Sedimentary records and stable lead isotopes reveal increasing anthropogenic impacts on heavy metal accumulation in a plateau lake of China over the last 100 years

Abstract

Plateau lakes in China are faced with heavy metal contamination. The present study investigated the concentrations, sources, and ecological risks of 11 heavy metals in sediments of Lake Fuxian over the last 100 years. The concentrations of V (124–244 mg/kg), Cr (69.3–127 mg/kg), Cu (59.4–105 mg/kg), Ni (36.0–66.3 mg/kg), and Co (15.4–25.5 mg/kg) significantly decreased in the last 100 years while Cd, Sb, Pb, and Zn had contrary trends. In the last 100 years, correlations between the heavy metals changed in reverse due to the combined influences of lithogenic and anthropogenic sources. In the last 40 years, the lithogenic sources mainly contributed to the concentrations of As, Hg, V, Cr, Co, Ni, and Cu, with the rates of 55 %− 85 %. Moreover, Cd, Sb, Pb, and Zn were mainly affected by anthropogenic sources (e.g., mining activities and human settlement change), with the contribution rates of 53 %− 80 %. The change of stable Pb isotope in the sediment cores indicated that galena mining was the main source of Pb. With increasing anthropogenic activities, there was a possibility of 90 % that a moderate ecological risk might appear in the last 40 years. Among the heavy metals, Cd should attract attention because it contributed 96 % to the combined ecological risk.