Organic Matter of the Bottom Sediments of the Ca Gau and Long Tau Rivers in the Can Gio Biosphere Reserve (Vietnam)

E. A. Tikhonova1,*, O. V. Soloveva1, Nguyen Trong Hiep2

1 A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Sevastopol, Russia

2 Southern Branch of Joint Vietnam-Russia Tropical Science and Technology Research Center, HoChiMinh, Vietnam

* e-mail: tihonoval@mail.ru

Abstract

The purpose of the work is to assess the level of organic substances, including oil hydrocarbons, and the effect of water dynamics on the content of these substances in the bottom sediments of the river – sea contact zone of the Ca Gau and Long Tau Rivers located on the territory of the buffer zone of the Can Gio Biosphere Reserve (Vietnam, Southeast Asia). The following indicators of the ecological well-being of the water area were identified: physical-chemical indicators of water (pH, eH, salinity, temperature), concentration of chloroform-extractable substances and oil hydrocarbons in bottom sediments. Determination of chloroform-extractable substances in bottom sediments was carried out by the gravimetric method, oil hydrocarbons were determined by infrared spectrometry. The measurements were carried out on an FSM-1201 spectrophotometer. In the bottom sediments of the river Ca Gau and Long Tau, the recorded concentrations of chloroform-extractable compounds (from 54 to 90 mg/100 g) and oil hydrocarbons (from 9.6 to 13.8 mg/100 g) were close to trace levels. The study of some rivers of the Can Gio Reserve showed that this water area can be characterized as relatively safe in terms of the determined parameters. As a result of active water circulation in estuarine areas of rivers flowing in mangroves, physical-chemical characteristics of the environment underwent significant changes during the high tide: increase in salinity (by 1–5 PSU) and pH (by 0.24–0.31 units on average), and decrease in redox potential (by 9–18 mV). However, no close correlation between the changes in physical-chemical characteristics of the environment and the content of organic substances was revealed. This phenomenon is probably associated with the movement of bottom sediments and is only significant for chloroform-extractable substances in the estuarine part of the Long Tau River.

Keywords

river bottom sediments, chloroform-extractable substances, oil hydrocarbons, Can Gio Biosphere Reserve, Vietnam

Acknowledgments

The study was carried out by researchers of the Joint Vietnam-Russia Tropical Science and Technology Research Center and the A.O. Kovalevsky Institute of Biology of Southern Seas of RAS according to their research projects: 1) Ekolan E-3.4. Ecosystem of the Mekong River in the context of global climate change and anthropogenic impact; and 2) Molismological and biogeochemical foundations of homeostasis of marine ecosystems. (no. 0556-2021-0001, state registration no. 121031500515-8). The authors express their sincere gratitude for providing primary prepared and delivered material to the staff of the Department of Radiological and Chemical Biology of IBSS: N. N. Tereshchenko, leading research associate, Ph.D., I. G. Sidorov, junior research associate, and O. D. Chuzhikova-Proskurnina, leading engineer.

For citation

Tikhonova, E.A., Soloveva O. V. and Nguyen Trong Hiep, 2022. Organic Matter of the Bottom Sediments of the Ca Gau and Long Tau Rivers in the Can Gio Biosphere Reserve (Vietnam). Ecological Safety of the Coastal and Shelf Zones of the Sea, (3), pp. 117–127. doi:10.22449/2413-5577-2022-3-117-127

DOI

10.22449/2413-5577-2022-3-117-127

References

  1. Gugliotta, M., Saito, Y., Ta, T.K.O. and Nguyen, V.L., 2019. Valley-Confinement and River-Tidal Controls on Channel Morphology along the Fluvial to Marine Transition Zone of the Ðồng Nai River System, Vietnam. Frontiers in Earth Science, 7, p. 202. doi:10.3389/feart.2019.00202
  2. Wu, Y., Zhang, J., Cho, K.W., Hong, G.H. and Chung, C.S., 2004. Origin and Transport of Sedimentary Organic Matter in the Yalujiang Estuary, North China. Estuaries, 27(4), 583–592. Available at: http://www.jstor.org/stable/1353472 [Accessed: 15 August 2022].
  3. Gorbunov, A.O., Kovalev D.P. and Kovalev, P.D., 2019. The Sediment Transported by the Flow in the Eroding Area of the Mordvinov Gulf Coast (Sakhalin Island). Geosystems of Transition Zones, 3(2), pp. 209–218. doi:10.30730/2541-8912.2019.3.2.209-218 (in Russian).
  4. Krein, A. and Schorer, M., 2000. Road Runoff Pollution by Polycyclic Aromatic Hydrocarbons and Its Contribution to River Sediments. Water Research, 34(16), pp. 4110–4115. https://doi.org/10.1016/S0043-1354(00)00156-1
  5. Burgess, R.M., Terletskaya, A.V., Milyukin, M.V., Povolotskii, M., Demchenko, V.Y., Bogoslavskaya, T.A., Topkin, Yu.V., Vorobyova, T.V., Petrov A.N. et al., 2009. Concentration and Distribution of Hydrophobic Organic Contaminants and Metals in the Estuaries of Ukraine. Marine Pollution Bulletin, 58(8), pp. 1103–1115. https://doi.org/10.1016/j.marpolbul.2009.04.013
  6. Shigaeva, T.D., Polyak, Yu.M. and Kudryavtseva, V.A., 2020. The Redox Potential as an Index of the State of Environmental Entities. Biosfera, 12(3), pp. 111–124. doi:10.24855/BIOSFERA.V12I3.549 (in Russian).
  7. Jansen, S., Walpersdorf, E., Werner, U., Billerbeck, M., Böttcher, M.E. and de Beer, D., 2009. Functioning of Intertidal Flats Inferred from Temporal and Spatial Dynamics of O2, H2S and pH in Their Surface Sediment. Ocean Dynamics, 59(2), pp. 317–332. doi:10.1007/s10236-009-0179-4
  8. Davies, O.A., 2014. Tidal Influence on the Physico-Chemistry Quality of Okpoka Creek, Nigeria. International Journal of Biological Sciences and Applications, 1(3), pp. 113–123. Available at: http://article.aascit.org/file/pdf/9030758.pdf [Accessed: 15 August 2022].
  9. Tam, N.F.Y. and Wong, Y.S., 2000. Spatial Variation of Heavy Metals in Surface Sediments of Hong Kong Mangrove Swamps. Environmental Pollution, 110(2), pp. 195–205. doi:10.1016/s0269-7491(99)00310-3
  10. Belkina, N.A., 2015. [The Role of Bottom Sediments in the Formation of the Chemical Composition of Surface Waters in the Humid Zone (Case Study of Lakes in Karelia)]. In: V. G. Pryazhinskaya, ed., 2015. [Scientific Support for the Implementation of the Water Strategy of the Russian Federation until 2020: Collection of Academic Papers, Petrozavodsk, 6–11 July 2015]. Petrozavodsk: Karelian Research Centre, RAS, pp. 395–400 (in Russian).
  11. Lomakin, P.D., 2018. Field of the Dissolved Organic Matter Content in the Taganrog Bay (the Sea of Azov). Physical Oceanography, 25(6), pp. 459–471. doi:10.22449/1573-160X-2018-6-459-471
  12. Mironov, O.G., Milovidova, N.Yu. and Kiryukhina, L.N., 1986. On Maximum Permissible Concentrations of Petroleum Products in Bottom Sediments of the Black Sea Littoral. Hydrobiological Journal, 22(6), pp. 76–78 (in Russian).
  13. Tikhonova, E.A., 2021. Organic Matter of Bottom Sediments of the Crimean and Caucasian Coasts (Azov and Black Seas). Ecological Safety of Coastal and Shelf Zones of Sea, (3), pp. 52–67. doi:10.22449/2413-5577-2021-3-52-67 (in Russian).
  14. Tikhonova, E.A., Kotelyanets, E.A. and Soloveva, O.V., 2021. Sea Bottom Sediments Pollution of the Crimean Coast (The Black and Azov Seas). In: T. Chaplina, ed., 2021. Processes in GeoMedia - Volume II. Springer Geology. Cham, Switzerland: Springer Nature Switzerland AG, pp. 199–211. https://doi.org/10.1007/978-3-030-53521-6_23
  15. Tikhonova, E.A., Soloveva, O.V. and Burdiyan, N.V., 2022. Bottom Sediments of the Kazantip Nature Reserve Coastal Water Area (Azov Sea) as an Indicator of the Water Area Wellbeing. In: T. Chaplina, ed., 2022. Processes in GeoMedia – Volume V. Springer Geology. Cham, Switzerland: Springer Nature Switzerland AG, pp. 253–262. https://doi.org/10.1007/978-3-030-85851-3_28
  16. Tikhonova, E.A., Soloveva, O.V., Mironov, O.A. and Burdiyan, N.V., 2020. Sanitary and Biological Characteristics of the Laspi Reserve Coastal Waters (the Black Sea). Ecological Safety of Coastal and Shelf Zones of Sea, (3), pp. 95–106. doi:10.22449/2413-5577-2020-3-95-106 (in Russian).
  17. Han, L., Wang, Y., Xu, Y., Wang, Y., Zheng, Y. and Wu, J., 2021. Water- and Base-Extractable Organic Matter in Sediments from Lower Yangtze River-Estuary-East China Sea Continuum: Insight into Accumulation of Organic Carbon in the River-Dominated Margin. Frontiers in Marine Science, 8, 617241. doi:10.3389/fmars.2021.617241

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