Heavy metal pollution and potential health risk assessment of white rice around mine areas in Hunan Province, China

摘要

To assess the pollution situation and human health risks, the concentrations of heavy metals Pb, Cd, Cu, and Zn in paddy soils and white rice around seven mining-affected areas in Hunan Province were analyzed. The ranges of concentrations of Pb (23.9-1595.8 mg kg(-1)), Cd (0.3-9.5 mg kg(-1)), Cu (31.2-321.5 mg kg(-1)) and Zn (56.1-3478.9 mg kg(-1)) in all paddy soils were significantly higher than Hunan background values and even exceeded the maximum permissible concentrations for paddy soil quality recommended by the Ministry of Environmental Protection of China. The geoaccumulation index (I- (geo) ) showed that Cd (1.42-6.33) was the predominant pollutant in all paddy soils, while Zn was the least important element. The concentrations of Pb, Cd, Cu, and Zn in white rice ranged from 0.18 to 0.72 mg kg(-1), 0.10 to 1.32 mg kg(-1), 3.83 to 5.95 mg kg(-1), and 8.64 to 18.18 mg kg(-1), respectively. Human health risk, associated with these heavy metals, was assessed based on hazard quotients (HQ) and hazard indexes (HI) for adults through consumption of white rice. HQ values of heavy metals (except for Cd) in most of mining-affected areas were below 1.0, while the HI of all heavy metals in all mine areas was higher than 1.0, the maximum acceptable level, suggesting that consumption of such contaminated white rice was a health risk. Except for the Leng Shui-Jiang mine area, Cd was the major contributor to the risk in the mine areas through white rice consumption, amounting to over 67 % of the HI, while Zn was a minimal contributor compared to the other metals.