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; e-ISSN 1726-4189, more
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| Keywords |
Marine/Coastal; Brackish water |
| Authors | | Top |
- Pastor, L.
- Cathalot, C.
- Deflandre, B.
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- Viollier, E.
- Soetaert, K.
- Meysman, F.J.R., more
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- Ulses, C.
- Metzger, E.
- Rabouille, C.
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| 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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