典型农业湿地腐殖质对两种杀菌农药光降解作用的研究

发布时间：2018-04-23 23:11

本文选题：溶解性有机质 + 活性氧物种　；参考：《江西农业大学》2016年硕士论文

【摘要】：环境土壤、水体中各类有机农药大量积累,已经成为农业湿地土壤污染及地表水主要的污染源。水中普遍存在的溶解态有机质(DOM)诱导产生的活性氧物种(ROSs)对环境中有机农药的降解有重要的意义。农田作为特殊的湿地环境,其产生的ROSs的种类和浓度可能受到人为干扰的影响,使得对农业环境中有机农药可能存在不同的降解行为。本文研究了稻田来源的腐殖质和藕塘来源的腐殖质对两种杀菌农药——三环唑和咪鲜胺的光解动力学和影响因素。通过提取抚河二灌区源头水稻田和藕塘的表层水和沉积物中的腐殖质,用氙灯模拟太阳光,研究了两种不同来源的腐殖质组分对咪鲜胺和三环唑间接光解作用,以及pH、腐殖质浓度对两者光解的影响,并探讨了ROSs对农药的降解作用,得到以下主要结论:(1)在纯水中,咪鲜胺不能直接光解,三环唑有微弱的直接光解。腐殖质的来源和农药的分子结构共同影响了农药的间接光解。咪鲜胺在稻田腐殖质中的降解速率大于藕塘腐殖质,三环唑在藕塘腐殖质中的降解速率大于稻田腐殖质。在两种不同来源的腐殖质中,两种农药皆表现出胡敏酸中的降解速率大于稻田富里酸。(2)在稻田腐殖质中,高浓度的腐殖质对咪鲜胺和三环唑的降解产生抑制作用,可能是由于腐殖质对ROSs的猝灭作用以及腐殖质对农药激发态的还原作用。在藕塘腐殖质中,咪鲜胺的降解速率受到高浓度藕塘腐殖质的抑制,三环唑的降解速率则随藕塘腐殖质浓度升高而升高。来源不同导致两种来源的腐殖质组分在pH值变化时有反应出不同的效应。在稻田来源的腐殖质组分中,随着pH的升高,咪鲜胺和三环唑的降解速率降低。在藕塘来源的腐殖质组分中,随着pH的升高,咪鲜胺和三环唑的降解速率升高。(3)三环唑和咪鲜胺与HO?反应速率常数分别为4.25±0.30×109 M-1·s-1、3.79±0.07×109M-1·s-1。咪鲜胺和三环唑与1O2反应速率常数分别为7.31±0.40×107 M-1·s-1和5.06±2.3×107 M-1 s-1。咪鲜胺在腐殖质中的光解途径是HO?和1O2,在稻田来源的腐殖质中,1O2的贡献率远大于HO?,而在藕塘来源的腐殖质中,HO?的贡献率远大于1O2。HO?是三环唑间接光解的最主要的途径。(4)稻田腐殖质产生ROSs的能力可能强于藕塘腐殖质,且稻田腐殖质产生HO?能力大于产生1O2的能力,而藕塘腐殖质产生1O2的能力大于产生HO?的能力。腐殖质生成ROSs的能力与腐殖质浓度和溶液pH值有关。
[Abstract]:The accumulation of various kinds of organic pesticides in environmental soil and water body has become the main pollution source of agricultural wetland soil pollution and surface water. The dissolved organic matter (DOM) induced reactive oxygen species (Ros) in water is of great significance to the degradation of organic pesticides in the environment. As a special wetland environment, the species and concentration of ROSs produced by farmland may be affected by human disturbance, which may lead to different degradation behaviors of organic pesticides in agricultural environment. In this paper, the photolysis kinetics and influence factors of humus from paddy field and lotus root pond on two kinds of fungicidal pesticides, tricyclazole and prochloraz, were studied. By extracting humus from surface water and sediment of paddy field and lotus root pond at the source of Fuhe No.2 Irrigation District, the indirect photolysis of prochloraz and tricyclazole by two kinds of humus components from different sources was studied by using xenon lamp to simulate solar light. The effects of pH and humus concentration on the photolysis were also discussed. The main conclusions were as follows: 1) in pure water, prochlorfenamine could not be photolysis directly, but tricyclazole had weak direct photolysis. The source of humus and the molecular structure of pesticides affect the indirect photolysis of pesticides. The degradation rate of prochloraz in the humus of paddy field was higher than that in the lotus root pond, and the degradation rate of tricyclazole in the humus of lotus root pond was higher than that of the humus in rice field. In two kinds of humus from different sources, both pesticides showed that the degradation rate of Hu Min acid was higher than that of rice-field fulvic acid.) in rice field humus, the high concentration of humus inhibited the degradation of prochloraz and tricyclazole. It may be due to the quenching of ROSs by humus and the reduction of excited state of pesticide by humus. In the humus of lotus root ponds, the degradation rate of prochloramines was inhibited by the humus of high concentration lotus root ponds, while the degradation rate of tricyclazole increased with the increase of humus concentration in lotus root ponds. The humus components from two sources have different effects when pH value changes. In the humus components from paddy field, the degradation rate of chlorpromazine and tricyclazole decreased with the increase of pH. In the humus components from lotus root ponds, the degradation rate of prochloraz and tricyclazole increased with the increase of pH. The reaction rate constants are 4.25 卤0.30 脳 109M-1 s-1C 3.79 卤0.07 脳 109M-1 s-1respectively. The reaction rate constants of prochloraz and tricyclazole with 1O2 were 7.31 卤0.40 脳 107M-1 s-1 and 5.06 卤2.3 脳 107M-1 s-1respectively. The photolysis pathway of prochloraz in humus is HOO? And 1O _ 2, the contribution rate of 1O _ 2 in humus from paddy field was much higher than that of HOA, but in the humus from lotus root pond, the contribution rate was much higher. The contribution rate is much greater than that of 1O2.HO. The ability of humus to produce ROSs may be stronger than that of lotus root pond humus, and the rice field humus produce HOO? The ability of producing 1O2 is greater than that of producing 1O2, while the ability of humus to produce 1O2 is greater than that of producing HOO? The ability of The ability of humus to produce ROSs is related to the concentration of humus and pH value of solution.
【学位授予单位】：江西农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X592

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