Characterization and determination of lipophilic hydrocarbons in the Chao Phraya, Bang Pakong and Tha-Chin rivers and the Upper Gulf of Thailand.

Carbon tetrachloride extracts of water samples collected from the Chao Phraya, Bang Pakong and Tha-Chin rivers and the Upper Gulf of Thailand in the rainy season (1983) and dry season (1984) were studied in order to characterize and determine the lipophilic hydrocarbons. The major lipophilic organic compounds present were n-alkanes (C17-C33), dibutyl phthalate and di(2-ethylhexyl) phthalate. However, polyaromatic hydrocarbons were hardly detectable level (0.1 microgram/l by high-performance liquid chromatography). The concentrations of these lipophilic hydrocarbons were correlated with the effective rainfall content of the river. These data suggest a multiplicity of sources ranging from indigenous biological materials to petroleum activities.