大宝山矿区上坝村农田土壤重金属污染特征

Characteristics of Heavy Metal Pollution in Farmland Soils of Shangba Village in Dabaoshan Area

了解大宝山矿区农田土壤中重金属污染的变化特征和迁移规律对其将来的污染防治具有重要作用。以大宝山下游地区的上坝村农田土壤为研究对象,研究了距离灌溉口不同距离45个土壤表层样点中重金属含量及空间分布。研究表明,Cu、Cd、Zn、As、Pb的超标率分别为100%、78%、67%、56%和100%,说明大宝山矿区农田土壤的污染是以Cu、Pb和Cd污染为主的多金属复合污染。个别点位的土壤中As和Pb含量超过了中国农用地土壤污染风险管制值,需采取严格管控措施。这7种金属元素含量在农田的空间分布表明,土壤中As、Cu、Fe、Pb和Zn的浓度随着与灌溉口距离的增大而降低,而Cd和Mn则不同,其分布与距离灌溉口的距离无关。重金属的综合污染指数1. 0 <PI <4. 50,平均值为2. 07,土壤污染程度属中轻度污染,农产品质量安全、农作物生长或土壤生态环境可能存在风险,应当加强土壤环境监测和农产品协同监测。

Understanding the distribution and migration of heavy metals in farmland is of great significance to its future agro-environmental pollution control and management.Content and space distribution of heavy metal contamination in farmland of Dabaoshan area and45surface layer soil samples were taken from agricultural soils at different distances from irrigation water entrance in the farmland near the Dabaoshan downstream-Shangba village.The results showed that the rates of exceeding standard on Cu,Cd,Zn,As and Pb were100%,78%,67%,56%and100%,respectively.It was illustrated that the soil of cropland was polluted primarily by heavy metals compound contamination including Cu,Pb and Cd.Strict control measures are required because of As and Pb content in some individual sites beyond the risk intervention values for soil contamination of agricultural land in China.The distribution of the seven heavy metals suggested that the concentrations of As,Cu,Fe,Pb and Zn decreased quickly with the distance to the entrance of irrigation water,while the concentrations of Cd and Mn showed a different trend which was not related to the entrance of irrigation water.The degree of soil pollution classified as moderate and mild pollution as a result of the comprehensive pollution index ranged from1.0to4.50,2.07in average.There might be risks in the quality security of agricultural products,crop growth or soil ecological environment,so relevant departments should strengthen soil environmental monitoring and agricultural product coordination monitoring.