The Community Characteristics Of Soil Animals In Lead-Zinc Mine Contaminated Region, Hui County

During April, June and October from2011to2012, six sample areas (20m x20m) were chosen from lead-zinc mine polluted regions in Hui County, Gansu province.And then, total54soil samples (surface depth,0~5cm; middle,5~15cm; deepdepth,15~30cm) were randomly taken by a five point method which looks like aplum flower. The soil animals were separated by hands, Tullgren and Baermannmethods, and the specimens were separately preserved in75%ethanol and10%formalin solutions. Their classification, identification, and statistics were finishedunder the stereoscope and optical microscope. As results:(1) The141355soil animals belonged to97genera were obtained from lead-zincmine pollution areas in Hui County. The seasonal distribution characteristic of soilanimal numbers was as follows: autumn> spring> summer in dry environment; andthat was as follows: summer> autumn> spring in humid environment. The verticaldistribution of soil animal numbers was as follows: surface> middle> deep. That forsample regions was6#>1#,2#,3#>4#, and5#. The soil environment quality wasevaluated preliminarily by the combine of soil animal community characteristic indexand environmental factors. As a result, the polluted degree of soil environment wasincreased as follows:6#(as a control, slightly polluted)>1#,2#,3#>4#,5#sample(moderate to severe pollution).(2) Community characteristics of soil animals inhabited at dry environment in6sampling areas of lead-zinc mine pollution zone, Hui County. The total of soil animals,including large, medium and micro size, was84609, belonging to2phyla,7classes,11orders,57families and72genera. The number of soil animals obtained in springwas17203, and20.33%of the total catch. That in summer was30473, accounted for36.02%of the total catch. For autumn,36933soil animals accounted for43.65%ofthe total catches. The7718larger soil animals was accounting for9.12%of the totalcatches, micro and medium-sized soil animals was76891, accounting for90.88%ofthe totals. The dominant larger taxa were larva and adult of Staphylinidae, larvae ofChironomidae, accounting for56.12%of the larger individuals. And that of micro andmedium-sized groups were Onychiurus and Podura, accounting for35.20%of thetotal catches. The seasonal quantity dynamic characteristics was autumn> summer> spring.The vertical characteristic of soil layers was surface layer> middle>deep. The spacedistribution characteristic for sampling area was6#>1#,2#,3#>4#, and5#. The soilanimal groups in six samples were classified by clustering analysis (Nearest neighbor).As a result,3#,5#,1#and2#,4#were merged into a set, and6#was an independentlyset. The diversity index (H’) for spring was6#>5#>4#>1#>3#>2#, that for summerwas6#>1#>2#>4#>5#>3#, and that for autumn was6#>2#>1#>3#>5#>4#.The highest diversity index was always6#. The results showed that the environmentalqualities of1#~5#samples were polluted to a certain degree.(3) Community characteristics of soil animals inhabited at humid environment in6sampling areas of lead-zinc mine pollution zone, Hui County. The total of soilanimals was56746individuals, belonging to2phyla,3classes,8orders,16familiesand25genera. The individuals of Enchytraeus were17891, accounting for31.53%ofthe total catches. The dominant genera were Enchytraeus and Lumbriculus,accounting for87.57%of the total lined earthworms. The number of soil nematodeswas38855, accounting for68.47%of the total catches. The dominant genera wereTylenchus and Ironus, accounting for59.23%of the total nematodes. The surfaceoccupying characteristics was obvious. The complexity of community structure,diversity and richness for soil animals was6#>1#>2#>3#>4#>5#, and the seasonalchanges was summer> autumn> spring.(4) The relation between soil animals and environment factors. The soil animalcommunity distribution characteristics were related to soil temperature, humidity, pH,seasons and soil depth at a certain extent. However, the most important relationshipwas associated with the soil content of lead and zinc.(5) The soil environmental quality in these regions was preliminary evaluated bythe seasonal distribution, space and vertical variation characteristics of soil animalcommunity, and soil lead-zinc contents. The results showed that the polluted degreesof soil environment were as followed:6#(control, slightly polluted)>1#,2#,3#>4#,and5#(moderate to severe pollution).