This paper is the result of environmental geological survey engineering.

Objective China has the richest antimony (Sb) resources all over the world. In recent years, antimony and its associated arsenic pollution have become a typical environmental problem in our country. This paper focuses on the vertical distribution and the distribution characteristics in different functional areas of pollutants in the antimony smelting site, aiming to provide assistance in clarifying the soil pollution risks of the antimony smelting industry.

Methods This paper presents the results of a study conducted to investigate the differentiated characteristics of soil antimony (Sb) and arsenic (As) pollution levels in different functional areas and the cumulative migration of pollutant contents in the vertical direction. Soil samples were collected at different depths from four typical antimony smelting plants in different key functional areas. The single pollution index method was employed to ascertain the pollution degree of surface soil Sb and As in different functional areas. In order to analyse the ecological risk of surface soil Sb and As, the grading standard for potential ecological risk was adjusted in a reasonable manner according to the toxicity response coefficients of heavy metals Sb and As.

Results The soil Sb and As contents exhibited a vertical distribution, with the highest concentrations observed in the surface layer, followed by the middle layer and finally the deep layer. Furthermore, the Sb and As contents in the surface layer exhibited high variability. The varies of Sb and As contents in different functional areas is obvious, and the overall performance is storage area > wastewater treatment area > production area.As the depth increased, the average Sb content exceeded the standard in all three functional zones. However, the average As content exceeded the standard only in the storage area of the middle layer and did not exceed the standard in the deep layer. The pollution level and ecological risk of Sb and As in the three functional zones were as follows: storage area > wastewater treatment area > production area, moreover, the maximum value of pollution risk was in the storage area. As for Sb, heavy pollution points accounted for the highest ration in three functional zones, and the ecological risk is “extremely strong”.As for As, the proportion of “clean”/ “not yet clean” is considerable in three functional zones exception for storage area, and the ecological risk in the wastewater treatment area and the production area is “medium”.

Conclusions Years of anthropogenic production and operation activities at the antimony smelting site have resulted in significant pollution and enrichment of Sb and As in the surface layer of soil. A vertical view of the data reveals that Sb is the primary pollutant, with pollution levels exceeding the standard migrating to the middle and deep layers. The pollution level of its accompanying element, As, is still acceptable, with the majority concentrated in the surface layer. In the three functional areas, the storage area owns the highest level of pollution and ecological risk. Additionally, the wastewater treatment area should be concerned in case of the pollution occurs.