Vertical distribution of pharmaceuticals in lake sediments-citalopram as potential chemomarker

The use of pharmaceuticals has increased enormously over the last few decades and serious concerns about their environmental fate and effects have arisen. Thus far, there is little knowledge about the historical pollution of the environment by pharmaceuticals. In the present study, sediment columns from three lake sites adjacent to wastewater treatment plants were collected, further divided in 2- or 2.5-cm slices, and analyzed for 15 pharmaceuticals by liquid chromatography-tandem mass spectrometry. In addition, sediment columns were historically interpreted by analyzing fecal sterols (coprostanol and cholesterol) as well as organic material and organic carbon. Several pharmaceuticals were detected in sediments, the most abundant being citalopram, bisoprolol, and propranolol. At site A, pharmaceuticals prevailed only in the uppermost 15 cm, whereas at site B they existed in the whole sediment column (0-30 cm). Pharmaceuticals were not found in site C sediments. Based on the sterol analyses, municipal wastewater contamination at sites A, B, and C was found in the uppermost 15, 30, and 20 cm, respectively. For the first time, contamination of sediments by pharmaceuticals was demonstrated below the subsurface (up to a depth of 30 cm). When considering the consumption and the observed concentration profiles of pharmaceuticals, a clear increasing trend of citalopram toward the surface was evident at site A.