Community Characteristics Of Ciliates In Lead-zinc-contaminated Areas Of Huixian County, Gansu Province

The community characteristics of soil ciliates in Lead-zinc-contaminated agricultural areas of Huixian County,Gansu Province in winter were studied by the"non-flooded petri dish method", the observation in vivo and"three level ten-fold dilution method"from October 2006 to May 2008. The determination of the concentrations of lead and zinc in the various samples was also measured using an atomic absorption spectrophotometer by the Upstream Yellow River Water Environment Monitoring Center. The results based on the study were summarized as follows:1. 136 species were totally identified in 5 sampling sites, including 36 unnamed species and 3 new records of soil ciliates in China, belonging to 3 classes, 11 orders, 38 families and 54 genera.Hypotrichida and Prostomatida were dominant groups,occupied 32.35% and 20.59% of the total species respectively.Colpodida and Scuticociliatida were subdominant groups, occupied 13.23% and 9.56% of the total species respectively.Oligotrichida was incidental group,only 1 species,occupied 0.74%.82 and 72 species were indentified in Control site 1 and Control site 2 respectively,while 51,54 and 44 species were identified in pollution soil sites of Muba,Xiancheng and Changqu.2. The determination of the concentrations of lead and zinc in sampling sites of Control 1,Control 2,Muba,Xiancheng and Changqu were carried out 2 times.The results were as follows:â‘ The lead concentrations were respectively 211mg/kg, 182 mg/kg, 434 mg/kg,427 mg/kg and 490 mg/kg in the 5 sampling sites and the zinc concentrations were respectively 48.4 mg/kg,46.8 mg/kg,392 mg/kg,166 mg/kg and 1194 mg/kg in the first time.â‘¡The lead concentrations were respectively 203mg/kg, 125 mg/kg, 302 mg/kg,443 mg/kg and 464 mg/kg in the 5 sampling sites and the zinc concentrations were respectively 23.5 mg/kg,15.6 mg/kg,388 mg/kg,223 mg/kg and 571 mg/kg in the second time.3. The community structures of soil ciliates were greatly disturbed and simplified by lead and zinc,which was charccterized by obvious reduction of species number and decrease of species diversity.Analysis of community parameters of various sites in 4 seasons showed that the species number and species diversity in Control site 1 and Control site 2 were both higher than that of Changqu site,Xiancheng site and Muba site significantly,but the abundance change of soil ciliates among various sites was complex and no regularity.Analysis of seasonal dynamics of community parameters in various sites showed that the species number and species diversity of ciliates in Control site 1 and Control site 2 in winter were maximum,while that were maximum in sites of Changqu,Xiancheng and Muba in spring. The abundance of soil ciliates in the 5 sampling sites in winter were maximum and in summer were minimum,and in spring were generally equal to that of in winter,which indicated that the abundance of soil ciliates in various sites had obvious seasonal changes. Analysis of community structure of soil ciliates in 4 seasons showed that the species diversity and community structure in Control site 1 and Control site 2 were higher than that of Muba site,Xiancheng site and Changqu site,which indicated that the community structure of soil ciliates had been greatly influenced and simplified by lead and zinc pollution.4. The dominant groups in various sites in 4 seasons were Hypotrichida, Colpodida, Scuticociliatida, Prostomatida and Nassulida,which had no obvious seasonal changes.However,the dominant species in various sites had obvious seasonal changes, and the dominant species in pollution sites were different from that in control sites. L. eurystoma and D. revoluta in control sites were uniquely dominant species which could not adapt to the lead and zinc pollution soil environment very well,were sensitive species in pollution soil environment. H. grandinella, H. setosa, C. versatile, C. glaucoma, P.vorax, P.angusta, C. steini, P.vorax, P.angusta, C. steini, L. sphagnetorum and G. affine which were not sensitive to the lead and zinc pollution and could adapt to a wider rang of soil environment,were widespread dominant species in pollution sites and control sites. T. chilense, N. picta, P. difficilis, C. inflate and H. similes were uniquely dominant species in pollution sites,and there need more work to confirm that whether these species could be thought as the indicator in lead and zinc pollution soils.5. The results of correlation analysis between community parameters and environmental factors in 4 seasons showed that the chief factors affects the species numbers and species diversity were all the contents of heavy metals(Pb,Zn) which had a significantly negative correlation.But the chief factors affects the abundance were different with the seasonal changes,in summer was pH while in spring was soil temperature,and the every factors in both fall and winter had no significant correlation on abundance.