对长江三角洲某典型废旧电子产品拆解场地周边基本农田保护区水稻土进行了采样及土壤基本理化性质和重金属污染特征研究。结果表明,该地区水稻土pH变化范围为3.8~4.4,平均为4.1,较我国第二次土壤普查的该区表层水稻土pH6.0降低了2个单位,存在着严重的酸化现象。农田土壤中Cu、Cd全量平均值分别达到土壤环境质量二级标准值的8.6倍和31.0倍,综合污染指数为32.3,已达严重污染程度。土壤pH降低提高重金属的活性,Cu、Cd的0.1mol L^-1 HCl提取率分别达到了72.0%和50.8%。在水稻籽粒中,Cd的含量已达到国家粮食卫生标准的2倍多,对该农田保护区农产品安全构成风险,需要采取措施对其进行控制和修复。
Basic properties and heavy metal contents were investigated of paddy soil next to a typical used electronic device disassembling site in the Yangtze River Delta. Results show that its soil pH varied from 3. 8 to 4. 4, with an average of 4. 1 , which was obviously lower than that ( pH = 6.0) obtained during the Second National Soil Survey of China, demonstrating severe soil acidification. Its Cu and Cd content was 8.6 and 31.0 times as much as that, respectively, of Grade Ⅱ Criteria of the National Standard for Environment Quality. Its synthetic pollution index reached 32.3, indicating serious pollution. Soil pH is a leading factor influencing soil pollution of heavy metals, because lower pH improves activity of heavy metals. The extraction rate of Cu and Cd with 0.1mol L^-1HCl was 72.0% and 50. 8% , respectively, and their accumulation in the plant of rice was significant, especially in grains, where the content of Cd was 2 times as high as the criterion in the National Hygienic Standards for Grains. Obviously, soil acidification and heavy mental pollution synchronously existed in this farmland, posing potential health risk through the food chain. It is, therefore, essential to take positive measures to control the pollution and remedy the polluted soil.