Fate of pesticides in a shallow reservoir

Abstract

Based on the horizontal and vertical distributions of pesticides in the river and the reservoir, the fates of pesticides in these systems were investigated in this study. Four pesticides, i.e., MEP, thiobencarb, BPMC and isoprothiolane had the highest concentrations among the eighteen pesticides. These pesticides in suspended components except isoprothiolane were detected not only during stormy weather days but also during dry weather days. The percent detection of pesticides in suspended component was 59.8-61.9% in MEP, 34.6-38.9% in thiobencarb and 17.0–19.0% in BPMC. However, isoprothiolane in the suspended component was undetectable. These pesticides in the suspended component have existed as a part of the suspended solids in the river, then disappeared by sedimentation during the flow of the river from the upper stream to the backwater in the reservoir. On the other hand, the pesticides in the dissolved components that flowed into the reservoir were uptaken or adsorbed by phytoplankton. Moreover, the concentrations of the less absorptive pesticides like isoprothiolane have decreased by dilution and diffusion in the reservoir.

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

“…Fenitrothion is a powerful insecticide that is widely used against many insects and crustaceans. Fenitrothion and isoporthiolane have also been detected with high frequency by other investigators in Japan (Numabe et al, 1992;Itagaki et al, 2000;Kondoh et al, 2001;Tanabe et al, 2001;Sudo et al, 2002). The pesticides with highest mean concentrations were isoprothiolane, fenitrothion and iprodione (37, 35 and 34 ng/l, respectively) (as 5 sites average), while those with lowest mean concentrations were pencycuron, diazinon, tolclofos-methyl and dithiopyr (5, 6, 7 and 8 ng/l, respectively) ( Table 4).…”

“…Target compounds were extracted from the acidified samples using an automated solid phase extraction (SPE) apparatus according to the method of Itagaki et al (2000) with some modifications. The cartridges (OASIS 60 mg Waters, Milford Ma, U.S.A.) were washed sequentially with 5 ml dichloromethane, 5 ml methanol and 5 ml Milli-Q water (Millipore.…”

“…The concentration of fenitrothion, diazinon and isoprothiolane in Seta river water were 0.006, 0.023 and 0.331 µg/l, respectively (Sudo et al, 2002). Itagaki et al (2000) reported that fenitrothion was detected with 0.008 µg/l of mean concentration in Minaga river water, while Numabe et al (1992) reported that fenitrothion concentration was 0.025 µg/l in Kozakura river water. The concentration levels of simazine (0.024 µg/l), diazinon (0.024 µg/l), fenitrothion (0.036…”

Assessment of pesticide residues in freshwater areas affected by rice paddy effluents in Southern Japan

“…Thorough searches using the databases of Thomson Scientific (2007) and GeNii (2007) Kajinashi River, Ibaraki (Tada & Hatakeyama 2000) Sakura River, Ibaraki (Ueji & Inao 2001) Kozakura River, Ibaraki (Nakano, et al 2004) Sugao Marsh, Ibaraki (Kawakami, et al 2005; Lake Kasumigaura, Ibaraki (Nohara & Iwauma 1996a;1996b) Lake Biwa, Shiga Okamura, et al 2002) Lake Kojima, Okayama (Okamura, et al 1999) Yodo River, Osaka (Yamaguchi, et al 1992) Saijo Basin, Hiroshima (Parveen, et al 2005a;2005b) Kurose River, Hiroshima (Derbalah, et al 2003) Minaga River & Minaga Reservoir, Hiroshima (Itagaki, et al 2000) Map source: http://www.craftmap.box-i.net Kagoshima (This study) Fig. 1 Study sites of most published papers on pesticide residue concentrations in freshwater areas around Japan for information regarding concentrations of pesticides in freshwater areas in southern Japan yielded negative results.…”

Photodegradation kinetics of fenitrothion in various aqueous media and its effect on steroid hormones biosynthesis

“…This process is responsible for the disappearance and the enhanced photooxidation rates of organic compounds through the production of photoreactants such as hydroxyl radicals (Mansour et al, 1999). Therefore, photodegradation studies of pesticides allow for the modeling of pesticide Nishikawa, 1995;Itagaki et al, 2000;Kondoh et al, 2001;Tanabe et al, 2001;Sudo et al, 2002). Furthermore, fenitrothion is known for its acute toxicity toward nontarget organisms and, after application, different types of degradations affect this pesticide, such as photolysis, hydrolysis and biological degradation (Lacorte and Barcelo, 1994).…”