柴达木盆地表土重金属污染与来源分析

柴达木盆地主要土类为盐化荒漠土和石膏荒漠土，为了了解区内表层土壤重金属的污染特征、空间分布及污染源，在盆地内以主要沉积地貌为对象，以25 km左右为采样半径，共采集了129件表土（0~10 cm）样品，对表土中的As、Ba、Cr、Mn、Nb、Ni、Pb、Ti、Zn和Zr等10种重金属进行含量测定，并利用富集因子（EF）、地累积指数（I_geo）及绝对主成分-多元线性回归（APCS-MLR）受体模型等初步定量分析了重金属的污染程度及潜在来源.结果表明，柴达木盆地10种表土重金属元素自20世纪60年代以来，有不同程度的富集，As与Pb可能存在点源污染，整个盆地总体上在尚清洁状态到低污染之间，APCS-MLR分析表明，表土重金属受2个来源影响，分别为自然因子和交通因子，As、Cr、Mn、Nb、Ni、Ti、Zn和Zr受自然因素影响，Ba和Pb受自然因素和交通运输双重影响.

Evaluation and Sources of Heavy Metal Pollution in the Surface Soil of the Qaidam Basin

To understand surface soil heavy metal pollution characteristics, and the spatial distribution and sources of pollution in the main sedimentary features of the Qaidam Basin, a total of 129 topsoil samples(0-10 cm) were collected within a 25 km radius. The concentrations of As, Ba, Cr, Mn, Nb, Ni, Pb, Ti, Zn, Zr, and ten kinds of heavy metals were determined, the degree of contamination and potential sources quantitatively analyzed based on enrichment factors(EFs), the ground accumulation index(I_geo), and the absolute principal component-multiple linear regression(APCS-MLR) receptor model. The results showed that the surface soils of the Qaidam Basin have experienced pollution from ten kinds of heavy metals since the 1960s, with varying degrees of enrichment. As and Pb represent probable point source pollutants, and the basin as a whole shows negligible to low levels of pollution. The APCS-MLR analysis showed that heavy metal pollution derives from two sources, natural factors and anthropogenic(transportation) sources. Specifically, As, Cr, Mn, Nb, Ni, Ti, Zn, and Zr are associated with natural sources, while Ba and Pb are associated with both natural and anthropogenic sources.