Self-Purification Capacity And Physico-Chemical Assessment On A River Basin Pressured By Anthropogenic Influences: Example Of The Osam River, Bulgaria
https://doi.org/10.24057/2071-9388-2025-3964
Abstract
Various anthropogenic impacts alter the structure and functioning of natural components, and the process of self-recovery in a damaged environment is more relevant than ever. Water quality worsens due to pollution with organic and inorganic chemical substances, and understanding the ability of aquatic streams to self-purify is a key challenge facing the scientific community. This article, dedicated to the Osam River (Bulgaria), provides knowledge on how eight physico- chemical elements change their concentrations from upper to lower reaches and to what extent the river manages to self- purify of pollutants. The paper is based on information concerning the values of DO2, N-NH4, N-NO3, N-NO2, N-tot, P-PO4, P-tot, and BOD5, recorded at four sampling sites from 2015 until 2021. Water quality is classified into one of three classes of physico-chemical status (excellent, good, or moderate) following the guidelines in Regulation H-4/14.09.2012 for surface water characterization. The self-purification coefficient of Tumas (α) is computed to determine the extent to which the river is able to rid itself of pollutants. The results indicate that water quality changes from upstream to downstream due to the inflow of untreated wastewater discharged from various sources and the ongoing self-purification processes. In the upper section, the river fails to get rid of phosphate pollution caused by households and industry, while in the lower sector, nitrate loading from agriculture is most disturbing. The current research focuses on the ability of rivers to restore their natural conditions under various anthropogenic impacts and points to the need for more effective control of unregulated discharges.
About the Authors
Kalin K. SeymenovBulgaria
Acad. G. Bonchev Str., Sofia, 1113
Kristina M. Gartsiyanova
Bulgaria
Acad. G. Bonchev Str., Sofia, 1113
Atanas V. Kitev
Bulgaria
Acad. G. Bonchev Str., Sofia, 1113
Krasya P. Kolcheva
Bulgaria
Acad. G. Bonchev Str., Sofia, 1113
References
1. Alexander R., Bohlke J., Boyer E., David M., Harvey J., Mulholland P., Seitzinger S., Tobias C., Tonitto C., and Wollheim W. (2009). Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes. Biogeochemistry, 93(1), 91–116. DOI: 10.1007/s10533-008-9274-8
2. Benoit R. J. (1971). Self-purification in natural waters. Water Pollution Handbook, 1. Dekker, New York, USA.
3. Bukaveckas P. (2007). Effects of channel restoration on water velocity, transient storage, and nutrient uptake in a channelized stream. Environmental Science & Technology, 41(5), 1570–1576. DOI: 10.1021/es061618x
4. Chalov S. R., Moreido V., Urošev M., Golosov V., Zlatić M., Kasimov N. (2024). Advances in catchment and river erosion and pollutants’ transport studies: from monitoring to modelling to management. GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY, 17(4), 6–9. DOI: 10.24057/2071-9388-2024-0608
5. European Parliament and the Council of the European Union 2000. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Communities L 327, 22.12.2000. 73 p.
6. Fisenko A. (2006). Natural purification of rivers and creeks through froth formation process. Research Journal Of Chemistry And Environment, 10(1), 24–29.
7. Gartsiyanova K. (2015). Anthropogenic influences on the water quality in the Osam River Basin. PhD Thesis, National Institute of Geophysics, Geodesy, and Geography, Sofia, Bulgaria.
8. Gartsiyanova K., and Varbanov M. (2015). Comparative assessment of the water quality in the river Osam. Science and technologies, Nautical and Environmental Studies, 6(2), 91–94.
9. Gartsiyanova K., Genchev S., and Kitev A. (2023). Evaluation of land cover, land use and water quality in the regions with various anthropogenic activities – a case study of the Osam River Basin, Bulgaria. European Journal of Materials Science and Engineering, 8(1), 3–10. DOI: 10.36868/ejmse.2023.08.01.003
10. Government of the Republic of Bulgaria (2012). Regulation Н-4 from 14 September 2012 for surface water characterization. Available from: Naredba H-4.pdf.
11. Gurjar S. K., and Tare V. (2019). Spatial-temporal assessment of water quality and assimilative capacity of river Ramganga, a tributary of Ganga using multivariate analysis. Journal of Cleaner Production, 222, 550–564. DOI: 10.1016/j.jclepro.2019.03.064
12. Hishe T. G. (2020). Evaluation of point source pollutants impact on water quality and self-purification capacity of Abay River in Ethiopia. Civil Environment Research, 12(3), 1–8. DOI: 10.7176/CER/12-3-01.
13. Hristova N. (2012). Hydrology of Bulgaria. Tip-Top Press, Sofia.
14. Ignatova N. (1992). Conservation of water purity. Zemizdat, Sofia.
15. Mala J., and Maly J. (2009). Effect of heavy metals on self-purification processes in rivers. Applied Ecology and Environmental Research, 7(4), 333–340.
16. Medupe M., and Letshwenyo M. (2025). Investigation of self-purification and water quality index during dry and rainy seasons in the Khurumela Stream (Botswana). Journal of Ecohydraulics, 10(1), 1–18, DOI: 10.1080/24705357.2024.2363755
17. Menezes P., Bittencourt P., Farias S., Bello P., Oliveira L., and Fia R. (2015). Deoxygenation rate, reaeration and potential for self-purification of small tropical urban streams. Revista Ambiente & Água, 10(4), 748–757. DOI: 10.4136/ambi-agua.1599
18. Midyurova B., Belovski I., Dimova-Todorova M. (2021). Assessing the self-purification capacity of surface waters in Mladezhka River. Journal of Environmental Protection and Ecology, 22(1), 1–7.
19. Montreuil O., Merot P., and Marmonier P. (2010). Estimation of nitrate removal by riparian wetlands and streams in agricultural catchments: Effects of discharge and stream order. Freshwater Biology, 55, 2305–2318. DOI: 10.1111/J.1365-2427.2010.02439.X
20. Sakke N., Jafar A., Dollah R., Hair A., Asis B., Mapa M., Abas A. (2023). Water Quality Index (WQI) analysis as an indicator of ecosystem health in an urban river basin on Borneo Island. Water, 15(15):2717. DOI: 10.3390/w15152717.
21. Salih S., Mohammad A., and Mohammed F. (2021). Study on the Self-purification of Tanjaro River. Tikrit Journal for Agricultural Sciences, 21(4), 54–62. DOI: 10.25130/tjas.21.4.7
22. Šaulys V., Survile O., and Stankeviciene R. (2020). An assessment of self-purification in streams. Water, 12(1):87. DOI: 10.3390/w12010087
23. Seymenov K. (2022). Assessment of water pollution with nitrogen and phosphorus along the course of a river: A case study from Northern Bulgaria. Journal of the Bulgarian Geographical Society, 47, 35–44. DOI: 10.3897/jbgs.e97971
24. Tumas R. (2003). Water Ecology. Naujasis Lankas, Kaunas.
25. Vagnetti R., Miana P., Fabris M., and Pavoni B. (2003). Self-purification ability of a resurgence stream. Chemosphere, 52, 1781–1795. DOI: 10.1016/S0045-6535(03)00445-4
26. Velev S. (2010). Climate of Bulgaria. Heron Press Publishing House, Sofia.
27. Vismara R. (1992). Applied Ecology. Hoepli U, Torino.
28. Xu J., Jin G., Tang H., Mo Y., Wang Y. G., and Li L. (2019). Response of water quality to land use and sewage outfalls in different seasons. Science of The Total Environment, 696. DOI: 10.1016/j.scitotenv.2019.134014
29. Zhang M., Wang L., Mu C., Huang X. (2022). Water quality change and pollution source accounting of Licun River under long-term governance. Scientific Reports, 12, 2779. DOI: 10.1038/s41598-022-06803-6.
30. Zhang X., Chen P., Han Y., Chang X., and Dai S. (2022). Quantitative analysis of self-purification capacity of non-point source pollutants in watersheds based on SWAT model. Ecological Indicators, 143. DOI: 10.1016/j.ecolind.2022.109425
Review
For citations:
Seymenov K.K., Gartsiyanova K.M., Kitev A.V., Kolcheva K.P. Self-Purification Capacity And Physico-Chemical Assessment On A River Basin Pressured By Anthropogenic Influences: Example Of The Osam River, Bulgaria. GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY. 2025;18(3):80-87. https://doi.org/10.24057/2071-9388-2025-3964