Study On Preparation Of Fluroxypyr Residues And The Degradation Of Fluroxypyr In Soils

Fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2-pyridinyl-l-methylheptyl ester) is a herbicide widely used in agriculture. It is used for control of a wide range of broadleaf weeds in sugar cane, cereals, sweet corn and olive trees. Fluroxypyr long-term used or used properly, it will pollute different environmental media.Therefore, the systematic research of the Fluroxypyr residual in different environmental media as well as the behavior of degradation in the soils, in order to evaluate Fluroxypyr on the environmental media and even on non-target organisms and provide a theoretical basis for the potential threat. It will provide guidance on the safe use of Fluroxypyr. A few of research had been conducted on the fluroxypyr behavior in the soil, so in thesis we study the determination of fluroxypyr residue in environment and behavior of degradation in soils.A method for determination of herbicide fluroxypyr in water, soil and wheat by high-performance liquid chromatography (HPLC) was developed. Water samples was extracted and purified and collected by solid-phase extraction. Soil sample was extracted by ethyl acetate/petroleum ether (2:1, V/V) oscillately; wheat sample was extracted by acetonitrile/water (4:1, V/V) oscillately and purified and collected by by Florisil extraction column. The calibration curves were determined in the range of0.625～20.0mg L-1, with the correlation coefficients (R2)0.9997and the minimal detection limits being0.01mg L-1. The spiked recoveries of water sample were91.8%～93.9%, the relative standard deviation were0.7%～1.2%, the spiked recoveries of soil sample were90.1%～94.1%, the relative standard deviation were0.7%～1.9%, the spiked recoveries of wheat sample were93.5%～94.9%, the relative standard deviation were4.2%～5.4%.Effect of temperature, moisture, SOM and surfactant on degradation of fluroxypyr at8mg kg-1in soil was investigated at the time intervals of0,1,2,4,6,8,11,15and21days. The application of activated DOM of sludge and straw to contaminated soil by fluroxypyr could significantly enhance the degradation of fluroxypyr in soils. However, the degradation rate did not necessarily increase with increasing amounts of added DOM. Environmental factors such as temperature, moisture and soil type controled on the rate of fluroxypyr decomposition in soil. The microorganism was the most important factor on the degradation of fluroxypyr. The SOM was also one of main reasons of affecting degradation of fluroxypyr in soil. The degradation pathway of fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2-pyridinyl-1-methylheptyl ester) in soil for6days might be losing1-methylheptyl ester to produce4-amino-3,5-dichloro-6-fluoro-2-pyridinyl-acid. The research found that it is necessary to develope cost-effective techniques for the remediation of fluroxypyr-contaminated soils.