Interannual and seasonal variability of chemical runoff along the main delta branches of the Kuban River

The long-term interannual and seasonal variability of the chemical runoff along the main branches of the Kuban River delta was investigated. We analyzed the data of systematic observations on water runoff and the concentrations of the main ions, biogenic and organic substances, phenols, oil products and heavy metals for the period from 2008 to 2018. The annual and seasonal runoff of dissolved chemicals in the main branches of the Kuban River delta, i. e. the Protoka branch and the Kuban branch, was calculated. The chemical composition of water in the main branches of the Kuban River delta is practically the same, and the greatest differences are characteristic of the concentrations of chlorides, iron compounds, copper and oil products. Multidirectional trends of changes in the ionic composition and content of biogenic elements were revealed. There was a synchronous increase in the concentration of sulphates and ammonium nitrogen in both deltaic branches of the Kuban River; the content of nitrates and nitrites in the Kuban branch practically did not change, while it was decreasing in the Protoka branch. At the same time, the maximum frequency of exceeding the MPC for all components is rather low, and a low level of water pollution is typical. The chemical runoff along the delta branches is rather similar, especially in terms of the runoff of sulphates, organic substances and biogenic elements. The greatest differences by 20–22% are observed in the runoff of chlorides, iron and copper compounds. It is shown that the runoff of chlorides and sulphates, as well as biogenic and organic substances, is interconnected with water runoff. In general, the distribution of chemical runoff along the delta branches is uniform, its seasonal variability corresponds to changes in water amount during the principal seasons, while some differences are observed only for chlorides and iron compounds. Under actual climatic changes and anthropogenic impact, the revealed features and trends of variability of chemical runoff along the main branches of the Kuban River delta are of great practical importance. The data obtained can be used for predictive estimates of the removal of chemicals into the coastal zone of the Sea of Azov.

1. Bryzgalo V.A., Nikanorov A.M., Kosmenko L.S., Reshetnyak O.S. Ust’evye ekosistemy krupnykh rek Rossii: antropogennaya nagruzka i ekologicheskoe sostoyanie [Estuarine ecosystems of major rivers in Russia: anthropogenic load and ecological state], Rostov-on-Don, Southern Federal University Press, 2015, 164 p. (In Russian)

2. Bryzgalo V.A., Nikanorov A.M., Reshetnyak O.S. Izmenchivost’ ekologicheskogo sostoyaniya rechnykh zon ust’evykh ekosistem krupnykh rek Rossii [Ecological state variability of mouth ecosystems of big rivers of Russia], Voda: khimiya i ekologiya, 2013, no. 12, p. 15–21. (In Russian)

3. Gidrologiya del’ty i ust’evogo vzmor’ya Kubani [Hydrology of the delta and estuarine coast of the Kuban River], V.N. Mikhailov, D.V. Magritsky, A.A. Ivanov (еds.), Moscow, GEOS, 2010, 728 p. (In Russian)

4. Gidrologiya: uchebnik dlya vuzov [Hydrology: textbook for universities], V.N. Mikhailov, S.A. Dobrolyubov (еds.), Moscow, Berlin, Direct Media, 2017, 752 p. (In Russian)

5. Korotaev V.N., Babich D.B., Mikhailov V.N. Estuarnodel’tovye sistemy Rossii i Kitaya: gidrologo-morfologicheskie protsessy. Geomorfologiya i prognoz razvitiya [Estuarine-deltaic systems of Russia and China: hydrological- morphological processes, geomorphology and forecast of evolution], Moscow, GEOS, 2007, 445 p. (In Russian)

6. Lurie P.M., Panov V.D., Tkachenko Yu.Yu. Reka Kuban’: gidrografiya i rezhim stoka [The Kuban River: hydrography and flow regime], St. Petersburg, Gidrometeoizdat Publ., 2005, 498 p. (In Russian)

7. Magritsky D.V., Ivanov A.A. Vodnyi balans del’ty r. Kuban’ i ego mnogoletnie izmeneniya [Water balance of the Kuban River delta and its long-term fluctuations], Vestn. Mosk. un-ta, Ser. 5, Geogr., 2008, no. 5, p. 59–67. (In Russian)

8. Mikhailov V.N. Ust’ya rek Rossii i sopredel’nyh stran: proshloe, nastoyashchee i budushchee [Estuaries of rivers in Russia and neighboring countries: past, present and future], Moscow, GEOS, 1997, 413 p. (In Russian)

9. Nikanorov A.M., Bryzgalo V.A., Kosmenko L.S., Kondakova M.Yu. Dinamika pritoka rastvorennykh khimicheskikh veshchestv i antropogennaya nagruzka na ust’evuyu oblast’ r. Kuban’ [Dynamics of chemical substance inflow and anthropogenic load on the Kuban River mouth area], Voda: khimiya i ekologiya, 2011, no. 9, p. 9–16. (In Russian)

10. Nikanorov A.M., Bryzgalo V.A., Kosmenko L.S., Reshetnyak O.S. Rol’ khimicheskogo rechnogo stoka v antropogennoi transformatsii sostoyaniya vodnoi sredy Eniseiskoi ust’evoi oblasti [The role of chemical river runoff in the anthropogenic transformation of the state of the aquatic environment in the Enisei River mouth area], Vodnye resursy, 2010, no. 4, p. 434–444. (In Russian)

11. Nikanorov A.M., Bryzgalo V.A., Reshetnyak O.S., Kosmenko L.S., Kondakova M.Yu. Antropogennaya transformatsiya ekologicheskogo sostoyaniya i transport zagryaznyayuschikh veshchestv po dline reki Kubani [Anthropgenic transformation of the ecological state and pollutants’ transport along the Kuban River], Vodnoe khozyaistvo Rossii: problemy, tekhnologii, upravlenie, 2013, no. 2, p. 108–118. (In Russian)

12. RD 52.24.643–2002. Metodicheskie ukazaniya. Metod kompleksnoi otsenki stepeni zagryaznennosti poverkhnostnykh vod sushi po gidrokhimicheskim pokazatelyam [Guidance document 52.24.643–2002. Methodological guidelines. A method for complex assessment of the degree of contamination of land surface waters by hydrochemical indicators], St. Petersburg, Gidrometeoizdat Publ., 2003, 49 p. (In Russian)

13. Skhema kompleksnogo ispol’zovaniya i okhrany vodnykh ob”ektov basseina reki Kuban’, kn. 2, Otsenka ekologicheskogo sostoyaniya i klyuchevye problemy rechnogo basseina [Scheme of integrated use and protection of water bodies in the Kuban River basin, book 2, Assessment of the ecological state and key problems of the river basin], Krasnodar, Kuban Basin Water Management, 2014, 133 p. (In Russian)

14. Sorokina V.V., Ivlieva O.V., Lurie P.M. Dinamika stoka na ust’evykh uchastkakh rek Don i Kuban’ vo vtoroi polovine XX veka [River flow alteration within the mouth areas of the Don and Kuban rivers in the second half of the 20th century], Vestnik Yuzhnogo nauchnogo tsentra RAN, 2006, vol. 2, no. 2, p. 58–67. (In Russian)

15. Tkachenko A.N., Tkachenko O.V., Lychagin M.Yu. Potoki tyazhelyh metallov v akval’nyh sistemah del’t Dona i Kubani [Fluxes of heavy metals in the aquatic systems of the Don and Kuban River deltas], Doklady Akademii nauk, 2017, vol. 474, no. 2, p. 234–237. (In Russian)

16. Zaslavskaya M.B., Efimova L.E. [Seasonal variability of dissolved- solid yield in the Arctic seas of Russia], Materialy nauchnoj konferencii “Sovremennye problemy gidrohimii i monitoringa kachestva poverhnostnyh vod” [Proceedings of the Scientific conference “Modern problems of hydrochemistry and surface water quality monitoring”], 2015, pt. 1, p. 44–48. (In Russian)

17. AIS GMVO. Avtomatizirovannaya informatsionnaya sistema gosudarstvennogo monitoringa vodnykh ob”ektov [Automated Information System for State Monitoring of Water bodies], URL: https://gmvo.skniivh.ru/ (access date 09.01.2021). (In Russian)

18. Kuban River Delta: Group of limans between Kuban & Protoka rivers, URL: https://rsis.ramsar.org/ris/674 (access date 24.01.2021).

19. Vodno-bolotnye ugodiya Rossii [Wetlands of Russia], URL: http://www.fesk.ru/wetlands/5.html (access date 24.01.2021). (In Russian)