Heavy metals and polycyclic aromatic hydrocarbons in soils and vegetables in an electronic waste processing site, south China

摘要

In the present study, a primitive e-waste processing facility was investigated. Soils of ewaste open burning sites, surrounding paddy fields and vegetable gardens, as well as common vegetable samples were collected and analysed for heavy metals and polycyclic aromatic hydrocarbons (PAHs). Results showed that the soils of former burning sites had the highest concentrations of Cd, Cu, Pb and Zn with the mean values of 17.1, 11140, 4500, 3690 mg kg-1, respectively. The soils of nearby paddy fields and vegetable gardens also had relatively high concentrations of Cd and Cu. In the edible tissues of vegetable, the concentrations of Cd and Pb in most samples exceeded the maximum level of metals for food in China. Sequential leaching tests revealed that Cu, Pb and Zn were dominantly associated with the residual fraction followed by the carbonate/specifically adsorbed phases except for Cd, which was mainly in the extractable form in paddy fields and vegetable soils. The PAHs analysis showed the concentration of 17 PAHs in soils varied between 0.1 and 10.6 mg kg-1, with the descending order of burning sites (4.87 mg kg-1) > vegetable gardens (0.71 mg kg-1) > paddy fields (0.27 mg kg-1). In the edible tissues of vegetable, the mean concentration of the total PAHs reached 0.54 mg kg-1. The data showed that past primitive e-waste processing operations caused severe pollution to local soils and vegetable. The clean-up of former burning sites should be the priority task in the future remediation work.