【作者】 王兆炜；

【导师】 林琦； 陈英旭；

【作者基本信息】 浙江大学 ， 环境工程， 2005， 硕士

【摘要】 近年来,我国部分农业土壤环境日趋恶化,土壤污染表现出由一般性单一污染向复杂性、复合型污染转变。进入土壤环境的污染物在植物根际会产生一定的根际微生物生态效应,根际微生物生态系统又影响着各种污染物质在土壤环境中的迁移、转化,某种程度上决定着污染物质在环境中的归趋。本文以根际土壤微生物活性和微生物群落结构作为主要研究内容,研究在有机—重金属复合污染（PCP—Cu、Pyrene—Cu）胁迫下不同植物（黑麦草、番薯、水稻等）的根际微生物生态效应。主要结论如下: （1）在PCP污染胁迫下,土壤的呼吸作用和微生物生物量都较对照无污染土壤有明显降低。随着PCP初始添加浓度的增大微生物生物量碳降低程度更大,但根际缓解了这种降低。同浓度的Pyrene污染,黑麦草和萝卜根际以及非根际对照土壤呼吸强度、微生物生物量碳都较没有污染时有所增强,而且在植物根际增加更大。PCP、Pyrene污染对黑麦草和萝卜及其他植物根际以及非根际土壤代谢熵的影响随不同污染和植物根际不同。 （2）在Cu污染下,污染对非根际土壤呼吸强度表现出了一定的刺激作用。在Cu 150mg·kg^-1和300mg·kg^-1两个污染水平下,黑麦草和萝卜根际都减弱了污染对土壤呼吸强度的刺激。当Cu 300mg·kg^-1时,Cu污染抑制了微生物量碳。不同植物根际表现出一定的对Cu污染的根际作用,根际缓解了重金属对微生物的毒害作用,根际微生物生物量碳较非根际土壤的下降程度有明显的减缓。 （3）PCP—Cu复合污染对黑麦草根际和萝卜根际及对照非根际土壤呼吸强度的影响有所不同,变化表现出一定的复杂性。随着复合污染的加重,根际和非根际微生物生物量都有明显的下降,但在根际中的下降程度较非根际小,根际作用缓解了复合污染对根际微生物活性的毒害。Pyrene—Cu复合污染下,根际及非根际对照土壤的呼吸强度都有所增强,而且呼吸强度随着复合污染（水平）浓度的增大而增大。随着复合污染的加重,根际和非根际微生物生物量都有降低,与PCP-Cu不同的是Pyrene—Cu复合污染下微生物生物量降低程度小,而且个别情况下还会出现根际微生物生物量的增大。PCP—Cu以及Pyrene—Cu进入土壤环境,由于有机、重金属及其复合时对土壤中微生物造成毒性,引起土壤代谢熵的变化。当PCP—Cu以及Pyrene—Cu以高浓度复合存在时,非根际及根际土壤代谢熵都较更多还原

【Abstract】 Combined pollution caused by organic pollutant and heavy metal is one of the important soil pollution forms. The rhizosphere is a dominant site of microbial activity in soil and whereas it can be shown that soil pollution can influence the function of this comic zone. There is an established need to monitor effects of organic-heavy metal combined pollution on rhizosphere microbial ecology given the soil heavy metal contamination with the simultaneity of organic pollution is an emerging problem. In this paper, the effect of organic-heavy metal combined pollution （PCP —Cu, Pyrene— Cu） on rhizosphere microbial activity and bacterial community were studied using some sensitive microbial ecological indexes such as soil respiration rate, microbial biomass carbon and ecophysiological index. Here the main results of this study are presented:（ 1 ） The soil respiration rate and microbial biomass carbon decreased obviously under the PCP pollution stress. Wth the increase of PCP concentration, the microbial biomass carbon decreased deeply and rhizosphere mitigate the detrimental effects of PCP on siol microbial biomass carbon. But at the same concentration Pyrene pollution level, the soil respiration rate and microbial biomass carbon of no-planted soil and rhizosphere of ryegrass and radish were increased. And the increase of rhizosphere is more obvious than no-planted soil. The effects of PCP, Pyrene on the metabolic quotient were different between different plant rhizoshere and no-planted soil.（ 2 ） The pollution of copper stimulated the soil respiration rate of no-planted soil. The rhizosphere of ryegrass and radish weakened the stimulation of soil respiration rate under pollution (150mg·kg^-1 Cu and 300mg·kg^-1 Cu) condition. The microbial biomass carbon was restrained under 300mg·kg^-1 Cu pollution stress. The plants had a rhzosphere effect, which lightened the toxicity of copper pollution on rhizosphere microbes.（ 3 ） The effect of PCP-Cu combined pollution on respiration rate of no-planted soil and rhizosphere of ryegrass and radish was complex. With the deterioration of PCP-Cu combined pollution, the microbial biomass carbon decreased obviously. Because of rhisozphere effect, the decrease of rhizosphere was not obvious as no-plnted soil. But under the Pyrene—Cu combined pollution, with the aggravation of combined pollution stress,the soil respiration of no-planted and rhizosphere wasenhanced. At the same time, the microbial biomass carbon of no-planted soil and rhizosphere decreased to some extent. PCP-Cu, Pyrene-Cu combined pollution caused the change of metabolic quotient, When Cu existed with organic pollutants together at higher concentration, the soil metabolic quotient of no-planted soil and rhizosphere increased more obvious than control soil.（ 4 ） In heavy metals contaminated soil, the copper—toletrant bacterial colony of rhizosphere ryegrass had the largest ecophysiological index and stability. In only heavy metals contaminated soil, the PCP-tolerant bacteria also existed in no-planted soil and ryegrass rhizosphere. After introducing PCP into heavy meals contaminated soil, PCP—toletrant bacterial colony of no-planted soil displayed early and had a higher ecophysiological index than rhizosphere.（ 5 ） The microbes that can used pyrene to growth were existed in rhizosphere of ryegrass and radish. After 15 day degradation experiment, the Pyrene of 80 mg·L^-1 can be degraded completely. Because the joint toxicity of PCP-Cu combined pollution to microbes was complex, the growth and degrading ability of the PCP degrading microbes was different.更多还原