Effects Of Heavy Metals On Structure And Physiology Of Soil Animal Community

Among all kinds of pollutions heavy metal pollution is a seriousenvironmental problem in the world. The main sources of the heavy metal pollutioninclude transportation, sewage irrigation, solid wastes, pesticides, fertilizers and airsettlements. In recent years, with the development of economy, more and more pollutantsentered the environment. The functions of soil ecology will become maladjusted beausethe the environment can't decompose t pollutants through the abilities of self-restore. Thehuman being has great interest of the sustainable utilization of soil resources since TheSecond World. In order to indicate the functions of soil, scientists invented the term of soilquality or soil health. Researchers have recently recognized the needs for a reliable andsystematic way to assess soil quality. And a soil quality index has been developed whichincludes chemical properties, physical properties and soil biological properties.Soil biological properties is a important index in indicating soil quality. And soilfauna is an essential part of soil environment. It is involved in many aspects of organicmatter decomposition, partial regulation of microbial activities, nutrient cycles andcrumbly structure. Pollutants caused by transportation in the soil result in both qualitativeand quantitative changes in fauna, which directly affect soil function.The objectives of the present study are to investigate the fauna community in paddysoils polluted by heavy metals around a national road called 104 in Shangyu County,Zhejiang province, and to examine the effect of added Pb on soil fauna communitystructure and ecological indicators in a experiment. The results are summarized as follows:Pb(NO₃)₂ polluted experiments on the soil are taken and soil animal 1289 indcollected, which subordinated to 3 Phylums, 7 Classes. The study is conducted to evaluatethe effects of plumbum on soil fauna. The result shows that there existed a closerelationship between the concentration of Pb and the community structure of soil fauna.Among the 1289 individuals collected in the experiments, the dominant genera areCollembola, Prostigmata and Oribatida, which take the 78.2% of total amount. With theincreasing of concentration Pb, the species and quantities of soil animal decrease as well as the diversity index. Collembola and Acarina are most sensitive to soil Pb pollution.The acute toxicity of heavy metal plumbum is studied by the methods of artificial soilexperiment. The result indicates that the 24h and 48h's LD₅₀ is 4385.31mg.kg^-1 and2951.21mg.kg^-1 respectively to Pheretima guillelmi. The results show the sperm distortionrate of the Earthworm increase with the rising concentration of plumbum, which showsevidencely dose-response relationship.The purpose of the experiment is to study the harm of the lead nitrate to blood-redcell of Pheretima guillelmi. The distance that earthworm crawls along in a minute alongwith dye the poisonous number of of increment and dye the rising of the poisonous densitybecome short. The nitric acid lead harms the function to the sport function and blood-redcell poisons of the earthworm.. The abnormal phenotype of sperm mainly occurred on thehead of sperm. As the head contains most of the genetic materials, it is speculated that leadmay act on DNA and result in abnormal morphology. It was concluded the locomotorability and the sperm morphology, have a potential role in risk assessment and P. guillelmicould be served as choice specie in standard toxicological testing.In the agricultural ecology of Shangyu, the dominant species are Collembola andAcariformes. Their frequencies are 32.01% and 20.39%, respectively. Diptera, Nematoda,Araneae, Hirudinea, Diplura are common species. In the Acariformes communityEremulidae, Epilohmanniidae and Scheloribatidae are the dominant species, theirfrequencies are 25.05%, 11.91%and 11.64%. The common species included Oppiidae,Tectocepheidae, Brachychthoniidae, Cepheidae, Hermanniidae Sellnick, Licnodamaeida,Haplozetidae, Xylobatidae, their frequencies are 7.22%, 8.03%, 8.03%, 7.69%, 3.81%,1.84%, 7.83%, 5.24%, respectively.