扬州市耕地土壤重金属污染现状与演变趋势

Heavy Metal Pollution Situation and Changing Tendency in Farmland Soil of Yangzhou City

[目的]研究2012年扬州市耕地土壤重金属污染现状及2002年以来的变化趋势。[方法]采集扬州市耕地土壤样品,分别测定总镉、总砷、总铬、总汞、总铅含量,加权统计计算平均值、标准差、变异系数等,并与2002年的数据进行对比分析。[结果]2012年扬州市不同重金属元素污染指数从高到低依次为总镉、总砷、总铬、总汞、总铅,不同重金属元素污染超标面积比例从高到低为总镉、总汞、总砷、总铅,总铬全部合格。与2002年相比,土壤中总镉、总铅含量均显著上升,总汞、总铬含量上升未达显著水平,总砷含量则显著下降;总镉、总汞、总砷、总铅超标面积比例均上升。[结论]重金属污染特别是总镉、总汞污染亟需引起高度重视。土壤总镉、总汞、总铅含量变异系数明显增大,说明总镉、总汞、总铅有明显的点源污染特点。

[Objective] To research the heavy metal pollution situation in farmland soil of Yangzhou City in 2012 and the changing tendency since 2002. [Method] Farmland soil samples in Yangzhou City were collected. The contents of total cadmium,arsenic,chromium,mercury and lead were detected. The average value,standard deviation and coefficient of variation were calculated by weighting statistics,and compared with the data in 2002. [Result] According to the pollution index,the order of heavy metal elements from high to low was total cadmium,total arsenic,total chromium,total mercury and total lead in Yangzhou City in 2012. Excessive polluting area ratios of heavy metal elements were in the order of total cadmium,total mercury,total arsenic,total lead and total chromium,which were all qualified. Compared with data in 2002,contents of total cadmium and lead enhanced significantly in 2012; contents of total mercury and chromium showed no significant enhancement; but content of total arsenic reduced significantly. Excessive area ratios of total cadmium,total mercury,total arsenic and total lead increased. [Conclusion] More attention should be paid to heavy metal pollution,especially total cadmium and mercury pollution. Variance coefficients of total cadmium,total mercury and total lead had obvious characteristics of point pollution.