Hostname: page-component-7c8c6479df-p566r Total loading time: 0 Render date: 2024-03-28T23:45:24.129Z Has data issue: false hasContentIssue false

Depositional Processes of Organic Matter in the Rhône River Delta (Gulf of Lions, France) Traced by Density Fractionation Coupled with Δ14C and δ13C

Published online by Cambridge University Press:  09 February 2016

Flora Toussaint*
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement UMR 8212, CEA-CNR-UVSQ Gif-sur-Yvette, France
Nadine Tisnérat-Laborde
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement UMR 8212, CEA-CNR-UVSQ Gif-sur-Yvette, France
Cécile Cathalot
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement UMR 8212, CEA-CNR-UVSQ Gif-sur-Yvette, France
Roselyne Buscail
Affiliation:
Centre de Formation et de Recherche sur les Environnements Méditerranéens, UMR 5110, CNRS, Perpignan, France
Philippe Kerhervé
Affiliation:
Centre de Formation et de Recherche sur les Environnements Méditerranéens, UMR 5110, CNRS, Perpignan, France
Christophe Rabouille
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement UMR 8212, CEA-CNR-UVSQ Gif-sur-Yvette, France
*
2Corresponding author. Email: flora.toussaint@lsce.ipsl.fr.

Abstract

As a main source of freshwater and particles, the Rhône River plays a major role in the biogeochemical cycle of organic carbon (OC) in the Mediterranean Sea. To better understand the origin of organic matter and the processes leading to its export to the coastal sea near the Rhône River, we measured radiocarbon (Δ14C) and stable carbon isotopes (δ13C) in the sediments of the delta, after density fractionation. In April 2007, 3 sites located along an offshore transect (A, C, and E) were sampled for surface sediments, and bulk sediment was separated into 4 fractions of different densities (<1.6, 1.6–2, 2–2.5, and >2.5 g cm−3). In order to better understand the evolution of the OC along the transect, we investigated the OC sources and their evolution for each density fraction. Bulk OC shows a large increase in δ13C from −27.2′ nearshore to −24.5′ at offshore stations while Δ14C decreased from 59′ to −320′. The distribution of δ13C with density displayed a convex pattern at all stations. Except for fraction >2.5 g cm−3, δ13C increases by 2.5′ between stations A and E, indicating a loss of terrestrial signature. The distribution of Δ14C versus density had a concave pattern at all stations: at a single station, it showed a large heterogeneity with a difference of 500–600′ between the <1.6 and 2–2.5 g cm−3 fractions. A decrease in Δ14C of −400′ among the different density fractions was observed along the offshore transect. The density fraction >2.5 g cm−3 had less variability, with an average δ13C of −24.6 ± 0.4′ and Δ14C of −370 ± 115′. Several processes may explain this distribution: retention in the prodelta of large particles; mineralization of all fractions during the transport and deposition in the delta and shelf sediments; and dilution of terrestrial particles in continental shelf pool.

Type
Articles
Copyright
Copyright © 2013 by the Arizona Board of Regents on behalf of the University of Arizona 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arnarson, TS, Keil, RG. 2001. Organic-mineral interactions in marine sediments studied using density fractionation and X-ray photoelectron spectroscopy. Organic Geochemistry 32:1401–15.Google Scholar
Arnold, M, Bard, E, Maurice, P, Valladas, H, Duplessy, JC. 1989. 14C dating with the Gif-sur-Yvette Tandetron accelerator: status report and study of isotopic fractionation in the sputter ion source. Radiocarbon 31(3):284–91.Google Scholar
Bock, MJ, Mayer, LM. 2000. Mesodensity organo-clay associations in a near-shore sediment. Marine Geology 163:6575.Google Scholar
Bourgeois, S, Pruski, AM, Sun, M-Y, Buscail, R, Lantoine, F, Kerhervé, P, Vétion, G, Rivière, B, Charles, F. 2011. Distribution and lability of land-derived organic matter in the surface sediments of the Rhône prodelta and the adjacent shelf (Mediterranean Sea, France): a multi proxy study. Biogeosciences 8:3107–25.Google Scholar
Burdige, DJ. 2007. The preservation of organic matter in marine sediments: controls, mechanisms and an imbalance in sediment organic carbon budgets? Chemical Reviews 107:467–85.Google Scholar
Cai, W-J. 2011. Estuarine and coastal ocean carbon paradox: CO2 sinks or sites of terrestrial carbon incineration? Annual Review of Marine Science 3:123–45.Google Scholar
Cathalot, C. 2009. Fate and impact of fluvial inputs on continental margins: biogeochemical and environmental importance of the recycling in the sediments of the Rhône River prodelta , Université Pierre et Marie Curie.Google Scholar
Cathalot, C, Rabouille, C, Pastor, L, Viollier, E, Buscail, R, Grémare, A, Treignier, C, Pruski, A. 2010. Temporal variability of carbon recycling in coastal sediments influenced by rivers: assessing the impact of flood inputs in the Rhône River prodelta. Biogeosciences 7:1187–205.Google Scholar
Cathalot, C, Rabouille, C, Tisnérat-Laborde, N, Toussaint, F, Kerhervé, P, Buscail, R, Bowles, K, Sun, M-Y, Tronczynski, J, Lansard, B, Treignier, C, Pastor, L, Tesi, T, Miserocchi, S. 2013. The fate of river organic carbon in coastal areas: a study in the Rhône River delta using multiple isotopic (δ13C, Δ14C) and organic tracers. Geochimica et Cosmochimica Acta 118:3355.Google Scholar
Charmasson, S, Bouisset, P, Radakovitch, O, Pruchon, AS, Arnaud, M. 1998. Long-core profiles of Cs-137, Cs-134, Co-60 and Pb-210 in sediment near the Rhône River (northwestern Mediterranean Sea). Estuaries 21:367–78.Google Scholar
Charrier, J, Bauer, J, Druffel, E, Coffin, R, Chanton, J. 1999. Evidence for the ages of assimilated carbon. Limnology and Oceanography 44(3):730–6.Google Scholar
Darnaude, AM, Salen-Picard, C, Polunin, NVC, Harmelin-Vivien, ML. 2004. Trophodynamic linkage between river runoff and coastal fishery yield elucidated by stable isotope data in the Gulf of Lions (NW Mediterranean). Oecologia 138:325–32.Google Scholar
Dickens, FA, Bladock, AJ, Smernik, JR, Wakeham, GS, Arnarson, ST, Gélinas, Y, Hedges, IJ. 2006. Solid-state 13C NMR analysis of size and density fractions of marine sediments: insight into organic carbon sources and preservation mechanisms. Geochimica et Cosmochimica Acta 70:666–86.Google Scholar
Galy, V, Eglinton, TI. 2011. Protracted storage of biospheric carbon in the Ganges-Brahmaputra basin. Nature Geoscience 4:843–7.Google Scholar
Glaser, B, Balashov, E, Haumaier, L, Guggenberger, G, Zech, W. 2000. Black carbon in density fractions of anthropogenic soils of the Brazilian Amazon region. Organic Geochemistry 31:669–78.CrossRefGoogle Scholar
Goni, MA, Monacci, N, Gisewhite, R, Crockett, J, Nittrouer, C, Ogston, A, Alin, SR, Aalto, R. 2008. Terrigenous organic matter in sediments from the Fly River delta-clinoform system (Papua New Guinea). Journal of Geophysical Research 113: F01S10, doi:10.1029/2006JF000653.Google Scholar
Harmelin-Vivien, M, Dierking, J, Banaru, D, Fontaine, M, Arlhac, D. 2010. Seasonal variation in stable C and N isotope ratios of the Rhône River inputs to the Mediterranean Sea (2004–2005). Biogeochemistry 100(1–3):139–50.Google Scholar
Hatté, C, Poupeau, J-J, Tannau, J-F, Paterne, M. 2003. Development of an automated system for preparation of organic samples. Radiocarbon 45(3):421–30.Google Scholar
Hedges, JI, Keil, RG, Benner, R. 1997. What happens to terrestrial organic matter in the ocean? Organic Geochemistry 27:195–212.Google Scholar
Keil, RG, Montlucon, DB, Prahl, FG, Hedges, JI. 1994. Sorptive preservation of labile organic matter in marine sediments. Nature 370(6490):549–52.Google Scholar
Kerhervé, P, Minagawa, M, Heussner, S, Monaco, A. 2001. Stable isotopes (13C/12C and 15N/14N) in settling organic matter of the northwestern Mediterranean Sea: biogeochemical implications. Oceanologica Acta 24:S77S85.Google Scholar
Kim, J-H, Schouten, S, Buscail, R, Ludwig, W, Bonnin, J, Sinninghe Damsté, JS, Bourrin, F. 2006. Origin and distribution of terrestrial organic matter in the NW Mediterranean (Gulf of Lions): exploring the newly developed BIT index. Geochemistry, Geophysics, Geosystems 7: Q11017, doi:10.1029/2006GC001306.Google Scholar
Lansard, B, Rabouille, C, Denis, L, Grenz, C. 2008. In situ oxygen uptake rates by coastal sediments under the influence of the Rhône River (NW Mediterranean Sea). Continental Shelf Research 22:1501–10.Google Scholar
Lansard, B, Rabouille, C, Denis, L, Grenz, C. 2009. Benthic remineralization at the land-ocean interface: a case study of the Rhône River (NW Mediterranean Sea). Estuarine, Coastal and Shelf Science 81:544–54.Google Scholar
Marion, C, Dufois, F, Arnaud, M, Vella, C. 2010. In situ record of sedimentary processes near the Rhône River mouth during winter events (Gulf of Lions, Mediterranean Sea). Continental Shelf Research 30:1095–107.CrossRefGoogle Scholar
Miralles, J, Radakovitch, O, Aloisi, J-C. 2005. 210Pb sedimentation rates from the Northwestern Mediterranean margin. Marine Geology 216:155–67.Google Scholar
Ollivier, P, Radakovitch, O, Hamelin, B. 2011. Major and trace element partition and fluxes in the Rhône. Chemical Geology 285:1531.Google Scholar
Pastor, L, Cathalot, C, Deflandre, B, Viollier, E, Soetaert, K, Meysman, FJR, Ulses, C, Metzger, E, Rabouille, C. 2011a. Modeling biogeochemical processes in sediments from the Rhône River prodelta area (NW Mediterranean Sea). Biogeosciences 8:1351–66.Google Scholar
Pastor, L, Deflandre, B, Viollier, E, Cathalot, C, Metzger, E, Rabouille, C, Escoubeyrou, K, Lloret, E, Pruski, AM, Vetion, G, Desmalades, M, Buscail, R, Gremare, A. 2011b. Influence of the organic matter composition on benthic oxygen demand in the Rhône River prodelta (NW Mediterranean Sea). Continental Shelf Research 31(9):1008–19.Google Scholar
Pont, D, Simonnet, JP, Walter, AV. 2002. Medium-term changes in suspended sediment delivery to the ocean: consequences of catchment heterogeneity and river management (Rhône River, France). Estuarine, Coastal and Shelf Science 54:118.Google Scholar
Radakovitch, O, Charmasson, S, Arnaud, M, Bouisset, P. 1999. Pb-210 and caesium accumulation in the Rhône delta sediments. Estuarine, Coastal and Shelf Science 48:7792.Google Scholar
Raimbault, P, Durrieu de Madron, X. 2003. Research activities in the Gulf of Lion (NW Mediterranean) within the 1997–2001 PNEC project. Oceanologica Acta 26:291–8.Google Scholar
Raymond, PA, Bauer, JE. 2001. Use of 14C and 13C natural abundances for evaluating riverine, estuarine, and coastal DOC and POC sources and cycling: a review and synthesis. Organic Geochemistry 32:469–85.Google Scholar
Richter, DD, Markewitz, D, Trumbore, SE, Wells, CG. 1999. Rapid accumulation and turnover of soil carbon in a re-establishing forest. Nature 400(6739):56–8.Google Scholar
Sempéré, R, Charriere, B, Van Wambeke, F, Cauwet, G. 2000. Carbon inputs of the Rhône River to the Mediterranean Sea: biogeochemical implications. Global Biogeochemical Cycles 14:669–81.Google Scholar
Stuiver, M, Polach, HA. 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355–63.Google Scholar
Tesi, T, Miserocchi, S, Goni, MA, Langone, L. 2007. Source, transport and fate of terrestrial organic carbon on the western Mediterranean Sea, Gulf of Lions, France. Marine Chemistry 105:101–17.Google Scholar
Wakeham, GS, Canuel, AS, Lerberg, JE, Mason, P, Sampéré, PT, Bianchi, ST. 2009. Partitioning of organic matter in continental margin sediments among density fractions. Marine Chemistry 115:211–25.Google Scholar
Yechieli, Y, Sivan, O, Lazar, B, Vengosh, D, Ronen, D, Herut, B. 2001. 14C in seawater intruding into the Israeli Mediterranean coastal aquifer. Radiocarbon 43(2B):773–81.Google Scholar