1
|
Lin H, Mao X, Wei Y, Li S, Qin J, Zhu S, Su S, He T. Metabolic pathways of methylmercury in rotifer Brachionus plicatilis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167063. [PMID: 37709075 DOI: 10.1016/j.scitotenv.2023.167063] [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: 07/15/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/16/2023]
Abstract
Methylmercury (MeHg) readily accumulates in aquatic organisms while transferring and amplifying in the aquatic food chains. This study firstly explores the in vivo accumulation sites and metabolic regulation of MeHg in the rotifer Brachionus plicatilis by aggregation-induced emission fluorogen (AIEgen) and metabolomics. Fluorescent image analysis by AIEgen showed that MeHg in B. plicatilis mainly occured in the ciliary corona, esophagus, mastax, stomach and intestine in the direct absorption group. In the other group, where B. plicatilis were indirectly supplied with MeHg via food intake, the accumulation of MeHg in the rotifer occurred in the ciliary corona, various digestive organs, and the pedal gland. However, the MeHg accumulated in the rotifer is difficult to metabolize outside the body. Metabolomics analysis showed that the significant enrichment of ABC transporters was induced by the direct exposure of rotifers to dissolved MeHg. In contrast, exposure of rotifers to MeHg via food intake appeared to influence carbon, galactose, alanine, aspartate and glutamate metabolisms. Besides, the disturbed biological pathways such as histidine metabolism, beta-alanine metabolism and pantothenate and CoA biosynthesis in rotifers may be associated with L-aspartic acid upregulation in the feeding group. The significant enrichment of ABC transporters and carbon metabolism in rotifers may be related to the accumulation of MeHg in the intestine of rotifers. In both pathways of MeHg exposure, the arginine biosynthesis and metabolism of rotifers were disturbed, which may support the hypothesis that rotifers produce more energy to resist MeHg toxicity. This study provides new insight into the accumulation and toxicity mechanisms of MeHg on marine invertebrates from the macro and micro perspectives.
Collapse
Affiliation(s)
- Hangyu Lin
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Xiaodong Mao
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Yanlin Wei
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Songzhang Li
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Jianguang Qin
- College of Science and Engineering, Flinders University, South Australia 5001, Australia
| | - Song Zhu
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Shengqi Su
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China.
| | - Tao He
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China.
| |
Collapse
|
2
|
Gutensohn M, Schaefer JK, Yunda E, Skyllberg U, Björn E. The Combined Effect of Hg(II) Speciation, Thiol Metabolism, and Cell Physiology on Methylmercury Formation by Geobacter sulfurreducens. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7185-7195. [PMID: 37098211 PMCID: PMC10173453 DOI: 10.1021/acs.est.3c00226] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The chemical and biological factors controlling microbial formation of methylmercury (MeHg) are widely studied separately, but the combined effects of these factors are largely unknown. We examined how the chemical speciation of divalent, inorganic mercury (Hg(II)), as controlled by low-molecular-mass thiols, and cell physiology govern MeHg formation by Geobacter sulfurreducens. We compared MeHg formation with and without addition of exogenous cysteine (Cys) to experimental assays with varying nutrient and bacterial metabolite concentrations. Cysteine additions initially (0-2 h) enhanced MeHg formation by two mechanisms: (i) altering the Hg(II) partitioning from the cellular to the dissolved phase and/or (ii) shifting the chemical speciation of dissolved Hg(II) in favor of the Hg(Cys)2 complex. Nutrient additions increased MeHg formation by enhancing cell metabolism. These two effects were, however, not additive since cysteine was largely metabolized to penicillamine (PEN) over time at a rate that increased with nutrient addition. These processes shifted the speciation of dissolved Hg(II) from complexes with relatively high availability, Hg(Cys)2, to complexes with lower availability, Hg(PEN)2, for methylation. This thiol conversion by the cells thereby contributed to stalled MeHg formation after 2-6 h Hg(II) exposure. Overall, our results showed a complex influence of thiol metabolism on microbial MeHg formation and suggest that the conversion of cysteine to penicillamine may partly suppress MeHg formation in cysteine-rich environments like natural biofilms.
Collapse
Affiliation(s)
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, New Jersey 08901, United States
| | - Elena Yunda
- Department of Chemistry, Umeå University, SE- 90187 Umeå, Sweden
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, SE- 90187 Umeå, Sweden
| |
Collapse
|
3
|
Koenigsmark F, Chiu M, Rivera N, Johs A, Eskelsen J, Leonard D, Robertson BK, Szynkiewicz A, Derolph C, Zhao L, Gu B, Hsu-Kim H, Pierce EM. Crystal lattice defects in nanocrystalline metacinnabar in contaminated streambank soils suggest a role for biogenic sulfides in the formation of mercury sulfide phases. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:445-460. [PMID: 36692344 DOI: 10.1039/d1em00549a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
At mercury (Hg)-contaminated sites, streambank erosion can act as a main mobilizer of Hg into nearby waterbodies. Once deposited into the waters, mercury from these soils can be transformed to MeHg by microorganisms. It is therefore important to understand the solid-phase speciation of Hg in streambanks as differences in Hg speciation will have implications for Hg transport and bioavailability. In this study, we characterized Hg solid phases in Hg-contaminated soils (100-1100 mg per kg Hg) collected from the incised bank of the East Fork Poplar Creek (EFPC) in Oak Ridge, TN (USA). The analysis of the soil samples by scanning electron microscopy-energy dispersive spectroscopy indicated numerous microenvironments where Hg and sulfur (S) are co-located. According to bulk soil analyses by extended X-ray absorption fine structure spectroscopy (EXAFS), the near-neighbor Hg molecular coordination in the soils closely resembled freshly precipitated Hg sulfide (metacinnabar, HgS); however, EXAFS fits indicated the Hg in the HgS structure was undercoordinated with respect to crystalline metacinnabar. This undercoordination of Hg-S observed by spectroscopy is consistent with transmission electron microspy images showing the presence of nanocrystallites with structural defects (twinning, stacking faults, dislocations) in individual HgS-bearing particles. Although the soils were collected from exposed parts of the stream bank (i.e., open to the atmosphere), the presence of reduced forms of S and sulfate-reducing microbes suggests that biogenic sulfides promote the formation of HgS nanoparticles in these soils. Altogether, these data demonstrate the predominance of nanoparticulate HgS with crystal lattice defects in the bank soils of an industrially impacted stream. Efforts to predict the mobilization and bioavailability of Hg associated with nano-HgS forms should consider the impact of nanocrystalline lattice defects on particle surface reactivity, including Hg dissolution rates and bioavailability on Hg fate and transformations.
Collapse
Affiliation(s)
- Faye Koenigsmark
- Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Michelle Chiu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Nelson Rivera
- Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Jeremy Eskelsen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Donovan Leonard
- Manufacturing Demonstration Facility Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Boakai K Robertson
- Department of Biological Sciences, Alabama State University, Montgomery, AL 36104, USA
| | - Anna Szynkiewicz
- Department of Earth and Planetary Sciences, University of Tennessee at Knoxville, Knoxville, TN 37996, USA
| | - Christopher Derolph
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Linduo Zhao
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Heileen Hsu-Kim
- Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| |
Collapse
|
4
|
Steele E, Alebous HD, Vickers M, Harris ME, Johnson MD. Co-culturing experiments reveal the uptake of myo-inositol phosphate synthase (EC 5.5.1.4) in an inositol auxotroph of Saccharomyces cerevisiae. Microb Cell Fact 2021; 20:138. [PMID: 34281557 PMCID: PMC8287684 DOI: 10.1186/s12934-021-01610-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 06/08/2021] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Myo-Inositol Phosphate Synthase (MIP) catalyzes the conversion of glucose 6- phosphate into inositol phosphate, an essential nutrient and cell signaling molecule. Data obtained, first in bovine brain and later in plants, established MIP expression in organelles and in extracellular environments. A physiological role for secreted MIP has remained elusive since its first detection in intercellular space. To provide further insight into the role of MIP in intercellular milieus, we tested the hypothesis that MIP may function as a growth factor, synthesizing inositol phosphate in intercellular locations requiring, but lacking ability to produce or transport adequate quantities of the cell-cell communicator. This idea was experimentally challenged, utilizing a Saccharomyces cerevisiae inositol auxotroph with no MIP enzyme, permeable membranes with a 0.4 µm pore size, and cellular supernatants as external sources of inositol isolated from S. cerevisiae cells containing either wild-type enzyme (Wt-MIP), no MIP enzyme, auxotroph (Aux), or a green fluorescent protein (GFP) tagged reporter enzyme (MIP- GFP) in co- culturing experiments. RESULTS Resulting cell densities and microscopic studies with corroborating biochemical and molecular analyses, documented sustained growth of Aux cells in cellular supernatant, concomitant with the uptakeof MIP, detected as MIP-GFP reporter enzyme. These findings revealed previously unknown functions, suggesting that the enzyme can: (1) move into and out of intercellular space, (2) traverse cell walls, and (3) act as a growth factor to promote cellular proliferation of an inositol requiring cell. CONCLUSIONS Co-culturing experiments, designed to test a probable function for MIP secreted in extracellular vesicles, uncovered previously unknown functions for the enzyme and advanced current knowledge concerning spatial control of inositol phosphate biosynthesis. Most importantly, resulting data identified an extracellular vesicle (a non-viral vector) that is capable of synthesizing and transporting inositol phosphate, a biological activity that can be used to enhance specificity of current inositol phosphate therapeutics.
Collapse
Affiliation(s)
- Erika Steele
- The University of Alabama, The Institute of Social Science Research, PO Box 8702161, Tuscaloosa, AL 35487 USA
| | - Hana D. Alebous
- Department of Biological Sciences, School of Science, The University of Jordan, PO Box 11942, Amman-Jordan, Jordan
| | - Macy Vickers
- Department of Biological Sciences, The University of Alabama, PO Box 870344, Tuscaloosa, AL 35487 USA
| | - Mary E. Harris
- Department of Biological Sciences, The University of Alabama, PO Box 870344, Tuscaloosa, AL 35487 USA
| | - Margaret D. Johnson
- Department of Biological Sciences, The University of Alabama, PO Box 870344, Tuscaloosa, AL 35487 USA
| |
Collapse
|
5
|
Liu C, Chen L, Liang S, Li Y. Distribution of total mercury and methylmercury and their controlling factors in the East China Sea. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 258:113667. [PMID: 31810718 DOI: 10.1016/j.envpol.2019.113667] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 11/13/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) is among contaminants of public concern due to its prevalent existence, high toxicity, and bioaccumulation through food chains. Elevated Hg has been detected in seafood from the East China Sea (ECS), which is one of the largest marginal seas and an important fishing region in the northwestern Pacific Ocean. However, there is still a lack of knowledge on the distribution of Hg species and their controlling factors in the ECS water column, thus preventing the understanding of Hg cycling and the assessment of Hg risks in the ECS. In this study, two cruises were conducted in October 2014 and June 2015 in order to investigate the distribution of total Hg (THg) and methylmercury (MeHg) and their controlling factors in the ECS. The concentrations of THg and MeHg were determined to be 4.2 ± 2.8 ng/L (THg) and 0.25 ± 0.13 ng/L (MeHg) in water from the ECS. The level of Hg in the ECS occupied the higher rank among the marginal seas, thus indicating significant Hg contamination in this system. Both the THg and MeHg presented complicated spatial distribution patterns in the ECS, with high concentration areas located in both the nearshore and offshore areas. Statistical analyses suggest that temperature (T) and Hg in sediment may be the controlling factors for THg distribution, while dissolved organic matter (DOM), T, and MeHg in the sediment may be the controlling factors for MeHg distribution in the seawater of the ECS. The relative importance of these environmental factors in Hg distribution depends on the water depth. T-salinity (S) diagram analyses showed that water mass mixing may also play an important role in controlling THg and MeHg distribution in the coastal ECS.
Collapse
Affiliation(s)
- Chang Liu
- Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao, 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
| | - Lufeng Chen
- Institute of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Shengkang Liang
- Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao, 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
| | - Yanbin Li
- Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao, 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China.
| |
Collapse
|
6
|
Schwartz GE, Olsen TA, Muller KA, Brooks SC. Ecosystem Controls on Methylmercury Production by Periphyton Biofilms in a Contaminated Stream: Implications for Predictive Modeling. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:2426-2435. [PMID: 31365146 DOI: 10.1002/etc.4551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/12/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
Periphyton biofilms produce a substantial fraction of the overall monomethylmercury (MMHg) flux in East Fork Poplar Creek, an industrially contaminated, freshwater creek in Oak Ridge, Tennessee. We examined periphyton MMHg production across seasons, locations, and light conditions using mercury stable isotopes. Methylation and demethylation rate potentials (km, trans av and kd, trans av , respectively) were calculated using a transient availability kinetic model. Light exposure and season were significant predictors of km, trans av , with greater values in full light exposure and in the summer. Season, light exposure, and location were significant predictors of kd, trans av , which was highest in dark conditions, in the spring, and at the upstream location. Light exposure was the controlling factor for net MMHg production, with positive production for periphyton grown under full light exposure and net demethylation for periphyton grown in the dark. Ambient MMHg and km, trans av were significantly correlated. Transient availability rate potentials were 15 times higher for km and 9 times higher for kd compared to full availability rate potentials (km, full av and kd, full av ) calculated at 1 d. No significant model for the prediction of km, full av or kd, full av could be constructed using light, season, and location. In addition, there were no significant differences among treatments for the full availability km, full av , kd, full av , or net MMHg calculated using the full availability rate potentials. km, full av was not correlated with ambient MMHg concentrations. The present results underscore the importance of applying transient availability kinetics to MMHg production data when estimating MMHg production potential and flux. Environ Toxicol Chem 2019;38:2426-2435. © 2019 SETAC.
Collapse
Affiliation(s)
- Grace E Schwartz
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Todd A Olsen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Katherine A Muller
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| |
Collapse
|
7
|
Chalana A, Karri R, Mandal SC, Pathak B, Roy G. Chemical Degradation of Mercury Alkyls Mediated by Copper Selenide Nanosheets. Chem Asian J 2019; 14:4582-4587. [DOI: 10.1002/asia.201901077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/19/2019] [Indexed: 11/12/2022]
Affiliation(s)
- Ashish Chalana
- Department of ChemistrySchool of Natural SciencesShiv Nadar University NH91 Dadri, Gautam Buddha Nagar UP 201314 India
| | - Ramesh Karri
- Department of ChemistrySchool of Natural SciencesShiv Nadar University NH91 Dadri, Gautam Buddha Nagar UP 201314 India
| | - Shyama Charan Mandal
- Department of ChemistryInstitute of Technology (IIT) Indore (India), Discipline of Metallurgy Engineering and Material Science, Indian Institute of Technology (IIT) Indore India
| | - Biswarup Pathak
- Department of ChemistryInstitute of Technology (IIT) Indore (India), Discipline of Metallurgy Engineering and Material Science, Indian Institute of Technology (IIT) Indore India
| | - Gouriprasanna Roy
- Department of ChemistrySchool of Natural SciencesShiv Nadar University NH91 Dadri, Gautam Buddha Nagar UP 201314 India
| |
Collapse
|
8
|
Li Y, Zhao J, Zhong H, Wang Y, Li H, Li YF, Liem-Nguyen V, Jiang T, Zhang Z, Gao Y, Chai Z. Understanding Enhanced Microbial MeHg Production in Mining-Contaminated Paddy Soils under Sulfate Amendment: Changes in Hg Mobility or Microbial Methylators? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1844-1852. [PMID: 30636405 DOI: 10.1021/acs.est.8b03511] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Elevated methylmercury (MeHg) production in mining-contaminated paddy soils, despite the high fraction of refractory HgS(s), has been frequently reported, while the underlying mechanisms are not fully understood. Here, we hypothesized that sulfate input, via fertilization, rainfall, and irrigation, is critical in mobilizing refractory HgS(s) and thus enhancing Hg methylation in mining-contaminated paddy soils. To test this hypothesis, the effects of sulfate amendment on Hg methylation and MeHg bioaccumulation in mining-contaminated soil-rice systems were examined. The results indicated 28-61% higher net MeHg production in soils under sulfate amendment (50-1000 mg kg-1), which in turn increased grain MeHg levels by 22-55%. The enhancement of Hg methylation by Hg mobilization in sulfate-amended soils was supported by two observations: (1) the increased Hg(aq) release from HgS(s), the dominant Hg species in the paddy soils, in the presence of sulfide produced following sulfate reduction and (2) the decreases of refractory HgS(s) in soils under sulfate amendment. By contrast, changes in the abundances/activities of potential microbial Hg methylators in different Hg-contaminated soils were not significant following sulfate amendment. Our results highlight the importance to consider enhanced Hg mobility and thus methylation in soils under sulfate amendment.
Collapse
Affiliation(s)
- Yunyun Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation , Fujian Agriculture and Forestry University , Fuzhou 350002 , Fujian China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023 , China
- Environmental and Life Sciences Program (EnLS) , Trent University , Peterborough , Ontario Canada
| | - Yongjie Wang
- School of Geographic Sciences , East China Normal University , Shanghai 200241 , China
| | - Hong Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Yu-Feng Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Van Liem-Nguyen
- School of Science and Technology , Örebro University , SE-70281 , Örebro , Sweden
| | - Tao Jiang
- Department of Environmental Science and Engineering, College of Resources and Environment , Southwest University , Chongqing 400716 , China
- Department of Forest Ecology and Management , Swedish University of Agricultural Sciences , Umeå SE-90183 , Sweden
| | - Zhiyong Zhang
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Zhifang Chai
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| |
Collapse
|
9
|
Rosati G, Heimbürger LE, Melaku Canu D, Lagane C, Laffont L, Rijkenberg MJA, Gerringa LJA, Solidoro C, Gencarelli CN, Hedgecock IM, De Baar HJW, Sonke JE. Mercury in the Black Sea: New Insights From Measurements and Numerical Modeling. GLOBAL BIOGEOCHEMICAL CYCLES 2018; 32:529-550. [PMID: 29861543 PMCID: PMC5969270 DOI: 10.1002/2017gb005700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 01/19/2018] [Accepted: 03/01/2018] [Indexed: 05/21/2023]
Abstract
Redox conditions and organic matter control marine methylmercury (MeHg) production. The Black Sea is the world's largest and deepest anoxic basin and is thus ideal to study Hg species along the extended redox gradient. Here we present new dissolved Hg and MeHg data from the 2013 GEOTRACES MEDBlack cruise (GN04_leg2) that we integrated into a numerical 1-D model, to track the fate and dynamics of Hg and MeHg. Contrary to a previous study, our new data show highest MeHg concentrations in the permanently anoxic waters. Observed MeHg/Hg percentage (range 9-57%) in the anoxic waters is comparable to other subsurface maxima in oxic open-ocean waters. With the modeling we tested for various Hg methylation and demethylation scenarios along the redox gradient. The results show that Hg methylation must occur in the anoxic waters. The model was then used to simulate the time evolution (1850-2050) of Hg species in the Black Sea. Our findings quantify (1) inputs and outputs of HgT (~31 and ~28 kmol yr-1) and MeHgT (~5 and ~4 kmol yr-1) to the basin, (2) the extent of net demethylation occurring in oxic (~1 kmol yr-1) and suboxic water (~6 kmol yr-1), (3) and the net Hg methylation in the anoxic waters of the Black Sea (~11 kmol yr-1). The model was also used to estimate the amount of anthropogenic Hg (85-93%) in the Black Sea.
Collapse
Affiliation(s)
- G. Rosati
- OGS, National Institute of Oceanography and Experimental Geophysics, OCE Research Section, ECHO GroupTriesteItaly
- Department of Life SciencesUniversity of TriesteTriesteItaly
| | - L. E. Heimbürger
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography UM 110MarseilleFrance
| | - D. Melaku Canu
- OGS, National Institute of Oceanography and Experimental Geophysics, OCE Research Section, ECHO GroupTriesteItaly
| | - C. Lagane
- Observatoire Midi‐Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul‐SabatierToulouseFrance
| | - L. Laffont
- Observatoire Midi‐Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul‐SabatierToulouseFrance
| | - M. J. A. Rijkenberg
- NIOZ, Royal Institute for Sea Research, department of GCOUtrecht UniversityDen BurgNetherlands
| | - L. J. A. Gerringa
- NIOZ, Royal Institute for Sea Research, department of GCOUtrecht UniversityDen BurgNetherlands
| | - C. Solidoro
- OGS, National Institute of Oceanography and Experimental Geophysics, OCE Research Section, ECHO GroupTriesteItaly
- ICTP, The Abdus Salam International Centre for Theoretical PhysicsTriesteItaly
| | - C. N. Gencarelli
- CNR, Institute of Atmospheric Pollution Research, Division of Rende, UNICAL‐PolifunzionaleRendeItaly
| | - I. M. Hedgecock
- CNR, Institute of Atmospheric Pollution Research, Division of Rende, UNICAL‐PolifunzionaleRendeItaly
| | - H. J. W. De Baar
- NIOZ, Royal Institute for Sea Research, department of GCOUtrecht UniversityDen BurgNetherlands
| | - J. E. Sonke
- Observatoire Midi‐Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul‐SabatierToulouseFrance
| |
Collapse
|
10
|
Hsu-Kim H, Eckley CS, Achá D, Feng X, Gilmour CC, Jonsson S, Mitchell CPJ. Challenges and opportunities for managing aquatic mercury pollution in altered landscapes. AMBIO 2018; 47:141-169. [PMID: 29388127 PMCID: PMC5794684 DOI: 10.1007/s13280-017-1006-7] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The environmental cycling of mercury (Hg) can be affected by natural and anthropogenic perturbations. Of particular concern is how these disruptions increase mobilization of Hg from sites and alter the formation of monomethylmercury (MeHg), a bioaccumulative form of Hg for humans and wildlife. The scientific community has made significant advances in recent years in understanding the processes contributing to the risk of MeHg in the environment. The objective of this paper is to synthesize the scientific understanding of how Hg cycling in the aquatic environment is influenced by landscape perturbations at the local scale, perturbations that include watershed loadings, deforestation, reservoir and wetland creation, rice production, urbanization, mining and industrial point source pollution, and remediation. We focus on the major challenges associated with each type of alteration, as well as management opportunities that could lessen both MeHg levels in biota and exposure to humans. For example, our understanding of approximate response times to changes in Hg inputs from various sources or landscape alterations could lead to policies that prioritize the avoidance of certain activities in the most vulnerable systems and sequestration of Hg in deep soil and sediment pools. The remediation of Hg pollution from historical mining and other industries is shifting towards in situ technologies that could be less disruptive and less costly than conventional approaches. Contemporary artisanal gold mining has well-documented impacts with respect to Hg; however, significant social and political challenges remain in implementing effective policies to minimize Hg use. Much remains to be learned as we strive towards the meaningful application of our understanding for stakeholders, including communities living near Hg-polluted sites, environmental policy makers, and scientists and engineers tasked with developing watershed management solutions. Site-specific assessments of MeHg exposure risk will require new methods to predict the impacts of anthropogenic perturbations and an understanding of the complexity of Hg cycling at the local scale.
Collapse
Affiliation(s)
- Heileen Hsu-Kim
- Department of Civil & Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, NC 27708 USA
| | - Chris S. Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101 USA
| | - Dario Achá
- Unidad de Calidad Ambiental, Instituto de Ecología, Carrera de Biología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China
| | - Cynthia C. Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037-0028 USA
| | - Sofi Jonsson
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Svante Arrhenius väg 8, 11418 Stockholm, Sweden
| | - Carl P. J. Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
| |
Collapse
|
11
|
Carbon Amendments Alter Microbial Community Structure and Net Mercury Methylation Potential in Sediments. Appl Environ Microbiol 2018; 84:AEM.01049-17. [PMID: 29150503 PMCID: PMC5772229 DOI: 10.1128/aem.01049-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/28/2017] [Indexed: 01/08/2023] Open
Abstract
Neurotoxic methylmercury (MeHg) is produced by anaerobic Bacteria and Archaea possessing the genes hgcAB, but it is unknown how organic substrate and electron acceptor availability impacts the distribution and abundance of these organisms. We evaluated the impact of organic substrate amendments on mercury (Hg) methylation rates, microbial community structure, and the distribution of hgcAB+ microbes with sediments. Sediment slurries were amended with short-chain fatty acids, alcohols, or a polysaccharide. Minimal increases in MeHg were observed following lactate, ethanol, and methanol amendments, while a significant decrease (∼70%) was observed with cellobiose incubations. Postincubation, microbial diversity was assessed via 16S rRNA amplicon sequencing. The presence of hgcAB+ organisms was assessed with a broad-range degenerate PCR primer set for both genes, while the presence of microbes in each of the three dominant clades of methylators (Deltaproteobacteria, Firmicutes, and methanogenic Archaea) was measured with clade-specific degenerate hgcA quantitative PCR (qPCR) primer sets. The predominant microorganisms in unamended sediments consisted of Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria Clade-specific qPCR identified hgcA+Deltaproteobacteria and Archaea in all sites but failed to detect hgcA+Firmicutes Cellobiose shifted the communities in all samples to ∼90% non-hgcAB-containing Firmicutes (mainly Bacillus spp. and Clostridium spp.). These results suggest that either expression of hgcAB is downregulated or, more likely given the lack of 16S rRNA gene presence after cellobiose incubation, Hg-methylating organisms are largely outcompeted by cellobiose degraders or degradation products of cellobiose. These results represent a step toward understanding and exploring simple methodologies for controlling MeHg production in the environment.IMPORTANCE Methylmercury (MeHg) is a neurotoxin produced by microorganisms that bioacummulates in the food web and poses a serious health risk to humans. Currently, the impact that organic substrate or electron acceptor availability has on the mercury (Hg)-methylating microorganisms is unclear. To study this, we set up microcosm experiments exposed to different organic substrates and electron acceptors and assayed for Hg methylation rates, for microbial community structure, and for distribution of Hg methylators. The sediment and groundwater was collected from East Fork Poplar Creek in Oak Ridge, TN. Amendment with cellobiose (a lignocellulosic degradation by-product) led to a drastic decrease in the Hg methylation rate compared to that in an unamended control, with an associated shift in the microbial community to mostly nonmethylating Firmicutes This, along with previous Hg-methylating microorganism identification methods, will be important for identifying strategies to control MeHg production and inform future remediation strategies.
Collapse
|
12
|
Paranjape AR, Hall BD. Recent advances in the study of mercury methylation in aquatic systems. Facets (Ott) 2017. [DOI: 10.1139/facets-2016-0027] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity, it has become imperative to examine how mercury may enter biotic systems through its methylation to bioavailable forms in aquatic environments. Recent development of stable isotope-based methods in methylation studies has enabled a better understanding of the factors controlling methylation in aquatic systems. In addition, the identification and tracking of the hgcAB gene cluster, which is necessary for methylation, has broadened the range of known methylators and methylation-conducive environments. Study of abiotic factors in methylation with new molecular methods (the use of stable isotopes and genomic methods) has helped elucidate the confounding influences of many environmental factors, as these methods enable the examination of their direct effects instead of merely correlative observations. Such developments will be helpful in the finer characterization of mercury biogeochemical cycles, which will enable better predictions of the potential effects of climate change on mercury methylation in aquatic systems and, by extension, the threat this may pose to biota.
Collapse
Affiliation(s)
- Avnee R. Paranjape
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| | - Britt D. Hall
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| |
Collapse
|
13
|
Mazrui NM, Jonsson S, Thota S, Zhao J, Mason RP. Enhanced availability of mercury bound to dissolved organic matter for methylation in marine sediments. GEOCHIMICA ET COSMOCHIMICA ACTA 2016; 194:153-162. [PMID: 28127088 PMCID: PMC5257343 DOI: 10.1016/j.gca.2016.08.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The forms of inorganic mercury (HgII) taken up and methylated by bacteria in sediments still remain largely unknown. From pure cultures studies, it has been suggested that dissolved organic matter (DOM) may facilitate the uptake either by acting as a shuttle molecule, transporting the HgII atom to divalent metal transporters, or by binding HgII and then being transported into the cell as a carbon source. Enhanced availability of Hg complexed to DOM has however not yet been demonstrated in natural systems. Here, we show that HgII complexed with DOM of marine origin was up to 2.7 times more available for methylation in sediments than HgII added as a dissolved inorganic complex (HgII(aq)). We argue that the DOM used to complex HgII directly facilitated the bacterial uptake of HgII whereas the inorganic dissolved HgII-complex adsorbed to the sediment matrix before forming bioavailable dissolved HgII complexes. We further demonstrate that differences in net methylation in sediments with high and low organic carbon content may be explained by differences in the availability of carbon to stimulate the activity of Hg methylating bacteria rather than, as previously proposed, be due to differences in HgII binding capacities between sediments.
Collapse
Affiliation(s)
- Nashaat M. Mazrui
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton CT 06340, USA
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs CT 06269, USA
| | - Sofi Jonsson
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton CT 06340, USA
- Center for Environment and Sustainability, University of Gothenburg, Box 170, SE-405 30,Gothenburg, Sweden
| | - Sravan Thota
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs CT 06269, USA
| | - Jing Zhao
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs CT 06269, USA
| | - Robert P. Mason
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton CT 06340, USA
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs CT 06269, USA
| |
Collapse
|
14
|
Yin L, Yu K, Lin S, Song X, Yu X. Associations of blood mercury, inorganic mercury, methyl mercury and bisphenol A with dental surface restorations in the U.S. population, NHANES 2003-2004 and 2010-2012. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2016; 134P1:213-225. [PMID: 27639196 DOI: 10.1016/j.ecoenv.2016.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 05/09/2023]
Abstract
The potential adverse health effects of mercury from amalgam and bisphenol A (BPA) from composite resin have been significant concerns. It is unclear whether dental restorative materials significantly contribute to mercury or BPA levels. The purpose of this study is to use NHANES data including 14,703 subjects (2003-2004: n=7514; 2011-2012: n=7189) to examine the association between Dental Surface Restorations (DSR) and blood total mercury (THg), inorganic mercury (IHg), methyl mercury (MeHg) and urinary BPA through the stratification of covariates and multivariate analysis. Subjects were divided into three groups based on the number of dental surface restorations (DSRs, 0, 1-8, >8). Blood THg and IHg in 2003-2004 were significantly higher in the subjects with DSR (geometric mean of 0.48, 0.69 and 1.17μg/l for THg; 0.32, 0.33 and 0.39μg/l for IHg with DSR 0, 1-8 and >8). Similarly, increases of THg, IHg and MeHg were also observed in 2013-2014 (geometric mean of 0.51, 0.69 and 0.99μg/l for THg; 0.40, 0.49 and 0.66μg/l for MeHg; 0.20, 0.22 and 0.29μg/l for IHg with DSR 0, 1-8 and >8). Linear regression model analysis revealed blood THg and IHg in 2003-2004 and THg, IHg and MeHg in 2011-2012 were quantitatively associated with the number of DSRs. A dramatic decrease in urinary BPA from 2003 to 2004-2011-2012 was observed, but no significant increase with DSRs in either period of study. In conclusion, significant increases in blood THg, IHg, and MeHg in the subjects with DSRs are confirmed in a nationally representative population, a critical step in assessing the potential risk of adverse effects from dental restorative materials, but no association between dental fillings and urinary BPA was found.
Collapse
Affiliation(s)
- Lei Yin
- Department of Environmental Health Science, University of Georgia, Athens, GA, USA
| | - Kevin Yu
- Department of Environmental Health Science, University of Georgia, Athens, GA, USA
| | - Simon Lin
- The Center for Pediatric Dentistry, University of Washington, USA
| | - Xiao Song
- Department of Epidemiology and Biostatistics, University of Georgia, Athens, GA, USA
| | - Xiaozhong Yu
- Department of Environmental Health Science, University of Georgia, Athens, GA, USA.
| |
Collapse
|
15
|
Liem-Nguyen V, Jonsson S, Skyllberg U, Nilsson MB, Andersson A, Lundberg E, Björn E. Effects of Nutrient Loading and Mercury Chemical Speciation on the Formation and Degradation of Methylmercury in Estuarine Sediment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6983-90. [PMID: 27258391 DOI: 10.1021/acs.est.6b01567] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Net formation of methylmercury (MeHg) in sediments is known to be affected by the availability of inorganic divalent mercury (Hg(II)) and by the activities of Hg(II) methylating and MeHg demethylating bacteria. Enhanced autochthonous organic matter deposition to the benthic zone, following increased loading of nutrients to the pelagic zone, has been suggested to increase the activity of Hg(II) methylating bacteria and thus the rate of net methylation. However, the impact of increased nutrient loading on the biogeochemistry of mercury (Hg) is challenging to predict as different geochemical pools of Hg may respond differently to enhanced bacterial activities. Here, we investigate the combined effects of nutrient (N and P) supply to the pelagic zone and the chemical speciation of Hg(II) and of MeHg on MeHg formation and degradation in a brackish sediment-water mesocosm model ecosystem. By use of Hg isotope tracers added in situ to the mesocosms or ex situ in incubation experiments, we show that the MeHg formation rate increased with nutrient loading only for Hg(II) tracers with a high availability for methylation. Tracers with low availability did not respond significantly to nutrient loading. Thus, both microbial activity (stimulated indirectly through plankton biomass production by nutrient loading) and Hg(II) chemical speciation were found to control the MeHg formation rate in marine sediments.
Collapse
Affiliation(s)
| | - Sofi Jonsson
- Umeå Marine Sciences Centre, Umeå University , SE-910 20 Hörnefors, Sweden
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences , SE-901 83 Umeå, Sweden
| | - Mats B Nilsson
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences , SE-901 83 Umeå, Sweden
| | - Agneta Andersson
- Umeå Marine Sciences Centre, Umeå University , SE-910 20 Hörnefors, Sweden
| | - Erik Lundberg
- Umeå Marine Sciences Centre, Umeå University , SE-910 20 Hörnefors, Sweden
| | | |
Collapse
|