A 15,400-year record of natural and anthropogenic input of mercury (Hg) in a sub-alpine lacustrine sediment succession from the western Nanling Mountains, South China.

Abstract

A 15400-year mercury (Hg) accumulation history was reconstructed from a lake sediment core collected from Daping Swamp in western Nanling Mountains, South China. Our results show that the natural input of Hg was deeply influenced by varying climatic conditions. Under wet and warm conditions, increased surface soil organic matter induced by improved vegetation conditions favor an increased input of surface soil-bound Hg to the lake, thus leading to higher Hg accumulation rate, and on the other hand, the direct atmospheric wet deposition of Hg into the lake would also be enhanced. In contrast, under relatively cold and dry conditions, it would display an inverse picture. The signal of anthropogenic influence possibly derived from regional Hg pollution likely started at ~ 3400cal. years BP, roughly corresponding to the early stage of the Shang Dynasty in Chinese history. Four periods of increased anthropogenic Hg inputs appeared in ~ 3358-2170, ~ 2170-1730, ~ 1369-1043, and especially ~ 600-250cal. years BP, corresponded to the Shang and Zhou, the Qin and Han, the Sui and Tang, and the Ming and Qing dynasties in China, respectively. A clearly weakened anthropogenic input occurred between~1750 and 1400cal. years BP, coinciding with the Three Kingdoms to the Southern and Northern Dynasties. Our results revealed the history of the natural Hg accumulation since the Last Deglacial period, and the existence of regional atmospheric Hg induced from anthropogenic activity spanning the last ~ 3400years.