Reducing PEC uncertainty in coastal zones: a case study on carbamazepine, oxcarbazepine and their metabolites.
Résumé
To assess pharmaceutical contamination in surface waters at a national and regional scale, different geo-referenced watershed models PhATETM and GREAT-ER were used. These models incorporate spatial and temporal characteristics of the receiving environment allowing more accurate and realistic PECs than those calculated according to EMEA guidelines methodology. In coastal zone, models including the diffusion are scarce; however, this interface between the land and the sea should also been affected by drugs contamination.
Thus, the aim of the present project is to propose a model to assess pharmaceuticals concentrations in a coastal zone receiving effluents from a WTP through a submarine outfall. For this purpose, pharmaceuticals, carbamazepine (Cbz), oxcarbazepine (OxCz) and their main metabolites were selected. In effluents, PECs calculation took into account in addition to the common wastewater fate, the initial Cbz and OxCz prescriptions, their metabolisms and their excretion rates. The obtained PECs results were similar to the measured concentrations (MECs) in the wastewater effluent. In the coastal zone, PECs were calculated taking into account the diffusion in the coastal zone through the submarine outfall using the hydrodynamic numeric model MARS 3D. PEC values in coastal zone were in agreement with MECs, measured using the passive
samplers polar organic chemical integrative sampler implemented around the submarine outfall. The combined approach considering both detailed local consumption of parent compounds and their human metabolisms, in association with the diffusion estimation in coastal water allowed a reliable estimation of the pharmaceutical PEC for parent compounds and metabolites. MARS 3D model allows a refined assessment of concentrations in seawater influenced by specific mechanisms occurring. It can be further applied to others molecules, including elimination half-lives.