Photolysis of the insecticide imidacloprid in water and water-paddy soil systems

살충제 imidacloprid의 물 및 물-토양계 중 광분해

  • Ihm, Yang-Bin (Pesticide Safety Division, National Institute of Agricultural Science & Technology) ;
  • Kyung, Kee-Sung (Hazardous Substances Division, National Institute of Agricultural Science & Technology) ;
  • Kim, Chan-Sub (Pesticide Safety Division, National Institute of Agricultural Science & Technology) ;
  • Choi, Byeong-Ryeol (Agricultural Pests Division, National Institute of Agricultural Science & Technology) ;
  • Hong, Soo-Myung (Rural Developement Administration) ;
  • Lee, Jae-Koo (Department of Agricultural Chemistry, College of Agriculture, Chungbuk National University)
  • 임양빈 (농업과학기술원 농약평가과) ;
  • 경기성 (농업과학기술원 유해물질과) ;
  • 김찬섭 (농업과학기술원 농약평가과) ;
  • 최병렬 (농업과학기술원 농업해충과) ;
  • 홍수명 (농촌진흥청) ;
  • 이재구 (충북대학교 농화학과)
  • Published : 2004.03.30

Abstract

To elucidate the photolysis characteristics of the insecticide imidacloprid in the environment, $[^{14}C]$imidacloprid was treated into water and paddy soil-water system. In water system, the amount of $^{14}C$-radioactivity distributed in aqueous phase was rapidly increased up to 80% of total $^{14}C$ in water during 7 days of exposure to sunlight. Also, the amounts of imidacloprid in water at day 0 and 3 days after treatment were 1.2461 and 0.8594 mg/kg, respectively, not being detected 7 days after treatment, indicating rapid degradation of imidacloprid in water by sunlight. One photodegradation product, imidacloprid urea, in which the $N-NO_2$ moiety of imidacloprid was replaced by oxygen, was detected from water in water and water-paddy systems. The amount of the metabolite detected from water in water system was 0.0112 mg/kg 1 day after treatment and reached the top concentration of 0.0391 mg/kg 7 days after treatment. In case of water-paddy system, its amount was 0.0117 mg/kg 1 day after treatment and reached the highest concentration of 0.0259 mg/kg 3 days after treatment. Rapid transformation of imidacloprid into polar compounds continued until 7 days after treatment, considering that 80% of $^{14}C$ in water distributed in aqueous phase 7 days after treatment, amount of imidacloprid was 1.6538 mg/kg at day 0 and 0.8785 mg/kg 1 day after treatment, not being detected after 15 days, indicating rapid degradation of imidacloprid in water-paddy soil system by sunlight. The direct degradation of imidacloprid to imidacloprid urea would be a major photodegradation pathway in water and water-paddy soil systems.

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