Evaluation and Source Analysis of Heavy Metal Pollution in Grassland Soils under Different Management Modes in Altay, Xinjiang

In order to study the characteristics and sources of heavy metal pollution within different grassland soil categories in Altay, 147 soil samples were collected in Fuyun County according to grassland type, and the contents of seven heavy metals (Cu, Pb, Cr, Zn, As, Ni, and Cd) were determined. The heavy metal pollution in the soil was evaluated using the Nemerow pollution and geological accumulation index methods. The absolute principal component score-multiple linear regression model (APCS-MLR) model was used to analyze the sources of heavy metals and the contribution rate of the pollution sources. The results showed that (1) the heavy metal content of 0 similar to 10 cm soil in the mining area was generally higher than the remaining two layers. Natural grassland was the most seriously contaminated, and the order of its contamination was Zn > Pb > Ni > Cd > Cu > Cr > As. (2) The evaluation results of the comprehensive pollution index showed that Ni and Cd were the main pollutants in five grassland types, and the evaluation results of the geological accumulation index method showed that natural grasslands were more polluted. (3) Three pollution sources were obtained according to the analysis using the APCS-MLR model, including natural and mining activity sources (32.6%), industrial coal combustion and sewage sources (24.7%), and an unknown source (42.7%). The results of the study can provide a basis for pollution control and ecological protection in the grasslands of Altay.