Biogeochemical influences on net methylmercury formation proxies along a peatland chronosequence

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