中国镉矿的区域分布及土壤镉污染风险分析

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

系统地分析和评价了中国镉矿的区域分布及长期采选冶活动所带来的土壤镉污染风险。研究结果表明,截至2005年底,中国累计探明镉资源储量约为719.47kt,保有镉资源储量约为587.37kt,且多与铅矿、锌矿等以共、伴生形式存在。中国镉矿主要分布在中部、西南部及华东地区,这些地区的镉资源探明储量占中国累计探明总储量的88.0%,保有储量占中国总保有储量的87.1%。据统计,中国镉采出量约为136.10kt,主要集中在西南地区,其镉采出量占中国总采出量的59.4%。镉污染事件主要发生在镉矿相对丰富及采选冶活动较密集的云南、广东、湖南、贵州等地区,大部分矿冶区及周边土壤呈现重度镉污染,农作物中含镉量超出《食品中污染物限量》(GB 2762—2005)中限值。

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 ~//0 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, Hu- nan, 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 cadmi- um in crops were significantly higher than the maximum levels of cadmium in foods in China （GB 2762-2005）.