Heavy metal concentrations in soil and agricultural products near an industrial district

This study investigated heavy metals in soils and agricultural products near an industrial district in Dongguan City. The concentrations of Cu, Zn, Pb, Cd, Hg, and As in soil and agricultural products from vegetable and banana fields were determined. Results indicated that except for Zn in one sample and Cd in five samples, the majority of the samples were notably enriched by heavy metals compared with background values. The concentrations of heavy metals (mg·kg⁻¹ dry soil) in agricultural soils in the study area ranged from 22.2 to 93.0 for Cu, 31.2 to 213.6 for Zn, 47.6 to 133.5 for Pb, 0.01 to 0.67 for Cd, 0.15 to 0.56 for Hg, and 20.5 to 28.9 for As. Among these soil samples, concentrations of Cu, Zn, Cd, and Hg in 20.6%, 8.8%, 29.4% and 38.2% soil samples, respectively, exceeded Chinese maximum allowable concentrations (MAC) for agricultural soil. The concentrations of Zn, Pb, and Cd were significantly higher in vegetable than in banana fields. Cu, Zn, Pb, Cd, and Hg accumulated in the topsoil of vegetable fields, but only Pb and Hg accumulated in banana fields. Zn, Cd, and Hg accumulated more easily in flowering cabbage than other vegetables. Cu, Zn, and As were accumulated more easily in banana than lettuce, bunching onion and eggplant. Therefore, the findings suggest more attention should be focused on the accumulation of heavy metals in banana. This study presents a practical methodology for screening crops with lower bio-concentration factors for heavy metals to reduce metal contaminants in the general food supply chain.