青藏高原表土重金属污染评价与来源解析

为了解青藏高原表层土壤重金属的污染特征、空间分布及污染来源,沿东北-西南方向对青藏高原表土(0～20 cm)样品进行了采集,对土壤中的Ba、Cd、Co、Cr、Cu、Fe、Mn、Mo、Ni、Pb、Sb、Sc和Zn等13种重金属总量进行了分析,并利用主成分分析-绝对主成分分数-多元线性回归(PCA-APCS-MLR)受体模型初步定量解析了重金属的潜在来源.结果表明Cd和Sb均显著超标,分别是20世纪70年代青藏高原土壤背景值的2. 13与1. 52倍.富集因子(EF)、地累积指数(I_(geo))和Nemero综合指数(PN)分析同样表明青藏高原表土主要以Cd和Sb污染为主,但污染程度普遍不高.在空间分布方面,青藏高原中部、东南部及东北部均呈不同程度污染,但中部及东南部污染相对较重. PCA-APCS-MLR分析表明,青藏高原土壤重金属主要有3个来源,分别为自然、交通和采矿等综合因素. Co、Cr、Cu、Fe、Mn、Ni和Sc主要受自然因素影响,Ba、Cd、Mo和Pb主要受交通因素影响,Zn主要受自然和交通因素共同影响,Sb主要受采矿、自然和交通等综合因素影响.青藏高原土壤重金属污染防治过程中应着重考虑受交通、采矿等综合因素影响下的Cd和Sb污染.

Evaluation and Source of Heavy Metal Pollution in Surface Soil of Qinghai-Tibet Plateau

Spatial distribution and source apportionment of heavy metals in the surface soil of the Qinghai-Tibet Plateau was investigated to gain an understanding of the pollution characteristics. The surface soil (0-20 cm) samples were collected from the northeast to the southwest in the study area. The total amount of 13 heavy metals (Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sc, and Zn) was determined. The potential sources of heavy metals were preliminarily apportioned and identified by the principal component analysis-absolute principal component score-multiple linear regression (PCA-APCS-MLR) receptor model. Results show that the average contents of Cd and Sb significantly exceed the environment standard, and they were 2.13 and 1.52 higher than the soil background values of the Qinghai-Tibet Plateau in the 1970s, respectively. The enrichment factor (EF), geo-accumulation index (I_geo), and Nemero synthesis index (PN) were used to evaluate the surface soil heavy metal contamination, which indicated that Cd and Sb also were pollutants in the Qinghai-Tibet Plateau with a limited pollution level. Various levels of pollution were presented at the central, southeastern, and northeastern regions of the Qinghai-Tibet Plateau, while the central and southeastern areas exhibited relatively severe pollution levels. The PCA-APCS-MLR levels revealed that three main sources of heavy metals in the soil of the Qinghai-Tibet Plateau were the natural source, traffic activities, and the mining industry, in that order. Cobalt, Cr, Cu, Fe, Mn, Ni, and Sc, were largely affected by natural sources, while Ba, Cd, Mo, and Pb were mainly affected by traffic activities. Specifically, Zn gave priority to natural and traffic sources, and Sb was jointly affected by natural sources, traffic activities, and the mining industry. Therefore, Sb and Cd pollution from traffic activities and the mining industry should be noted in control plans for the heavy metal pollution in soil of the Qinghai-Tibet Plateau.