The fate of organic matter in mangrove sediments subject to variable environmental conditions (French Guiana).

International audienceDuring the four last years, a National research Programme for Coastal Environment (PNEC) was partly devoted to the littoral of French Guiana. Several field trips allowed to sample twinned sedimentary cores from both the mangroves and the unvegetated sediments, and various vascular plants specific to these swamps. An elemental, pyrolytic and optical study of total sedimentary organic matter (OM), completed with stable isotope and molecular analyses, was carried out on these sets of samples and coupled with a study of pore waters (physico-chemical properties and dissolved organic content) collected in the mean time, during contrasted seasons. The development and age of mangrove marshes and forests was assessed by parallel studies performed by ecologists