Metal (loid)s pollution characteristics and ecotoxicity evaluation in soil nearby a silver smelting yard

The spatial distribution characteristics of metal(loid)s (Cu, Zn, Cd, As, and Pb) in the soil of a silver smelting zone located in Chenzhou, Hunan province, China and their ecological toxicity were studied in this paper. The results showed that the average concentration of these metal(loid)s in the soil of the silver smelting yard and surroundings decreased in the order: Pb > Cu > Zn > As > Cd, and all of these metal(loid)s greatly surpassed the local background. In general, the concentration of metal(loid)s in soil decreased with the increase in distance from the pollution source in the horizontal direction. In addition, the metal concentration decreased with an increase of depth. The geo-accumulation index and toxic unit analysis revealed that the smelting yard was extremely contaminated and Cu, Cd, and As exhibited the most toxic effects in this area. Furthermore, in soils nearby smelting yard, higher contamination was found in the lower geographical forms than in the higher parts of the terrain.