Column experiments on the transport behavior of pharmaceutically active compounds in the saturated zone

In recent years, a number of pharmaceutical residues have been detected in surface water, groundwater, and even in drinking water. Laboratory column experiments with disturbed samples of aquifer material (median grained sand) have been conducted to obtain information about the transport behavior of selected pharmaceutically active substances (carbamazepine, clofibric acid, diclofenac, ibuprofen, propyphenazone) in the saturated zone. During a testing period of ten days the pharmaceutically active compounds were added to test water, which was natural groundwater from the same aquifer, and changes of their concentrations were observed at the outflow of the column. The transport behavior of the substances was independent of pH, temperature, oxygen content, and the concentration of groundwater constituents. Compared to the tracer lithium, a retardation factor (R-d) of 2.8 was observed for carbamazepine which was the most strongly retarded substance of all the test compounds. For ibuprofen the retardation factor of 4.0 could only be estimated because of the low concentration ratio (C/C-0 = 0.45) measured in the lab experiment. While the drugs diclofenac (R-d = 2.6) and propyphenazone (R-d = 2.0) were transported more slowly than lithium, a retardation factor of 1.1 was found for the metabolite clofibric acid. The transport behavior of the observed drugs is characterized by different sorption and degradation processes. Ibuprofen was degraded whereas under aerobic conditions no or only low degradation was observed for carbamazepine (C/C-0 = 0.85) and diclofenac (C/C-0 = 0.88), and no degradation was found for propyphenazone (C/C-0 = 1.0). Clofibric acid was not influenced by sorption or degradation processes.