Evaluation and Source of Heavy Metal Pollution in Surface Soil of Qinghai–Tibet Plateau
(2.Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin, China 300387)
(3.Skate Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China 100085)
【Abstract】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 the soil background values of the Qinghai–Tibet Plateau in the 1970 s, respectively. The enrichment factor (EF), geo-accumulation index (Igeo), and Nemero synthesis index (PN) were used to evaluate the surface soil heavy metal pollution, which indicated that Cd and Sb were also pollutants in the Qinghai–Tibet Plateau with a limited contamination grade. Various levels of contamination were presented at the central, southeastern, and northeastern areas of the Qinghai–Tibet Plateau, while the central and southeastern areas exhibited high contamination grades. The PCA–APCS–MLR levels revealed that three main sources of heavy metals in the soil of the Qinghai–Tibet Plateau were the natural, traffic, and mining factors. Co, Cr, Cu, Fe, Mn, Ni, and Sc were largely affected by natural sources, while Ba, Cd, Mo, and Pb were mainly affected by traffic factors. Specifically, Zn was influenced mainly by natural and traffic factors, and Sb was jointly affected by natural, traffic, and mining factors. Therefore, Sb and Cd contamination from traffic and mining factors should be noted in control plans for the heavy metal pollution in soil of the Qinghai–Tibet Plateau.
【Keywords】 Qinghai–Tibet Plateau; surface soil; heavy metals; sources; PCA–APCS–MLR receptor model;
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