The Residue Dissipation Dynamics Of Diniconazole In Soil And Wheat And Its Microbial Degradation

At first, residues analytical methods of diniconazole in wheat and soil were established. The result showed that the average recoveries were 79.28%-100.64% when the added levels were from 0.02mg/kg to 1.00 mg/kg. The CV varied from 2.99% to 6.37%, the limit of detection was 0.02 ng, and the limit of detection was 0.02 mg/kg. The analysis was easy, quick, sensitive and accurate. The method accords with the demand of pesticides residue analysis. And dissipation dynamics of diniconazole in wheat were learned in Tianjing and Hefei. An optimal degradational bacteria was isolated from activated sludge which was collected from pesticide factory, as well as biodegradation of diniconazole ,were studied in this paper. The results were as follows.Residual dissipation dynamics experiment showed that the original depositions were 1.960mg/kg, 1.239mg/kg, respectively;the dissipation half-lives of diniconazole in wheat were 9.69 days and 8.55 days, respectively.The original depositions were 1.364mg/kg, 1.760mg/kg, respectively, and the dissipation half-lives of diniconazole in soil were12.95 days and 14.17 days respectively, in Tianjing during 2006 and 2007.Residual dissipation dynamics of diniconazole in wheat followed Kinetic model.The original depositions of diniconazole in wheat in Hefei in 2006 was 1.153mg/kg; the original depositions in 2007 was 0.709mg/kg; the dissipation halflives of diniconazole in wheat in Hefei in 2006 and 2007 were 7.10 days and 6.77 days, respectively.The original depositions of diniconazole in soil were 1.847mg/kg, 1.355mg/kg, respectively, and the dissipation half-lives were 13.03 days and 11.97 days respectively, in Hefei during 2006 and 2007.Six bacteria named 1#,2#,3#,4#,5#,6# which can utilize diniconazole as sole carbon source were isolated from activated sludge collected from sewage-treating system of pesticide factory,then, the optimal degradation conditions on diniconazole of these bacteriums were studied. The results showed that six bacteria all were aerobiosis. The degradation efficiency to diniconazole of 1#,3#,4#,6# could reach above 30% and 1# was predominant bacterium. The optimum temperature, pH, bacteria mutterlauge and diniconazole initial concentration for degradation of diniconazole by the 1# were 30～35℃, 7.0, 10% of 0.404mg/L and 30mg/L, respectively. 78.14%of the diniconazole was degraded in 6 days shaking at speed of 150 r/min and at above-mentioned optimal conditions. The degradation effect of this superior bacterium named 1# was better than mixed bacteria. In the above optimum conditions, diniconazole (50 mg/L) was added to the culture fluid and fermented for 0 days,6 days,10 days respectively.The biodegradation products were extracted respectively,and were measured by GC-MS.The results showed that the biodegradation products were innocuous matters, such as CO2 and H2O. These result may offer basic data and reference to disposing diniconazole in waste water.