河岸带土壤重金属元素的污染及危害评价

Heavy metal pollution and its ecological risk assessment of riparian soils

测定了金水河流域河岸带土壤部分重金属的全量和土壤水溶液的离子含量,运用污染指数和生态风险评价法对流域内土壤重金属进行评价。不同土地利用类型中,漫滩V、Cr含量最高(130.89、363.29mg·kg-1),草地Ni、Pb、Ti、Mn、Zn、Cu含量最高(32.52、24.61、4378.09、1289.62、91.44、29.71mg·kg-1)。这主要是因为草地、漫滩能够有效吸附和沉积重金属,同时人类活动明显增加重金属生态危害。金水河流域河岸带土壤Cr、Pb、Zn均超过土壤环境质量标准(GB15618-1995)。与此同时,河漫滩白浆化棕壤和钙质粗骨土碳酸钙含量高,对Pb、Zn有较强的吸附和固定作用,能够有效吸附和沉积重金属;河漫滩人类干扰较重,造成其重金属含量较高。评价结果表明,流域河岸带内重金属环境污染达到中、重度污染,生态危害等级为轻微到中等级别。提高土壤腐殖质含量是减轻污染危害及增强土壤自净能力的重要措施。

Riparian soil samples were collected from utary of the upper Hanjiang River, to determine the and the ion contents in soil water solution. Pollution forest-dominated Jinshui River basin, a tribtotal contents of several heavy metals in soil index and ecological risk index were used to evaluate the riparian soils heavy metals pollution. Within the basin, riparian soils heavy metals pollution was from moderate to severe, and the ecological risk was from minor to moderate. Among different land use types, flood plain had the highest contents of soil V （130. 89 mg·kg^-1 ） and Cr （363.29 mg·kg^-1 ）, whereas grassland had the highest contents of soil Ni （32.52 mg·kg^-1）, Pb （24.61 mmg·kg^-1）, Ti （4378.09mg·kg^-1）, Mn （1289.62 mg·kg^-1）, Zn （91.44 mg·kg^-1）, and Cu （29.71 mg·kg^-1）, mainly due to the effective adsorption and accumulation of these heavy metals by the flood plain and grassland soils and the increasing human activities. The Cr, Pb, and Zn contents in the riparian soils were over the lim- its of National Standard （GB 15618-1995）. In addition, the albic brown earth and calcic-skeletol soil in flood plain had high content of calcium carbonate which had strong capability in adsorbing and solidifying Pb and Zn. The heavy metals pollution of the riparian soils increased the potential risk of regional ecosystem and agrieuhure security. It would be important to increase soil humus content to alleviate the pollution and enhance the soil self-purification.