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Modeling biogeochemical processes in sediments from the Rhone River prodelta area (NW Mediterranean Sea)
Pastor, L.; Cathalot, C.; Deflandre, B.; Viollier, E.; Soetaert, K.; Meysman, F.J.R.; Ulses, C.; Metzger, E.; Rabouille, C. (2011). Modeling biogeochemical processes in sediments from the Rhone River prodelta area (NW Mediterranean Sea). Biogeosciences 8(5): 1351-1366. dx.doi.org/10.5194/bg-8-1351-2011
In: Gattuso, J.P.; Kesselmeier, J. (Ed.) Biogeosciences. Copernicus Publications: Göttingen. ISSN 1726-4170, more
Peer reviewed article  

Available in Authors 

Keywords
    Marine; Brackish water

Authors  Top 
  • Pastor, L.
  • Cathalot, C.
  • Deflandre, B.
  • Viollier, E.
  • Soetaert, K.
  • Meysman, F.J.R.
  • Ulses, C.
  • Metzger, E.
  • Rabouille, C.

Abstract
    In situ oxygen microprofiles, sediment organic carbon content, and pore-water concentrations of nitrate, ammonium, iron, manganese, and sulfides obtained in sediments from the Rhône River prodelta and its adjacent continental shelf were used to constrain a numerical diagenetic model. Results showed that (1) the organic matter from the Rhône River is composed of a fraction of fresh material associated to high first-order degradation rate constants (11–33 yr−1); (2) the burial efficiency (burial/input ratio) in the Rhône prodelta (within 3 km of the river outlet) can be up to 80 %, and decreases to ~20 % on the adjacent continental shelf 10–15 km further offshore; (3) there is a large contribution of anoxic processes to total mineralization in sediments near the river mouth, certainly due to large inputs of fresh organic material combined with high sedimentation rates; (4) diagenetic by-products originally produced during anoxic organic matter mineralization are almost entirely precipitated (>97 %) and buried in the sediment, which leads to (5) a low contribution of the re-oxidation of reduced products to total oxygen consumption. Consequently, total carbon mineralization rates as based on oxygen consumption rates and using Redfield stoichiometry can be largely underestimated in such River-dominated Ocean Margins (RiOMar) environments.

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