Study On Photolysis And Leaching Rule Of Chlorothalonil In Soil

Pesticides in the soil degradation rate of speed, and impact of persistent pesticides in the environment, the effectiveness and dangers. In recent years, more and more injury problems caused by pesticide residues, resulting in huge economic losses, have also seriously affected the health of consumers. Summer into the rainy season as rainwater leaching of pesticides in the soil there will be a considerable amount of water into the groundwater, threatening the safety of water.Photodegradation of pesticides in the soil to identify the factors that affect pesticide degradation in soil, provide a theoretical basis for the remediation of polluted soil, and possible pesticide residues in the soil to a minimum;study of pesticides from soil leaching to the water phase concentration variation is to provide a theoretical reference to the contaminated area groundwater monitoring in order to protect the safety of water.This article selection of fungicide chlorothalonil for pesticide pollution characteristics as representative, the law of the photolysis and leaching in the soil, photolysis experiment the following conclusions:(1) light source, the photolysis rate constants and half-life of chlorothalonil also significantly different. High pressure mercury lamp of the photolysis rate constant, the shortest half-life, and its rate constant is5.41times and2.82times under sunlight and UV light exposure to sunlight photolysis rate constant minimum.(2) had a greater influence of temperature on the degradation of chlorothalonil. With increasing temperature in the high-pressure mercury lamp irradiation, the light of chlorothalonil degradation rate constant increased significantly, by10℃1.54x10-2h,-1increased to40℃8.62x10-2·h-1, the photolysis half-life shortened from45h to7.8h.(3) soil pH chlorothalonil photolysis. High pressure mercury lamp irradiation, chlorothalonil photodegradation in soil pH of11the rate constant of7.81x10-2·h-1for7.9h half-life of the shortest in the soil at pH4and7photolysis slower half-life of15.2h and14.3h, respectively. Visible, the alkaline conditions more conducive to the photolysis of chlorothalonil in the photolysis of alkaline soils was significantly faster than the acid and neutral soils.(4) soil moisture have a significant impact on the degradation of chlorothalonil., With the increase in soil moisture in the high-pressure mercury lamp irradiation, the photolysis of chlorothalonil in soil accelerated noticeably, half-life reduced to30%by the water content of 10%14.2h7.2h, shortened nearly times.The leaching experiment the following conclusions:(1) use a different pH value of leaching solution, leaching of chlorothalonil are quite different. Chlorothalonil leaching decreases with the increase of pH. Residues in the soil is just the opposite, showing features increase with the pH value increases, and most of the distribution in the upper soil layer.(2) the type of leaching solution on the leaching of chlorothalonil in the soil has a certain influence. The content of the soil solution from soil leaching of chlorothalonil is less than the amount of distilled water as the leaching solution, leaching out, but the difference is not great.(3) continuous leaching, the leaching speed increases, the leaching of chlorothalonil also significantly increased. Intermittent leaching, leaching, and the longer intermittent leaching of chlorothalonil is the less. Overall, the continuous leaching of chlorothalonil leaching was significantly higher than the intermittent leaching.(4) The amount of organic matter to add the higher the leaching of chlorothalonil is low, the two were negatively correlated. Chlorothalonil in the soil residue distribution is just the opposite, the higher the amount of organic matter to add more of chlorothalonil residues in the soil.