三唑磷在土壤中的降解与吸附特性

三唑磷农药在江西红壤，河南二合土和东北黑土中均具易降解性，其土壤降解半衰期分别为28．3，3．75、3．28d，降解速率次序为东北黑土〉河南二合土〉江西红壤。土壤对三唑磷的吸附性能强弱次序为：河南二合土〈江西红壤〈东北黑土。其Freundich吸附常数分别为2，17．6，70．100。尽管河南二合土对三唑磷农药的吸附性弱（koc〈300）．且三唑磷的水溶解度〉30mg／kg，但由于三唑磷农药的易土壤降解性，正常施用，其对地下水的实际污染风险较小。

A Study on Degradation and Adsorption Characteristics of Triazophos in Soil

The degradation and adsorption of triazophos in three different soils were studied in laboratory in accordance with the criterion for environment safety assessment of chemical pesticides.The results have shown that triazophos can be degraded rapidly in Jiangxi red soil,Henan fluvio-aquic soil and Northeast black soil with their degradation half-time of 28.3,3.75 and 3.28 days respectively.The degradation rates are consistent with both of pH values and organic matter contents in the soils.The data of adsorbing triazophos in the above soils well fit to the empirical Freundich adsorption isotherm with the adsorption coefficient (K_d) ranged from 2.17 to 10.0.The extent of adsorbing triazophos is the most for Northeast black soil and the least for Henan fluvio-aquic soil.The soil texture is a dominant factor that affects the adsorption of triazophos,and the next is the organic matter content in the soil.The water solubility of pesticide is another important factor too.Although the adsorp- tion of triazophos in Henan fluvio-aquic soil is poor with K_(OC)<300 and triazophos solubility in water is over 30 mg/ L,however,there will be little risk of groundwater contamination by triazophos when the pesticide is applied normally due to its ready degradation in surface soil.