Spatio-temporal dynamics of nutrients at the water-sediment interface: case of the Nokoue lagoon in Southern Benin

• Published in: Environmental monitoring and assessment Vol. 196; no. 1; p. 2
• Main Authors: Socohou, Akilou Amadou, Djihouessi, Metogbe Belfrid, Tigo, Béatrix Amen, Viainon, Vignon Mechtilde, Adandedji, Firmin Mahoutin, Adounpke, Julien, AINA, Martin Pépin
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 2024; Springer Nature B.V
• Subjects: Analysis; Anthropogenic factors; Atmospheric Protection/Air Quality Control/Air Pollution; Benin; Benthos; Biogeochemical cycle; Biogeochemical cycles; Brackishwater environment; China; Climatic conditions; Cluster analysis; Correlation analysis; Discriminant analysis; Earth and Environmental Science; Ecology; Ecosystem; Ecotoxicology; Environment; Environmental Management; Environmental Monitoring; Estuaries; Eutrophication; Human influences; Hydrologic regime; Lagoons; Lakes; Monitoring/Environmental Analysis; Multivariate analysis; Nitrogen - analysis; Nutrients; Nutrients - analysis; Phosphorus; Phosphorus - analysis; Quality assessment; River channels; River mouth; River mouths; Sediment-water interface; Water Pollutants, Chemical - analysis; Water quality; Water quality assessments; Watersheds; Benin; China; Phosphorus; Benthic processes; Lake Nokoué; Multivariate analysis; Nitrogen; Eutrophication
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-023-12115-7

Lake Nokoué, a major component of the hydrographic system of the Ouémé delta, is the largest lagoon-estuarine ecosystem in Benin. Recent studies have shown that benthic processes would actively participate in the maintenance of the eutrophication and biogeochemical cycle of this ecosystem. In order to understand the implication of the bottom on the quality of the waters of the lake, a monthly follow-up of ten (10) parameters of quality of the waters of the bottom was undertaken from July 2020 to December 2021 on a network of nineteen (19) stations distributed on the whole lake. Univariate and multivariate analysis techniques were used to assess the spatial and temporal dynamics of these waters. The Kruskal–Wallis test, PCA, correlation analysis and discriminant analysis all showed a very marked influence of the hydrological regime on the concentration of nutrients compared to the influence of anthropogenic activities around the lake and an influence of climatic conditions on internal processes. Indeed, water inflows from the Ouémé watershed are the main contributors of phosphorus in the lake while benthic processes are the most important contributors of nitrogen. Cluster analysis defined three significantly different areas in Lake Nokoué: the channel, the centre of the lake and the river mouth. A single station in each cluster could be used for a spatial assessment of water quality over the entire lake.