Studies On The Photochemical Degradation Of Octachlorodipropyl Ether On The Soil Surface

In this paper, the photochemical degradation of octachlordipropyl ether (OCDPE) on soil surface irradiated by UV light and sunlight was investigated. The effects of different types of soils, soil moisture, adding of OCDPE, pH value, TiO2, surfactants and pesticides on photolysis of OCDPE on the soil surfaces were studied under UV light.The main results were summarized as following:1. The photolysis of OCDPE on soil surface followed the first kinetic formula. The photolytic rate of OCDPE under UV light was15.7times than its under sunlight, the photodegradation half-lives of which were11.44h and7.48d respectively. The photolytic rates of OCDPE in different soil ranged as:red loam soil> cultivated fluviogenic soil> rice soil, the photodegradation half-lives of OCDPE of which were11.44h,14.00h and20.63h, respectively. The photolysis rates of OCDPE accelerated with the increasing of soil moisture, the photodegradation half-lives of OCDPE in dry soil was1.3-2.6times than its in wet soil.2. The photolysis half-lives of OCDPE in soils of pH7.2, pH5.4and pH9.8were in this paper,8.68h,11.44h and26.05h, respectively. The photolysis of OCDPE in neutral soil was more rapid than acid or alkaline soils. The photolytic rates of OCDPE were negatively correlated with the fortified concentrations. The photodegradation half-lives of OCDPE prolonged from10.47h to15.64h when its fortified concentrations increased from0.2mg-kg-1to10mg-kg-1. TiO2could greatly promote the photolysis of OCDPE. The photodegradation half-lives reduced from11.44h to4.74h when TiO2dosage increased from0to3%.3. Selected surfactants showed different effects on the photolysis of OCDPE on soil surface. Tween80had no observable effect on the photolysis of OCDPE.601#,603#,0201B,2201and SDBS showed the photosensitive effect on the photolysis of OCDPE.2201and SDBS exhibited distinct photosensitizing effect on the degradation of OCDPE, and photosensitive rates were20.99%and30.52%respectively. The photolytic rates of OCDPE accelerated with the concentration increasing of2201and SDBS, but the photolytic rate decreased when the concentration of SDBS was increased to5mg-kg-1.4. Fenvalerate, bifenthrin, deltamethrin, lambda-cyhalothrin, dimethoate and dichlorrvos showed the photoquenching effects on the photolysis of OCDPE on the soil surface. Fenvalerate and bifenthrin exhibited distinct photoquenching effect on the photolysis of OCDPE, and the photoquenching rates were215.58%and132.01%, respectively. Phoxim, chlorpyrifos and acephate showed the photosensitive effects on the photolysis of OCDPE, and photosensitive rates were14.89%,21.26%and19.54%, respectively. Beta-cypermethrin, fenpropathrin and parathion had no observable effect on the photodegradation of OCDPE. The photolytic rates of OCDPE accelerated with the concentration increasing of chlorpyrifos and acephate, but the photolytic rate decreased when the concentration was increased to5mg·kg-1.5. Photodegradation products of OCDPE on soil surface were detected by HPTLC.Fraction (Rf=0.19) were isolated from photodegradation products of OCDPE by column chromatography, and identification of which are under research.