台州市路桥区重金属污染对土壤动物群落结构的影响

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

通过对台州市路桥区峰江再生园区及周围的8个样地采样调查,分析了重金属污染对土壤动物多样性的影响。对研究区域进行大量取样调查并测定土样中Cu、Zn、Pb、Cd的含量。计算出重金属综合污染指数,运用地理信息系统(G IS)技术中的插值法根据重金属综合污染指数制作重金属综合污染趋势图。结合重金属综合污染趋势图与实地勘察,共设置8个采样地。研究方法为大型土壤动物采用野外分层手捡计数,中小型土壤动物用取土器分层取土,带回室内分别用干湿漏斗分离并镜检。结果表明:(1)8个样地共获得土壤动物844只,分属于4门9纲20个类群,其中优势类群为蜱螨目、弹尾目和线虫纲,其他为常见类群和稀有类群。(2)8个样地中土壤动物的个体数量存在极显著性差异(P<0.01),类群数存在极显著性差异(P<0.01)。在严重污染区,土壤动物的数量和类群数稀少,而轻度污染区土壤动物的密度大、群落多样性高,稀有类群大量出现。表明重金属污染能对土壤动物多样性构成严重影响,土壤动物群落的类群和个体数量随污染程度的加重而减少(3)用群落多样性指标DG衡量重金属污染对土壤动物多样性的影响,结果为随着综合污染指数的减小,DG指数逐渐增大。(4)用简单相关性分析表明土壤动物数量变化与综合污染指数具有极显著负相关性(相关系数-0.86),与有机质含量有一定相关性(相关系数0.42)。在轻度污染的样地中,土壤动物的数量随有机质含量的升高而上升,表明在严重的污染区,重金属的毒性对土壤动物的影响是主要的,而在轻度污染区,有机质含量可能成为影响土壤动物多样性的主要因素。(5)从弹尾目的等节跳科和球角跳科在8个样地中的分布特点可知,本地区的等节跳科对重金属污染的耐受力最强。球角跳科数量大、密度高,对重金属污染较敏感,可作为重金属污染的指示生物。

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.