TRACING DOWN PHARMACEUTICALS IN UNSATURATED ZONE

Pharmaceutically active substances and metabolites are found at concentrations up to the microgram/L-level in groundwater samples from the Berlin (Germany) area and from several other locations world wide. Among the compounds detected in groundwater are clofibric acid (blood lipid regulator), propyphenazone (analgesic), diclofenac (anti-inflammatory), ibuprofen (anti-inflammatory), and carbamazepine (antiepileptic). Pharmaceuticals are measured up to the mg/L range in surface and groundwater. However, concentrations detected in groundwater are generally much lower. Among the most important input paths of drugs are excretion and disposal into the sewage system. Groundwater contamination is likely to be due to leaky sewage systems, influent streams, bank filtration, and irrigation with effluent water from sewage treatment plants. There are no known natural sources of the above mentioned pharmaceuticals. The sewage irrigation plants south of Berlin were in operation for 100 years. After cessation of sewage irrigation several pharmaceuticals commonly found in groundwater were analyzed but only very few were detected. Interestingly, only clofibric acid, primidone and propyphenazone were detected. Experiments in the laboratory were conducted using sediment material from the Berlin area and artificial sewage effluent to evaluate the transport and sorption behavior of selected drugs in the unsaturated zone under conditions comparable to waste water reuse conditions. Results of the column experiments show that clofibric acid exhibits no degradation and almost no retardation (Rf = 1.1) whereas ibuprofen is almost completely biodegraded under aerobic conditions. Diclofenac shows quite high retardation at lower pH values indicating that most of Diclofenac at the sewage irrigation farms was sorbed in the unsaturated zone. Carbamazepine shows no degradation in the soil column experiments but significant retardation under the prevailing conditions. We conclude that clofibric acid will show the transport behavior of a conservative tracer, whereas diclofenac and ibuprofen are either sorbed or degraded in the unsaturated zone.