• 作者： 陳玉麟; 杜政榮; 王一雄
• 作者服務機構： 國立臺灣大學農業化學系
• 中文摘要： 為探討氣候及土壤性質對除草劑草滅淨(Simazine)的影響，除進行田間試驗外，並在實驗室內控制溫度和水分含量，來觀察其殘留情況。 田間試驗結果顯示夏季高溫多雨，其消失速率較快，而冬季低溫少雨，其消失速率較慢。但氣候不是影響其消失速率之唯一原因，有機質含量及pH值也是影響草滅淨消失速率之重要因素。 實驗室研究草滅淨之分解速率係在三種土壤質地中進行。在90％田間容水量之水分含量下四種不同溫度中，以及在20℃下四種不同水分含量下，顯示在溫度與草滅淨之土壤中殘留間有顯著之關係存在，而土壤水分含量與分解作用之間亦有正相關的趨勢。本研究結果顯示，方程式H=AM 配合Arrhenius equation及First-order rate law，可用來預測草滅淨在田間消失之狀況。
• 英文摘要： This study is a part of the international collaborative experiment on simazine persistence carried outin Taiwan. Field experiments with Taichung clay loam in different seasons and Taipei loam soils showed asignificant difference between climate and degradation rate. Simazine had a half-life of 18 days in thesummer which is relatively hot and wet, a half-life of 24 days in the cooler and dryer winter season of theTaichung area, but in the medium temperature and medium precipitation of the autumn season of theTaipei area, the half-life was found to be 14 days. These results indicate that climate was not the onlyfactor affecting degradation of simazine, but soil properties may also be related to the degradation rate.The residual data from field experiments also showed that the kinetic model bases on the hyperbolic ratelaw describes the degradation rate of this herbicide in the field better than first-order kinetics. Laboratory studies of degradation rates performed with 4 different temperatures at soil moisturecontent of 90% field capacity and 4 different soil moisture contents at 20℃ on 3 types of soil texture,loam ,clay loam and sandy loam, showed a significant relationship between the temperature and the residueof simazine in soil, and also a positive tendency was observed between soil moisture content and degrada-tion. The adsorption of simazine followed the Freundlich equation and the adsorption isotherm curve isS-type, which indicates that simazine was adsorbed with a flat orientation on the soil surface at low con-centration but was vertical at high concentrations. Degradation of simazine in the field can be predictedby using the equation H=AM ,combined with the Arrhenius equation and the first-order rate law.
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