Environmental geochemistry of an abandoned mercury mine in Yanwuping, Guizhou Province, China.

The distribution of mercury (Hg) and methylmercury (MeHg) in paddy soil and rice grain (polished), and Hg in surface waters and gaseous elemental Hg (GEM) in atmosphere at the Yanwuping Hg mining district (YMM), Guizhou Province, China was investigated. Results exhibited high total Hg (Hg(T)) and MeHg concentrations in soil at sites adjacent to calcine pile and tailings, and ranged from 5.6 to 240mgkg(-1) and 0.66 to 7.3µgkg(-1), respectively. Concentrations of Hg(T) in rice ranged from 10 to 45µgkg(-1), and high MeHg concentrations were also observed ranging from 3.2 to 39µgkg(-1). The elevated Hg(T) and MeHg concentrations in soil in the vicinity of calcine pile and tailings reflected in high MeHg concentrations in rice. Those data were significantly correlated with MeHg concentration in soil confirming that soil is the major source of MeHg in rice. The highest Hg concentrations in water, otherwise rather low, ranging from 3.8 to 51ngl(-1) for Hg(T) and of 0.14 to 2.7ngl(-1) for MeHg(T), were found at the proximity of calcine pile suggesting that untreated mine wastes are the principal source of Hg in the nearby area. Huge emissions of GEM were also detected from calcines affecting the whole area, ranging from 12 to 180ngm(-3) with an average of 46±35ngm(-3). The distribution patterns of Hg and MeHg observed in the environmental compartments suggest an elevated contamination of Hg in the region. Elevated high MeHg concentrations in rice might pose a potential health risk to local populations.