The Research And Analysis Of The Degradation Of Four Kinds Of Organophosphorus Pesticide

In this paper we study a method which can mensurate four kinds of organophosphorus pesticide residue of methamidophos, equigard, trichlorton and dimethoate. Through the research of the degradation of four kinds of organophosphorus pesticide on the vegetables in Anji Village, the suburb of Nanning, Guangxi, and the comparison of the laws of degradation of the productions of dimethoate pesticide in open fields and in vinyl houses, the results indicates that:1 .The experiment prove that the method mentioned in the paper is simple and speedy and tried.2. The laws of degradation of the four types of organophosphorus pesticide all conform to the mathematic model of the polynomial regression equation in one unknown or the mathematic model of exponential function.3. In 1.5-time application quantity, the degradation speeds of the four types of organophosphorus pesticide are mainly identical with the degradation speed in the constant application quantity of pesticide.4. Under the same environmental condition, the order of half-life period of the four types of organophosphorus pesticide from long to short is: methamidophos>dimethoate>equigard>trichlorton.5. Using equigard, trichlorton, and dimethoate pesticide in theproduction of open field, if we pick the vegetables in the safe intervals prescribed in "Guideline of safe handling of pesticide", pesticide residue all can be within the State standard range of the highest pesticide residue tolerance (value of MRL)6. Using dimethoate pesticide in the production of vinyl houses, the pesticide residue of the vegetables picked after safe intervals, is evidently beyond the range of standard highest residue tolerance (value of MRL) of the state7. The degradation speed of vegetables in vinyl houses is obviously slower than that of the vegetables in open field. In the sunlight shading vinyl houses, the half-life period (T0 5) of dimethoate is increased from 2.05 days to 3.29 days, 60% longer than that in the open field.8. The major factors that cause degradation differences of pesticide in vinyl houses and in open fields are rainfall and light intensity and wind, among which light rainfall and intensity are possibly the key factors.