Chemistry Behavior Of Triadimefon In Aquatic Environment

Bactericide triadimefon {1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl) butanone} is being popularized to use all over the world today,but very little information is available about its behaviors in aquatic biology.In order to comprehensively evaluate environmental security of triadimefon and for its reasonably application and ecological environmental restoration,the chemistry behaviors that include the photolysis and hydrolysis of triadimefon in aquatic environment were studied,the influence factors were also referred to.The main conclusion obtained were listed as follows.Chapter one was introduction,in which the basic concepts,theories and current advances were reviewed briefly on photolysis,hydrolysis and toxicity to aquatic biology of pesticides.In addition,research advance of triadimefon was summarized concisely.The contents and significances of this research was also included in this chapter.In the chapter two the photolysis of triadimefon in aqueous solutions and organic solvents was studied under the sunlight and HPML.The results showed that:(1) The photodegradation kinetics were strongly dependent on the solvent and on the irradiation wavelength.Triadimefon was stable in organic and aquatic solutions under sunlight.After kept in sunlight for 50h,the photolytic rate was 6.1 %,5.8%,4.7% and 3.0% ,respectively.However,the photolytic rate of triadimefon was very high under HPML.The photolytic rates of traidimefon in different solutions showed following sequences: pure water>acetone>methanol>hexane,and the photolytic half life was 34.15min,46.21min,60.27min and 79.67min,respectively. (2) The photolytic rate was negatively correlated to the dosage in aquatic solution,that is ,the more the dosage,the lower the photolytic rate.In addition,when the original dosage was fixed,the concentration of triadimefon was gradually falling with the passing time,but the photolytic rate became large then inclined to calm down.(3)The photolytic rates of triadimefon in different lamp-house and medium showed following sequences: quartz cuvette + HPML>glass cuvette + HPML >quartz cuvette + sunlight>glass cuvette + sunlight>darkroom.(4) It was considered that acetone was a kind of photosensitive substance to photolysis of triadimefon and the photosensitize rate was found distinctly related to quantity of acetone, and the dissolved oxygen had an important effect on photooxidation of triadimefon.(5) The photolytic rates of traidimefon in different aquatic solutions showed following sequences:pure water>well water>river water>pond water.The photolytic half life was 34.15,38.09,42.52 and 49.87min,respectively. The results agreed with the higher degradation quantum yields of triadimefon obtained in aqueous solution and confirmed that themain degradation pathways were solvent dependent.Direct photoreaction was an important dissipation pathway of triadimefon in natural water systems.The water content which included dissolved organic and inorganic matrix affected the behavior of triadimefon in different natural water systems.Chapter three was the chemistry degradation of triadimefon in aquatic environment.Results were observed as follow:(l)Hydrolysis of triadimefon in the buffer solutions of pH5,6,7,8,9 can be described by the first-order kinetics equation.Hydrolysis of triadimefon increased with the increasing pH value of the solution,and its hydrolysis half life in the buffer solutions was 288.81,13.81,5.71,2.12 and 1.36d,respectively,suggesting that triadimefon was stable in acid water and its hydrolysis easily took place in basic water. (2)The higher temperture was helpful for the hydrolysis process.When the pH value was 6,7 and 8,the activation energy of hydrolysis for triadimefon was 85.65,79.53 and 74.70kJ/mol,respectively.When the pH value was 9, the temperature coefficient was 2.6. The activation energy(Ea) and activation enthalpy(AH) had no visible relation with the temperature,but the activation entropy(AS) increased with the increasing temperature,and the mean activation entropy was -20.29kJ/mol-K.(3) The degradation of triadimefon in simulated aquatic environment was similar to that in buffer solution.The hydrolytic half life of the four treatment was 5.30,6.21,1.14 and 1.58d,respectively.In short,the hydrolytic rate of triadimefon in natural solution was larger than that in distilled water.In the chapter four,the determination method of chlorophyll a in the experiment of duckweed growth inhibiton was optimized.Moreover, a static experiment was made to probe into the union toxicity of fungicide triadimefon and cadmium(Cd2+) to assess the eco-environment effect and toxicity correctly. The results indicated:(l)The optimum method was as follows.First,the sample was added 25mL compound solution which consisted of acetone and ethanol,then extracted by ultrasonic for 5 min .Finally,the quantity of chlorophyll a was determined by spectrophotometer.The optimum method was more timesaving,simple and the obtaining rate was more great than the traditional method of Arnon. (2)The 96I1IC50 of triadimefon to duckweed was 5.47mg/L,and the 96hIC50 of cadmium(Cd2+) to duckweed was 1.52mg/L. The 96hlC50 of union effect to duckweed was 9.19 mg/Land the effect on concentration of chlorophyll a was heightened with the increasing concentration of xenobiotics. The S value was 2.77 and the AI was minus 1.77 which showed that the antagonistic effect was existed.In addition,triadimefon was helpful for the synthesization of chlorophyll a.When the concentration of triadimefon was 15mg/L,the content of chlorophyll a was increased by 35.19% than the check.While in the Cd treatment, the content of chlorophyll a was obviously declined than the check .The union treatment also resulted in the content of chlorophyll a of duckweed declined ,but the trend was not so obvious when contrasted...