Journal of Water Resource and Protection, 2025, 17(6), 403-424 https://www.scirp.org/journal/jwarp ISSN Online: 1945-3108 ISSN Print: 1945-3094 DOI: 10.4236/jwarp.2025.176020 Jun. 17, 2025 403 Journal of Water Resource and Protection First Study of Seawater Carbonate Chemistry Variability in a Portion of the Southern Atlantic Coast of Cameroon: Impact of Organic Pollution Ulrich Joel Felicien Bilounga 1,2,3 , Fils Mamert Onana 1,4* , Antoine Arfao Tamsa 5 , Anselme Crepin Mama 3 , Paul Alain Nana 3 , Emmanuel Henock Dicka 2 , Thomas Ewoukem Efole 1,4 1 Ecosystems and Fisheries Resources Laboratory, Postgraduate School for Pure and Applied Sciences, University of Douala, Douala, Cameroon 2 Specialized Research Station for Marine Ecosystems, Institute of Agricultural Research for Development, Kribi, Cameroon 3 Department of Oceanography, Institute of Fisheries and Aquatic Sciences, University of Douala, Douala, Cameroon 4 Department of Aquatic Ecosystems Management, Institute of Fisheries and Aquatic Sciences, University of Douala, Douala, Cameroon 5 Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon Abstract The carbonate system variability and acidification process remain little under- stood in the coastal ocean of Cameroon. The aim of this study was to assess the variability of the carbonate system in a portion of the southern coast of Cameroon, and the influence of local seawater physicochemical and biological properties on keys parameters of this system. The study was carried out at three fixed sampling stations (Bp, Kb, and Eb), from September 2021 to Au- gust 2022 involving all the seasons encountered in the study area. The car- bonate system was determined from Total alkalinity (TA), pH, temperature and salinity, using the CO 2 SYS_xls program. In addition, nutrients (nitrate, nitrite, phosphate and nitrogen ammonia) and chlorophyll-a data were col- lected simultaneously at each station. The results showed a high variability of the carbonate system parameters on both temporal and spatial scale. TA and bicarbonate ions ( 3 HCO − ) were significantly different between the large rainy season (LRS) and small rainy season (SRS), while 2 CO and 2 CO partial pres- sure ( 2 pCO ) were significantly different between Kb and Eb sampling stations (p-value < 0.05). The critical thresholds for ocean acidification (OA) seems to not been reached in the southern coastal ocean of Cameroon, given the means values of pH (8.14 ± 0.17), aragonite (3.31 ± 1.3 Ω) and calcite (5.3 ± 2.05 Ω) saturation states obtained. Salinity appears as the main driver of the variability of TA in the study area, while, nitrogen ammonia and the dissolved carbon How to cite this paper: Bilounga, U.J.F., Onana, F.M., Tamsa, A.A., Mama, A.C., Nana, P.A., Dicka, E.H. and Efole, E.T. (2025) First Study of Seawater Carbonate Chemistry Variability in a Portion of the Southern Atlantic Coast of Cameroon: Im- pact of Organic Pollution. Journal of Water Resource and Protection, 17, 403-424. https://doi.org/10.4236/jwarp.2025.176020 Received: March 6, 2025 Accepted: June 14, 2025 Published: June 17, 2025 Copyright © 2025 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access