Organic carbon production, mineralization and preservation on the Peruvian margin.

Dale, Andrew W., Sommer, Stefan, Lomnitz, Ulrike, Montes, Ivonne, Treude, Tina, Liebetrau, Volker, Gier, Jessica, Hensen, Christian, Dengler, Marcus, Stolpovsky, Konstantin, Bryant, Lee D. and Wallmann, Klaus (2015) Organic carbon production, mineralization and preservation on the Peruvian margin. Biogeosciences (BG), 12 . pp. 1537-1559. DOI 10.5194/bg-12-1537-2015.

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Abstract

Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.

Document Type: Article
Additional Information: The Supplement related to this article is available online at doi:10.5194/bgd-11-13067-2014-supplement. - WOS:000350987900016
Keywords: organic carbon preservation, carbon accumulation, Peru margin, model, burial efficiency
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R05
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > SFB 754
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-12-1537-2015
ISSN: 1726-4170
Projects: Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 15 Sep 2014 09:55
Last Modified: 13 Apr 2017 08:02
URI: http://oceanrep.geomar.de/id/eprint/25619

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