除草劑伏寄普在茶園土壤中的消散

許渭鑫     王一雄     顏瑞泓^*

 國立台灣大學農業化學系

摘要

本研究探討在四種茶園土壤中，除草劑伏寄普(Fluazifop-butyl)在土壤-水系統中的等溫吸附係數及在不同溫度與含水量下在土壤中的降解以及在土壤管柱中的移動；並利用BAM模式與GWP模式模擬，以瞭解除草劑伏寄普施用於茶園後，在環境中之分佈及命運。由實驗結果得知，伏寄普在土壤-水系統中的等溫吸附線主要依循Freundlich方程式，提高溫度會使土壤對伏寄普的吸附能力增強。伏寄普在土壤中的降解速率隨溫度提高而加快，但與水分含量關係不明顯。在40℃處理下，此一殺草劑一天內就已經降解超過50%，分解速率相當快速。在田間處理(25℃及60%飽和含水量)下，伏寄普的半衰期為0.2~2天。在土壤管柱實驗中，伏寄普僅能在管柱頂端0~6 cm處偵測到殘留，淋洗過程中淋洗液中都沒有偵測到殘留。由BAM模式模擬結果發現，伏寄普皆僅殘留於土層深度0~2 cm處。由GWP模式模擬結果發現，伏寄普在四種茶園土壤中都不會對地下水造成污染，此與管柱移動實驗結果相符。以實驗結果推論，伏寄普雖然容易受土壤吸附，但因在土壤中極不安定，因此並不易造成污染。所以用於茶園雜草防治，伏寄普不易造成環境污染。

 關鍵詞: 消散，除草劑，伏寄普，茶園

The dissipation of fluazifop-butyl in tea garden soils

Wey-Shin Sheu, Yei-Shung Wang, Jui-Hung Yen^*

Department of Agricultural Chemistry, Nation Taiwan University, Taipei, Taiwan

ABSTRACT

        Fluazifop-butyl has been recommended for controlling weeds in tea garden in Taiwan since 1982.   In this study, experiments were designed to find out (1) the sorption isotherm, (2) the dissipation, and (3) movement of fluazifop-butyl in four different tea garden soils. The possibility of fluzaifop-butyl to contaminate groundwater was also assessed by the behavior assessment model (BAM) and groundwater pollution-potential (GWP) model.    The result shows that the sorption isotherm of fluazifop-butyl in the soils followed Freundlich equation. The relation between temperature and K_d value were not significant. Dissipation of fluazifop-butyl took place rapidly in the soils at 40°C. The T_½ of fluazifop-butyl was 0.2~2 days under 60% of water holding capacity at 25°C.   In soil column experiment, fluazifop-butyl was found to be very immobile, not detectable in the leaching liquid. Using BAM and GWP models to evaluate the possibility of this herbicide to leak into groundwater in four tea garden soils, we found the fluazifop-butyl would not contaminate groundwater under local meteorological conditions.

Key words: Dissipation, herbicide, fluazifop-butyl, tea garden