Sedimentary records from an alpine wetland in southwestern China reveal the timing of Anthropocene human impact

Quantitatively distinguishing the historical record of potentially harmful trace element (PHTE) pollution in alpine wetland sediments enables an understanding of the nature and scale of Anthropocene human impact. In this study, we present PHTE and stable isotope (Pb and Hg) records for a sediment core from Jiulongchi wetland, Fanjing Mountain, southwest China. We calculate the chemical index of alteration and enrichment factors, and conduct multivariate statistics to reveal that the PHTEs in these wetland sediments were mainly regulated by weathering and erosion processes, as well as organic matter content. The pollution history for the last 1300 years is reconstructed from stable Pb and Hg isotopes, PHTE enrichment factors and accumulation rates. Coal combustion is shown to be a major anthropogenic source for PHTE input into the wetland, commencing in the 1940s and amplified during the 1950s. The research findings reflect the pattern of anthropogenic environmental changes in a remote tourist-hotspot area, which can aid in formulating policies to achieve a sustainable and environmentally healthy future for a vulnerable but important ecosystem.