某污灌区污水-土壤-地下水污染物分布特征

通过对某污灌区灌溉水、土壤及地下水的取样分析,研究了灌区污染物的分布特征。结果表明:灌区主要污染物为重金属Zn、多环芳烃和农残六六六。不同污染物分布特征不同。重金属主要富集于土壤表层,如Zn大部分富集于耕植层中(0～30cm),但浓度过高,其可向深部迁移。多环芳烃按分子量可分为三类,小分子量芳烃迁移过程中降解转化显著;中分子量芳烃迁移至深部土壤和地下水,土壤各深度吸附量几乎相同;大分子量芳烃化学性质稳定,易吸附沉积于表层土壤和底泥中。农残六六六迁移深度至少可达50m。

Distribution Characteristics of Contaminants in Wastewater-Soil-Groundwater in a Wastewater Irrigation Area

By sampling and analysis of irrigation water,soil and groundwater in a wastewater irrigation area,the distribution characteristics of contaminants in soil and groundwater were studied.The results indicated that the major contaminants are heavy metal Zn,polycyclic aromatic hydrocarbons(PAHs) and pesticide residues HCH in the wastewater irrigation area.The distribution characteristics are different for different contaminants.Heavy metals are mainly accumulated in soil surface,such as Zn,which is mostly accumulated in the arable layer(0～30 cm),but it will migrate to deep soil when its concentrations are high enough.According to molecular weight,PAHs can be divided into three categories.In the process of migration,small molecular weight PAHs degrade dramatically;medium molecular weight PAHs can migrate to deep soil and groundwater,and the adsorption capacity is almost the same at different depths;high molecular weight PAHs are stable in chemical property,they can be easily deposited and adsorbed on surface soils and sediments.Pesticide residues HCHs can migrate so deeply as to be 50m at least.