Keywords: nutrients, organic substances, migration of population, diffuse sources, point sources, russian aggression

The full-scale invasion of Ukraine by russian troops has caused massive population displacement. The International Organization for Migration noted that the number of officially registered internally displaced persons is 38% of the total number of refugees. The abrupt migration of population to the western regions of Ukraine has created an additional burden within the river basins. The priority migration destination was cities, while others dispersed to rural areas. In the first case, population growth led to an additional load on the municipal infrastructure and increased the impact of point sources on river ecosystems. In the second case, it has created conditions for an increasing of diffuse pollution. The results of water utilities reporting in the western regions of Ukraine (by the 2TP-Vodhosp form) indicate the rising in 2022of wastewater discharge compared to the volume in 2021. Based on the analysis of organic substances (BOD5 and COD) and nutrients (ammonium nitrogen and phosphorus), a significant increase in their content was revealed for rivers in the Vistula basin, the upper and middle parts of the Dniester basin, sub-basins of the Danube (Tisza, Prut, and Siret rivers). These substances are formed as a result of the vital activity of living organisms and are protein in nature, which makes them characteristic indicators of municipal wastewater. By calculating the mass balance, it was shown that in Lviv, the load of ammonium nitrogen increased to about 67 tons per year, and phosphorus - 31 tons per year. The relative share of the load from point sources reached 37% and 87%, respectively. The average impact of point sources due to military actions was 8.3% for nitrogen compounds and 7.5% for phosphorus compounds. Against this background, the content of nitrate nitrogen compounds, which are formed mainly by diffuse sources, decreased. Most of the small rivers in the western region of Ukraine had deviations from the 'good' ecological status. The reason for this was a small natural flow, which does not allow for effective dilution of insufficiently treated wastewater from municipal wastewater treatment plants. Among them, the Poltva River was the most polluted water body in Ukraine.

1. The destruction of the dam led to large-scale flooding in Irpin: what are the consequences. Ecopolitic.com.ua. (15.04.2022).] [in Ukrainian]. URL: https://ecopolitic.com.ua/ua/news/v-irpeni-rujnuvannya-dambi-prizvelo-do-masshtabnih-zatoplen-yaki-naslidki/

2. Interview with the director of the Demography Institute of the NASU, E.M. Libanova. 2022 URL: https://www.youtube.com/watch?v=EQSxGuh3RX8

3. Number of IDPs. gow.ua (11.05.2022). URL: https://minre.gov.ua/2022/05/11/kilkist-vnutrishno-peremishhenyh-osib-vpo-v-ukrayini-perevyshhyla-8-mln-lyudej-zvidky-j-kudy-yihaly-najbilshe/

4. Ovchinnikova Yu.Yu (Edited by). (2023). Materials of the meeting of the Verkhovna Rada Committee on Environmental Policy on the topic: «The impact of military actions on the environment in Ukraine and restoring to its natural state» (10 November 2022). Kyiv: The Verkhovna Rada Committee on Environmental Policy and Nature Management, 184 p. URL: https://uncg.org.ua/wp-content/uploads/2023/05/Materialy-slukhan-2-1-1.pdf

5. Vistula River Basin Management Plan (2025-2030). Project. URL: https://davr.gov.ua/fls18/tu/RBMP_Wisla/purb_w.pdf

6. Dniester River Basin Management Plan. Project. 2022. URL: https://davr.gov.ua/fls18/tu/RBMP_Dniester/purb_dnis.pdf

7. The Tysa River subbasin Management Plan. Project. 2022. URL:https://buvrtysa.gov.ua/newsite/wp-content/uploads/2022/12/Tysa_PURB_2-1-100.pdf

8. KMU Resolution №. 758 of September 19, 2018 'On Approval of the Procedure for State Water Monitoring.' URL: https://zakon.rada.gov.ua/laws/show/758-2018-%D0%BF#Text

9. Splodytel A., Golubtsov O., Sorokina L., Sploditel A., Chumachenko S.(2023) The impact of Russia's war against Ukraine on the soil condition of Ukraine. Analysis results - Kyiv:CO “Center for Environmental Initiatives” «Ecoaction», 32p. URL: https://ecoaction.org.ua/wp-content/uploads/2023/03/zabrudnennia-zemel-vid-rosii-summary.pdf

10. Association Agreement between Ukraine and the European Union. URL: https://zakon.rada.gov.ua/laws/show/984_011#Text

11. V.K. Khilchevskyi, O.M. Gonchar, M.R. Zabokrycka et al.(2013). The hydrochemical regime and water quality of the Dniester surface water basin in Ukraine. K.: Nika-Centre, 256 p.

12. Bin He, Shinjiro Kanae, Taikan Oki, Yukiko Hirabayashi, Yosuke Yamashiki, Kaoru Takara (2011). Assessment of global nitrogen pollution in rivers using an integrated biogeochemical modeling framework. Water Research 45 2573-2586.

13. Bridie A.L., Wolff C.J.M., Winter M. (1979). BOD and COD of some petrochemicals. Water Research. Volume 13, Issue 7, Pages 627-630. URL: https://doi.org/10.1016/0043-1354(79)90011-3

14. Djodjic F, Villa A. (2015) Distributed, high-resolution modelling of critical source areas for erosion and phosphorus losses. AMBIO 2015, 44(Suppl. 2): S241–S251. doi: 10.1007/s13280-014-0618-4.

15. European Environment Agency (23.11.2020) URL: https://www.eea.europa.eu/publications/92-9167-059-6-sum/page002.html

16. Francis, R. A. (2011). The impacts of modern warfare on freshwater ecosystems. Environ. Manage. 48, 985–999.

17. CIS Technical Guidance 28 on the Preparation of an Inventory of Emissions, Discharges and Losses of Priority and Priority Hazardous Substances. URL:https://op.europa.eu/en/publication-detail/-/publication/f80f5bdd-d3bd-4e0d-ab51-07e971dceb52.

18. Hatfield J.L. and Follett R.F. (Eds) (2008) Nitrogen in the Environment: Sources, Problems, and Management Elsevier Inc. All rights reserved. URL: https://doi.org/10.1016/B978-0-444-50486-9.X5000-6

19. Henderson-Sellers B. and Markland H. R. (1987). “Decaying Lakes: The Origins and Control of Cultural Eutrophication,” John Wiley & Sons Ltd., Hoboken.

20. Lam Q.D., Schmalz B., Fohrer N. (2010) Modeling point and diffuse source pollution of nitrate in a rural lowland catchment using the SWAT model. Agricultural Water Management 97(2):317-325. URL: https://doi.org/10.1016/j.agwat.2009.10.004

21. Osadcha N., Luzovitska Yu, Ukhan O. et al (2022). Methodology for assessing the surface water pollution by nutrients. Ukrainian Geographical Journal 2022 (4) 37-48. DOI: https://doi.org/10.15407/ugz2022.04.037.

22. OSPAR Guidelines for Harmonized Quantification and Reporting Procedures for Nutrients (HARP-NUT): Guideline 7: Quantification and reporting of the monitored riverine load of nitrogen and phosphorus, including flow normalization procedures. Reference number: 2004-2-E.

23. Pieterse N.M, Bleuten W., Jørgensen S.E. (2003). Contribution of point sources and diffuse sources to nitrogen and phosphorus loads in lowland river tributaries. Journal of Hydrology 271 213–225. https://doi.org/10.1016/S0022-1694(02)00350-5

24. Rapid Environmental Assessment of Kakhovka Dam Breach Ukraine, 2023, UNEP, 2023, 130 p. URL: https://wedocs.unep.org/20.500.11822/43696

25. Savenets M., Osadchyi V., Komisar K., Zhemera N., Oreshchenko A. (2023) Remotely visible impacts on air quality after a year-round full-scale Russian invasion of Ukraine. Atmospheric Pollution Research. 14 (11). 101912. URL: https://doi.org/10.1016/j.apr.2023.101912

26. Seitzinger, S.P., Kroeze, C., Bouwman, A.F., Caraco, N., Dentener, F. and Styles, R.V. (2002). “Global Patterns of Dissolved Inorganic and Particulate Nitrogen Inputs to Coastal Systems: Recent Conditions and Future Projections,” Estuaries, 25(4b), 640–655.

27. Shumilova, O., Tockner, K., Sukhodolov, A., Khilchevskyi, V., De Meester, L., Stepanenko, S., et al. (2023). Impact of the Russia–Ukraine armed conflict on water resources and water infrastructure. Nature Sustainability, 1–9(5), 578–586. URL: https://doi.org/10.1038/s41893-023-01068-x

28. van Breemen, N., Boyer, E.W., Goodale, C.L., Jaworski, N.A., Seitzinger, S., Paustian, K., Het- ling, L., Lajtha, K., Eve, M., Mayer, B., van Dam, D., Howarth, R.W., Nadelhoffer, K.J. and Billen, G. (2002). “Where Did all the Nitrogen Go Fate of Nitro- gen Inputs to Large Watersheds in the Northeastern U.S.A”, Biochemistry, 57/58, 267–293.