Climate change and mercury in the Arctic: Abiotic interactions

Chételat, John; McKinney, Melissa A.; Amyot, Marc; Dastoor, Ashu; Douglas, Thomas A.; Heimbürger‐Boavida, Lars‐Eric; Kirk, Jane L.; Kahilainen, Kimmo K.; Outridge, P.M.; Pelletier, Nicolas; Skov, Henrik; Pierre, Kyra A. St.; Vuorenmaa, Jussi; Wang, Fei‐Yue

doi:10.1016/j.scitotenv.2022.153715

Cited by 76 publications

(42 citation statements)

References 230 publications

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“…We anticipated that higher MeHg concentrations would covary with a greater extent of peatlands and occur within the rapidly thawing discontinuous permafrost regions. In northern freshwaters, reduced PD is predicted to occur with permafrost thaw and the associated release of DOM (Chételat et al 2022). Our investigation of microbial‐driven methylation was exploratory since connections between hgc A gene abundance and MeHg concentrations remain unclear (Christensen et al 2019).…”

Section: Figmentioning

confidence: 99%

Controls on methylmercury concentrations in lakes and streams of peatland‐rich catchments along a 1700 km permafrost gradient

Thompson

Kuhn

Winder

et al. 2023

Limnology & Oceanography

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Permafrost thaw may increase the production of neurotoxic methylmercury (MeHg) in northern peatlands, but the downstream delivery of MeHg is uncertain. We quantified total mercury (THg) and MeHg concentrations in lakes and streams along a 1700 km permafrost transect in boreal western Canada to determine the influence of regional permafrost extent compared to local lake and catchment characteristics. In lakes, we assessed sediment microbial communities and modeled potential rates of water column photodemethylation (PD). Regardless of permafrost conditions, peatlands were the primary sources of MeHg across the transect as MeHg concentrations in streams increased with aromatic dissolved organic carbon (DOC), iron, and lower pH. Higher DOC and greater catchment peatland extent were further associated with higher stream %MeHg (MeHg/THg). Peatland lakes were potential MeHg sinks, with lower MeHg concentrations than streams (mean AE 1SD: 0.19 AE 0.23 and 0.47 AE 0.77 ng MeHg L À1 , respectively), and larger stream catchments had lower %MeHg where PD may occur in abundant small lakes. Microbial communities in lake sediments showed that abundance of Hg reducing genes (merA) predominated over Hg methylating (hgcA) and MeHg demethylating (merB) genes. The effects of permafrost extent on MeHg processes in lakes were secondary to the influence of local catchment characteristics, but lakes in regions with less permafrost had higher DOC concentrations, higher %MeHg, and lower potential rates of PD. Our study highlights a need to understand the impacts of climate change on MeHg source and sink processes, particularly as mediated through changes to peatland DOC, to improve projections of future MeHg concentrations in northern catchments.

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Section: Figmentioning

confidence: 99%

Controls on methylmercury concentrations in lakes and streams of peatland‐rich catchments along a 1700 km permafrost gradient

Thompson

Kuhn

Winder

et al. 2023

Limnology & Oceanography

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“…MeHg is formed by microbial methylation of inorganic mercury that deposits in waterways after atmospheric emission from coal-fired power plants and burning of gold-mercury amalgams during artisanal gold mining 3,4 . After conversion to the organic form, MeHg bioconcentrates and biomagnifies in the aquatic food web and humans are exposed via consumption of contaminated fish and seafood 4-6 . Clinically apparent MeHg neurotoxicity, including gross motor impairment, was first documented after high dose poisoning events that occurred in Minamata, Japan 7 and Iraq 8 (reviewed in 9,10 ).…”

Section: Introductionmentioning

confidence: 99%

High exposure variance enables candidate biomarker detection in a small EWAS of methylmercury-exposed Peruvian adults

Weinhouse

Perez

Ryde

et al. 2022

Preprint

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Background: Methylmercury (MeHg) is an environmental pollutant of global public health concern. MeHg is associated with immune dysfunction but the underlying mechanisms are unclear. The most common route of MeHg exposure is through consumption of fatty fish that contain beneficial n-3 polyunsaturated fatty acids (PUFA) that may protect against MeHg toxicity. Objectives: To better inform individual costs and benefits of fish consumption, we aimed to identify candidate epigenetic biomarkers of biological responses that reflect MeHg toxicity and PUFA protection. Methods: We profiled genome-wide DNA methylation using Illumina Infinium MethylationEPIC BeadChip in whole blood from N=32 individuals from Madre de Dios, Peru. Madre de Dios has high artisanal and small-scale gold mining activity, which results in high MeHg exposure to nearby residents. We compared DNA methylation in N=16 individuals with high (>10 μg/g) vs. N=16 individuals with low (<1 μg/g) total hair mercury (a proxy for methylmercury exposure), matched on age and sex. Results: We identified hypomethylated (i.e., likely activated) genes and promoters in high vs. low MeHg-exposed participants linked to Th1/Th2 immune imbalance, decreased IL-7 signaling, and increased marginal zone B cells. These three pathways are feasible mechanisms for MeHg-induced autoimmunity. In addition, we identified candidate epigenetic biomarkers of PUFA-mediated protection: hypomethylated enhancer binding sites for retinoid X receptor (RXR) and retinoic acid receptor α (RARα). Last, we observed hypomethylated enhancer and promoter binding sites for glucocorticoid receptor (GR), which is associated with developmental neurotoxicity, and transcription factor 7-like 2 (TCF7L2), which is associated with type 2 diabetes (T2D) risk. Discussion: Here, we identify a set of candidate epigenetic biomarkers for assessing individualized risk of autoimmune response and protection against neurotoxicity due to MeHg exposure and fish consumption. In addition, our results may inform surrogate tissue biomarkers of early MeHg exposure-related neurotoxicity and T2D risk.

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“…Considering that aquatic mammals have some of the highest tissue Hg concentrations and can contribute substantially to dietary Hg exposure for specific subpopulations, ,, there is a need to more actively monitor their Hg concentrations and update consumption advisories accordingly. This is especially important in light of predictions that Hg concentrations in aquatic mammals will be altered via abiotic and biotic responses to global change. − …”

Section: Resultsmentioning

confidence: 99%

Co-considering Selenium Concentrations Alters Mercury-Based Fish and Seafood Consumption Advice: A Data Compilation and Critical Assessment

Zampetti

Brandt

2023

Environ. Sci. Technol. Lett.

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There has been persistent interest in the mediating role of the micronutrient selenium (Se) in mercury (Hg) toxicity since the 1960s. Despite many unresolved questions regarding Se− Hg interactions, considerable research has been performed to document Se:Hg molar ratios in aquatic animals as a basis for inferring the health risks associated with their consumption. We compiled the co-reported Se and Hg data for 386 shellfish, finfish, and aquatic mammals from 89 papers to assess differences in consumption safety categorizations according to health risk metrics that (a) consider Hg concentrations alone or (b) co-consider Se and Hg concentrations. Species-specific mean Hg concentrations for 23% of all data points in our database exceeded the FAO/ WHO maximum level, and 68% and 83% had estimated daily intake per meal values for adults and children above the Joint FAO/WHO Expert Committee on Food Additives Provisional Tolerable Daily Index. In contrast, only 12% of data points would be categorized as unsafe for consumption on the basis of their 1:1 Se:Hg molar ratios. Se-inclusive risk metrics reversed safety categorizations for a majority of high-trophic level species that are most likely to exceed Hg-based risk thresholds. Adopting Se-inclusive risk metrics has potentially significant implications for seafood consumer health and is likely premature.

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Climate change and mercury in the Arctic: Abiotic interactions

Cited by 76 publications

References 230 publications

Controls on methylmercury concentrations in lakes and streams of peatland‐rich catchments along a 1700 km permafrost gradient

Controls on methylmercury concentrations in lakes and streams of peatland‐rich catchments along a 1700 km permafrost gradient

High exposure variance enables candidate biomarker detection in a small EWAS of methylmercury-exposed Peruvian adults

Co-considering Selenium Concentrations Alters Mercury-Based Fish and Seafood Consumption Advice: A Data Compilation and Critical Assessment

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