【作者】 何敏超；

【导师】 和文祥； 薛泉宏；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2006， 硕士

【摘要】 土壤酶和微生物共同推动土壤的代谢过程。许多国内外学者运用土壤酶来监测外源污染物对土壤生态系统的扰动,取得了令人满意的研究结果。氯苯类有机物在环境中广泛存在,由于其具有不同程度的毒性,生物累积性和持久性,对环境和人畜健康具有潜在危害。美国EPA和中国环境保护部门都将邻二氯苯列入优先监测的环境黑名单。但采用土壤酶作为目标物,国内外鲜见研究环境中邻二氯苯的生态毒理效应的报道,因此此研究在理论和实践上具有重要意义,最终为环境保护和建材等提供理论依据。为此本研究通过模拟方法,我国北方和南方的塿土和红壤作为供试土样,首次采用酶动力学手段,较为系统地研究土壤三大主要水解酶的活性特征与邻二氯苯之间的关系及影响因素,以期了解其间的作用机理等。得到的主要结论有:(1)土壤脲酶、转化酶以及碱性磷酸酶均可表征土壤肥力水平的高低;(2)加入邻二氯苯之后,除个别土样(塿土中肥、红壤低肥)脲酶活性受到激活外,其余供试土样脲酶的活性基本上受到抑制。(3)土壤转化酶活性受到邻二氯苯的强烈抑制,在低浓度时,转化酶活性急剧降低,供试土样的酶活性降幅达到34.84～65.29 %,随后随浓度增加,酶活性的降幅明显减缓。表明土壤转化酶对邻二氯苯十分敏感,可作为土壤受到邻二氯苯污染的一个临界指标。(4)供试土壤碱性磷酸酶酶活性表现出与转化酶类似的规律性变化,即初始浓度时酶活性急剧降低,随后降幅减缓。但总的来讲,土壤酶活性的变化值相对较小。(5)对照处理土样,土壤脲酶Km值变化呈现高肥>中肥>低肥的规律性变化,土壤脲酶Vmax为:中肥、高肥>低肥土样;邻二氯苯加入土壤后,土壤脲酶的Km变化较小,绝大多数土样脲酶的Vmax增大,说明邻二氯苯通过加快土壤内酶与底物复合物的解离速度来提高土壤脲酶活性的。从机理上证明了邻二氯苯激活脲酶活性的原因。(6).碱性磷酸酶的动力学参数受土壤类型影响较大,如加入邻二氯苯后,塿土碱性磷酸酶Km值高肥和低肥土样的增大,中肥波动性变化;酶的最大反应速度Vmax降低,揭示出其间的作用机理为非竞争性抑制。红壤则表现出土样碱性磷酸酶Km变化无规律,基本处于一个数量级;碱性磷酸酶Vmax高肥力和低肥力土样增加,表现出激活的特征;(7).供试土样转化酶Km和Vmax值总体呈现高肥>中肥和低肥的变化趋势,但变幅较小。加入邻二氯苯后,塿土转化酶Km和Vmax值都降低,揭示出其是一种混合更多还原

【Abstract】 Soil enzymes and microorganisms finished soil metabolism reactions together; many scientists got the better results on soil enzyme monitoring the soil pollution by pollutants in soil ecology. Chlorobenzene is existed in environment, is one kind of pollution with more toxicity and bioaccumulation and persistence, had more harmful to the health of people and livestock. For example, the Di-chlorobenzene is listed a key substance that should be prior to monitor by EPA (Environment Protection Agency) in USA and Environmental protection bureau in China. It is less reported to study the Di-chlorobenzene ecological toxicity by soil enzyme, so there are much importance to research their influence in environment in theory and practice, finally in order to supply basis for environmental protection and remediation.By simulating method, we systematically studied the relationship between soil main hydrolyase (soil urease, invertase and alkaline phosphatase) and Di-chlorobenzene in Lou soils and red soils, and influencing factors. It is first time for us to study the enzymatic kinetic parameters in contaminated soils by Di- chlorobenzene in china, in order to understand the reaction mechanism between soil enzyme and Di-chlorobenzene. The results were as following:(1) Soil urease, invertase and alk-phosphatase could indicate the level of soil fertility.(2) With dichlorobenzene adding, urease activity of almost all soils tested were inhabited excepted several samples (middle fertility Lou soil and low fertility Red soil).(3) Soil invertase was remarkably inhabited by dichlorobenzene. Soil invertase activities showed a sharp decrease (about 34.84-65.29%)at low concentration of dichlorobenzene, then the content became slower trend. Soil invertase is more sensitive to dichlorobenzene than urease, and can be an index of soil polluted by dichlorobenzene.(4) Soil alk-phosphatase activities have the same changing law with soil invertase activity. Generally there is a little change in soil alkaline-phosphatase activities after adding pesticide.(5) soil urease Km values had such order: high-fertility soil sample>middle-fertility soil sample>low-fertility soil sample in uncontaminated soils, Vmax of middle-fertility and high-fertility samples were higher than that of low-fertility samples. When adding dichlorobenzene into soils, soil urease Km values had a little change, their Vmax increased in更多还原