TITLE:
Conception of an Optimized Sequential Extraction Protocol for Studying Phosphorus Mobility in the Sediments from a Tropical Lagoon Estuary
AUTHORS:
Hicham Cheick Abbas, Marcel Konan Yao, Arthur Fabrice Kouadio Konan, Jean-Claude Bénié Drida Bi
KEYWORDS:
Atlantic Ocean, Eutrophication, Ébrié System, Phosphorus, Sequential Phosphorus Extraction Protocol
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.15 No.10,
October
31,
2025
ABSTRACT: This study aimed to develop an optimized and adapted sequential phosphorus extraction protocol for the superficial sediments from the area II of the Ébrié system. To that end, four existing protocols (Bonzongo, Hieltjes and Lijklema, Paludan and Jensen, and Azzouz) were assessed. The adapted protocol was designed based on the one that exhibited the highest seasonal recovery rates and allowed for the analysis of a greater number of phosphorus fractions. Protocol optimization was achieved by adjusting the extractant volumes from 10 to 50 mL to minimize interferences with colorimetric orthophosphate analysis. Sediment samples were collected over one year, from January to December 2024, and the mean seasonal concentrations of total phosphorus and its various fractions were measured in accordance with ISO 6878 standard. Only the Bonzongo and the Paludan and Jensen protocols showed recovery rates exceeding 80% during the rainy and cold seasons. The Paludan and Jensen protocol, offering the ability to analyze a larger number of phosphorus fractions, was therefore selected as the foundation for the optimized protocol. This new protocol achieved seasonal phosphorus recovery rates ranging from 87.5% ± 6.3% to 114.7% ± 15.5%, demonstrating high precision and notable efficiency for studying phosphorus mobility in these sandy sediments. This study highlighted the necessity of developing a sequential extraction protocol specifically tailored to the sediments from a given study area to assess the mobility of phosphorus.