苏南经济快速发展区土壤有效态镉含量影响因素及分布特征

研究了农田土壤有效态镉含量的影响因素及分布特征。结果表明：① 土壤有效态Cd含量总体较高，平均值为0.092 mg/kg，最大值高达0.354 mg/kg，且土壤Cd的平均活化率高达53%，Cd是该区主要的重金属污染物之一；②土壤表层有效态Cd含量与全Cd含量呈极显著正相关，回归分析表明该区农田土壤有效态Cd含量主要受全Cd含量的影响；③在不同经济功能区，有效态Cd和土壤Cd的活化率均以化工区为高，在不同地貌区，二者均以中部平原区最高，中部平原区Cd的活化率显著高于北部洼区；④在土壤剖面上，土壤有效态Cd含量和土壤Cd的活化率均以表层为高，表明土壤Cd的环境风险主要集中在表层20 cm。

CHARACTERISTICS IN THE DISTRIBUTION OF AVAILABLE CADMIUM IN SOIL WITH ANALYSIS OF ITS INFLUENTIAL FACTORS IN FAST ECONOMY DEVELOPING REGION OF SOUTH JIANGSU PROVINCE

Characteristics in the distribution of available cadmium in soil in kunshan City of Jiangsu Province was investigated in the present study.The content of available Cd in soil is relatively high,with the average being at 0.092 mg/kg and the maximum 0.354 mg/kg,and the available rate of soil Cd up to 53%.It is indicated that Cd is one of the main pollutants among heavy metals in soil in this area.The content of available Cd is significantly positively correlated with the content of total Cd in the upper layer soil,with the equation being at y=0.748 9x-0.029 8(r=0.886>r_0.01=0.463,n=30).It is shown that the content of available Cd in soil is mainly affected by the total Cd in soil in this area.The available Cd and available rate of Cd are reltively high in areas with chemical factories,although the function of these areas may differ in economy,and these two parameters are high in the middle plain areas of different physiognomy in this city.The available rate of Cd is significantly higher in the middle plain area than in the north low area.Overall,in soil the available content and available rate of Cd is higher in the upper layer,indicating that the environmental risk of Cd exists mainly in the upper 20 cm layer of soil.