Influence of heavy metal pollution on soil animal community in Luqiao,Taizhou City

FengJiang Recycling Metal Corporation of Luqiao district in Taizhou City is located in the southeast of Zhejiang Province,which is the biggest electronic waste disassembly base in China.It was established in the 1970s and an area of about 10 km2.Due to the rough disassembly technology and manual labor of the individual workshop,heavy metal and chemical pollution could not be treated effectively.Residue and waste water produced by e-waste disassembling were discharged into the nearby farmland and water through air,dirty irrigation,and slagheaps,which resulted in heavy pollution.Heavy metal pollutants,especially Cu,Zn,Cd and Pb produced by e-waste disassembling were seriously beyond the limit of the soil′s capacity to tolerate,which were harmful to the environment.At present,the research into heavy metal pollution and soil animal diversity mainly focuses on the effects of soil biological and ecological toxicology caused by urban industry and drainage of metal mine pollutant.However,there is no report about the study of the relationship between heavy metal pollution from e-waste disassembling and soil animal diversity.This study chooses the biggest electronic waste disassembly base in China to discuss the influence of the heavy metal content,regional distribution and toxicological effects on the community structure and diversity of soil animals.Through a large amount of sampling from the target district,this study determined the contents of Cu、Zn、Pb and Cd.Through figuring out the integrated index of the heavy metal pollution,the trend chart of heavy metal integrated pollution was made by the method of interpolation in Geographical Information System(GIS).Combining this trend chart with field surveys,8 sample plots were set.The methods included layer handpicking in the field for soil macro-fauna and layering with a geotome;separation through Baermann and Tullgren methods,and examination through microscope indoor for meso-micro soil fauna.The results showed that:(1) 844 specimens from 8 sample plots were collected,which respectively belonged to 4 phyla,9 classes,and 20 orders.Among them,Collembola,Acarina and Nematoda were dominant groups,and the others were common groups and rare groups.(2)There was a great significant difference among the number of the soil animals in 8 different sample plots(P0.01),and also a comparable difference among the amount of groups of soil animal in the 8 plots(P0.01).In the severely polluted area,the amount of soil animal and the amount of groups of soil animal were rare,while there was a high density and diversity of soil animal in the slightly polluted area.This indicated that the heavy metal pollution had an effect on the diversity of soil animal.The worse the pollution is,the fewer the groups and individuals of soil animals amount is.(3) Moreover,the effect of heavy metal pollution on the diversity of soil animal was measured by the Shannon-Wiener index and DG(Density-groups) index.The lower the integrated index of pollution is,the higher the Shannon-Wiener index and the DG index is.(4) This showed a significant negative correlation between the amount of soil animals and integrated index of pollution(related coefficient-0.86).It also showed a certain correlation between the amount of soil animals and the organic content values(related coefficient 0.42).In the slightly polluted area,the amount of soil animal rose with the increase of organic content.It showed that heavy metal toxicity had a main effect on the soil animal in the severely polluted area,and that organic content might be the key factor in the slightly polluted area.(5) The distribution of Collembola in the 8 sample plots showed that Isotomidae had the highest tolerance to the heavy metal pollution.Hypogastruridae,with a large number and high density,was sensitive to the heavy metal pollution.The latter can be the indicator organism for the heavy metal pollution in this district.