Studies On Adsorption And Mobility Of Triadimefon In Soil And Its Effects On Soil Enzymes

The adsorption of triadimefon in four tested soils with a batch equilibrium method and leaching in soil columns were studied .The influence of triadimefon on the activity of catalase and urease in soil under different concentration and different cultivated time was also studied.The main results were summarized as following:The adsorption of triadimefon in tested soils gave an approximate fit to the Freudlich empirical equation ,the range of R2 values between 1gCs and 1gCeq, was from 0.9677-0.9926,which indicated the most distinct correlation.Adsorption was not proportional to solution concentration with a constant partitioning of triadimefon between the solution phase and the sorbent. In the isotherm equation Cs=KdCeq1/n , the range of 1/n values was 0.7753-0.9874,which also showed the degree of isotherm nonlinearity.The adsorption mainly influenced by organic and clay content,which were positively correlated with Kd values ,the R2 values respectively were 0.9364 and 0.95.But the cation was not correlated with Kd values. The average Koc values for four tested soils was 256.According to the classification of mobility of pesticide in soil ,the mobility of triadimefon in soil belonged to the medium .The quantities of triadimefon adsorbed by soil got down with the increasing tempreature.The adsorption in soil belonged to physical adsorption.under the control of 200 mm water falling through the four unsaturated soil columns during 24h,the order of the mobility of triadimefon in soil was Hechao soil >red soil >reddish yellow soil >Masha soil ,the quantities of triadimefon leached out respectively were 15. 87%, 9. 56%, 0.72%, 0.68% .Compared with unsaturated soil column, in saturated soil column,the quantities of triadimefon leached out increased 20.21%,which indicated that the mobility of triadimefon in saturated soil increased. While 200 mm stimulated acide rain falling through unsaturated soil columns, the mobility of triadimefon in soil got down As the acidity of simulated acid rain were raised, the quantities of triadimefon in leaching water decreasing 22.89% (pH was 4.5)and 34.36%(pH was 3.5) .Which indicated that the adsorption of triadimefon in soil increased with the decreasing of pH values.While under the concentration of 1 mg/kg and 5 mg/kg, The activity of catalase was inhibited by triadimefon, the term was short, only one day. As the cultivated time got long, the inhibiition got weak, showed as stimulation.The tendency of activation was "get strong -get weak". Under 50 mg/kg, the time of inhibition was as long as 20 days . The inhibition of triadimefon to urease was stronger than that of catalase. And its revive time was also very late. The time of inhibition was over 20 days. During the whole experiment, the activity of urease expressed as "inhibition -revive".Author: Zhou Anwen(Encironmental Science and Engineering) Directed by: Associated professor Guo Zhengyuan...