氟环唑在稻田环境中的残留消解及土壤吸附研究

发布时间：2018-12-12 02:37

【摘要】：氟环唑是一种三唑类的广谱杀菌剂。目前国内外有关于氟环唑在小麦、苹果、梨与葡萄上的残留消解研究报道,而关于稻田环境中氟环唑的残留消解,以及在土壤中的吸附行为研究报道甚少。本文主要研究了氟环唑在稻田生态环境中(稻田田水、稻田土壤和水稻植株)的残留降解行为及其在土壤中的吸附规律,为氟环唑在稻田环境中的安全使用提供科学的依据。主要结论如下：(1)建立了氟环唑在稻田环境样品中残留量检测的简易实验室前处理方法方法和HP-5柱分离-ECD检测器检测的气相色谱分析方法。田水样品用二氯甲烷：丙酮混合液提取；水稻植株样品用二氯甲烷：乙腈混合溶液提取；稻田土壤、稻壳、稻米样品用甲醇：石油醚混合溶液提取,经弗罗里硅土柱净化；采用气相色谱电子捕获检测器测定。氟环唑的添加回收率实验是在田水、田土中添加0.05-1. OOmg/kg氟环唑标样；水稻植株、稻壳、稻米中添加0.025-0.50mg/kg氟环唑标样,其平均回收率为78.5%-101.1%,相对标准偏差为2.0%-7.7%,符合农药残留量分析与检测的技术要求。(2)研究了氟环唑在稻田环境中的消解动态和最终残留。实验结果表明：可以用一级动力学方程(C,=Coe-kl)来描述氟环唑在水稻环境中的消解动态。选择南北不同气候地点,于2013-2014年在长沙和北京郊区进行了氟环唑的田间试验,氟环唑在稻田田水、土壤与水稻植株中的平均半衰期分别是3.60d、13.38d、4.20d。因此表明氟环唑属于易消解农药(T1/230d)。最终残留实验结果表明：氟环唑施药剂量为900g／hm2,施药次数2次,最后一次施药后间隔28d时,氟环唑在稻米中的残留量均没有超过MRL值(0.05 mg/kg).(3)氟环唑在五种不同的供试土壤中的吸附平衡时间是24h,吸附原理可以用Freundlich等温吸附方程拟合,吸附能力大小是：湖南红壤山东褐土)黑龙江黑土)重庆紫土)湖南河潮土。在五种土壤中的吸附都表现为物理吸附(AG40 kJ/mol)。氟环唑的吸附量随pH值的变化而变化,当pH值从7上升至11时,吸附量也是随着增大的。当土壤环境温度为25℃时,氟环唑的吸附量达到最高点。当钙离子浓度在0. 05mol/L时,氟环唑的吸附量是最大的。阳离子表面活性剂CTAB对氟环唑在土壤中的吸附起抑制作用,阴离子表面活性剂SDBS对氟环唑在土壤中的吸附先起抑制作用后起促进作用。
[Abstract]:Fluoxazole is a kind of wide spectrum fungicides of triazole. At present, there are some reports on the residue digestion of fluoxazole in wheat, apple, pear and grape, but there are few reports on the residual digestion of fluoxazole in paddy field environment and the adsorption behavior in soil. In this paper, the residual degradation behavior of fluoxazole in the ecological environment of paddy field (paddy field water, paddy field soil and rice plant) and its adsorption in soil were studied, which provided a scientific basis for the safe use of fluoxazole in paddy field environment. The main conclusions are as follows: (1) A simple laboratory pretreatment method for the determination of flucyclazole residues in environmental samples of paddy fields and a gas chromatographic analysis method for HP-5 column separation and ECD detector detection have been established. Field water samples were extracted with dichloromethane: acetone mixed solution, rice plant samples were extracted with dichloromethane and acetonitrile mixed solution, paddy soil, rice husk and rice samples were extracted with methanol: Petroleum ether mixed solution and purified by Florion silica column. Gas chromatographic electron capture detector was used. The recovery rate of fluoxazole was 0.05-1 in field water and field soil. OOmg/kg fluoxazole standard sample; The average recovery was 78.5% and 101.1%, and the relative standard deviation was 2.0-7.7%, and the average recovery rate was 78.5% -101.1%, and the relative standard deviation was 2.0-7.7%. It meets the technical requirements of pesticide residue analysis and detection. (2) the degradation dynamics and final residues of fluoxazole in paddy field environment were studied. The experimental results show that the first-order kinetic equation (C _ (C) -Coe-kl) can be used to describe the digestion dynamics of fluocyrazole in rice environment. A field trial of fluoxazole was carried out in Changsha and the suburbs of Beijing from 2013 to 2014. The average half-life of fluoxazole in paddy field, soil and rice plant was 3.60 days, 13.38 days and 4.20 days, respectively. Therefore, flucyclazole belongs to easily digestible pesticide (T 1 / 230 d). The results of the final residue test showed that the dose of fluoxazole was 900g / hm ~ (2), the number of times of application was 2 times, and the interval of 28 days after the last application was 28 days. The adsorption equilibrium time of flucyclazole in five different soils was 24 h, and the adsorption principle could be fitted by Freundlich isothermal adsorption equation. The adsorption capacity is: red soil, Shandong cinnamon soil, Heilongjiang black soil, Chongqing purple soil) Hunan river tidal soil. Physical adsorption (AG40 kJ/mol) was observed in the five soils. The adsorption capacity of flucyclazole changed with the change of pH value. When the pH value increased from 7 to 11:00, the adsorption capacity also increased. When the soil temperature was 25 鈩，

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