Methylmercury cycling in high arctic wetland ponds: Sources and sinks

Igor Lehnherr, Vincent L. St. Louis, Craig A. Emmerton, Joel D. Barker, Jane L. Kirk

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


The sources of methylmercury (MeHg; the toxic form of mercury that is biomagnified through foodwebs) to Arctic freshwater organisms have not been clearly identified. We used a mass balance approach to quantify MeHg production in two wetland ponds in the Lake Hazen region of northern Ellesmere Island, NU, in the Canadian High Arctic and to evaluate the importance of these systems as sources of MeHg to Arctic foodwebs. We show that internal production (1.8-40 ng MeHg m-2 d-1) is a much larger source of MeHg than external inputs from direct atmospheric deposition (0.029-0.051 ng MeHg m -2 d-1), as expected. Furthermore, MeHg cycling in these systems is dominated by Hg(II) methylation and MeHg photodemethylation (2.0-33 ng MeHg m-2 d-1), which is a sink for a large proportion of the MeHg produced by Hg(II) methylation in these ponds. We also show that MeHg production in the two study ponds is comparable to what has previously been measured in numerous more southerly systems known to be important MeHg sources, such as temperate wetlands and lakes, demonstrating that wetland ponds in the High Arctic are important sources of MeHg to local aquatic foodwebs.

Original languageEnglish (US)
Pages (from-to)10514-10522
Number of pages9
JournalEnvironmental Science and Technology
Issue number19
StatePublished - Oct 2 2012
Externally publishedYes


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