Polyaromatic hydrocarbons in the Caspian Sea during 2017–2021

The article presents the results of study of polyaromatic hydrocarbons in the Northern Caspian and the Middle Caspian marine environment. The spatial and temporal dynamics of PAHs concentration is described on the basis of the materials gathered during 2017–2021. The study was based on the results of industrial environmental monitoring of the licensed areas of mineral resources use in the northern and middle part of the Caspian Sea. The data of industrial environmental monitoring were analyzed by standard statistical methods. It should be noted that the seasonal variability of PAHs concentrations in the Northern Caspian is characterized by the spring increase in PAHs amount for almost all period under study. A common feature of PAHs dynamics in the northern part of the sea is an upward trend from 2017 to 2020 and its decrease in 2021. No seasonal patterns in the variability of PAHs were found for the Middle Caspian. There are not found stable trends in PAHs concentrations in this region. Concentration range and fraction in the sum of all PAHs were determined for each of the PAH components. As a result of the study the dynamics of water content of marker hydrocarbons, such as pyrene, benz(a)pyrene, fenantren, acetenaften, anthracene, chrysene and naphthalene, was revealed. A redistribution of the mass share of the main components of PAHs occurred in 2019. Acetenaften, fenantren and naphthalene were the most common in the Caspian Sea water. Analysis of molecular-diagnostic ratios proves the presence of anthropogenic and natural sources of polyarenes and the mixed origin of hydrocarbon pollution in the Caspian Sea. Analysis of molecular-diagnostic ratios shows the presence of anthropogenic and natural sources of polyarenes and the mixed origin of hydrocarbon pollution in the Caspian Sea. A number of patterns have been identified through correlation analysis. There is a strong feedback between the ratios (pyrene + benz(a)pyrene)/(fenantren + chrysene) and fenantren/anthracene in the Northern Caspian. And there is also a direct correlation between the ratios naphthalene/fenantren and anthracene/(anthracene + fenantren). Analysis of correlation relationships of indicator ratios in the Middle Caspian did not reveal any dependencies, which may indicate a variety of sources of contamination by polyaromatic hydrocarbons. 

1. Drugov Ju.S., Rodin A.A. Ekologicheskie analizy pri razlivah nefti i nefteproduktov [Ecological Analyses of Oil and Oil Spills], Saint-Petersburg, Anatolija Publ., 2000, 250 p. (In Russian)

2. Haiyan Y., Yongfeng L., Changxu H. et al. Polycyclic aromatic hydrocarbons in surface waters from the seven main river basins of China: Spatial distribution, source apportionment, and potential risk assessment, Science of the Total Environment, 2021, vol. 52, 141764.

3. Haustov A.P., Redina M.M. Policiklicheskie aromaticheskie uglevodorody kak geohimicheskie markery neftjanogo zagrjaznenija okruzhajushhej sredy [Polycyclic aromatic hydrocarbons as geochemical markers of oil pollution of the environment], Ekspozicija Neft’ Gaz, 2014, no. 4 (36), p. 92–96. (In Russian)

4. Kljonkin A.A., Pavlenko L.F., Skrypnik G.V., Larin A.A. Biogenic hydrocarbons and their effect on oil pollution estimates of the Sea of Azov, Water Resources, 2010, no. 5, p. 699–705.

5. Nemirovskaja I.A. Neft’ v okeane. Zagrjaznenie i prirodnye potoki [Oil in the ocean. Pollution and natural flows], Moscow, Nauchnyj mir Publ., 2013, 456 p. (In Russian)

6. Nemirovskaja I.A. Neftjanye uglevodorody v okeane [Petroleum Hydrocarbons in the Ocean], Priroda, 2008, no. 3, p. 17–27. (In Russian)

7. Nemirovskaja I.A. Uglevodorody v vodah i donnyh osadkah Barentseva morja v period izmenchivosti ledovogo pokrova [Hydrocarbons in water and sediments of the Barents Sea during the period of ice cover variability], Geohimija, 2020, no. 7, p. 679–692. (In Russian)

8. Nemirovskaja I.A., Onegina V.D., Konovalov B.V. Uglevodorody vo vzvesi i osadkah razlichnyh rajonov rossijskogo sektora Chernogo morja [Hydrocarbons in suspension and sediments of various regions of the Russian sector of the Black Sea], Morskoj gidrofizicheskij zhurnal, 2017, no. 4, p. 48–59. (In Russian)

9. Odintsova T.A., Bachurin B.A. Nauchno-metodicheskie podhody k organizacii monitoringa neftjanyh zagrjaznenij [Scientific and methodological approaches to the organization of oil pollution monitoring], Gornyj informacionno-analiticheskij bjulleten’, 2011, no. 6, p. 176–182. (In Russian)

10. Ostrovskaja E.V., Kolmykov E.V., Holina O.I. et al. Uglevodorodnoe zagrjaznenie severo-zapadnoj chasti Kaspijskogo morja [Hydrocarbon pollution of the north-western part of the Caspian Sea], Jug Rossii: ekologija, razvitie, 2016, no. 1, p. 137–146. (In Russian)

11. Ostrovskaja E.V., Kolmykov E.V., Kurapov A.A., Makarova E.N. Metodologija identifikacii istochnikov i monitoring hronicheskogo zagrjaznenija uglevodorodami morskoj sredy Severnogo Kaspija [Methodology of source identification and monitoring of chronic hydrocarbon pollution of the marine environment of the Northern Caspian Sea], Ekologicheskaja, promyshlennaja i energeticheskaja bezopasnost’, 2007, no. 4, p. 1015–1017. (In Russian)

12. Ostrovskaja E.V., Nemirovskaja I.A., Brehovskih V.F. et al. Uglevodorody vody i vzvesi v rajone geohimicheskogo bar’era del’ty r. Volga – Severnyj Kaspij [Hydrocarbons of water and suspension in the geochemical barrier area of the Volga River delta – Northern Caspian], Jug Rossii: ekologija, razvitie, 2009, no. 4, p. 150–158. (In Russian)

13. Petrova V.I., Batova G.I., Kursheva A.V. et al. Geochemistry of polycyclic aromatic hydrocarbons of the bottom sediments of the Eastern Arctic Shelf, Oceanology, 2008, no. 2, p. 196–203.

14. Tepe Ya., Aydın H., Ustaoğlu F., Taştekin Ö. Occurrence and characteristics of PAHs in coastal seawater off the city of Samsun on the Black Sea coast of Turkey, Regional Studies in Marine Science, 2024, vol. 74, 103552.

15. Tobiszewski M. Application of Diagnostic Ratios of PAHs to Characterize the Pollution Emission Sources, 5th International Conference on Environmental Science and Technology, Singapore, 2014, р. 41–44.

16. Wang, Y.Z., Zhang, S.L., Cui, W.Y. et al. Polycyclic aromatic hydro-carbons and organochlorine pesticides in surface water from the Yongding River basin, China: seasonal distribution, source apportionment, and potential risk assessment, Sci. Total Environ, 2018, р. 419–429.

17. Younis A.M., Hanafy S., Elkady E.M. et al. Polycyclic aromatic hydrocarbons (PAHs) in Egyptian red sea sediments: Seasonal distribution, source Identification, and toxicological risk assessment, Arabian Journal of Chemistry, 2023, vol. 16. 104999.

18. Yuanxin C., Ming X., Baodong W. et al. Spatiotemporal distribution, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the urbanized semi–enclosed Jiaozhou Bay, China, Science of the Total Environment, vol. 717, 2020, 137224.