Regional distribution of cadmium minerals and risk assessment for potential cadmium pollution of soil in China

Cadmium reserves,mineral resources distribution,and soil pollution caused by mining and smelting activities in China were analyzed in this study.The results showed that the accumulative proved reserves and available reserves of cadmium in China were 719.47 and 583.37 kt,respectively,and most of which existed in paragenetic or associated ores such as lead and zinc up to the end of 2005.The cadmium contained minerals were mainly distributed in the southwest,central south and north China,where the accumulative proved reserves and available reserves of cadmium accounted for 88.0% and 87.1% of the country total reserves.Large amount of cadmium had been released to the environment during the process of mining and utilizing ore deposits.The mined amount of cadmium reached 136.10 kt,and most of them were distributed in southwest China,where the exploited quantity of cadmium accounted for 59.4% of the total quantity of mined cadmium.Cadmium pollution mainly happened in Yunnan,Guangdong,Hunan,Guizhou provinces where there were rich in cadmium resources and intense nonferrous metal mining and smelting activities.Soils from the intense mining activities areas were heavily polluted with cadmium and the contents of cadmium in crops were significantly higher than the maximum levels of cadmium in foods in China(GB 2762-2005).