三唑磷农药在土壤中的降解与吸附特性研究

Degradation and Adsorption Characteristics of Triazophos in Soils

采用室内模拟试验方法,研究了三唑磷在3种不同类型土壤中的降解特性、吸附特性及其影响因素,分析了该农药对地下水的污染风险性。结果表明,三唑磷在江西红壤、河南二合土和东北黑土等3种土壤中的降解半衰期分别为28.3、3.75和3.28d,降解速率依次为东北黑土>河南二合土>江西红壤,均具易降解性。3种土壤对三唑磷的吸附常数Kf分别为10.0、2.17、6.70,河南二合土对三唑磷的吸附性最弱。对于三唑磷农药,影响土壤吸附性的主要因素为土壤质地,其次为土壤有机质,此外,水溶解度也是重要因素。综合考虑农药水溶解度、土壤降解与土壤吸附特性,正常施用,三唑磷母体进入地下水造成污染的风险较小。

The degradation and adsorption of triazophos in three different soils were studied in laboratory in accordance with the criterion for chemical pesticide environment safety assessment, The results showed that triazophos was degraded rapidly in Jiangxi red soil, Henan fluvioaquic soil and Northeast black soil. Half-time of triazophos degradation were 28.3, 3.75 and 3.28 d in the three different soils respectively. The degradation rate was in the order： Northeast black soil〉Henan fluvio-aquic soil〉 Jiangxi red soil, which was consistent with both of the pH and contents of soil organic matters. The adsorption data of triazophos in the above soils were better fitted by the empirical Freundich adsorption isotherm, with the adsorption constant （K：）ranged from 2.17 tol0.0. The extent of triazophos adsorbed by soils followed： Northeast black soil〉 Jiangxi red soil 〉 Henan fluvio-aquic soil. The soil texture was the dominant factor which affected the adsorption of tfiazophos in soils, next was the soil organic matter content. Besides, the water solubility of pesticide was the important factor too. There was few risk to groundwater polluted by triazophos when the pesticide was used normally due to its rapid degradation in surface soil, although adsorption of triazophos in Henan fluvio-aquic soil was poor with Koc〈300 and triazophos＂ solubility in water was more than 30 mg. L^-1.