To further understand and assess the effect of oil exploitation on soil environment in the Longdong region of the Loess Plateau

China

soil microbial-community characteristic and its relation with soil environ-mental factors under different oil pollution degrees were investigated by using plate culture and multivariate analysis. Results show that:(1)as for the total number of soil microorganism

the site plots(S1-3)surround-ing oil pollution sources(30m)demonstrated the top

and followed by the site plots(S7-9)

200 maway from the pollution sources

as well as the site plots(S4-6)

100 maway from the pollution sources

demonstrated the bottom. Besides

the group of actinomycetes with a smaller number played a more important role in the change of Shannon-Wiener index. (2)The environmental factors including soil organic matter

TPHs

saltrate and available P in the site plots(S1-3)demonstrated the top but the bottom in the site plots(S7-9); and however

soilp H

available N and available K in the site plots(S7-9)demonstrated the top but the bottom inthe site plots(S1-3). (3)Principal component analysis(PCA)indicated that soil TPHs exerted the greatest in-fluence among the 8 environmental factors

and its increase directly developed the content of soil salt

organic matter and available P

which further affected other environmental factors including soil moisture

pH vaule

bacteria

fungi

actinomycetes and even total microbial amount. The results above revealed that rational de-velopment of soil bacteria and actinomycetes resources and exogenous supply of nutrition concerning N and Kcould stimulate the growth of native oil degradation bacterium and then raise the petroleum hydrocarbon deg-radation efficiency during the process of bio-remediation on petroleum-contaminated soil in the Longdong re-gion of the Loess Plateau

China.