Three different fluorescent whitening agents (FWAs) were examined in sediment cores of Greifensee, a small lake in Switzerland. Two of these FWAs (DAS 1 and DSBP) are currently used in domestic detergents. The third one (BLS) was contained in detergents until some years ago. During sewage treatment, FWAs are only partly eliminated, and, hence, residual amounts reach the aquatic environment. They are partly associated with particles (K_d=30 - 440 L/kg) and can, therefore, settle to the bottom of surface waters. This behavior and their persistence to biodegradation allow the application of FWAs as molecular markers for domestic waste water. Total DAS 1 and DSBP inventories in the sediments of Greifensee were found to be 18 - 270 mg/m~2 and 7 - 80 mg/m~2. With increasing distance from the discharge points, FWA inventories generally decreased. A sediment profile in Greifensee collected by means of a freeze core device shows the input history of FWAs from their first use in the mid 1960s. Because the equilibrium of FWAs in lake sediments between dissolved and particulate fraction lays strongly on the particulate side, remobilization in the sedimentary core is assumed to be negligible. Thus, concentrations in a particular sediment layer can be attributed to the inputs occuring at the time of deposition.
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