Distribution And Potential Ecological Risk Analyze Of Heavy Metals In Typical E-waste Dismantling Area

E-waste is one kind of new pollutants which generated in recent years and caused environment problems because of complex components and high level of pollutants. E-waste dismantling industry's main job is to remove E-waste from our country or imported products. The most harmful process of environmental pollution is electronic dismantaling, acid sites, burning sites bring Cu?Pb to occur pollution.Recengtly studies show, ecological systems exsist excessive quantity of heavy metals like Cd?Cr?Cu?Pb?Zn?Ni in E-waste treating area. There is excessive heavy metals like Cd?Cu?Pb?Zn even in the animal or plant body, human blood, breast milk and so on. Therefore, it is necessary to study heavy metal pollution degree and ecological risk in E-waste treating area. It can provide theoretical reference for environmental governance and industry regulation.We selected Longtang town, Qingyuan city, Guangdong province as the study area. Based on "Qingyuan E-waste dismantling heavy metal management project"(the first phase project) to summarized pollution sources as irrigation canals, dismantling sites, E-waste slag. Choose eight typical site as study area analysing the heavy metal content of Cd?Cr?Cu?Pb?Zn ? Ni ? Fe ? Mn, pollution degree, distribution characteristics, correlation and source, physical-chemical properties and potential ecological risk.According to different sources of pollution, collecting samples from these "source", and analyze heavy metal content to obtain the intensity of pollution source. Among them, the irrigation channel collect the canal mud, dismantling site collect wastewater, waste slag collect itself. Micro scale grid is adopted in the farmland around the pollution source, it can be used to understand the pollution degree and pollution source to the surrounding farmland.According to the results, the maximum value of Cd?Cr?Cu?Pb?Zn and Ni in the irrigation canal sediment is 3.19?265.42?715.22?1070.6?894.27 and 306.19 mg.kg-1; The waste water of dismantling sites is 0.35?5.9?3.4?42.4?0.94 and 0.74 mg.L-1; E-waste slag is 2.92?143.08?2081.05?9885.91?767.99?94.94 mg.kg-1. Accordingly, the maximum value of Cd?Cr?Cu?Pb?Zn and Ni in the the farmland soil surrounding irrigation canal is 1.45?82.77?328.67?186.78?300.18?60.49?19831.98 and 220.98 mg.kg-1; Dismantling sites is 1.16?77.56?1166.91?281.54?180.47?29.04?23565.92 and 192.46 mg.kg-1; E-waste slag is 0.72?46.86?807.68?1325.97?878.65?42.38?13502.31?147.14?19831.98 and 271.92 mg.kg-1.Comparing with the Environmental quality standard for soils GB15618-1995, we found Cd?Cu and Zn exceeding standard in the the farmland soil surrounding irrigation canal; Dismantling sites is Cd?Cu; E-waste slag is Cd?Cu?Pb and Zn. According to regularity of horizontal distribution of excessive heavy metals, Cd ? Cu ? Pb and Zn followed porphyritic distribution regularity, concentrated in the vicinity of pollution sources except Cd. So we could conclude that Cu?Pb and Zn in local farmland soil comes from this three typical sources, while Cd's exceeding may be due to factors such as the sewage irrigation or fertilizer.The farmland soil comprehensive pollution index aroud three kinds of pollution sources showed: dismantling site > E-slag > irrigation canal.By establishing regression equation, pollution degree is related distance with a nonlinear function in E-waste treating area(r > 0.75).Studying area soil showed acid-stage(pH < 6.5), high quantity of electrical conductivity and high organic matter. With the increase of depth, pH, conductivity and organic matter decreased. Moreover Cd ? Cu ? Pb and Zn in the the farmland soil surrounding irrigation canal and dismantling site correlated with electrical conductivity or organic matter.Potential ecological risk assessment results show that the pollution level of medium or strong surrounding three kinds of pollution sources. Among them, farmland soil pollution level surrounding irrigation canal and E-waste slag is higher. Potential ecological risk of six heavy metal elements in the sequence by Cd>Cu>Pb?Ni>Zn?Cr.Based on the above analysis, it can be seen in the e-waste dismantling area of farmland soil generally presents the contents of Cd?Cu exceeded, and potential ecological risk of heavy metals is higher, which will affect the local agricultural products, animals and plants. Therefore, according to the conclusions of this study, first of all should be to ditch desilting regularly, so as not to clay pipes in a Cd with the variation of environmental factors to release to the irrigation water causing pollution. Secondly, the dismantling of the workshop to prohibit the indiscriminate discharge of waste water resulting in pollution. And further carry out retail admission work to achieve unified management of the park. At the end of the investigation and the residue removal destruction. From the results of the pollution map, these three kinds of pollution sources of heavy and moderate pollution area is small, so we can use of the technology of the soil remediation in order to adapt to local actual situation.