International Science Community Association International Research Journal of Environmental Sciences 14 1 2025 01 22 Fractionation and biodisponibility of phosphorus in the sediments of the river Mékrou 30 42 EN Victoria T. Sanyaolu 1 Department of Biological Science, Lagos State University of Science and Technology, Ikorodu – Lagos, Nigeria Oluwafemi Fadayini 2 Department of Chemical Engineering, Lagos State University of Science and Technology, Ikorodu – Lagos, Nigeria Toyin T. Oshin 3 Department of Chemical Science, Lagos State University of Science and Technology, Ikorodu – Lagos, Nigeria Wirnkor Verla Andrew 1 Group Research in Analytical Chemistry, Environment and Climate Change (GRACE & CC), Department of Chemistry, Imo State University Owerri, P. M. B 2000, Imo State, Nigeria Ngozi Verla Evelyn 2 Department of Environmental Technology, FUTO, Owerri, Imo State, P. M. B. 1526, Nigeria Victoria Ekweogu Chinonye 3 Department of Environmental Technology, FUTO, Owerri, Imo State, P. M. B. 1526, Nigeria Edewede Diagi Bridget 4 Department of Environmental Technology, FUTO, Owerri, Imo State, P. M. B. 1526, Nigeria Ndubuisi Iwuoha Godson 5 Department of Pure and industrial chemistry, Uniport, Choba, Rivers State, Nigeria Ngozi Aririguzo Bernadine 6 Department of Soil Sciences and Technology, Federal University of Technology, PMB 1526, Owerri, Imo State, Nigeria Dicuangco John Dave A. 1 Department of Biology, College of Arts and Sciences, Don Honorio Ventura State University, Bacolor, Pampanga 2001, Philippines Nolasco Glen S. 2 Department of Biology, Institute of Arts and Sciences, Mabalacat City College, Mabalacat City, Pampanga2010, Philippines CAKPO Arthur Romuald 1 Laboratoire de Chimie Physique-Matériaux et Modélisation Moléculaire (LCP3M), Unité de recherche de Chimie Inorganique, Ingénierie des Matériaux et Environnement (URCIIME), Faculté des Sciences et Techniques (FAST), Université d’Abomey - Calavi , République du Bénin FANOU Narcisse 2 Laboratoire de Chimie Physique-Matériaux et Modélisation Moléculaire (LCP3M), Unité de recherche de Chimie Inorganique, Ingénierie des Matériaux et Environnement (URCIIME), Faculté des Sciences et Techniques (FAST), Université d’Abomey - Calavi , République du Bénin GOUDJO Ferdinand 3 Laboratoire de Chimie Physique-Matériaux et Modélisation Moléculaire (LCP3M), Unité de recherche de Chimie Inorganique, Ingénierie des Matériaux et Environnement (URCIIME), Faculté des Sciences et Techniques (FAST), Université d’Abomey - Calavi , République du Bénin SAGBO Etienne 4 Laboratoire de Chimie Physique-Matériaux et Modélisation Moléculaire (LCP3M), Unité de recherche de Chimie Inorganique, Ingénierie des Matériaux et Environnement (URCIIME), Faculté des Sciences et Techniques (FAST), Université d’Abomey - Calavi , République du Bénin SOUMANOU Mohamed M. 5 Laboratoire d’Etude et de Recherche en Chimie Appliquée (LERCA), Ecole polytechnique d’Abomey-Calavi (EPAC), Université d’Abomey- Calavi, République du Bénin > Research Paper 2024 7 10 2025 01 22 The watershed of the Mekrou River is a large cotton production area where there is an overuse of agricultural inputs. This exaggerated use of agricultural fertilizers is likely to lead to phosphorus pollution of this river. The objective of this research work is to study the fractionation of phosphorus in the sediments of the Mekrou River to assess its bioavailability. For this, samples were taken from eight sites along the Mekrou River in two campaigns. The physicochemical parameters as well as the total phosphorus content and its fractionation were determined. The results obtained reveal a high rate of total phosphorus in the sediments, which amounts to 3465.73 µg/g of sediment on average for the two campaigns, indicating phosphorus pollution. Similarly, the total phosphorus content increases from 3016.58µg/g in December 2021 to 3914.88µg/g in February 2022. The fractionation results are as follows: labile P (0.41% of total P), Fe-P (1.68% of Ptotal), Al-P (0.23% of Ptotal), Ca-P (0.20% of Ptotal) Porg (15.43% of Ptotal) and P-residual (82.04% of Ptotal). The directly assimilable labile fraction is low, but the relatively high proportion of the organic fraction constitutes a danger for the watercourse because under certain optimal conditions, it can end up in the water column through the phenomenon of salting out and contribute to the eutrophication. To effectively assess the pollution rate of this river, it is desirable to study the effect of pH on the release of phosphorus and also to conduct the same study on the other pollutants in this river. The same studies could be carried out on other rivers in Benin whose watersheds are agricultural production areas. Copyright@ International Science Community Association