CHARACTERIZATION OF HEAVY METAL POLLUTION IN VEGETABLE FIELD SOILS AND HEALTH RISK ASSESSMENT IN DAYU COUNTY, CHINA

The content of seven heavy metals (Cd, Pb, Cu, Cr, Zn, As, and Hg) in soil samples that collected from vegetable fields surrounding sewage irrigation district in Dayu County of China were detected and analyzed. The purpose of the analysis is to determine the harmful effects of heavy metal pollution to agricultural development through characterize the heavy metal pollution characteristics of soil. This study evaluated the heavy metal pollution index and the results show that, except for Pb, Cr, and Zn, the amount of majority heavy metals in most sites exceeded the Soil Environmental Quality Standard grade II level. In particular, the Cd pollution is the most serious with its contents exceed the standard level by 18.3 times. The nemerow comprehensive pollution index (NCPI) analysis shows that 90% of the sampling points are under moderate or severe pollution. In particular, NCPI is maximized to 13.22 in S-6. According to potential ecological risk (PER) assessment, the single-factor PER (Er) is Cd > Hg > As > Cu > Pb > Cr > Zn. The Er of Cd is maximized to 1,833.33 in S-6, indicating that Cd pollution in this site is extremely serious. Results of the comprehensive PER index (RI) indicats that all sites are under strong ecological risks. Therefore, soil pollution caused by heavy metals can severely harm the local agro-ecological environment.