Occurrence and fate of linear and branched alkylbenzenesulfonates and their metabolites in surface waters in the Philippines

Laguna de Bay in the Philippines is one of the largest freshwater lakes in Asia and is considered a primary source of drinking water, but also receive s daily discharges of effluent from both domestic and industrial activities . Branched alkylbenzenesulfonates (ABS), which were banned in Europe and wi thdrawn from the market in the U.S. since the mid-1960s, but not in Southea st Asia, and linear alkylbenzenesulfonates (LAS) are anionic surfactants us ed in detergent formulations and are therefore main components of effluent discharges. The presence of both LAS and ABS in several water streams in th e catchment area of Laguna de Bay was determined using liquid chromatograph y-mass spectrometry (LC-MS). The concentration levels of LAS (1.2-73 and 2. 2-102 mug l(-1)) and ABS (1.1-75 and 1-66 mug l(-1)) in some tributaries of Laguna de Bay and its outlet (Pasig River) to Manila Bay were assessed in December 1999 and March 2000, respectively. The LAS/ABS ratio was calculate d as an indication of the extent of the distribution and fate of these surf actants in the surface water. The nearer the location to the metropolitan a rea of Manila, the higher the levels of LAS and ABS detected in the waters. Moreover, the extent of biodegradation was investigated by monitoring thei r alkyl homologue distribution and the presence of sulfophenylcarboxylate ( SPC) metabolites. Similarly, differences in the levels of SPC and the homol ogues were apparent at the different sampling points. Presumably, even the quite recalcitrant ABS form SPCs under the conditions present in Southeast Asia. Since wastewater treatment facilities are not well established in dev eloping countries like the Philippines, the call for the use of environment ally friendly chemicals is of even higher significance. (C) 2001 Elsevier S cience B.V. All rights reserved.