Thallium Contamination and Ecological Risk Assessment of Soil in Jiulong Alpine Mountain Area in Western Sichuan of China

Owing to an increase in the critical mineral resources exploration and national ecological security construction, an environmental impact assessment was performed to evaluate the thallium contamination and ecological risk of soil in Jiulong alpine mountain area, western Sichuan Province, China. Based on the analysis of thallium content in 1037 soil samples, the pollution level and spatial variation of the thallium in all of the soil samples of the study area were comprehensively evaluated by multiple evaluation methods. The results show that, the thallium content in soil of the study region was 0.30–2.23 mg/kg with the mean of 0.94 mg/kg, which was slightly higher than soil background of “Three Rivers” regions (0.7 mg/kg) of southwest China and soil background value (0.6 mg/kg) of China. The overall trend is gradually decreasing from northwest to southeast. The parameters of geo-accumulation index indicates that the thallium pollution level in Jiulong alpine mountain area was generally low, most of them are less than 0.5, with the max Igeo 0.97. The soil as a whole has no potential ecological risk of thallium, which mainly under the control of natural geological background. Additionally, the investigation of this type of ecological environment survey provides insights for the sustainable development possibilities of critical mineral resources exploration in western Sichuan, China.