【作者】 刘丽；

【导师】 袁峰；

【作者基本信息】 合肥工业大学 ， 环境科学， 2010， 硕士

【摘要】 随着社会经济的不断发展,环境中的重金属污染日益加剧。铜陵地区是我国重要的铜工业生产基地之一,但发达的矿业活动同时也带来了严重的环境污染,已有研究显示,矿区不同功能区表层土壤中的Zn、Cu、Pb、Cd、Cr等严重超标。重金属是对生态环境危害极大的污染物之一,它们进入环境后不易被生物降解,大部分参与食物链循环,最终在生物体内积累,生物体正常生理代谢活动被破坏。微生物可以通过生物吸附、溶解、氧化还原等作用降低环境中的重金属,分离研究耐重金属的微生物用于吸附和积累重金属是治理重金属污染的有效措施之一。本文选择安徽铜陵新桥矿区土壤为研究对象,对其中的微生物含量与重金属含量作了对比分析,并对土壤中筛选得到的耐受微生物进行生长特性和吸附特性研究,对菌株吸附重金属的机理进行初探。通过研究铜陵新桥矿区污染土壤中重金属污染元素含量与土壤中微生物生物量之间的对应关系,发现土壤中细菌、放线菌、高铁还原菌三种菌种对污染元素的敏感程度不同,其敏感程度依次是:放线菌>细菌>高铁还原菌。矿集区土壤中As、Au、Cd、Zn、Cu、Pb元素含量与土壤中细菌、放线菌、高铁还原菌数量之间的相关关系为:As、Au、Zn、Cu与细菌和放线菌,Cd、Pb与放线菌的含量呈负相关关系,指示了土壤中高浓度污染元素对微生物的抑制作用;Cd、Pb与细菌,Cd、Zn与高铁还原菌的含量呈正相关关系, Au、Pb、As与高铁还原菌数量的关系不明显。本文充分利用微生物受自然环境重金属胁迫而产生耐性这一特点,进行土壤中耐Cu、Cd微生物的筛选研究,成功获得两株耐Cu、Cd的菌株。一株为耐Cu2+50g/L的菌株,经鉴定为类芽孢杆菌Cohnella.sp.编号为S108,另一株为耐Cd2+6000mg/L的真菌菌株,经鉴定为Fungal sp.编号为IS021。分别对菌株的生长特性和吸附特性进行研究,结果表明,菌株S108的生长最适pH是8.0,装液量为250mL三角瓶中装50mL培养基,铜浓度对菌株的生长影响不大,菌株IS021的生长最适pH是7.0,装液量为50mL,镉浓度对菌株的生长影响大,高浓度抑制了菌株的生长。菌株S108对Cu2+的最佳吸附条件为pH为8,菌龄为3d,Cu2+初始浓度为100mg/L,且菌株在吸附时间为12h时达到最大吸附量68%。菌株IS021对Cd2+的最佳吸附条件是pH为7,菌龄为2d,Cd2+初始浓度为100mg/L,菌株在吸附时间为7h时达到吸附平衡,其最大吸附量是65%。pH对两种菌株的吸附特性有一定的影响, pH过高和过低都不利于微生物的吸附;菌龄对菌株的吸附特性影响很大,在试验中应选择合适菌龄;重金属的初始浓度提高使得菌株的吸附率由于吸附位点的饱和而下降电镜观察和能谱分析图谱结果表明,菌株S108吸附Cu2+主要是基于其细胞表面的吸附沉淀作用,菌株IS021对Cd2+的吸附主要是细胞表面的生物吸附作用。微生物可能通过其表面的带电电荷和活性位点来结合重金属,从而使溶液中的金属离子减少。更多还原

【Abstract】 With the development of social economy, the pollution of heavy metal increases greatly. Tongling district is one of the most important copper industry production bases in our country. However, the prosperous mining activities also caused serious environmental pollution. It has been investigated that the amount of Zn、Cu、Pb、Cd、Cr and other in different functional areas of the Mining are serious exceeded. Heavy metals are extremely harmful to the ecological enviroment. They are hard to biodegradation when entered the environment, therefore , most of them participated in the food chain circle and eventually accumulated in the biological and then destroy some normal physiological and metabolic activities. Microorganisms could reduce the content of heavy metals through biosorption, dissolving, reducing and redox. The purpose of isolation and study the bacteria toleranced towards heavy metals, which can adsorb and accumulate heavy metals is a effective measure to solve the heavy metal pollution. The paper have choosed the siol of Tongling Xinqiao mining, Anhui and analyzed the correspondence between heavy metal pollution element contents and microbial biomass in the soil. Screening the tolerant microorganisms and study their growth characteristics of strains and the mechanism of heavy metal adsorption.Through the study of the correspondence between heavy metal pollution element contents and microbial biomass in the soil of Tongling ore district have found the bacteria, actinomycetes, high iron sulfate-reducing bacteria in the soil have the different levels of pollution in sensitive elements, their degree of sensitivity are: actinomycetes> bacteria> high iron sulfate-reducing bacteria. The relationship between the content of As, Au, Cd, Zn, Cu, Pb and the biomass of soil bacteria, actinomycetes, high iron sulfate-reducing bacteria in the soil of Tongling ore district are as: As, Au, Zn, Cu and bacteria and actinomycetes, Cd, Pb and actinomycetes all displayed negative correlation between levels, reflecting that high concentrations of pollution elements in soil on microbial inhibition. Cd, Pb and bacteria, Cd, Zn and high iron sulfate-reducing bacteria were positively correlated, Au, Pb, As and high iron sulfate-reducing bacteria showed not obvious relationship on the number.This study fully utilized the characteristic that microorganism may produce resistance after exposed to heavy metal in natural environment for a long time. Therefore, the research of screening bacteria tolerance towards Cu、Cd in soil and successfully obtained two strains. One strain is Cu-tolerant at 50g/L and identified as Paenibacillus Cohnella.sp., numbered as S108;another is Fungi strain that can be tolerant Cd2+ at 6000mg/L and identified as Fungal sp, numbered as IS021.By investigating the growth and adsorption characteristics of the strains it have concluded that: the optimum pH of the strain S108 growth is 8.0, 50ml medium was added to a 250ml flask, the effect of Cu2+concentration to the growth of strain was small. The optimum pH of strain IS021 is 7.0, 50ml medium, high Cd2+concentration inhibited the growth of strain. The best condition of strain S108 adsorpted Cu2+ are pH 8.0, strain age is 3d, the Cu2+ initial concentration is 100mg/L, the maximum adsorption time is 12h 68%. The best condition of strain IS021 adsorpted Cd2+ are pH 7.0, strain age is 2d, the Cu2+ initial concentration is 100mg/L, the adsorption time to equilium is 7h and the maximum adsorption was 65%. pH has some effect to the adsorption characteristic of the strains. Too high or low pH goes against the adsorption of microorganism; cell age has great impact on the adsorption characteristic of the strains; the initial concentration of heavy metal increases, will decrease the adsorption rate due to the saturation of adsorption point.The result of Electron microscope and energy dispersive analysis (EDS) shows that the adsorption of Cu2+ by the S108 is based on adsorption sedimentation on the surface of cells, meanwhile, the adsorption of Cd2+ by the IS021 is based on biosorption on the surface of cells. Microorganism may reduce the metal ion in the solution with its surface electricity and active spot.更多还原