The Occurrence of Pharmaceuticals in the River Rhine Basin

Over the last decade, various studies have investigated pharmaceuticals in surface waters. Most of these studies use a limited number of samples in time and space, which does not enable to reveal spatial and temporal trends. The current study uses an exceptionally large dataset, 48 to 127 pharmaceuticals were monitored at 7 sampling locations along the river Rhine in Suisse, Germany and the Netherlands between 2002 and 2008. The data were used to reveal both temporal trends and spatial variations in concentrations of pharmaceuticals over the course of the river Rhine. Additionally, concentrations were compared to the consumption in the Rhine catchment area.

The monitoring data reveal that concentrations of pharmaceuticals show rather narrow ranges that almost never exceed one order of magnitude. X-ray contrast media (e.g. Jomeprol, Jopamidol, Jopromide) showed the highest concentrations that varied between 0.1 and 0.4 µg L^-1, while concentrations of various other pharmaceuticals (e.g. Carbamazepine, Benzafibrate, Diclofenac, Ibuprofen, Pentoxifylline, Sotalol, Sulfamethoxazol) varied between 0.1 and 0.01 µg L^-1. Generally, the concentrations of the pharmaceuticals slightly increased or remained stable over the course of the Rhine. Furthermore most pharmaceuticals did not show temporal trends, except for Carbamazepine and Diclofenac that significantly decreased, and three X-ray contrast media (Amidotrzoic acid Johexol and Jomeprol) that significantly increased between 2002 and 2008. Additionally, concentrations were used to calculate the loads of the Rhine each year. These loads are compared to amounts consumed in the catchment area. It was observed that 1 – 17 % of the amount consumed in the catchment area could be recovered in the Rhine. This illustrates that metabolism by consumers and the removal at waste water treatment plants is rather limited for some pharmaceuticals.