PROGRAMME

The Dnieper River Basin is the main freshwater resource for Ukraine. Despite being used as source for drinking water, its water quality does not always meet the environmental standards. The basin is highly affected by regional and transboundary (from western Russia and Belarus) anthropogenic pollution loads (Safranov et al. 2016). Among others, regular and thoroughly planned environmental monitoring activities contribute to water quality management and pollution control. Over the last decade, Ukraine, as a member of European Union's Eastern Partnership countries, has agreed to adapt its water legislation to EU policies (Association Agreement between the European Union and its Member States, of the one part, and Ukraine, of the other part, 2014). Apart from the EU’s priority substances that have defined environmental quality standards (EQS) (Directive 2013/39/EU), contaminants of emerging concern released in the aquatic environment may have serious impact on the ecosystem and are examined as potential candidates for future legislation (Dulio et al. 2018). Regularly, some of these emerging contaminants are included in the EU Watch Lists, so that more data on their occurrence is collected to draw conclusions on their actual risk (Commission Implementing Decision (EU) 2020/1161). The assessment of the potential risk of the detected compounds in the environment is based on Predicted No-Effect Concentrations (PNECs). In this study, a monitoring campaign to assess the chemical pollution in the Dnieper River Basin was conducted in October 2020. The campaign involved the collection of surface water samples from 27 sites of the basin including the Dnieper River, its main tributaries, canals, reservoirs and the estuary. Some sites were directly impacted by wastewater discharges, while other sites were used for the production of drinking water. Moreover, 5 sites were chosen for collection of fish samples to investigate the potential bioaccumulation of organic contaminants in freshwater organisms (biota). The presence of heavy metals in biota samples was investigated as well. Generic sample preparation protocols for surface water and biota were employed for the extraction of a broad range of medium polar to polar emerging contaminants amenable to liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis. Data was acquired through the data-independent acquisition mode (broadband collision-induced dissociation (bbCID)) in m/z range of 50-1000. Analysis data for surface water and biota samples was screened for the presence of target emerging contaminants using an in-house developed database of 2,232 compounds (Gago-Ferrero et al. 2020). The screening criteria consisted of mass accuracy ± 2 mDa, retention time shift ± 0.2 min, evaluation of isotopic patten, detection of adduct ions and in-source and bbCID MS fragment ions. Method validation for a representative subset of target compounds and compound-specific validation for quantitation of the detected compounds was performed. Further screening for more than 65,000 suspect compounds was achieved by uploading the analysis data to NORMAN Digital Sample Freezing Platform (DSFP) (Alygizakis et al. 2019). Heavy metals such as Cd, Hg, Ni, Pb were determined in biota samples by ICP-MS after acidification with nitric acid, microwave digestion and dilution. Target screening revealed the presence of 161 environmental contaminants in total in surface water collected from the Dnieper River Basin. Pharmaceuticals, plant protection products and industrial chemicals were the main classes of the detected compounds. The highest frequency of detection (above 50%) was observed for the pharmaceuticals carbamazepine, fluconazole, lopinavir and the pesticides carbendazim, bentazon, terbuthylazine. The site of the Ros River (tributary of the Dnieper), where the city Bila Tserkva is located, had the highest cumulative concentration of environmental contaminants, probably impacted by the activities of nearby-located water treatment facilities. Other sites with high levels of chemical contamination were another site of the Ros River in Korsun Shevchenkivskyi, a site of the Dnieper River that receives the discharges of the wastewater treatment plant of Kiev (Bortnytsia aeration station), and a site of the Bilous River (tributary of the Dnieper) in the Chernihiv Oblast. 37 contaminants at concentration levels exceeding the EQS or lowest PNEC value were detected at least in one of the collected surface water samples. The highest exceedance was observed for the pesticides terbuthylazine, nicosulfuron, fipronil, carbendazim, and the pharmaceutical candesartan in surface water collected from some of the aforementioned sites. Moreover, great attention should be given to the EQS exceedance of atrazine, which is a priority substance in water (Directive 2013/39/EU), as well as to 7 detected compounds that are included in the EU Watch List 2020 (Commission Implementing Decision (EU) 2020/1161), from which fluconazole, prochloraz and tebuconazole had concentration levels exceeding the PNEC value. Furthermore, emerging contaminants with concentration above PNEC in sites used for drinking water intake must be under careful consideration. 4 organic chemicals and 2 heavy metals were detected at least in one biota sample, with the concentration levels of 4-formyl antipyrine exceeding PNEC in all samples and Hg exceeding EQS in the biota sample collected from a site of the Desna River (tributary of the Dnieper) 3 km away from the Desna Water Intake Station. Almost 400 organic compounds were tentatively identified (confidence level of 3 or above) through suspect screening by employing NORMAN DSFP, whereas the analysis data was stored in the platform for future retrospective screening. The results of this study were compared with older studies conducted in different river basins of Ukraine (the river basins of Danube (Liska et al. 2021), Dniester (Diamanti et al. 2020) and Siverskyi Donets (Nikolopoulou et al. 2021)) and the sea environment where the Dnieper ends up (the Black Sea (Slobodnik et al. 2017; Slobodnik et al. 2018)). More than half of the environmental contaminants identified in the Dnieper River Basin were detected in other Ukrainian rivers and the Black Sea as well. This comparison demonstrates an overview of the anthropogenic activities and the lifestyle in Ukraine that directly affect the ecosystem.