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Biogeochemical influences on net methylmercury formation proxies along a peatland chronosequence

Zhong, Shunqing and Bjorn, Erik and Bravo, Andrea G. and Hu, Haiyan and Zhong, Shunqing and Bertilsson, Stefan and Eklöf, Karin and Wang, Baolin and Åkerblom, Staffan and Nilsson, Mats and Bishop, Kevin and Hu, Haiyan and Skyllberg, Ulf (2021). Biogeochemical influences on net methylmercury formation proxies along a peatland chronosequence. Geochimica et Cosmochimica Acta. 308 , 188-203
[Research article]

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Abstract

A geographically constrained chronosequence of peatlands divided into three age classes (young, intermediate and old) was used to explore the role of biogeochemical influences, including electron donors and acceptors as well as chemical speciation of inorganic mercury (Hg(II)), on net formation of methylmercury (MeHg) as approximated by the fraction of MeHg to total mercury (THg) in the peat soil. We hypothesized that removing vascular plants would reduce availability of electron donors and thus net MeHg formation. However, we found no effect of the vascular plant removal. The sum of the potential electron donors (acetate, lactate, propionate and oxalate), the electron donation proxy organic C/Organic N, and the potential electron acceptors (Fe(III), Mn and sulfate) in porewater all showed significant correlations with the net MeHg formation proxies in peat soil (MeHg concentration and %MeHg of THg). Thus differences in both electron donor and acceptor availability may be contributing to the pattern of net MeHg formation along the chronosequence. In contrast, Hg(II) concentrations in peat porewater showed small differences along the gradient. A chemical speciation model successfully predicted the solubility of Hg and MeHg in the porewater. The modeling pointed to an enhanced concentration of Hg-polysulfide species in the younger peatlands as a potential factor behind increased Hg(II) solubility and methylation in the more nutrient-rich peatlands. This work contributes to the understanding of Hg and MeHg cycling in peatlands which can help guide mitigation measures to reduce aquatic MeHg biomagnification in peatland dominated landscapes. (C) 2021 The Authors. Published by Elsevier Ltd.

Authors/Creators:Zhong, Shunqing and Bjorn, Erik and Bravo, Andrea G. and Hu, Haiyan and Zhong, Shunqing and Bertilsson, Stefan and Eklöf, Karin and Wang, Baolin and Åkerblom, Staffan and Nilsson, Mats and Bishop, Kevin and Hu, Haiyan and Skyllberg, Ulf
Title:Biogeochemical influences on net methylmercury formation proxies along a peatland chronosequence
Series Name/Journal:Geochimica et Cosmochimica Acta
Year of publishing :2021
Volume:308
Page range:188-203
Number of Pages:16
Publisher:PERGAMON-ELSEVIER SCIENCE LTD
ISSN:0016-7037
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geochemistry
Keywords:Mercury, Methylmercury, Chronosequence, Peatland, Porewater, Hg solubility, Chemical speciation
URN:NBN:urn:nbn:se:slu:epsilon-p-113799
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-113799
Additional ID:
Type of IDID
DOI10.1016/j.gca.2021.06.010
Web of Science (WoS)000697126200011
ID Code:25562
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
S - Faculty of Forest Sciences
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:05 Oct 2021 15:25
Metadata Last Modified:05 Oct 2021 15:31

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