Occurrence of carbamazepine and five metabolites in an urban aquifer

• Urban groundwater (GW) contaminated by carbamazepine (CBZ) and 5 metabolites (MET).
• High concentrations are found when the aquifer is infiltrated by a polluted river.
• The fate of CBZ and METs appeared to be dependent on the GW redox conditions.
• Residence time could also play a major role in controlling their fate in aquifers.

This paper deals with urban groundwater contaminated with carbamazepine (CBZ) and five of its human metabolites in Barcelona. Groundwater samples were accordingly collected in the aquifers of Poble Sec and Besòs River Delta. Higher concentrations and more compounds were found in the Besòs River Delta aquifer, which is recharged by a river contaminated with treated effluent from numerous treatment plants. By contrast, the urban area of Poble Sec presented lower concentrations and fewer compounds. The results showed that CBZ could be attenuated in the Poble Sec aquifer since concentrations in groundwater were lower than those evaluated from mixing of the recharge sources. Conversely, CBZ and its human metabolites were not removed under the reducing conditions of the Besòs River Delta aquifer probably because of the short residence time in this aquifer.