【作者】 刘硕；

【导师】 曲东；

【作者基本信息】 西北农林科技大学 ， 环境科学， 2006， 硕士

【摘要】 异化Fe(III)还原过程对厌氧环境中有机物的代谢及一些无机物的形态转化具有显著的影响。多数异化Fe(III)还原微生物可通过利用H2和有机电子供体使Fe(III)还原,并从中获得能量进行生长。在受污染的含水土层中,异化Fe(III)还原过程通过作为污染物氧化的电子受体而使得有机污染物降解。纯培养研究进一步证实,一些异化Fe(III)还原微生物可以利用芳香化合物作为电子供体,促进芳香族碳水化合物的氧化过程。因此,异化Fe(III)还原过程在促进厌氧环境中有机污染物的降解,强化污染环境的微生物原位修复方面具有广阔的应用前景,已逐渐受到国内外学者的重视。本文选择我国典型的水稻土为供试材料,采用土壤泥浆厌氧恒温培养及微生物接种液混合培养的研究方法,初步探讨了厌氧微生物利用甲苯、苯胺、苯酚和苯甲酸以及作为唯一碳源时对微生物Fe(III)还原过程的影响,比较了不同浓度苯系物对Fe(III)还原过程影响的差异,以及电子穿梭体(AQDS)对Fe(III)—苯系物氧化还原体系的调节作用。通过对自然水稻土与有机质耗竭性水稻土的比较,研究了水稻土中Fe(III)还原过程对不同苯系物的利用潜力。采用模拟苯酚污染的土壤,探索了微生物Fe(III)还原过程对强化苯酚降解的可能性。主要得到以下结论:(1)由水稻土中提取的微生物可以利用苯系物作为唯一碳源,在厌氧降解的同时将电子转移给Fe(III),促使氧化铁还原为Fe(II),但利用不同苯系物的铁还原难易程度有所差异,铁还原率表现为苯甲酸最高(53.99 %),甲苯为最低(19.55 %)。4种苯系物作为碳源时的铁还原率均低于以葡萄糖为碳源时的铁还原率(71.16 %)。(2)混合培养过程中,不同浓度苯系物对氧化铁还原过程有不同程度影响。在所设置的浓度范围内,苯胺、苯酚、苯甲酸浓度为1.0~2.0 mmol/L时,促进铁还原过程;甲苯浓度为2.0~4.0 mmol/L时,促进铁还原过程。以2.0 mmol/L苯系物作为碳源时,蒽醌-2,6-二磺酸盐(AQDS)可明显地促进苯系物与氧化铁之间的电子传递。(3)土壤厌氧培养过程中,添加苯系物后抑制了土壤中铁还原反应,不同苯系物的抑制程度不同。苯酚、苯甲酸抑制程度较大,培养过程中基本上没有Fe(II)生成,甲苯、苯胺抑制程度较小,铁还原在一定程度上可以进行。添加外源氧化铁后,不同苯系物处理中铁还原程度都有增加,但增大程度不同,其中苯甲酸处理中Fe(II)累积量增加最多,甲苯、苯胺处理中也有一定程度增加,苯酚处理中增加程度最小。(4)采用耗竭性水稻土的厌氧培养过程中,添加苯系物后强烈地抑制了土壤中铁还原反应。苯酚和苯甲酸处理的抑制程度大,而甲苯和苯胺处理的抑制程度较小。和自然水稻土进行比较,有机质耗竭性水稻土中添加氧化铁后,各处理中Fe(II)累积量增加程度减小。更多还原

【Abstract】 Dissimilatory Fe(III) reduction significantly influences the metabolize of organic compounds and the fate of inorganic compounds in anaerobic environment. Most of microbes of dissimilatory Fe(III) reduction can utilize H2 and organic electron donors so as to cause Fe(III) reduction and gain energy for growth. In the contaminated aquifers, dissimilatory Fe(III) reduction serves as the electron acceptor to oxidate the contaminants. The study of pure culture illuminate that some microbes of Fe(III) reduction can utilize aromatic compounds as electron donors, and stimulate the oxidation of aromatic compounds. So, using Fe(III) reduction to stimulate the degeneration of organic compounds in aquifers, and to strengthen the bioremediation of contaminated environments have expansive foreground, and this was gradually regarded by more and more researchers.In this paper, the typical paddy soils in our country were used, and the soil solutions were incubated under anoxic atmosphere. The effects of benzene analogs (toluene, aniline, phenol, benzoic acid) serve as sole electron donors and different concentrations of benzene analogs on dissimilatory iron reduction were studied, and determine if AQDS can adjust the effects; The potential of utilization of Fe(III) reduction on benzene analogs were also studied in nature soils and exhausted soils. Adopt the soil contaminated by phenol, the possibility of strengthen the degeneration of phenol by microbic Fe(III) reduction were investigated. Some conclusive results were obtained as following.(1) Microbes in the inoculum can utilize benzene analogs with different extent; different concentrations of benzene analogs have different effect on iron reduction, Fe(III) reaction rate of benzene acid was highest (53.99%), which of toluene was lowest (19.55%), and the Fe(III) reaction rate of different benzene analogs were lower than when glucose served as carbon source.(2) Different concentrations of benzene analogs have different effect on iron reduction. when the concentrations of aniline, phenol, and benzoic acid are between 1.0 and 2.0mmol/L, and the concentration of toluene is between 2.0 and 4.0mmol/L, dissimilatory iron reduction that depends upon the microorganism activities can be strengthened, and anthraquione-2,6 -disulfonate obviously promoted electrons transferred from the benzene analogs to更多还原