Occurrence, sources and degradation of diuron, irgarol 1051 and fenitrothion in water, sediments, plankton and fishes of coastal sea and river waters, Japan

In this study Diuron (3-[3,4-dichlorophenyl]-1,1-dimethylurea), Irgarol 1051 (2-[tert-butylamino]-4-[cyclopropylamino]-6-[methylthio]-1,3,5-tri a zine) and Fenitrothion (O,O-Dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate) were monitored in Kurose River water (Japan) to assess the contribution of agriculture and urban activities to rive pollution. Duiron, Irgarol 1051 and Fenitrothion were also analyzed in marine samples (water, sediments, plankton and fishes) so as to assess the distribution pattern of these pesticides in Seto Inland Sea (Japan). Lastly, biodegradation and photodegradation of these pesticides was done. Using data in this study and literature information, the mass distribution of the pesticides in Seto Inland Sea were modelled. Chapter 1 presents a general overview of pesticide use, contamination and some of the studies that have been done in Japan. This study mainly aimed at assessing contamination of pesticides in river water and the marine environment. The use of pesticides in agriculture and the urban environment leads to contamination of surface water bodies like rivers. The rivers in turn end up contaminating larger surface water bodies. Therefore in this study water samples were first collected from Kurose River which drains into Seto Inland Sea and Diuron, Irgarol 1051 and Fenitrothion were analyzed. Next seawater, sediments, plankton and fishes were analyzed to identify the distribution pattern in marine samples. The persistence of these pesticides was assessed through biodegradation and photodegradation before using modelling to predict the distribution pattern of the pesticides. Chapter 2 presents a study that was conducted on the pesticides Diuron, Irgarol 1051 and Fenitrothion in Kurose River water from January to December, 2013 at six sites (Namitakiji, Tokumasa, Izumi, Ochiai, Hinotsume and Kurose Bunka Centre) in Higashi Hiroshima City, Japan for a period of one year to assess the contribution of agliculture and urban activities to pesticide pollution of the river. The maximum pesticide concentrations were; 4620 ngL super(-1), 50 ngL super(-1) and 370 ngL super(-1) for Diuron, Irgarol 1051 and Fenitrothion, respectively. While Diuron and Fenitrothion were detected at all sites, Irgarol 1051 was only present at Izumi, a high density urban and industrial area which also registered the highest concentrations of the pesticides. The pattern showed by Diuron and Fenitrothion was linked to farming activities. Also, Diuron and