【作者】 王聪颖；

【导师】 和文祥； 来航线；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2006， 硕士

【摘要】 农药因其广谱、高效、价廉等优点,在提高农产品产量和质量方面发挥了重要作用。但由于农药,特别是有机氯等类农药的大量施用,随之带来了许多土壤、水体等的环境问题,如农产品品质降低,土壤农药残留超标,土壤肥力水平降低等,最终对人畜的健康造成威胁。土壤酶作为土壤中重要的组成部分,参与包括土壤中发生的所有生物化学反应,在自然界营养物质循环、能量代谢、污染物监测与治理等方面发挥着十分重要的作用。农药通过各种途径进入土壤后,与土壤酶发生作用,因此以土壤酶作为目标物,开展农药生态毒理的研究,在理论上可揭示土壤酶与农药的作用机理,在实践上可为农药的清除、治理与监测提供理论依据。可见此方面的研究具有十分重要的理论和实践意义。但近十年来各国学者此方面的文献报道多局限于土壤酶活性的研究,且结论不尽一致,同时鲜见土壤酶动力学及其作用机理的研究报道。本论文选取农药一氯苯为材料,以催化土壤中碳、氮、磷循环的三种水解酶(脲酶、转化酶和碱性磷酸酶)为对象,较为系统地研究了有机氯类农药对土壤酶活性的影响及其因素,并采用动力学手段对二者的作用机理进行了探讨。结果表明:1.乙醇可显著激活土壤脲酶活性,其浓度与酶活性之间达到显著正相关关系。乙醇作用时间与土壤脲酶活性间关系可用抛物线模型可较好表征。动力学特征表明乙醇的加入导致土壤脲酶与底物(尿素)的亲和力增加,从本质上加速了脲酶-尿素复合物的解离,增强了酶促反应的速度,使酶促反应更易进行;对转化酶乙醇可明显抑制其活性,从动力学特征获知该抑制为完全抑制作用,包括竞争性和非竞争性。乙醇作用时间可明显降低土壤转化酶的活性,但规律性不强。2.土壤脲酶、转化酶、碱性磷酸酶活性在一定程度上可以用于表征不同类型土壤的肥力水平。3.一氯苯可显著抑制土壤转化酶和碱性磷酸酶的活性,而激活了土壤脲酶的活性,反映出土壤转化酶和碱性磷酸酶可在一定程度上表征土壤受一氯苯类物质的污染程度;同时我们得到了能够反映土壤轻微污染程度的生态剂量ED10值,塿土和红壤分别为5.3%和3.2%。4.一氯苯的加入导致土壤转化酶和碱性磷酸酶促反应的米氏常数Km增大,最大反应速度Vmax值减小,揭示出其间的作用机理为非竞争性抑制;高肥力的土壤由于其有机质和粘粒含量都比较高,因而对土壤酶的保护作用和对农药的缓冲作用较强,对一氯苯更多还原

【Abstract】 The pesticides play very important role in improving the qualities and yield of agricultural products because they are widely used, good effectiveness and low price. But the wide application of organochlorine pesticides lead to pollute soil and water. They can lead serious environmental problems such as reducing the quality of agricultural products, resulting high contents of pesticide’s remains in soil and reducing soil fertility. they can finally have a harm on health of people and animals.Soil enzymes are one of the important parts of soil. They can catalyze all biochemical reactions in soil, have remarkable affect on soil nutrimental substance recycling, energy transforming, monitoring soil pollution and remediation of soil or water. Pesticides have effect on soil enzymes after they entered the soil, it is important significance for us to study soil pesticide ecological toxicity by soil enzyme in theory and practice, for example reactional mechanism between soil enzyme and pesticide, give suggestions on remediation and monitoring to pollution.In rescent years, many scientists in different countries have studied the relationship between soil enzymes and pesticides, gotten some inconsistence results in soil enzymatic activity. It is seldom to report the enzymatic kinetic characteristics on this area. The urease, invertase and alkalinephosphatase are important hydrolyzable enzymes that can catalyze the recycling of C, N, and P. In this paper we systematically studied not only the influence of monochlorobenze on the activities of the three kinds of enzymes in Lou soil and Red soil, but also the mechanism between enzymes and the pesticides by enzymatic kinetics. We got the results as follows:1. Ethanol can remarkably increase the urease activity so that they have significant positive correlation with reaction time prolonging; the increasing degree of urease activity increases in decreasing trend. We can use model of parabola to regress their relationship. Ethanol can show the higher substrate affinity, and accelerate the breakdown the complex. Ethanol can remarkably inhibit soil invertase activity, the reactional mechanism is total competitive inhibition between ethanol and invertase, including no-competitive and competitive. With reaction time prolonging, ethanol can slightly inhibit soil invertase activity.更多还原