【作者】 李佳；

【导师】 龚道新；

【作者基本信息】 湖南农业大学 ， 环境科学， 2010， 硕士

【摘要】 三环唑是一种内吸性杀菌剂,主要用于防治稻瘟病,尤其对穗颈瘟病有很好的防治效果。三环唑在我国出现的较早,国内外对其研究也主要集中在防治稻瘟病的相关研究上,而关于其水解规律的研究鲜见报道。本文研究了三环唑在稻田生态环境中的残留降解行为,并探讨了pH值、温度、表面活性剂和无机盐的存在对三环唑水解的影响。这些研究对在我国推广和合理使用该农药,以及评价这种农药使用后的生态环境安全性有十分重大的现实意义。本论文的主要内容如下：(1)在我国自然环境条件下,三环唑在水稻生态环境中的降解符合化学反应一级动力学方程。2008年和2009年在湖南长沙、浙江杭州和广西南宁三个试验点的试验结果表明：三环唑在稻田水中的消解半衰期在7.87 d～9.00 d之间,平均半衰期为8.33 d；在稻田土壤中的消解半衰期在10.56 d～11.42 d之间,平均半衰期为10.93 d；在水稻植株中的消解半衰期在7.48 d～8.11 d之间,平均半衰期为7.81 d。(2)在水稻生长期采用三环唑250克／升悬浮剂按1500 g／hm2(有效成分含量为375.0 a.i.g/hm2)和2250 g／hm2(有效成分含量为562.5 a.i.g／hm2)兑水50kg/亩稀释后,均匀喷施于水稻茎叶,各试验处理分别施药2次和3次,每次间隔7天。三环唑在湖南长沙、浙江杭州和广西南宁三个试验点的稻田土壤中,在最后一次施药后的21d时其残留量在0.073～0.219 mg／kg之间；在稻秆中的残留量在0.557～1.189mg／kg之间；谷壳中的残留量在0.736～1.874 mg/kg之间；糙米中的残留量在0.094～0.366 mg／kg之间。试验结果发现在最后一次施药后的7d、14d和21d时,糙米中三环唑的残留量均未超过1.0mg／kg。因此,根据以上残留实验结果,建议参考欧盟制定的三环唑在大米中的MRL值(1.0mg／kg)。(3)在不同的pH值条件下三环唑的水解速率不同。碱性条件下三环唑的水解速率要比中性条件或酸性条件下的水解速率快。试验结果表明,pH=3时,三环唑水解半衰期为64.78d；pH=5时,水解半衰期为56.82d；pH=7时,水解半衰期为47.80d；pH=9时,水解半衰期为41.26d；pH=11时,水解半衰期为37.67d。(4)三环唑的水解速率随温度的升高而加快。当温度为15℃时,三环唑的水解半衰期为100.46 d；当温度为25℃时,其水解半衰期为60.80 d,；当温度为35℃时,其水解半衰期为30.01 d。试验中,温度每升高10℃,三环唑的水解常数平均增加1.84倍。(5)不同类型的表面活性剂对三环唑水解产生的影响不同。阴离子表面活性剂SDBS可以加快三环唑的水解反应速度；阳离子表面活性剂CTAB对三环唑的水解有抑制作用；非离子型表面活性剂TW-80对三环唑的水解无明显的影响。(6)无机盐对三环唑水解的影响试验表明,当添加强酸强碱盐(NaC1、KCl、CaCl2、NaNO3)时,由于盐析作用对三环唑水解产生抑制作用。当NaCl、KCl、CaCl2、NaNO3的添加浓度由0增至1mol／L,三环唑的水解半衰期分别增加了0.88%、7.55%、11.76%、31.04%；当添加强碱弱酸盐(NaHCO3)时,由于强碱弱酸盐水解后使水环境呈碱性而促进三环唑的水解。随着NaHCO3的浓度由0增至1mol／L,三环唑的水解半衰期缩短了75.47%。更多还原

【Abstract】 Tricyclazole is a kind of fungicide within the suction. It was always used in preventing and curing rice blast. Tricyclazole came to China for a long time. The studying on tricyclazole almost focus on the capability of preventing and curing the rice blast. But little information was availabled about its hydrolysis. In this paper, the residue degradation of tricyclazole in paddy has be studed; and the effect of tricyclazole hydrolysis has be studed on the pH, temperature, surface active agents and the presence of inorganic salt. It has a very great practical significance to promote and reasonably use the pesticide in our country, and to evaluate the safety after using. The major results were obtained as follows:(1) Under natural conditions in China, the degradation of tricyclazole in ecological environment followed the chemical reaction kinetic equation. in and three test points test The results of the test in Hunan Changsha, Guangxi Nanning, Zhejiang Hangzhou in 2008 and 2009 showed that:the degradation half time of tricyclazole was 7.87 d～9.00 d in the paddy water, with an average half-time of 8.33 d; the degradation half time was 10.56 d～11.42d in the paddy soil, with an average half-time of 10.93 d; in the degradation half time was 7.48 d～8.11d in rice plants, with an average half-life of 7.81 d.(2) The final residue indicated that when the rice plant was sprayed 2 to 3 times with 25% tricyclazole in the dosage of 1500 g/hm2 and 2250 g/hm2, and the last application was done at 7,14 or 21 days before harvesting, when the last application was done at 21 days before harvesting, the residues of tricyclazole in paddy soil ranged from 0.073 to 0.219 mg/kg; the residues of tricyclazole in rice plant changed from 0.557 to 1.198 mg/kg; the residues of tricyclazole in rice hull was from 0.736 to 1.874 mg/kg; the residues of tricyclazole in rice changed from 0.094 to 0.366 mg/kg. The residues of tricyclazole in rice were lower than 1.0 mg/kg. It suggested that the MRL of tricyclazole in rice was 1.0 mg/kg.(3) The hydrolysis rates of tricyclazole were different at different pH values. The hydrolysis rate of tricyclazole in alkaline solution was lower than in neuter solution or acid solution. The results showed that, when pH=3, the half-life of tricyclazole hydrolysis was 64.78 d; when pH=5, the half-life of hydrolysis was 56.82 d; when pH=7, the half-life of hydrolysis was 47.80 d; when pH=9, the half-life of hydrolysis was 41.26 d; when pH=11, the half-life of hydrolysis was 37.67 d.(4) The hydrolysis rate of tricyclazole accelerated with the rise of temperature. When the temperature was 15℃, the hydrolysis half-life of tricyclazole was 100.46 d. When the temperature was 25℃, the hydrolysis half-life was 60.80 d. When the temperature was 35℃, the hydrolysis half-life was 30.01d. Even the temperature increased 10℃, then the hydrolysis rate of tricyclazole accelerated 1.84 times as much as that before.(5) Different surfactant had dfifferent effect on the hydrolysis rate of tricyclazole. The anionic surfactant (SDBS) could increase the speed of the hydrolysis of tricyclazole. The cationic surfactant (CTAB) could decrease the speed of the hydrolysis of tricyclazole. The nonionic surfactant (TW-80) did not have special influence on the hydrolysis of tricyclazole.(6) Added strong acid and strong base salts (NaCl, KCl, CaCl2, NaNO3) into tricyclazole agueous. Due to salting-out effect which restrained hydrolysis of tricyclazole, when the concentration of NaCl, KCl, CaCl2, NaNO3 changed from 0 to 1 mol/L, the hydrolysis half-life of tricyclazole increased 0.88%,7.55%,11.76%, 31.04%, respectivily. Added strong base and weak acid salt (NaHCO3) into tricyclazole’s agueous solution, because dissociation of this salt can make water alkaline, it could accelerate its hydrolysis. When the concentration of NaHCO3 ranged from 0 to 1 mol/L, the hydrolysis half-life of tricyclazole decreased 75.47%.更多还原