Unravelling the pollution status of the Saronikos Gulf, Greece by investigating the chemical imprint of human-related activities in seawater and sediments, utilizing high resolution mass spectrometric workflows

Comprehensive monitoring of the marine environmental status of pollution is the first step towards unravelling the chemical imprint of anthropogenic activities. The EU’s strategy towards preserving the marine environment is facilitated by enacting relevant legislation, such as the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). The EU-funded RHE-MEDiation project was launched to destress the Mediterranean Sea from chemical pollution, aiming to set the baseline of pollution close to areas considered as pollution “hotspots” and implement new technologies towards reducing the chemical impact of human-related activities onto the Mediterranean Sea.  The Saronikos Gulf, Greece is highly impacted by activities of more than half of the Greek population. It specifically receives effluents from two wastewater treatment facilities, those of Psyttalia and Thriassio, as well as chemicals related to shipping activities from the port of Piraeus and the industrial zone of Elefsina. To assess the Gulf’s pollution status, the occurrence and distribution of more than 2,300 LC-amenable organic micropollutants was investigated in seawater and sediment samples. To that end, the technique of hybrid trapped ion mass spectrometry - quadrupole time-of-flight mass spectrometry (TIMS-QTOF-MS) was utilized. Wide scope target screening was employed on a database of more than 2,300 environmentally relevant chemicals including pharmaceuticals, coffee and tobacco related compounds, illicit drugs, artificial sweeteners, industrial chemicals, PFASs, plant protection products and surfactants, along with their respective metabolites and transformation products.  Analysis results indicate the presence of polar organic compounds, such as pharmaceuticals and hydrophilic industrial chemicals in tested seawaters, a matrix to which they pose greater affinity than the non-polar sediment layer. For example, antiepileptics pregabalin and carbamazepine, along with the latter’s human consumption metabolite 10-hydroxy-carbamazepine were determined in concentrations up to 43.8ng/L, while a mixture of corrosion inhibitors 4- and 5-methyl-benzotriazole, as well as mercaptobenzothiazole were omnipresent in concentration levels ranging between 1.68 and 21.3 ng/L.  In sediments tested, a variety of compounds with higher partition coefficient (log P) values, like lipophilic antibiotics, industrial chemicals and long-chain PFASs were determined. For example, legacy PFAS like perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were determined in concentration levels ranging ​​between 1.19 and 7.85μg/kg d.w. Semi-polar sulfonamide antibiotics sulfadiazine and sulfisoxazole were determined at concentrations up to 0.378 μg/kg d.w. Their presence can be attributed to their persistent nature, considering that their administration has diminished in recent years, due to their adverse side effects on human health. Possible pathways by which hydrophobic compounds are concentrated in the sediment compartment may include repelling effects by the aqueous seawater layer, although sorption effects onto microplastics, followed by precipitation has also been reported in the literature.  This work was funded by the European Union’s HORIZON EUROPE Research and Innovation Program under Grant Agreement No: 101113045 ‘RHE-MEDiation Responsive hub for long term governance to destress the Mediterranean Sea from chemical pollution’.