典型设施栽培土壤重金属含量变化及其风险评价

采用野外调查采样和室内分析相结合的方法,对典型设施栽培地山东寿光的部分土壤重金属含量进行测定,并根据温室蔬菜产地环境质量评价标准,选取单项污染指数法和尼梅罗综合指数法对土壤的重金属污染状况进行了环境质量评价。结果表明,重金属Cu、C r、Pb在设施栽培土壤耕层(0—20 cm)的含量达最大值,显著高于露地土壤;而设施栽培土壤中Zn和Cd的含量分别在20—40 cm和40—60 cm的土层达到最大值,其中Zn含量在0—20 cm和60—80 cm的土层显著高于露地土壤,Cd含量在0—20 cm,40—60 cm,60—80 cm和80—100 cm的土层显著高于露地土壤。从不同使用年限设施栽培土壤中重金属含量变化看出,重金属在设施栽培24~年的土壤中含量最高。对研究区设施栽培土壤重金属含量进行风险评估及分级发现,山东寿光设施土壤耕层主要受到重金属Cd的污染。

Risk assessments of heavy metals in typical greenhouse soils

Contents of copper(Cu), chromium(Cr), lead(Pb), zinc(Zn)and cadmium(Cd)in greenhouse soils were measured by using a flame atomic absorption spectrophotometer. The soil samples were collected in Shouguang, Shandong Province. The environmental quality of greenhouse soils was assessed by applying the single pollutant index method and the Nemerow comprehensive index method based on the environmental quality evaluation standards of farmland for greenhouse vegetables production. The results indicated that Cu, Cr and Pb accumulations in greenhouse topsoils(0-20 cm)were the largest and higher than those of open field topsoils. Soil Zn and Cd contents were the highest at the depths of 20-40 cm and 40-60 cm in greenhouse soils, respectively. There were significant differences of soil Zn content between greenhouse and open field soils at depths of 0-20 cm and 60-80 cm, while those of Cd contents were at depths of 0-20 cm, 40-60 cm, 60-80 cm and 80-100 cm. The maximum values of heavy metal contents of greenhouse soils occured when greenhouses were cultivated for 2 to 4 years. According to the risk evaluation results of the heavy metals in greenhouse soils, there was Cd contamination in greenhouse topsoils in Shouguang, Shandong Province.