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Despite the limited direct anthropogenic mercury (Hg) inputs in the circumpolar Arctic, elevated concentrations of methylmercury (MeHg) are accumulated in Arctic marine biota. However, the MeHg production and bioaccumulation pathways in these ecosystems have not been completely unraveled. We measured Hg concentrations and stable isotope ratios of Hg, carbon, and nitrogen in the feathers and blood of geolocator-tracked little auk from five Arctic breeding colonies. The wide-range spatial mobility and tissue-specific Hg integration times of this planktivorous seabird allowed the exploration of their spatial (wintering quarters/breeding grounds) and seasonal (nonbreeding/breeding periods) MeHg exposures. An east-to-west increase of head feather Hg concentrations (1.74-3.48 μg·g) was accompanied by significant spatial trends of Hg isotope (particularly ΔHg: 0.96-1.13‰) and carbon isotope (δC: -20.6 to -19.4‰) ratios. These trends suggest a distinct mixing/proportion of MeHg sources between western North Atlantic and eastern Arctic regions. Higher ΔHg values (+0.4‰) in northern colonies indicate an accumulation of more photochemically impacted MeHg, supporting shallow MeHg production and bioaccumulation in high Arctic waters. The combination of seabird tissue isotopic analysis and spatial tracking helps in tracing the MeHg sources at various spatio-temporal scales.
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http://dx.doi.org/10.1021/acs.est.0c03285 | DOI Listing |
Environ Sci Technol
September 2025
Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2R3, Canada.
Permafrost thaw in peatlands risks increasing the production and mobilization of methylmercury (MeHg), a bioaccumulative neurotoxin that poses a health hazard to humans. We studied 12 peatlands on a trophic gradient in northwestern Canada, including permafrost peat plateaus and thawed bogs and fens, to determine the effects of thaw on MeHg production from measures of soil and porewater MeHg and in situ methylation assays. The production of MeHg was greater in thawed peatlands, especially rich fens, as indicated by higher potential rates of microbial methylation of inorganic mercury (Hg) to MeHg and higher soil %MeHg (MeHg:total Hg).
View Article and Find Full Text PDFThe flooded soil conditions under which rice is typically grown are beneficial for boosting yield and decreasing herbicide inputs but may pose a food safety and environmental health risk. Flooded soils lead to reducing conditions and anaerobic metabolisms of soil microorganisms, which mobilizes arsenic from soil into soil solution, where it can be absorbed by rice roots and transported to grain. These conditions also promote the production and emission of methane (CH)-a potent greenhouse gas.
View Article and Find Full Text PDFEnviron Pollut
August 2025
Research Unit in Environmental and Evolutionary Biology (URBE), Institute of Life, Earth & Environment, University of Namur, Rue de Bruxelles, 61-B, Namur, 5000, Belgium.
While the ability of plastic particles to transport heavy metals is well established, their Trojan horse effect on aquatic organisms remains debated, as they are suspected of facilitating the penetration of chemicals in tissues but also of reducing bioavailability and accelerating pollutant elimination. Here, we investigated the combined effects of 250 nm polystyrene nanoplastics (NPs) and methylmercury (MeHg) on zebrafish larvae over a 30-day exposure period. Larvae were exposed to 1000 μg/L NPs, 1 μg/L MeHg (MeHg1), 10 μg/L MeHg (MeHg10), or their respective combinations (Mix1 and Mix10).
View Article and Find Full Text PDFEnviron Res
August 2025
Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China.
Methylmercury (MeHg), the most neurotoxic and bioaccumulative mercury (Hg) species, poses significant risks to human and ecosystem health. Predicting these risks requires elucidating the drivers of MeHg production, which peaks at redox interfaces in aquatic systems where the primary Hg methylators, sulfate-reducing bacteria (SRB), are most active. Elevated Hg(II) methylation at these zones is primarily driven by the active sulfur cycling, primarily mediated by Hg-methylating SRB and sulfur-oxidizing bacteria (SOB) interactions.
View Article and Find Full Text PDFJ Hazard Mater
August 2025
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; School of Environment, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China; Scho
Although methanogenic archaea are among the oldest microorganisms capable of mercury methylation, their contribution to methylmercury (MeHg) production has only recently gained attention. Studies with laboratory-cultivated methanogens elucidate the transformation of inorganic mercury (Hg) into MeHg, thereby uncovering underlying microbial methylation mechanisms. However, this field faces challenges such as significant Hg loss and unstable culture systems, which impede accurate assessment of these processes.
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