八氯二丙醚在土壤表面的紫外光解动力学研究

以紫外灯为光源,研究了八氯二丙醚在土壤表面的光化学降解动态以及不同因子对其光解的影响。结果表明,八氯二丙醚在土壤表面的光解动态符合化学反应一级动力学方程。八氯二丙醚在不同类型土壤中的光解速率为红壤>潮土>水稻土,光解半衰期分别为11.44、14.00h和20.63h。八氯二丙醚在中性土壤中光解速率最快,在偏酸或偏碱性土壤中光解半衰期均明显延长。土壤含水量增加,有利于八氯二丙醚的光解,干燥土壤(含水量为2%)中八氯二丙醚的光解半衰期是潮湿土壤的1.3~2.6倍。当土壤中八氯二丙醚添加浓度为0.2~10mg·kg-1时,其光解速率与添加浓度呈负相关关系;不同添加剂量的催化剂TiO2对八氯二丙醚的光解均表现出明显的光敏化作用,光解速率常数提高1.6~2.4倍。研究结果将为明确八氯二丙醚在土壤中的环境行为及其环境安全性评价提供科学依据。

Photodegradation Kinetics of Octachlorodipropyl Ether in Surface Soil Under UV Lamp

The photodegradation properties of pesticides have an important influence on pesticide residue and ecological environment safety evaluation. Octachlorodipropyl ethe(rOCDPE)is a chloroalkyl ether which was used as synergist for pyrethroid, organophosphorus and carba- mate insecticides. The acute toxicity of OCDPE is low, but it is now clear that OCDPE has subacute or chronic toxicity, for example subacute hepatotoxicity, cytotoxicity, carcinogenicity, and contact allergenicity. In this paper, the photolysis of OCDPE in surface soil and the associat- ed influencing factors were investigated under UV radiation. The results showed that the photolysis of OCDPE in soil followed the first kinetic formula. The photolytic rates of OCDPE in different soil ranged as:red soil > fluvo-aquic soil > rice soil, the photodegradation half-lives of which were 11.44 h, 14.00 h and 20.63 h, respectively. The photolysis of OCDPE was more rapidly in neutral soil than acid soil and alkaline soil. The photodegradation rate constants of OCDPE accelerated with the increasing of soil moisture, the photodegradation half -lives of OCDPE in dry soil was 1.3~2.6 times than those in wet soil. The photodegradation rate constants of OCDPE at initial concentration of 0.2~10 mg·kg-1 were negatively correlated with the initial concentrations. TiO2 fortified in the soil with selected dosages exhibited photosensitive ef- fects on OCDPE photodegradation, the photodegradation rate constants of which were improved about 1.6~2.4 times. The results will provide a scientific foundation for the environmental fate and safety evaluation of OCDPE in soil.