Mercury mining areas are considered as hot spots of Hg pollution, and the mercury pollution from large scale mercury mining (LSMM) has been widely studied worldwide in Hg mining areas. Known for its low recovery efficiency, high environmental costs, and poor health and safety measures, artisanal mercury mining (AMM) is periodically operated by the local peasants seasonally or according to the market price development. AMM can be widely distributed in the Hg mining area as a non-point pollution source to the local environment. Aiming to evaluate the environmental impacts from LSMM and AMM, Professor FENG Xinbin’s group at Institute of Geochemistry, Chinese Academy of Sciences (IGCAS) carried out a study on total mercury (THg) and methyl mercury (MeHg) in the mine waste, ambient air, stream water and soil samples collected from Wuchuan mercury (Hg) mining area, Guizhou, Southwestern China.

Their study showed that the mine wastes from both LSMM and AMM contained high THg concentrations, which are significant Hg contamination sources to the local environment; total gaseous mercury (TGM) concentrations in the ambient air near AMM furnaces were highly elevated, revealing that AMM retorting is a major source of Hg emission; THg concentrations in the stream water varied from 43 to 2100 ng/L, where the elevated values were mainly found in the vicinity of AMM and the mine waste heaps of LSMM; and furthermore, the surface soils were seriously contaminated with Hg, and the land using types and organic matter played important roles in the accumulation and transportation of Hg in soil.

The results of their study indicated that heavy Hg contaminations existed in the study area and were caused by both LSMM and AMM. The areas impacted by LSMM were concentrated in the historical mining and smelting facilities, while Hg pollution resulted from AMM can be distributed anywhere in the Hg mining area.

The above research was published in Environment International 42 (2012) 59-66.

(By LI Ping)