Distribution and quality of sedimentary organic matter on the Aquitanian margin (Bay of Biscay)

Citation
H. Etcheber et al., Distribution and quality of sedimentary organic matter on the Aquitanian margin (Bay of Biscay), DEEP-SEA II, 46(10), 1999, pp. 2249-2288
Citations number
109
Categorie Soggetti
Aquatic Sciences","Earth Sciences
Journal title
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
ISSN journal
09670645 → ACNP
Volume
46
Issue
10
Year of publication
1999
Pages
2249 - 2288
Database
ISI
SICI code
0967-0645(1999)46:10<2249:DAQOSO>2.0.ZU;2-3
Abstract
During the ECOFER experiment (French ECOMARGE program), surficial sediments were sampled on the Aquitanian margin with box corers and analyzed to dete rmine the quantity and quality of organic matter. Sediments from the margin are enriched in organic carbon (mean value 1.35%) in comparison to deep-se a and shelf sediments, due to a fine grain-size sedimentation. As sedimenta tion rates are high, the margin appears to be an organic depocenter. Some p referential organic enrichment zones were identified in the Cap-Ferret Cany on. There is a supply of continental material from the Gironde estuary, but marine contribution seems more possible than Adour or spanish rivers. No s easonal variations of organic matter were observed at the surface of sedime nts, suggesting mineralization processes of labile organic matter: average organic carbon consumption was evaluated to 9.0 g C m-(2) yr(-1). Rapid bio logical mineralization processes are lower than on the Mediterranean margin , mainly related to significant differences in water temperature. The great width of the canyon, its distance from the continent, and the current circ ulation pattern prevent any precise recording of the variable organic input s to the sediment and favor nepheloid transport, resuspension and shelf bre ak processes, which wipe out any print of fresh material input. An organic carbon budget indicates that an equilibrium between organic inputs and orga nic mineralization + accumulation is not obtainable. The supply of suspende d matter could have been minor during the year in question, and sedimentati on rates are still imprecise. (C) 1999 Elsevier Science Ltd. All rights res erved.