Abstract
The organophosphate pesticide fenitrothion and its degradation product 3-methyl-4-nitrophenol (3M4NP), which possesses greater mutagen formation potential (MFP) than fenitrothion, were monitored. A total of 109 samples were collected from 41 sites of 12 rivers in the Tokyo metropolitan area and 71 samples were collected from 4 sites of 2 streams close to paddy fields in Kanagawa, Japan. The concentrations of fenitrothion and 3M4NP were determined by GC/MS with selected ion monitoring after solid-phase extraction and derivatization of 3M4NP with N, O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA). Both fenitrothion and 3M4NP were below 1 μg/L (0 - 0.083 μg/L of fenitrothion and 0 - 0.156 μg/L of 3M4NP) in the river water samples, whereas fenitrothion and 3M4NP reached 0.16 and 1.6 μg/L, respectively, in the stream water samples. Seasonal and areal fluctuations were also observed in the streams. Nevertheless, the maximum concentration of 3M4NP appeared in late May at all sites. Furthermore, among the samples in which fenitrothion and/or 3M4NP were detected, 3M4NP largely contributed to the potential in 56% and 67% of the river and stream samples, respectively. These results strongly support the need for simultaneous monitoring of various pesticides and their degradation products, identification of degradation products and their MFP, and characterization of their behavior in water purification processes.
