Characterization of dissolved organic matter in tropical estuarine sediment pore waters under ultramafic influence Key

Other titles Caractérisation de la matière organique dissoute dans les eaux interstitielles sédimentaires d'estuaires tropicaux sous influence de bassins versants ultrabasiques
Type Dissertation
Date 2022-06
Language English
Ref. Mémoire de Master 2 MARRES de l'Université Côte d'Azur
Author(s) Mouras Naina1, 2
Contributor(s) Lemonnier HuguesORCID
Publisher Université Côte d'Azur / IFREMER
Keyword(s) Coastal sediment porewater, Photochemistry, Fluorescence spectroscopy, CDOM, Ultramafic environment, New-Caledonia
Abstract

To characterize the dissolved organic matter (DOM) in tropical estuarine, optical properties of coloured and fluorescent matter of porewater were measured in New-Caledonia coastal ecosystem. Surface sediment pore waters were analysed in four coastal area under different ultramafic influences, strongly (VKP, South of Nouméa), few (Dumbéa) to not impacted (Ouegoa) by mining activities. Five stations in triplicate were sampled. Absorption coefficients were low in the two stations under ultramafic soil and remarkably high in Dumbéa and Ouegoa. Spectral slope and SR ratio indicators revealed high molecular weight molecules at the Ouegoa and Dumbéa and low in VKP. Fluorescence spectroscopy and parallel factor (PARAFAC) modeling indicate that pore water is mostly composed of 4 components, which combine both autochthonous (Humic-like-mangrove C1, Tryptophane-like C2) and allochthonous materials (Fulvic-acid C3, terrestrial-humic-like C4) in the whole sites. C1 was found in abundance at the Ouegoa and VKP which are strongly surrounded by mangroves. C2 had a homogeneous distribution along the sites with a higher concentration at VKP. The pseudo-concentration of compounds C3 and C4, were high for the Ouegoa and Dumbéa sites. The strong site effect could be explained by three main factors, presence of mangrove, size of the catchment areas, and geological conditions.

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Mouras Naina (2022). Characterization of dissolved organic matter in tropical estuarine sediment pore waters under ultramafic influence Key. Mémoire de Master 2 MARRES de l'Université Côte d'Azur. https://archimer.ifremer.fr/doc/00783/89495/