Spatial Distribution and Migration of Cadmium in Contaminated Soils Associated with a Geochemical Anomaly: A Case Study in Southwestern China
Kai Luo 1  
,   Hongyan Liu 1, 2  
,   Zhipeng Zhao 1  
,   Jiahuan Long 3  
,   Jiafei Li 1  
,   Chang Jiang 1  
,   Cheng Rao 1  
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College of Resources and Environmental Engineering, Guizhou University, Huaxi District, Guiyang, P.R. China
College of Agriculture, Guizhou University, Huaxi District, Guiyang, P.R. China
Guizhou Provincial Academy of Agricultural Sciences, Huaxi District, Guiyang, P.R. China
Hongyan Liu   

Guizhou University, Huaxi District, Guiyang, Guizhou province, 550025 Guiyang, China
Submission date: 2018-04-14
Final revision date: 2018-08-28
Acceptance date: 2018-09-04
Online publication date: 2019-05-31
Publication date: 2019-07-08
Pol. J. Environ. Stud. 2019;28(5):3799–3807
The karst terrain of Guizhou in southwestern China is ecologically fragile, but has undergone severe heavy metal contamination. To assess such contamination, the spatial distribution of cadmium (Cd) within soils was studied in a lead (Pb)-zinc (Zn) smelting area, coal mining area, Pb-Zn mining area, sewage irrigation area, and an uncontaminated area. Cd concentrations were highest in topsoil, with the highest value of 23.36 mg/kg in the Pb-Zn mining area and lowest value of 0.46 mg/kg in the uncontaminated area. Cd content decreased from 0 to 0.8 m depth, then sharply increased, reflecting Cd precipitation within the contaminated soil profiles. Migration of Cd within the soil was affected by organic content in the Pb-Zn smelting area (R2 = 0.99**), coal mining area (r = 0.72*), and Pb-Zn mining area (r = 0.73*). In contrast, Cd accumulated within a clay horizon in the uncontaminated area, where the correlation between Cd and specific surface area was 0.78**; Cd concentrations reached 2.11 mg/kg within this horizon. Reducible, oxidizable, and acid-exchangeable fractions accounted for 60-80% of total Cd in soils having pH values of 5.05-6.86. This indicates that Cd could easily transfer from soil to food or water, leading to human health and environmental risks.