Emerging pollutants in reclaimed and surface waters in Tunisia: Occurrence of pharmaceuticals, biocides, and industrial compounds
Résumé
Pharmaceuticals compounds, personal care products, and industrial chemicals in addition to their metabolites belong to the group of emerging contaminants (ECs) frequently detected in effluents discharged in the receiving environment, thus contaminating surface waters and causing potential ecological and human health disruptions. In case of reuse of reclaimed water for irrigation or aquifer recharge, some ECs may contaminate the soil and the ground water. In Tunisia, very few research work exist on the occurrence of ECs in reclaimed and surface waters. The objective of this study is to investigate the existence of some pharmaceuticals (ibuprofene, ketoprofene, naproxene and dichlophenac, trimethoprim and sulphamethoxazole, furosemide, fenofibric acid, benzafibrate and gemfibrozil, atenolol and metoprolol and carbamazepine) as parent compounds, and transformation products (o-desmethyl-naproxene, 1-OH-ibuprofene, 2-OH-ibuprofene), biocides (trichlocarban and triclosan), and industrial compounds, (parabens, benzotriazoles, bisphenol A) and caffeine in reclaimed waters reused for irrigation and for aquifer recharge, and surface water in Tunisia. Water samples were taken from 3 sites: i) Nabeul (effluents from WTP and storage basin used for agricultural irrigation), ii) Korba (effluents from WTP and from infiltration basins used for aquifer recharge), and iii) Meliane River (estuary, discharge point of effluent). The results demonstrate the presence of ibuprofene and its metabolite 2-OH-ibuprofene, diclofenac, oxazepam, atenolol, sulphamethoxazole and carbamazepine in all samples with the highest concentrations at the discharge point of the WTP in the river (1770 ng/L for atenolol). Concentrations in effluents and in water from storage basin were rather similar indicating their likely persistence. Naproxene, trimethoprim, fenofibric acid, ketoprofene and 1-OH-ibuprofene were detected at the discharge point in the river, the effluent and the storage basin in Nabeul. In the latter, the concentrations were lower than in the effluent indicating either dilution or degradation. Except o-desmethyl-naproxene, benzafibrate and gemfibrozil, all other pharmaceuticals as well as methylparabene, propylparabene, tolyltriazoles, bisphenol A, trichlocarban, triclosan and caffeine were detected in the river water samples at concentrations ranging between 12 ng/L (trimethoprim) and 20,000 ng/L (caffeine). These results show that effluents represent important point and diffuse source for ECs in river water in Tunisia. During reuse (irrigation or aquifer recharge) detected ECs will be discharged onto soil and may infiltrate to groundwater, if not degraded in the meantime. Therefore studies are needed to know the fate of ECs in soil and aquifer and to evaluate their risks.