Epsilon Archive for Student Projects

Abstract

Mercury (Hg) is a neurotoxic heavy metal that can be taken up by vegetation from the atmosphere. Peatlands, formed by decomposed vegetation, store significant amounts of Hg, part of which is transported to downstream aquatic ecosystems. Peatlands also serve as a natural archive of atmospheric Hg concentrations in a chronological order, even though post-deposition processes can mobilize Hg from the peat. Understanding the fate of mercury in peatlands is important for predicting how ecosystems respond to changing atmospheric Hg concentrations. In this study, Hg concentrations in eight peat cores collected in 2025 from Degerö Stormyr, Sweden, were analyzed and compared with those in peat cores sampled in 2015 and 2020. We found that the Hg pool decreased over the last decade, and that different peat cores can exhibit very distinct biogeochemical properties even if sampled from the same site, separated by only a few meters. The vegetation growing on the peatland also showed variable Hg concentrations depending on species and the parts of plants analyzed. Our findings of large intra-variability in Hg levels highlight the importance of investigating multiple sites and cores to monitor Hg concentrations within the same peatland and of analyzing several cores from the same sites. It is also significant to include an analysis of plants, both surface vegetation and of plant macrofossils in the peat. They are to ensure a comprehensive investigation of Hg mobility in peatlands and a robust evaluation of temporal changes in atmospheric Hg levels using peat records.