oa Characterization of Organic Matter in Estuarine Wetlands: Mapping Biogeochemical Functions Using Remote Sensing Data

A study was conducted to examine the biogeochemical functions of wetlands in the Seine estuary (northwestern France). The research integrated remote sensing data with field data, including vegetation surveys and biogeochemical measurements. These measurements encompassed elemental analyses (organic carbon and nitrogen) and isotopic analyses (d¹³C and d¹5N) of soil and sediment organic matter. Furthermore, the analysis of dissolved organic matter in porewater was conducted using UV-Visible absorption and EEM fluorescence spectroscopy, while the measurement of enzymatic activities was performed using NAG and BG. An extensive multisource remote sensing work has been carried out across the entire study site to characterize variables measured from space, such as the different vegetation types, the periods of flooding, vegetation production, and humidity. A cross-referencing between these variables and field observations was conducted to assess the potential of remote sensing to retrieve the main ecosystem functions characteristics. This one-year biogeochemical monitoring study of contrasting wetlands in the Seine estuary, differing in vegetation, moisture, connectivity to the watercourse, and use, revealed spatial variations in organic matter characteristics, but very few seasonal variations. For the first time, a correlation matrix was established between biogeochemical field data and function indicators derived from satellite observations.