Abstract: Taking the soil of an old site of a relocated enterprise as the research object, the single factor index method, the geo-accumulation index method, and the potential ecological risk index method were used to comprehensively evaluate Pb pollution and ecological risk in the soil. The pollution causes and spatial distribution characteristics of Pb in the soil were also studied from multiple perspectives. The results show that the Pb content of 73.56% of the sampling points exceeded the standard. In terms of pollution level, the average values of single factor index and geo-accumulation index of Pb in the soil in the study site were 1.07 (slightly polluted) and 1.47 (moderately accumulated), respectively. Pb pollution in soil, was particularly heaviy from >6.0~10.0 meters below the soil surface, and then gradually decreased from below 10.0 meters. From the perspective of the causes of Pb pollution in soil, a large amount of backfilled iron sulfide slag, pollution leakage from the original production workshops and raw material storage area, building rubbish and extremely alkaline soil are the main causes of the high content and heavy pollution of Pb in the soil. However, the ecological risk of Pb in soil of this site is relatively low in generally. It could be concluded that the evaluation results of soil Pb pollution and its ecological risk by using multiple methods are relatively consistent and reliable.

Key words: Pb pollution, single factor index method, geo-accumulation index method, ecological risk