Study On Kinetics Of Three Pesticides Degradation In Chlorella Pyrenoidosa Cultures

The extensive use of pesticides, through various ways, then finally converge into the aquatic environment, resulting in water pollution to the environment. Algae due to its most live in the upper water, and the individual small short growth cycle, access to pesticides and other pollution are most sensitive. Study on the interaction of pesticide and algae as harmful pesticides on other aquatic animals and plants and the back of the food chain by instructions and avoid role. Organic pesticides are widely used in China at present, and often with the largest amount Choose the universal existence of representative organic pesticides in nature and phytoplankton, study the interaction relation in pure culture conditions, can provide a theoretical reference for the interaction between the organic pesticide and algae, to provide data support for the safety assessment of pesticides in water environment and its residue management.The acute toxicity tests of three pesticides malathion, cartap, thiamethoxam were carried out in Chlorella pyrenoidosa cultures. Algae with climate incubator laboratory pure culture, biological measurement of algae with microscope and hemacytometer, optical density by using UV spectrophotometer and refrigerated centrifuge, determination of Chlorella pyrenoidosa and chlorophyll content of algae as a reference index of algal biomass. The results showed that96h median effective concentrations (EC50) of malathion, cartap, thiamethoxam were12.0mg/1,2.51mg/1,3.27mg/1, respectively. When the pesticides were presented, growth of Chlorella pyrenoidosa was stimulated. The growth of Chlorella pyrenoidosa was relative to the coneentrations of pesticides. Results showed that the inhibition of Chlorella pyrenoidosa was stronger with pesticides in higher coneenrtations.Algae degradation of pesticides provides a new idea for the removal of residual control pollution in water environment. The degradations of three pesticides by Chlorella pyrenoidosa were also studied. Determination of algal biomass, change determination within10days of the culture flask pesticide content by high performance liquid chromatography (HPLC), analysis of its degradation, Chlorella pyrenoidosa had the capability to degrade these three pesticides. The second-order kinetic equation of these three pesticides degradations by Chlorella pyrenoidosa were summarized and described. Its half-life of hydrolysis on thiamethoxam, malathion, cartap is105.0,87.8,85.6,64.8,52.1h;141.5,78.8,55.9,38.7,24.3h;45.0,34.8,34.5,34.1,33.3h in BG-11medium. Its half-life was54.5,47.4,46.6,42.3,31.4h;31.4,30.3,26.0,24.1,22.3h;27.0,21.7,21.3,21.9,18.4h respectively.