【作者】 傅强；

【导师】 杨仁斌；

【作者基本信息】 湖南农业大学 ， 环境工程， 2009， 硕士

【摘要】 本文研究建立了在水土环境样品中马拉硫磷的残留量GC-NPD检测方法;马拉硫磷在水土环境中的消解和残留规律;马拉硫磷在水体中的光化学降解和环境因子的影响。主要研究结果如下:1、通过研究建立了水土环境样品中马拉硫磷的残留量GC-NPD检测方法:水土环境样品中马拉硫磷用丙酮溶液提取,二氯甲烷萃取,萃取液浓缩后用丙酮定容。GC-NPD检测马拉硫磷的色谱条件:进样口温度280℃,检测器温度300℃,色谱柱柱温230℃,载气流速2.5mL/min,尾吹气流:5.0 mL/min,H₂流速:3.0 mL/min,Air流速:60 mL/min。进样量为1μL,马拉硫磷的保留时间为2.1min,马拉硫磷的最小检出量为1.79×10^-11g。柑桔园土壤、稻田水和稻田土壤中的马拉硫磷添加回收率在78.59%-91.79%之间,变异系数在3.23%-9.15%之间,分析方法最小检出浓度分别为:稻田水0.002mg/kg、稻田土壤0.010mg/kg、桔园土壤0.010 mg/kg。马拉硫磷残留分析检测方法的准确度、重现性和精确度都符合农药残留量分析与检测方法的要求。2、湖南和浙江两地模拟试验建立了马拉硫磷在水体和土壤中的消解模型;马拉硫磷在桔园土壤中半衰期为1.0～2.0d,稻田水中消解半衰期为1.56～2.98d、稻田土壤中的消解半衰期为2.36～3.49d。马拉硫磷在自然环境中消解较快,属易降解的农药,在正常使用情况下,一般不会造成环境中的残留累积污染。3、马拉硫磷在不同光源下光降解速率为:高压汞灯（500W）＞高压汞灯（300W）＞太阳光,半衰期分别为70.7min、82.5min、3465min。（1）马拉硫磷初始浓度越大,其光解速率减小。（2）马拉硫磷在不同类型水体中的光降解半衰期相差不大,光降解速率为:池塘水＞稻田水＞蒸馏水。（3）高压汞灯下,马拉硫磷在pH缓冲溶液中的光解速率为:pH 10＞pH 4＞pH 7,半衰期分别为35.4 min、45.6 min、85.6min,表明中性条件下相对比较稳定。4、本实验表明,Fe³⁺、H₂O₂对马拉硫磷敏化作用显著,[Fe³⁺]:[H_O2]共同作用下对马拉硫磷的光催化降解影响分别比单独的Fe3⁺或H₂O₂作用的结果要强。Fe³⁺:H₂O₂为0.358mg/L:3.58mg/L时,马拉硫磷的半衰期从71.4min缩短到17.1min,光敏率达到76.05%。5、采用高压汞灯光照,类Fenton法处理马拉硫磷农药模拟废水,选取Fe³⁺投加量、H₂O₂投加量、温度和pH等影响较大的因素进行正交试验,结果表明:得出最佳水平组合:pH为4,Fe³⁺投加量为4.5mg/L,H₂O₂投加量为22.5 mg/L。马拉硫磷光降解最快,半衰期为4.27min。光解30min后,模拟废水中马拉硫磷降解率高达99.33%。更多还原

【Abstract】 In this paper,the GC-NPD method of residual determination of malathion in water and soil were established.The residual and degradation law of malathion were discussed through this method.The photolysis and environmental factors of malathion in aqueous solution were studied. The main study results were summarized as follows:1.The GC-NPD method of residual determination of malathion in water and soil was established.Malathion under water and soil conditions was extracted by acetone solution,and extracted by methylene dichloride,after concentrate the solution,detected by acetone.The chromatogram conditions for malathion by GC-NPD were established:the temperature of Injector,NPD detector and oven temperature were 280℃,300℃and 30℃,respectively.The flow rate of carrier gas（N₂）,make-up gas,hydrogen gas and Air were 2.5mL/min,5mL/min, 3.0mL/min and 60mL/min.The minimum detectable quantity was 1.79×10^-11g when the injection volume was 1μL and the retention time of malathion was 2.1mins.It was the chromatogram condition that the residue determination method of malathion in upland soil and the paddy water and soil was established.The minimum detectable quantity was 1.79×10¹¹g.The recoveries and RSD of malathion in citrus orchard soil,paddy water and soil were 78.59%-91.79%and 3.23%-9.15%.The minimum detectable concentration of malathion in paddy water,paddy soil and citrus orchard soil were 0.002 mg/kg,0.010 mg/kg and 0.010mg/kg, respectively.The extent of accuracy,repeatability and precision met the requirements for pesticide residue analysis.2.The degradation models of malathion in water and soil on Hunan and Zhejiang Province were established.The degradation half-lives of malathion in citrus orchard soil was 1.0～2.0d, and its half-lives in paddy soil was 1.56～2.98d,and paddy water was 2.36～3.49d.Malathion belongs to the kind of pesticide which is easy to degradate.If we use it under normal conditions, it will not cause pollution.3.The difference of photodegradation rate of Malathion under HPML and sunlight was comparatively distinctive.The order was that HPML（500W）＞HPML（300W）＞sunlight.The half-lives were 70.7mins,82.5mins and 3465 mins,respectively.（1） The higher the concentration of malathion is,the slower the photolysis rate is. （2） The difference among the half-lives of photodegradation of malathion in three different types of water were small,and the rate order was that pond water＞cropland water＞distilled water.（3）The effects on the photodegradation of Malathion at different values of pH were studied under the HPML.The photolysis rate of malathion under different pH was:pH10＞pH 4＞pH 7. The half-lives were 35.4mins 45.6mins and 85.6mins,respectively.It showed that malathion was relatively stable under neutral conditions.4.The experiment showed,Fe³⁺ and H₂O₂ had the photosensitivity effects on the photolysis of malathion.Compared with the single effect,the coexistence of Fe3+ and H₂O₂ strengthened the effects of photodegradation of malathion.When the concentration of Fe³⁺ was added to 0.358 mg·L^-1 and the concentration of H₂O₂ was added to3.58 mg·L^-1,the photodegradation half-life was 17.1mins with a photosensitive proportion of 76.05%.5.The simulated wastewater with malathion was treated by Fenton-like Reagent under HPML.On the basis of orthogonal tests,when the concentration of malathion was 4.5mg/L,the optimum photolysis conditions were as follows:pH=4,the concentration of Fe³⁺ was 4.5 mg/L, the concentration H₂O₂ of was 22.5 mg/L.The photodegradation half-life was 4.27mins.The photodegradation rate malathion in simulated wastewater was 99.33%after 30mins.更多还原