The Influence On Ammonia Oxidizing Microorganisms And Microbial Community Structure Under Soil PAHs Pollution

Firstly, in this study,we investigated the population of soil microognism,structure of community and the dose-response relationship between PNR of ammonia oxidizing microognisms and the concentration of PAHs in the way of adding pyrene into the soil to simultate PAHs pollution; then, taken the long-term contaminated soil with PAHs from Beijing Coking Plant as the samples, to determine the relationship between the species variables of ammonia oxidizing microognisms and environmental variables, in order to determine the effects on ammonia oxidization of each factors,and the influnce of PAHs on ammonia oxidizing microognisms and the processe of ammonia oxidization specially.The artificial simulation experiment added pyrene as PAHs pollution1) The number of culturable microorganisms:actinomycetes are not be significantly affected; bacterias are changed along with the increase of pyrene concentration and contaminate time, showed a reduced growth trend; fungi in the pyrene concentration 40μg/g showed a weak reduction,in pyrene concentration was 100μg/g showed a significantly increase compare to control.2) Soil PLFA analysis:the soil PLFA showed the decline trentd with the processing time in low concentrations of pyrene and the inhibition increased with the concentration of pyrene became higher; in the high concentrations of soil PLFA pyrene treatment soil PLFA always maintained at a lower level, inhibition rate was about 75%. Principal component analysis revealed that the microbial community structure changes with the PLFA abundance data.3) Moderate concentrations of pyrene significant effected on the PNR, the EC50 values of 1,7,15,35 day were 72.2μg/g,73.4μg/g,99.57μg/g,101.8μg/g, showed that moderate concentrations of pyrene can seriously affect the activity of ammonia oxidizing microognisms, and the EC50 values increased along with the treatment time. Moderate-high concentration of pyrene in the soil can exhibit acute toxicity, acute toxicity of low concentration of pyrene contamination was not obvious; pyrene chronic toxic effects on the PNR can be shown after 7 days contaminate, after 15 days or more processing time can be achieved steady state, and chronic toxic effects of pyrene concentration increases with the strengthening of pyrene.4) qAOA was about 1 order of magnitude higher than qAOB, but under the conditions of this study, the contaminate of pyrene did not significantly change ammonia oxidizing microbial community in abundance, thus, short-term contamination PAHs may act as competitive or noncompetitive inhibitor of AMO impact on the PNR.Comprehensive summary of the above findings, the response of soil PNR on PAHs was more sensitive and can be used as a sublethal effect indicators reflect the toxicity of PAHs, and acord with the other soil biological indicators'changes there, and reflects the resistance or adaptive on the PAHs, so that the soil PNR has a unique advantage in the research of toxicity of PAHs and is necessary to combine the analysis of long-term PAHs contamination soil to improve this research.Experiment of long-term PAHs contamination soil samples from Beijing Coking Plant1) The relationship between ammonia oxidizing microognisms species variables and soil environmental variables:soil pH and soil PNR has a weak positive correlation, SMC has no correlation with soil PNR. SMC and the pH value had no significant correlation with the qAOB, SMC has negative correlation with qAOA, pH value has a significant positive correlation with qAOA. The relationship between PNR and NH4+, NO2-and NO33-primarily reflected the influnce of species data to environmental factors.2) The relationship between species variables of ammonia oxidizing microognisms: the majority of samples showd that qAOA ware about 1-3 orders of magnitude higher than qAOB, but high concentrations of PAHs in the soil can make qAOB more. The relationship curve of qAOA and qAOB with PNR fitted two parameters'Logarithm curve, and qAOB curve fitting with the PNR (R=0.59; P<0.05) more significant correlation than qAOA curve fitting with the PNR (R=0.35; P>0.05), indicating that the soil PNR is impacted by the AOB greater.3) The relationship between PAHs and PNR: low-modrate concentrations(75μg/g as the dividing concentration) and high concentrations of PAHs effected the soil PNR with two different modes; soil PNR in PAHs<75μg/g increased with the increase of PAHs,And PAHs had positive relationship with qAOA and qAOB. In PAHs>75μg/g of soil, most PAHs had no correlation with the PNR, a few such as naphthalene showed a weak positive correlation with PNR, but the dihydroacenaphthylene, fluorene and phenanthrene showed negative correlation with PNR.