Studies On Heavy Metal And PCBs Contaminations In Soil Near E-waste Dismantling Area In Qingyuan, Guangdong, South China

E-waste recycling will make them a contamination source of heavy metal and persistent toxic substanees (PCBs).This study focuses on heavy metals (Cu、Pb、Cd、Cr、Zn、Ni) contamination,eco-toxicity and remediation of farmland soils by e-waste recycling in Quanyuan,Guang dong Province, China. The main results obtained are as the follows:(1)22 farmland soil samples,7 factory soil samples and 9 mountain soil samples were taken for 6 heavy metals(Pb、Cu、Cd、Zn、Cr and Ni)contamination、grading standard、 summary statistics and different existing forms study.The result show that72.7% of the soil samples contained one or more kinds of heavy metals with higher concentrations than the corresponding standard values, and 50% of the soil samples were heavy polluted,which indicated the source of the heavy metal contamination from uncontrolled e-waste recycling activities in Qingyuan town. The chemical partitioning results suggested that the heavy metals have transformed into the mobile fractions polluted the deep soils.(2)The total content of PCBs in the surface 0-20 cm farmland soil samples were ranged from 2.09 to 1335.80μg·kg-1 dry weight with the average of 162.92μg·kg-1, some heavily polluted sites were found. The soil samples at the dismantling workshop gates were also analyzed, the results indicated that the mean value of PCBs content was 2575.51μg·kg-1, and the average content of PCBs in the soil samples at the workshop gates was heavily higher than the average content in the farmland soil samples near the e-waste recycling area, e-waste was an important source of some toxic pollutants like PCBs. The contents of PCBs at 10 sampling sites but site 8 decreased in the 20～40 cm soil, most of PCBs were remained in the surface soil, and the capacity of vertical transportation of PCBs was weak.(3)The spatial changes of the populations of bacterium, actinomyces and fungi were obvious, however there were no significant correlations between these three microbial quantities and the total contents of PCBs and heavy metals.