Ecological And Health Risk Assessment Of Heavy Metal Pollution In Agricultural Soil From E-waste Recycling Area

The present thesis reviewed the electronic and electric waste (e-waste) recycling activities and the resulting problems of environmental pollution. Concentrations of heavy metals in agricultural soil taken from 8 farmlands close to the large-scale e-waste recycling plants, large-scale gold recovering plants and simple household e-waste recycling workshops were monitored. Ecological risk assessment and health risk assessment of the agricultural soil were conducted in e-waste recycling area. With the soil pollution investigation and risk assessment, suggestions for risk control in e-waste recycling area were discussed. The main conclusions are as follows:1. Investigation of agricultural soil pollution in e-waste recycling area Through statistical analysis, the e-waste recycling activities have brought serious heavy metal pollution to surrounding agricultural soil, of which 10% of the sampling sites were heavily polluted. Comparing the three sampling areas, it was found that the heavy metals pollution in simple household e-waste recycling workshops was most serious, where the e-waste recycling activities were mostly involved. There were great correlationships with concentrations of Cd, Cu, Cr, Pb, Zn, Hg in soil and e-waste recycling activities. Among these metals, Cd, Cu pollution were heaviest, followed by Hg and Pb.2. Ecological risk assessment of agricultural soil pollution in e-waste recycling area Typical contaminated soil from e-waste recycling plant, gold recovering plant and e-waste recycling workshop were chosen for ecological risk assessment analysis. Results showed that e-waste recycling activities have brought high ecological risk for surrounding agricultural soil. Simple household e-waste recycling workshop contributed much higher ecological risk while large-scale e-waste recycling plant or gold recovering plant contributed less. For the Hakanson potential ecological risk assessment, Hg and Cd had more contribution, while for ecological risk assessment, the main contributors were Cu, Pb and Zn.3. Health risk assessment of agricultural soil pollution in e-waste recycling area The results of health risk assessment suggested that agricultural soil from three kinds of sampling sites had high health risk. Both the non-carcinogenic risk and carcinogenic risk exceeded the reference values. Furthermore, the risk assessments also suggested that simple household e-waste recycling activities had caused higher health risk when compared with the other two e-waste recycling activities. Among the different heavy metal elements, Cd was the major non-carcinogenic substance and carcinogenic substance. The exposure pathways of health risks in different sites were similar, of which the food intake were the main route of exposure, contributing more than 85% of total health risk.