Abstract
Psychoactive drugs are classified as contaminants of emerging concern but there is limited information on their fate in surface waters. Here, we studied the photodegradation of three psychoactive drugs (sertraline, clozapine, and citalopram) in the presence of organic matter (WEOM) extracted under mild conditions from sediment of Lake Pamvotis, Greece. Spectral characterization of WEOM confirmed its humic-like nature. Preliminary experiments using chemical probes showed that WEOM was able to produce oxidant triplet excited state (3WEOM*), singlet oxygen (1O2), and hydroxyl radicals under irradiation with simulated solar light. Then, WEOM at 5 mgC L−1 was irradiated in the presence of the three drugs. It enhanced their phototransformation by a factor of 2, 4.2, and 16 for sertraline, clozapine, and citalopram, respectively. The drastic inhibiting effect of 2-propanol (5 × 10−3 M) on the reactions demonstrated that hydroxyl radical was the key intermediate responsible for drugs photodegradation. A series of photoproducts were identified by ultra-high performance liquid chromatography (UHPLC) coupled to high resolution mass spectrometry (HR-MS). The photodegradation of the three drugs proceeded through several pathways, in particular oxidations of the rings with or without O atom inclusion, N elimination, and substitution of the halogen by OH. The formation of halogenated aromatics was observed for sertraline. To conclude, sedimental natural organic matter can significantly phototransform the studied antidepressant drugs and these reactions need to be more investigated. Finally, ecotoxicity was estimated for the three target analytes and their photoproducts, using the Ecological Structure Activity Relationships (ECOSAR) computer program.
Highlights
Psychoactive drugs are widely used to treat diseases such as depressive symptoms and social anxiety disorder
The organic matter content in Lake Pamvotis sediments was found to vary between 4.8% and
We showed that the water-soluble organic constituents of sediments are able to induce the oxidation of drugs under simulated solar light
Summary
Psychoactive drugs are widely used to treat diseases such as depressive symptoms and social anxiety disorder. The increasing consumption of these compounds in developed countries enhances the risk of environmental contamination and adverse effects on human health and habitats [1]. They enter the aquatic environment mainly through hospital effluents and wastewater treatment plants and, being poorly degradable by traditional biological processes, they are present in relative high amounts in water bodies and sediments. There is no consistent literature data on the ecotoxicity of these compounds, it has been found that acute and chronic exposure
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