Abstract
Pesticides which include Diuron, Irgarol 1051 and Fenitrothion are toxic to non-target organisms as such their destruction is important for ecosystem safety. In this study photodegradation and biodegradation were conducted on Diuron, Irgarol 1051 and Fenitrothion apart from analysing their concentrations in Kurose River and the Seto Inland Sea, Japan. Data generated and further information from literature were used to predict their fate in Seto Inland Sea. Photodegradation was done by a solar simulator with samples removed at regular intervals for HPLC (equipped with UV-Vis detector, model SPD-10AV Shimadzu) analysis. Biodegradation was done by incubating samples in a Biotron incubator at 21 degrees Celcius for 3 months and samples were removed every 10 days for HPLC analysis. Also river and marine samples (water, sediments, plankton and fishes) were prepared for HPLC analysis by solid phase extraction (SPE). Biodegradation half-lives were longer than those of photodegradation. Also seawater half-lives were significantly higher (p < 0.05) than those of river water. Degradation pattern was Fenitrothion > Diuron > Irgarol 1051. In both river water and seawater samples, Diuron concentrations were highest. In river water it was attributed to high amounts used to control weeds while as in seawater it was due to huge quantities used in antifouling paints. Estimations of pesticide fate showed that ? 74% of the pesticide input amounts in Seto Inland Sea are lost to sediments while as the open ocean is an equally important sink.
