Distribution, seasonal pattern, flux and contamination source of pesticides and nonylphenol residues in Kurose River water, Higashi-Hiroshima, Japan

Distributions, seasonal variation, flux and contamination source of pesticides and nonylphenol were examined during the period from April 2001 to January 2002 at 5 sites (Namitakiji, Tokumasa-Kami, Izumi, Ochiai and Hinotsume) in Kurose River water, Higashi-Hiroshima, Japan. Water samples were collected monthly and subjected to solid phase extraction followed by GC-MS analysis. Nineteen pesticide compounds were detected and isoprothiolane (37 ng/l), fenitrothion (35) and iprodione (34) showed the highest mean concentrations (as 5 site averages), while pencycuron (5), diazinon (6), tolclofos-methyl (7) and dithiopyr (8) were the compounds of lowest mean concentrations. Nonylphenol, which is a degradation product of a nonylphenolpolyethoxylates that are used in a wide range of industrial and household products, had an average concentration of 305 ng/l. At each of the five sites, its concentration was greater than individual pesticides. The concentration levels of pesticides and nonylphenol were highest at Izumi (the downtown site of Higashi-Hiroshima) and were lowest at Namitakiji and Tokumasa-Kami (upstream sites). Concentrations and fluxes of both compounds tended to be higher during spring to summer and low during fall to winter at most of the sites. The total pesticides concentration was poorly correlated with nonylphenol concentration. A statistical analysis of water quality data suggested that their main sources appear to be different such as agricultural activity for pesticides and waste water discharge for nonylphenol.