Potential ecological risk of cadmium, lead and arsenic in agricultural black soil in Jilin Province, China

Potential ecological risk of cadmium (Cd), lead (Pb) and arsenic (As) in agricultural black soil in Jilin Province, China was analyzed by the methods of risk assessment based on dose–effect relationships and ecological risk index. Heavy Cd-contamination occurred mainly around the coal mine region. The accumulation area for Pb appeared mostly in the suburbs and roadsides, whereas the higher As content was mainly found in the farmland of suburb and coal mine vicinity. In acute toxicity test, Cd, Pb and As in the soil had adverse effects on both roots and shoots growth in soybean with the greatest toxicity of arsenic and the least toxicity of lead at the same concentration levels. Exposed to Cd, Pb and As, the EC₅₀ (50% effective concentration) values for the growth of soybean root (shoot) were 212.59 (376.70), 528.53 (828.69) and 194.60 (299.03) mg/kg, respectively. Results of potential ecological risk index showed that soil contamination from Cd in some samples had very high potential ecological risk; Pb contamination for almost all sampling sites had moderate ecological risk; while soil contamination from As had low ecological risk. With the present accumulation rate, concentrations of Cd, Pb and As in agricultural black soil near coal mine would reach the threshold values in 68, 175 and 120 years, respectively.