Particulate organic matter (POM) is a key component of biogeochemical cycles and constitutes the baseline of the food webs. In riverine systems, POM is a mixture of sources (e.g. terrestrial POM, phytoplankton, microphytobenthos) originating from different reservoirs. POM elemental and isotopic ratios are widely used in aquatic biogeochemistry and ecology to estimate and even quantify the origin and composition of POM. However, POM elemental and isotopic values are usually highly variable in space and time making their use restricted to snapshot studies or requiring a dense temporal sampling strategy. In this study, POM was sampled for C and N elemental and isotopic ratios along with miscellaneous environmental parameters with the aim of quantifying the composition of POM and identifying the drivers of its spatial and temporal variability at the river-estuary interface. This study has been performed in 28 temperate rivers of France with monthly to bimonthly sampling over one to four annual hydrological cycles. The diversity of studied rivers translates into a large diversity of environmental drivers, resulting in a complete comprehension of the dynamics of POM composition. After the determination of the elemental and isotopic signatures of the POM sources, the results of the mixing models will be presented. Then, the drivers of both the temporal and spatial dynamics of POM position will be determined. Finally, a typology of river-estuarine interfaces based on POM composition and drivers will be put forward.

Primary Presenter: FERCHICHE Florian, Univ.Bordeaux (florian.ferchiche@u-bordeaux.fr)

Authors:

Florian Ferchiche, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  (florian.ferchiche@u-bordeaux.fr)

Camilla Liénart, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  ()

Sébastien Aubin, MNHN, CRESCO, Station Marine de Dinard, F-35800 Dinard, France  ()

Mathieu Canton, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  ()

Karine Charlier, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  ()

Alexandra Coynel, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  ()

Jonathan Deborde, Univ. Pau & Pays Adour, CNRS, E2S UPPA – MIRA, UMR 5254 IPREM, F-64000 Pau, F-64600 Anglet, France. Now at : Ifremer, LITTORAL, LER/PC, F-17390 La Tremblade, France  ()

Mélanie Giraud, MNHN, CRESCO, Station Marine de Dinard, F-35800 Dinard, France  ()

Laureline Gorse-Labadie, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  ()

Emilie Grossteffan, Univ. Bretagne Occidentale, CNRS, IRD, OSU-IUEM, UAR 3113, F- 29280 Plouzané, France  ()

Orianne Joly, Univ. Caen Basse-Normandie, CREC-Station Marine, F-Luc-sur-Mer, France  ()

Philippe Kerhervé, Univ. Perpignan, CNRS, UMR 5110 CEFREM, F-66860 Perpignan, France  ()

Nicolas Lachaussée, La Rochelle Université, CNRS, UMR 7266 LIENSs, F-17000 La Rochelle, France  ()

Marion Olivry, MNHN, CRESCO, Station Marine de Dinard, F-35800 Dinard, France  ()

Philippe Pineau, La Rochelle Université, CNRS, UMR 7266 LIENSs, F-17000 La Rochelle, France  ()

Pierre Polsenaere, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France. Now at : Ifremer, LITTORAL, LER/PC, F-17390 La Tremblade, France  ()

Patrick Raimbaud, Aix-Marseille Université, Univ. de Toulon, CNRS, INSU, IRD, UMR 110 MIO, F-13288 Marseille, France  ()

Peggy Rimmelin-Maury, Univ. Bretagne Occidentale, CNRS, IRD, OSU-IUEM, UAR 3113, F- 29280 Plouzané, France  ()

Pierre-Guy Sauriau, La Rochelle Université, CNRS, UMR 7266 LIENSs, F-17000 La Rochelle, France  ()

Nicolas Susperregui, IMA, F-64100 Bayonne, France. Now at : CIDPMEM 64-40, F-64500 Ciboure, France  ()

Nicolas Savoye, Univ. Bordeaux, CNRS, EPHE, Bordeaux INP, UMR 5805 EPOC, F-33600 Pessac, France  ()