.
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23
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Tang W, Su Y, Gao Y, Zhong H. Effects of Farming Activities on the Biogeochemistry of Mercury in Rice-Paddy Soil Systems. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:635-642. [PMID: 31053868 DOI: 10.1007/s00128-019-02627-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
The biogeochemistry of mercury (Hg) in rice-paddy soil systems raises concerns, given that (1) the redox potential in paddy soil favors Hg methylation and (2) rice plants have a strong ability to accumulate methylmercury (MeHg), making rice an important source for MeHg exposure to humans. Therefore, all factors affecting the behavior of Hg in rice-paddy soils might impact Hg accumulation in rice, with its subsequent potential risks. As a typical wetland, paddy soils are managed by humans and affected by anthropogenic activities, such as agronomic measures, which would impact soil properties and thus Hg biogeochemistry. In this paper, we reviewed recent advances in the effects of farming activities including water management, fertilizer application and rotation on Hg biogeochemistry, trying to elucidate the factors controlling Hg behavior and thus the ecological risks in rice-paddy soil systems. This review might provide new thoughts on Hg remediation and suggest avenues for further studies.
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Affiliation(s)
- Wenli Tang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China
| | - Yao Su
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China
| | - Yuxi Gao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Laboratory of Metallomics and Nanometallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China.
- Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, ON, Canada.
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24
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Schwartz GE, Sanders JP, McBurney AM, Brown SS, Ghosh U, Gilmour CC. Impact of dissolved organic matter on mercury and methylmercury sorption to activated carbon in soils: implications for remediation. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:485-496. [PMID: 30724289 DOI: 10.1039/c8em00469b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Activated carbon (AC) amendments have shown promise in reducing inorganic mercury (Hg(ii) complexes, "Hg") and methylmercury (MeHg) risk in contaminated soils. However, the effectiveness of AC in Hg and MeHg immobilization has varied among studies, suggesting that site biogeochemistry might dictate efficacy. In this study, we examined the effect of dissolved organic matter (DOM) on MeHg and Hg sorption to AC. We evaluated the impact of Suwannee River Humic Acid (SRHA) on sorption to AC directly using an isotherm approach and in a soil/AC mixture using slurry microcosms. Aqueous sorption coefficients to AC (log KAC) for Hg-SRHA and MeHg-SRHA complexes were one to two orders of magnitude lower (Hg-SRHA = 4.53, MeHgSRHA = 4.35) than those for chloride complexes (HgCl2 = 6.55, MeHgCl = 4.90) and more closely resembled the log KAC of SRHA (3.64). In anoxic, sulfidic soil slurries, the KAC for sulfide species appeared stronger than for chloride or SRHA species for both Hg and MeHg. AC significantly reduced porewater concentrations of both ambient MeHg and a fresh Me199Hg spike, and the addition of up to 60 mg L-1 SRHA did not reduce sorption to AC. The AC also reduced ambient Hg and 201Hg porewater concentrations, but as SRHA concentration increased, the magnitude of solid phase sorption decreased. Speciation modeling revealed that SRHA may have impacted Hg distribution to the solid phase by reducing HgS precipitation. This study highlights the need for site-specific evaluation of AC efficacy and the value in developing biogeochemical models of AC performance for Hg control.
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Affiliation(s)
- Grace E Schwartz
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037, USA.
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25
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Wang AO, Ptacek CJ, Blowes DW, Gibson BD, Landis RC, Dyer JA, Ma J. Application of hardwood biochar as a reactive capping mat to stabilize mercury derived from contaminated floodplain soil and riverbank sediments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 652:549-561. [PMID: 30368184 DOI: 10.1016/j.scitotenv.2018.10.213] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/14/2018] [Accepted: 10/15/2018] [Indexed: 05/09/2023]
Abstract
Hardwood biochar (pyrolyzed at 700 °C), a potential candidate for Hg removal, has been proposed for use as reactive capping mats along groundwater discharge zones or riverbanks to control release of Hg from contaminated riverbank sediments. Frequent flooding and drainage in fluvial settings can influence the effectiveness of remediation systems in contaminated riverbank sediments and floodplain soils. This study evaluated the effectiveness of Hg removal using hardwood biochar under hydrogeochemical conditions representative of those present within a reactive capping mat installed in a fluvial setting. Two sets of treatment columns, containing 50% v.v biochar and quartz sand, were subjected to 100 weekly wetting/drying cycles that included dry air, water-saturated air, and drainage using leachate derived from two source columns as input solutions: 1. Passing simulated acid rain water through floodplain soil, 2. Passing river water through riverbank sediment. In both treatment columns, >80% of the Hg was retained on the biochar without promoting Hg methylation and the release of other unintended dissolved constituents (including N, P, DOC). Results from solidphase extraction analyses suggest that Hg accumulated near the air/biochar-sand interface (0-2 cm) in the treatment columns at low loadings but was present at greater depths at higher loadings. Results of micro X-ray fluorescence (μ-XRF) mapping and micro X-ray absorption near edge structure (μ-XANES) for the biochar collected at depths 0-2 cm in treatment columns suggest retention of Hg-bearing particles derived from riverbank sediment and floodplain soil within the pore structure of the biochar. Sulfur K-edge XANES analysis of the unused biochar and the biochar after treatment suggest formation of Hg complexes on the biochar surface. These results indicate that hardwood biochar is potentially an effective media for application in reactive mats for controlling Hg discharging from contaminated riverbank sediments.
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Affiliation(s)
- Alana O Wang
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Carol J Ptacek
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| | - David W Blowes
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Blair D Gibson
- Formerly at Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Richard C Landis
- Formerly at E.I. du Pont de Nemours and Company, Wilmington, DE 19085, USA
| | - James A Dyer
- Formerly at E.I. du Pont de Nemours and Company, Wilmington, DE 19085, USA
| | - Jing Ma
- Formerly at Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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26
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Rudd JWM, Bodaly RA, Fisher NS, Kelly CA, Kopec D, Whipple C. Fifty years after its discharge, methylation of legacy mercury trapped in the Penobscot Estuary sustains high mercury in biota. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 642:1340-1352. [PMID: 30045514 DOI: 10.1016/j.scitotenv.2018.06.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 06/02/2018] [Accepted: 06/06/2018] [Indexed: 06/08/2023]
Abstract
Fifty years ago, the Penobscot Estuary was contaminated by mercury discharged from the chlor-alkali plant located in Orrington, Maine, USA. Almost all of the mercury was discharged from the plant during the late 1960s and early 1970s. Despite the much lower mercury discharges in recent decades, present-day concentrations in surface sediment remain high (averaging 350-1100 ng/g dw) and are still high in blood of marsh birds (up to 10.5 μg/g), black duck muscle (0.8 μg/g), and lobster muscle (0.4 μg/g). Methyl mercury (MeHg) concentrations in marsh birds exceed levels that impair reproduction. There are health advisories for duck hunters and closures of shellfish fisheries. These continuing high mercury concentrations are caused by the trapping of legacy mercury in a mobile pool of sediment that is retained in the upper estuary above a tidally forced salinity front, which travels up and down the estuary each tidal cycle - slowing the transport of particulate mercury to Penobscot Bay. The trapped legacy mercury continues to be available for methylation 50 years after it first entered the estuary. This is demonstrated by the fact that rates of MeHg production are positively related to the inorganic mercury concentration in parts of the estuary with elevated concentrations of legacy mercury. Thus, remediation measures that would lower the THg concentration in surface sediment would lower the MeHg in birds, fish and shellfish. All of this new information leads us to recommend two remediation options. Addition of mercury binding agents may lower mercury concentrations in birds in some wetland areas. System-wide, we also recommend Enhanced Natural Recovery (ENR), a novel approach that involves the partial removal of the contaminated mobile sediment pool followed by replacement with clean-clay particulates to dilute inorganic mercury concentrations, which would lower methylation rates and mercury concentrations in biota.
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Affiliation(s)
- John W M Rudd
- R&K Research Inc., 675 Mount Belcher Heights, Salt Spring Island, B.C. V8K 2J3, Canada.
| | - R A Bodaly
- Penobscot River Mercury Study, 115 Oystercatcher Place, Salt Spring Island, B.C. V8K 2W5, Canada.
| | - Nicholas S Fisher
- School of School of Marine and Atmospheric Sciences, Stony Brook University, NY 11794-5000, USA.
| | - C A Kelly
- R&K Research Inc., 675 Mount Belcher Heights, Salt Spring Island, B.C. V8K 2J3, Canada.
| | - Dianne Kopec
- Penobscot River Mercury Study, 479 Beechwood Avenue, Old Town, ME 04468, USA.
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Gilmour C, Bell JT, Soren AB, Riedel G, Riedel G, Kopec AD, Bodaly RA. Distribution and biogeochemical controls on net methylmercury production in Penobscot River marshes and sediment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 640-641:555-569. [PMID: 29864668 DOI: 10.1016/j.scitotenv.2018.05.276] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 05/18/2018] [Accepted: 05/22/2018] [Indexed: 05/28/2023]
Abstract
The distribution of mercury and methylmercury (MeHg) in sediment, mudflats, and marsh soils of the Hg-contaminated tidal Penobscot River was investigated, along with biogeochemical controls on production. Average total Hg in surface samples (0-3 cm) ranged from 100 to 1200 ng/g; average MeHg ranged from 5 to 50 ng/g. MeHg was usually highest at or near the surface except in highly mobile mudflats. Although total Hg concentrations in the Penobscot are elevated, it is the accumulation of MeHg that stands out in comparison to other ecosystems. Surface soils in the large Mendall Marsh, about 17 km downstream from the contamination source, contained particularly high %MeHg (averaging 8%). In Mendall marsh soil porewaters, MeHg often accounted for more than half of total Hg. Salt marshes are areas of particular concern in the Penobscot River, for they are depositional environments for a Hg-contaminated mobile pool of river sediment, hot spots for net MeHg production, and sources of risk to marsh animals. We hypothesized that exceptionally low mercury partitioning between the solid and aqueous phases (with log Kd averaging ~4.5) drives high MeHg in Penobscot marshes. The co-occurrence of iron and sulfide in filtered soil porewaters, sometimes both above 100 μM, suggests the presence of nanoparticulate and/or colloidal metal sulfides. These colloids may be stabilized by high concentrations of aromatic and potentially sulfurized dissolved organic matter (DOM) in marsh soils. Thus, Hg in Penobscot marsh soils appears to be in a highly available for microbial methylation through the formation of DOM-associated HgS complexes. Additionally, low partitioning of MeHg to marsh soils suggests high MeHg bioavailability to animals. Overall, drivers of high MeHg in Penobscot marshes include elevated Hg in soils, low partitioning of Hg to solids, high Hg bioavailability for methylation, rapidly shifting redox conditions in surface marsh soils, and high rates of microbial activity.
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Affiliation(s)
- Cynthia Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States.
| | - James Tyler Bell
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | - Ally Bullock Soren
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | - Georgia Riedel
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | - Gerhardt Riedel
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | | | - R A Bodaly
- Penobscot River Mercury Study, Bangor, ME, US.
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28
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Bodaly RAD. Mercury contamination of the Penobscot River Estuary, Maine, USA. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 639:1077-1078. [PMID: 29929276 DOI: 10.1016/j.scitotenv.2018.05.127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 05/09/2018] [Accepted: 05/09/2018] [Indexed: 06/08/2023]
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29
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Sanders JP, Andrade NA, Menzie CA, Amos CB, Gilmour CC, Henry EA, Brown SS, Ghosh U. Persistent reductions in the bioavailability of PCBs at a tidally inundated Phragmites australis marsh amended with activated carbon. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2018; 37:2496-2505. [PMID: 29870109 DOI: 10.1002/etc.4186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/19/2018] [Accepted: 06/02/2018] [Indexed: 06/08/2023]
Abstract
In situ amendment of sediments with highly sorbent materials like activated carbon (AC) is an increasingly viable strategy to reduce the bioavailability of persistent, sediment-associated contaminants to benthic communities. Because in situ sediment remediation is an emerging strategy, much remains to be learned about the field conditions under which amendments can be effective, the resilience of amendment materials toward extreme weather conditions, and the optimal design of engineered applications. We report the results of a multiyear, pilot-scale field investigation designed to measure the persistence and efficacy of AC amendments to reduce the bioavailability of polychlorinated biphenyls (PCBs) in an intertidal Phragmites marsh. The amendments tested were granular AC (GAC), GAC with a layer of sand, and a pelletized fine AC. Key metrics presented include vertically resolved black carbon concentrations in sediment and PCB concentrations in sediment, porewater, and several invertebrate species. The results demonstrate that all 3 amendments withstood Hurricane Sandy and remained in place for the duration of the study, successfully reducing porewater PCB concentrations by 34 to 97%. Reductions in invertebrate bioaccumulation were observed in all amendment scenarios, with pelletized fine AC producing the most pronounced effect. The present findings support the use of engineered AC amendments in intertidal marshes and can be used to inform amendment design, delivery, and monitoring at other contaminated sediment sites. Environ Toxicol Chem 2018;37:2496-2505. © 2018 SETAC.
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Affiliation(s)
- James P Sanders
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore, Maryland, USA
- Exponent, Alexandria, Virginia, USA
| | - Natasha A Andrade
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore, Maryland, USA
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA
| | - Charles A Menzie
- Exponent, Alexandria, Virginia, USA
- Sediment Solutions, Ellicott City, Maryland, USA
| | - C Bennett Amos
- Exponent, Alexandria, Virginia, USA
- Sediment Solutions, Ellicott City, Maryland, USA
| | | | | | | | - Upal Ghosh
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore, Maryland, USA
- Sediment Solutions, Ellicott City, Maryland, USA
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30
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Yeager KM, Schwehr KA, Schindler KJ, Santschi PH. Sediment accumulation and mixing in the Penobscot River and estuary, Maine. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 635:228-239. [PMID: 29674257 DOI: 10.1016/j.scitotenv.2018.04.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 03/26/2018] [Accepted: 04/03/2018] [Indexed: 06/08/2023]
Abstract
Mercury (Hg) was discharged in the late 1960s into the Penobscot River by the Holtra-Chem chlor-alkali production facility, which was in operation from 1967 to 2000. To assess the transport and distribution of total Hg, and recovery of the river and estuary system from Hg pollution, physical and radiochemical data were assembled from sediment cores collected from 58 of 72 coring stations sampled in 2009. These stations were located throughout the lower Penobscot River, and included four principal study regions, the Penobscot River (PBR), Mendall Marsh (MM), the Orland River (OR), and the Penobscot estuary (ES). To provide the geochronology required to evaluate sedimentary total Hg profiles, 58 of 72 sediment cores were dated using the atmospheric radionuclide tracers 137Cs, 210Pb, and 239,240Pu. Sediment cores were assessed for depths of mixing, and for the determination of sediment accumulation rates using both geochemical (total Hg) and radiochemical data. At most stations, evidence for significant vertical mixing, derived from profiles of 7Be (where possible) and porosity, was restricted to the upper ~1-3cm. Thus, historic profiles of both total Hg and radionuclides were only minimally distorted, allowing a reconstruction of their depositional history. The pulse input tracers 137Cs and 239,240Pu used to assess sediment accumulation rates agreed well, while the steady state tracer 210Pb exhibited weaker agreement, likely due to irregular lateral sediment inputs.
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Affiliation(s)
- K M Yeager
- Sedimentary and Environmental Radiochemistry Research Laboratory (SER(2)L), Department of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506, United States.
| | - K A Schwehr
- Laboratory for Oceanographic and Environmental Research (LOER), Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77554, United States.
| | - K J Schindler
- Sedimentary and Environmental Radiochemistry Research Laboratory (SER(2)L), Department of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506, United States
| | - P H Santschi
- Laboratory for Oceanographic and Environmental Research (LOER), Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77554, United States.
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