Fate of Fluorescent Whitening Agents in the River Glatt
With the use of computer simulation (AQUASIM), the dynamic behavior of the two fluorescent whitening agents (FWAs) that are currently used in laundry detergents in Switzerland (DSBP, a distyrylbiphenyl, and DAS 1, a diaminostilbene) has been evaluated quantitatively for the River Glatt, a small highly polluted stream in Switzerland. The one-dimensional simulation was based on independently determined photolysis and sorption rate constants, and measured FWA concentrations at the beginning of the studied river section and in two major tributaries (effluents of sewage treatment plants). Concentrations of FWAs were 0.4−1.2 μg/L in river water and 2.9−5.7 μg/L in sewage, respectively, with very little diurnal variation. Direct photolysis and partitioning between aqueous phase and sediment and macrophytes were identified as the most important processes affecting the fate of DSBP and DAS 1 in the river. Simulation of FWA concentrations with photolysis as the only process yielded concentration traces with minima ...