污灌对潮土重金属含量及分布的影响——以开封市化肥河污灌区为例

以开封市化肥河污灌区为例,研究了污水灌溉对潮土中重金属(Cd、Pb、Cr、Cu、Zn、Ni和 As)含量及分布的影响。结果表明,污水灌溉已经导致了该区潮土较明显的重金属累积,其中Cd和As平均含量分别达1．70 mg/kg和26．28 mg/kg,远远超出了土壤环境二级标准值。进入潮土的重金属主要累积在潮土的耕作层,随着土壤深度的增加,重金属含量逐渐减少;相对其他重金属而言,As更易于在潮土表层滞留。污灌区潮土 Cu、As与Cd含量与距污染源距离呈线性相关。相关分析表明,污灌区土壤Cu、Zn、Pb、Ni和As含量与土壤理化性质及其他重金属含量有关,而土壤Cd和Cr含量则与其他重金属含量及土壤性质的相关性不明显。

Effect of Sewage Irrigation on Content and Distribution of Heavy Metals in Alluvial Meadow Soil--A Case Study of the Huafei River Sewage Irrigation Region in Kaifeng City

Samples of fluvo-aquic soils in the Huafei River sewage irrigation region of Kaifeng City were collected for determination of contents of Cu, Zn, Pb, Cr, Cd, Ni and As. The results indicated that sewage irrigation has led to obvious accumulation of heavy metal in the fluvo-aquic soil; the average contents of Cd and As reached 1.70 mg/kg and 26.28 mg/kg, respectively, far beyond the second grade criteria of the national standard for soil quality. Heavy metals entered into the fluvo-aquic soil from sewage and accumulated mainly in cultivated layer of the soil, showing a decreasing trend in concentration with the depth of the soil profile; among the seven heavy metals, As accumulated most easily in the cultivated layer. The contents of Cu, As and Cd in the soil were in linear correlation with distance from the source of pollution. Correlative analysis indicated that the contents of Cu, Zn, Pb, Ni and As in the soil were related to physical and chemical properties of the soil and contents of other heavy metals while the contents of Cd and Cr in the soil were not.