Effect Of Different Temperature And Moisture On The Remediation Of Oil Contaminated Soil By Bacterial-feeding Nematodes

Bioremediation of oil-contaminated soil is a complex process in which microorganisms are the main organisms for oil pollution removal but microbial remediation is greatly affected by environmental factors.In this paper,bacterial-feeding nematodes were selected as the research object to study the effects of environment temperature,water content and the species of bacterial nematode on soil microbial activity and community structure,and then to control the removal of soil oil pollution by microbes.To provide a preliminary theoretical basis and a new perspective for bioremediation of petroleum contaminated soil.1.Effects of different kinds of bacterial-feeding nematodes on oil degradation:sterilized oil contaminated soil?FSP?,uncontaminated nematode-free soil?S?,oil contaminated soil?SP?,oil contaminated soil?Caenorhabditis elegans??SPN1?,oil contaminated soil?Cephalobus persegnis??SPN2?,oil contaminated soil?Rhabditis Marina??SPN3?;The soil water content was adjusted to be 50%of the saturated water content in the soil and cultured at 22?.2.Effects of different temperature on oil degradation:sterilized oil contaminated soil?FSP?,uncontaminated nematode-free soil?S?,oil contaminated soil?SP?,oil contaminated soil+5 nematode g^-1 dry soil.The species of nematodes was Caenorhabditis elegans and cultured at 14??SPT1??22??SPT2??30??SPT3?.And the temperature of FSP,S,SP treatment was 22?.3.Effects of different soil moisture on oil degradation:sterilized oil contaminated soil?FSP?,oil contaminated soil?S?,oil contaminated soil?SP?,oil contaminated soil+5 nematode g^-1 dry soil.The species of nematodes was Caenorhabditis elegans and adjusted to 40%?SPM1?,50%?SPM2?,60%?SPM3?of saturated water content.The soil water content of FSP,S,SP treatment was adjusted to 50%of saturated soil moisture.The results show that:1.The oil degradation efficiency of SPN2 was the best,when the soil temperature was22?and the water content was 50%of the saturated water content,the oil degradation efficiency of the Cephalobus persegnis was the best.2.The oil degradation effect of SPT3 was the best,when inoculation of Caenorhabditis elegans and the water content was 50%of saturated water content,and the temperature of 30?had the best effect on oil degradation.3.The oil degradation efficiency of SPM3 was the best,when inoculation of Caenorhabditis elegans and the soil temperature was 22?,60%of saturated water content had different effect on oil degradation.4.Inoculation with bacterial-feeding nematodes increased the activities of basic respiration,dehydrogenase and urease in petroleum contaminated soil.The activity of dehydrogenase and urease of SPN2 was the highest.bacterial-feeding nematodes reduced the relative abundance of soil bacteria and fungi and changed the structure of microbial community.5.Controlling the temperature and water content of soil polluted by petroleum and the interaction between bacterial-feeding nematodes and microorganism can improve soil enzyme activity and soil quality.With the increase of temperature,the relative abundance of two communities of fungi and bacteria decreased,which was not conducive to the stability of soil ecosystem.Suitable soil moisture can increase the number of microbes,SPM2 has the highest number of microorganisms,but the microbial richness?S?decreases the most.The ratio of Gram-positive bacteria to Gram-negative bacteria decreased the least,and the ratio of fungi to bacteria decreased the most.