Accumulation Characteristics and Chemical Speciation of Cd, Zn and Pb in Soils Impacted by a Pb-Zn Mining Area

An exploratory study on soil contamination of Cd, Zn, Pb was carried out in the surroundings of a historical, abandoned Pb-Zn mining area in Hunan Province, China. The accumulation in soils and representative plants of Cd, Zn, Pb and their chemical speciation were investigated. The obtained results indicated that Cd, Zn and Pb presented a significant contamination compared with Environmental Quality Standards for Soils in China (GB 15618-1995). The geoaccumulation index suggested the degree of contamination: Pb > Cd > Zn. The modified BCR sequential extraction results showed that Cd, Zn, and Pb exist in soil in a relatively unstable form, and will exert a bad effect on the plants grown in the soil. Heavy metals in oranges collected in the sampling area were tested to identify the extent of pollution. The results confirmed that the sampled oranges were polluted with Pb, which exceeded the national food safety standard by 3.4 – 6.3 times. Heavy metals in branches and leaves showed different accumulation characteristics than the fruits.