根系分泌物对有机氯农药降解的影响效应及不同组分间影响差异

借助盆栽模拟实验,对比研究了苇状羊茅根系分泌物对土壤中OCPs总量及其主要组分的降解效应、土壤微生物群落动态(生物量碳及磷脂脂肪酸)的影响效应.结果显示:根系分泌物促进了土壤中OCPs的去除,添加根系分泌物后,土壤中OCPs的去除率(77.57%)显著高于对照组(33.49%);相同处理条件(污染水平、添加剂量)下,对HCHs、毒杀芬、HCB、艾氏剂、γ-氯丹的强化去除率普遍高于对OCPs总量的强化去除率(p0.05);对DDTs、灭蚁灵、硫丹Ⅰ、狄氏剂、环氧七氯的强化去除率普遍低于对OCPs总量的强化去除率.相同污染水平下,添加根系分泌物的污染土壤中微生物生物量碳也显著高于对照组;实验期间,细菌的磷脂脂肪酸占主导地位,其次为真菌,它们在土壤微生物群落中的动态变化与OCPs降解趋势相一致.可见,在OCPs降解过程中,根系分泌物的存在改变了根际土壤中细菌、真菌的种群数量及其群落结构,进而改善了对OCPs的降解效率.

Effects of Root Exudates on Degradation of Organochlorine Pesticides and Different Influence of Main Components

The study is to does a comparative study of the effects of the root exudates of tall fescue (Festuca arundinacea ) on degradation of the total amount of OCPs ,its main components in soil and also its influence on the community dynamics of soil microbe (microbial biomass carbon and phospholipid fatty acids ) by pot experiments .The results show that the root exudates of tall fescue evidently enhance the removal of OCPs significantly .When root exudates are added ,the OCPs removal rate in soil achieves approximately 77.57%which is higher than that of the control treatment which is only 33.49% .Under the same treatment condi-tions (contamination level ,same additive volume ) ,the enhanced removal rates of hexachlorocyclohexane (HCHs ) ,toxaphene ,hexachlorobenzene (HCB ) ,aldrin and γ-chlordane are much higher than the rate of the total amount of OCPs (p<0.05 )while the enhanced rate of dichloro-diphenyl-trichloroethanes (DDTs ) , mirex ,endosulfanⅠ ,dieldrin and heptachlor epoxide are always lower than that of the total amount of OCPs .Under the same contamination level ,after the addition of root exudates ,the microbial biomass carbon in soil is higher than that of the control treatment .During the experiment ,microbial community is dominated by phospholipid fatty acids ,and followed by fungi .Their dynamic change in soil microbial community corre-sponds to the trend of the OCPs degradation ,which indicates that the existence of the root exudates changes the population quantity and the community structure of the bacteria and fungi ,in rhizosphere soil and then enhances the degradation efficiency of OCPs in soil .