| The pollution status of polychlorinated biphenyls(PCBs)in the environment is a hot issue of concern to the environmental protection departments and scholars of all countries.The Jie Fang Zha irrigation area was selected as the study area,and 12 soil samples from the irrigation area were collected.The distribution characteristics of seven PCBs in the vertical direction of the soil under different conditions were analyzed,and the migration ability of PCBs was explored.The influence factors of PCBs were explored by pearson method.According to the multiple regression analysis,the main controlling factors of the impact were identified.The soil risk quality standard method and the RBCA model were used to evaluate the ecological risks and health risks caused by PCBs,so as to provide a scientific basis for the ecological agriculture in the Yellow River irrigation area and the treatment of PCBs in the soil.The main findings are as follows:1.Seven kinds of PCBs were detected in 0?40 cm soil.With the increase in depth,the detection rate of ?7PCBs also decreased.The composition of PCBs in the vertical direction of the soil is mainly low-chlorinated biphenyl,mainly concentrated in 0?20 cm soil layer.The content of highly chlorinated biphenyl in each layer is small,the detection rate is low,and the vertical distribution is relatively stable.The vertical distribution of?7PCBs in silty soil and silty loam showed a high-low-high trend,and the distribution trend in sandy loam showed low-high-low characteristics.The ?7PCBs contained in the layers of fruit and vegetable soil were the most,and they were consistent with the vertical distribution in the soil of oil crops.The vertical distribution of ?7PCBs in the soil of food crops showed a small vertical-high-low-high vertical variation.The distribution of low-chlorinated biphenyls and high-chlorinated biphenyls in different soil crop types is significantly different.2.The ratio of ?7PCBs to the surface layer is slightly floating around 0.77,and the distribution is relatively uniform.The migration ability of each monomer in the 0?40 cm soil layer is greater than 40?100 cm.The migration capability of PCB29 and PCB171 is poor.The migration capability of PCB5 and PCB98 is faster.Low-chlorinated biphenyls with low logKow are more likely to migrate to deeper soils and migrate faster,while high-chlorinated biphenyls have a weaker ability to diffuse into deeper soils.Some high chlorinated biphenyls migrate faster in soil than low-chlorinated biphenyls.3.The content of low-chlorinated biphenyls was related to the conductivity and organic matter content.The content of ?7PCBs is correlated with conductivity,organic matter content,and specific surface area.High-chlorinated biphenyl content was related to soil pH.There was a significant positive correlation between low chlorinated biphenyl content,?7PCBs content and clay content in 0?20 cm soil layer.The PCB171 and PCB201 in the 20?40 cm soil layer were significantly positively correlated with the conductivity.The content of low-chlorinated biphenyl and the content of ?7PCBs in the 80?100 cm soil layer were significantly positively correlated with organic matter.?7PCBs content,low-chlorinated biphenyl content is mainly controlled by conductivity,organic matter content,pH,especially the conductivity has a great influence on PCBs.4.Most PCBs were lower than ERL and had low biologic effects.A few surpass ERL,the incidence of toxic effects was 10%to 50%,but far below the ERM value,which is a moderate ecological risk level.The carcinogenic and non-carcinogenic risk of PCBs in soil of 20?40 cm was slightly higher than that of 0?20 cm.Oral feeding was the most important route of exposure to health risk.Children were the main victims of carcinogenic and non-carcinogenic risks.The carcinogenic and non-carcinogenic risks of PCBs in the soil were within acceptable limits,and the probability of high risk is extremely low and does not constitute a health hazard.The concentration of PCBs in the soil is the most sensitive factor. |
PDF Full Text Request