Interpretations of Hg anomalous sources in drainage sediments and soils in China

Abstract

China Geochemical Baselines project provides mercury dataset of drainage catchment sediments and soils during 2008–2012 in China. Fifty-seven mercury anomalous regions exceeding the risk limits of the China National Environmental Standards for Heavy Metals in Soil (GB 15618-1995) are delineated in China. The sources of Hg risk anomalies of the top and deep samples are variously interpreted with respect to geology/mineralisation and human activities. Nearly 72% anomalies (41 among the totaling 57 anomalous locations) are due to natural geological mineralisation belts and mining of Hg, As, Sb, Au, Ag, Pb, Zn, coal etc. The mining activities cause superimposed contents of Hg on the natural mineralisation belts. The influence of large-scale mining of Hg, non-ferrous metals and gold are significantly reflected in the geochemical maps. The anthropogenic sources of urbanisation emission, agriculture, coal combustion, and smelting industry cause the much more degree of mercury pollution in the eastern China where is highly populated and industrial density areas. Agriculture is an important Hg-emission source in the eastern China and Chengdu Plains where agricultural base for more than 2500 years in China. It is critical to carry out the follow-up detailed source investigation and monitor the temporal changes of Mercury in soils.