A cross-section analysis of sedimentary organic matter in a mangrove ecosystem under dry climate conditions: The Somone estuary, Senegal

Abstract

Mangrove sediments are an important organic matter (OM) reservoir and play a major role in the carbon cycle. Since the 1990s, these ecosystems were subjected to numerous studies, in order to quantify the sedimentary sink for organic carbon (OC) and to characterize the organic matter sources, but remain poorly studied in Western Africa. The aim of our study is to quantify the organic carbon content and to identify the OM origin stored in the Somone mangrove sediments. Studied area is characterized by a (i) dry climate conditions with a higher rate of evaporation, (ii) lack of freshwater input by river, and (iii) tide dominated system. Here, we focus on physico-chemical properties of sediments (temperature, pH and redox), sediment grain size, water content, particulate organic carbon and dissolved organic carbon from a series of 40cm-deep cores in four tidal contexts: mudflat, Rhizophora, and Avicennia mangroves and barren area. Results show that total organic carbon (TOC) contents...