PHARMACEUTICALS IN GROUNDWATER AS INDICATORS FOR REDOX CONDITIONS

Trace compounds in groundwater may be regarded as pollutants. However, due to their specific transport behaviour and chemical characteristics, trace compounds can also be utilized as indicators. These kinds of indicators may be applied in a wide field, e.g. to distinguish different recharge areas, to narrow the age of groundwater, and to retrieve information on chemical reactions along the flow path. The objective of this contribution is to study the redox conditions in groundwater and along the flow path using a set of different compounds, each of them different with regard to transport under specific redox conditions.

We chose different pharmaceutical compounds that have been detected regularly in groundwater world wide. These compounds are Sulfamethoxazole, Diclofenac, Ibuprofen, and Carbamazepine. These compounds were studied in the field and in laboratory soil columns. The water in the soil column was spiked with the four compounds and the specific redox conditions in the column were varied throughout the experiment.

Results show that Sulfamethoxazole was reduced under denitrifying conditions, whereas Ibuprofen was rather stable under denitrifying conditions. Diclofenac has shown to be reduced under oxidizing conditions, whereas Carbamazepine was not significantly influenced by the redox conditions. These results helped to understand previously reported occurrences and disappearances of Sulfamethoxazol and could be used - combined with the results on the transport of the other compounds - to deduce groundwater redox conditions along the flow path.