摘要
中国北方河套地区土壤、水中的砷及其它重金属元素导致人群井水砷中毒。该区井水砷中毒发病范围涉及7个旗县(五原县、杭锦后旗、乌拉特前旗、乌拉特后旗、临河市、磴口县、阿拉善左旗)的约6100km^2地域,受威胁人数达18万。然而,有关井水中砷的来源的专门研究工作开展得很少,本文基于对该区重金属元素在土壤、潜水中的分布特征研究,对其成因进行探索。结果显示,砷在潜水中的平均含量为0.483μg/g,在土壤中为13.74μg/g。这些含量水平显著高于世界卫生组织推荐(1984年)的0.05μg/g饮水砷含量标准及当地土壤的砷背景含量(5.20μg/g)。在污染区土壤及潜水中的重金属含量随离开上游阴山山前范围的距离增大而递减。区内潜水中的铅、锶同位素含量比值与上游矿区水中的铅、锶同位素比值紧密关联,土壤中的铅、锶同位素含量比值变化特征与人群中毒区土壤及潜水中的砷含量变化相应。数据揭示,污染物起源于位于河套地区上游的阴山山前矿业区。
In the Hetao region in northern China drinking water has become toxic due to the presence of arsenic (As)and other heavy metals in soil and water.The 7 counties in this region cover approx.6100 km 2,and in all 180 000 people are suffering from the toxic effects of contaminated drinking water.However.very few studies have been carried out in the region on the possible source of this arsenic.This paper is based on studies of the distribution of heavy metals in soil and groundwater.Results show that the average content of As is 0.483 μg g -1 in groundwater and 13. 74 μg g -1 in soil.These levels are higher than the drinking water standard of 0.05 μg g -1 recommended by the World Health Organization in 1984,and for the local back- ground level in soil (5.20 μg g -1 ).This heavy-metal content in water and soil de- creases gradually with increasing distance from the contaminated area,which fronts the Yin Mountains.The ratios of the Pb and Sr isotope contents in water are closely related to the ratios found in the water of the regions'mining area.and the ratios in soil correspond to the content of As in groundwater and soil in the area where pathological changes have been detected.Results suggest that the contaminants originate in the ore deposit zone fronting Yin mountains in the upper reaches of the Hetao Region.
