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Research article - Peer-reviewed, 2020

Shifts in mercury methylation across a peatland chronosequence: From sulfate reduction to methanogenesis and syntrophy

Hu, Haiyan; Wang, Baolin; Bravo, Andrea G.; Bjorn, Erik; Skyllberg, Ulf; Amouroux, David; Tessier, Emmanuel; Zopfi, Jakob; Feng, Xinbin; Bishop, Kevin; Nilsson, Mats B.; Bertilsson, Stefan;

Abstract

Peatlands are globally important ecosystems where inorganic mercury is converted to bioaccumulating and highly toxic methylmercury, resulting in high risks of methylmercury exposure in adjacent aquatic ecosystems. Although biological mercury methylation has been known for decades, there is still a lack of knowledge about the organisms involved in mercury methylation and the drivers controlling their methylating capacity. In order to investigate the metabolisms responsible for mercury methylation and methylmercury degradation as well as the controls of both processes, we studied a chronosequence of boreal peatlands covering fundamentally different biogeochemical conditions. Potential mercury methylation rates decreased with peatland age, being up to 53 times higher in the youngest peatland compared to the oldest. Methylation in young mires was driven by sulfate reduction, while methanogenic and syntrophic metabolisms became more important in older systems. Demethylation rates were also highest in young wetlands, with a gradual shift from biotic to abiotic methylmercury degradation along the chronosequence. Our findings reveal how metabolic shifts drive mercury methylation and its ratio to demethylation as peatlands age.

Keywords

Mercury; Methylation; Demethylation; Peatland; Chronosequence

Published in

Journal of Hazardous Materials

2020, volume: 387, article number: 121967
Publisher: ELSEVIER

Authors' information

Hu, Haiyan
Uppsala Univ
Hu, Haiyan
Chinese Acad Sci
Wang, Baolin
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Bravo, Andrea G.
CSIC
Bjorn, Erik
Umea Univ
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Amouroux, David
Univ Pau and Pays Adour
Tessier, Emmanuel
Univ Pau and Pays Adour
Zopfi, Jakob
Univ Basel
Feng, Xinbin
Chinese Acad Sci
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Uppsala University
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment

Associated SLU-program

Non-toxic environment

Sustainable Development Goals

SDG6 Clean water

UKÄ Subject classification

Environmental Sciences

Publication Identifiers

DOI: https://doi.org/10.1016/j.jhazmat.2019.121967

URI (permanent link to this page)

https://res.slu.se/id/publ/104966