VOLATILE ORGANIC-COMPOUNDS IN URBAN RIVERS AND THEIR ESTUARIES IN OSAKA, JAPAN

The levels and distribution of 55 volatile organic compounds (VOCs) we re determined by purge and trap GC-MS on water samples from 30 sites w ithin the urban rivers and estuaries of Osaka, a populated industriali zed city of Japan. Forty of 55 target VOCs listed in the US EPA Method 524.2 were detected. Dichloromethane (DCM) was found at higher levels at all of the sampling sites. The distribution of dominant VOCs follo wed four different patterns. First, the most common VOCs (DCM, toluene , trichloroethene and tetrachloroethene) showed concentration maxima i n the river segments, and the sites of maximum concentration fluctuate d due to irregular large spills and/or loadings. Second, one VOC (cis- 1,2-dichloroethene) was evenly distributed in particular rivers due to fixed loadings. Both of these patterns were found in the upper and mi ddle reaches. Third, some of VOCs (1,2,3-trichloropropane and benzene) were specific to a single industrial site and truceable to those sour ces. Finally, some VOCs showed no concentration maxima along the river s and entered from multiple sources (chloroform and bromadichlorometha ne). Diurnal variations of VOCs at the border of the city area, receiv ing domestic and industrial discharges, provided information to interp ret their observed downstream distribution and possible sources. (C) 1 997 Elsevier Science Ltd.