History metal (Pb, Zn, and Cu) deposition and Pb isotope variability in multiple peatland sites in the northern Great Hinggan Mountains, Northeast China

摘要

Placer gold mining is important anthropogenic sources of dust and metals that can strongly influence the environmental quality of the surrounding ecosystem. However, scarce studies have focused on evaluating the influence of placer gold mining on historical metal deposition in the surrounding ecosystem in the northern Great Hinggan Mountains, which is located at northeast of China. To address this research gap, four peatland cores with different distances to a gold placer in the northern Great Hinggan Mountains were selected in this study. Based on the Pb-210 depth-age model, historical variations in the Pb isotope and deposition fluxes of Pb, Cu, and Zn were reconstructed. The results show that metal deposition in the northern Great Hinggan Mountains was mainly influenced by the placer gold mining around the 1900s when the gold placer started to produce gold, and placer gold mining more seriously influenced the western sites that were closer to the placer gold mining. With increasing global metal productions after 1930, the proportion of the metals from placer gold mining sources gradually decreased, and part of Pb were transported via the atmosphere from other regions (e.g., Europe, East Asia). With the implementation of environmentally friendly policies and the decreasing anthropogenic production of Pb, Cu, and Zn around the world, deposition fluxes of these metals in the northern Great Hinggan Mountain began to decrease after 2000.