Effects Of Imidazolium ILs [C₈mim]BF₄ And [C₈mim]NO₃ On The Diversity Of Microbial Community In Soil

Ionic liquids（ILs）were considered as “green” solvents and have been used widely because of their excellent properties,such as nonflammability,synthetic flexibility,low vapor pressure and so on.However,because many ILs are used in many fields and attracted comprehensive concern from scientists,and also they are released into and eventually accumulate in the environment.The toxic effects of ILs on organisms have been shown in recent years,and have already got some results.On another hand,the soil microbial is considered as on of the important biological indicator to assess the quality of soil environment.So we can evaluate the toxic effects of ILs on the soil environment through the ecotoxicology of ILs on soil microbial community.In the present study,two large scale usage and typical imidazoles ionic liquid [C₈mim]BF₄ and [C₈mim]NO₃ were chosen,and the brown soil were chosen as the experimental soil,using the HPLC,dilute plate method,soil enzyme activity photometry method,T-RFLP and RT-PCR,studied the concentarion of ILs,the number of soil bacterial,fungi and actinomycete,soil urease,dehydrogenase,acid phosphatase and β-glucosidase activity,soil microbial community structure and functional gene diversity after the ILs incubation 10,20,30 and 40 days at 0,1.0,5.0 and 10.0 mg/kg.（1）The extraction recoveries of [C₈mim]BF₄ and [C₈mim]NO₃ from the soil were 81.5%-87% and 84.3%-85.2%.The concentrations of [C₈mim]BF₄ and [C₈mim]NO₃ were maintained stable during the whole incubation perids.Additionally,the concentrations of [C₈mim]BF₄ were changed no more than 5% after 40 days incubation time compared with that on the 0th day,and [C₈mim]NO₃ changed no more than 10%.（2）The population of soil bacteria,fungi and actinomycetes were inhibited significantly at 10.0 mg/kg of the whole incubation time both [C₈mim]BF₄ and [C₈mim]NO₃.Moreover,at the 5.0 mg/kg concentration of [C₈mim]BF₄ and [C₈mim]NO₃ were also decreased the population of the three kinds soil microbial at different incubation time.（3）All of the [C₈mim]BF₄ treatments stimulated the soil urease activity after 20 days incubation and then started to inhibited the urease activity,and the soil dehydrogenase and acid phosphatase activity were inhibited by [C₈mim]BF₄ at 10.0 mg/kg on day 20,all of the treatments of [C₈mim]BF₄ simulated theβ-glucosidase activity after 20 days incubation.The 10.0 mg/kg treatments of [C₈mim]NO₃ were inhibite the urease activity after 20 days incubation,and the high concentration of [C₈mim]NO₃ inhibited the dehydrogenase activity and stimulated the β-glucosidase activity at the later periods of the incubation tine.（4）Toxic effects of [C₈mim]BF₄ and [C₈mim]NO₃ on the diversity of soil microbial community structure were evaluated through T-RFLP methods.The present results indicated that both of the two kinds of ILs can’t change the dominant structure of the soil microbial community,but the diversity of the soil microbial community structure were decreased by the ILs and the banlance were disturbed.However,at the later period of the [C₈mim]NO₃ incubation time,the soil microbial community structure have a trend that recoveried to the control treatment.（5）The results of RT-PCR indicate that the copy number of AOA-amoA gene and AOB-amoA gene were decreased by [C₈mim]BF₄ and [C₈mim]NO₃ at different concentrations except 1.0 mg/kg,and this inhibition have a significant dose-effect relationship.