Benthic phosphorus cycling in the Peruvian oxygen minimum zone.
Lomnitz, Ulrike, Sommer, Stefan, Dale, Andrew W. , Löscher, Carolin R., Noffke, Anna, Wallmann, Klaus
and Hensen, Christian
(2016)
Benthic phosphorus cycling in the Peruvian oxygen minimum zone.
Biogeosciences (BG), 13
(5).
pp. 1367-1386.
DOI 10.5194/bg-13-1367-2016.
|
Text
bg-13-1367-2016.pdf - Published Version Available under License Creative Commons: Attribution 3.0. Download (2150Kb) | Preview |
|
|
Text (Supplement)
bg-13-1367-2016-supplement.pdf - Published Version Available under License Creative Commons: Attribution 3.0. Download (255Kb) | Preview |
Abstract
Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P at six stations, including the analysis of particles from the water column, surface sediments, and pore fluids, as well as in situ benthic flux measurements. A major fraction of solid-phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15). This suggests that the relative burial efficiencies of POC and TPP are similar under low-oxygen conditions and that the sediments underlying the anoxic waters on the Peru margin are not depleted in P compared to Redfield. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m−2 d−1), however, showing that a lack of oxygen promotes the intensified release of dissolved P from sediments, whilst preserving the POC / TPP burial ratio. Benthic dissolved P fluxes were always higher than the TPP rain rate to the seabed, which is proposed to be caused by transient P release by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments, indicating ongoing phosphorite formation. This is further supported by decreasing porewater phosphate concentrations with sediment depth, whereas solid-phase P concentrations were comparatively high.
Document Type: | Article |
---|---|
Keywords: | Oxygen minimum zone, phosphate, benthic P flux, Peru, mass balance, RV Meteor, M92 |
Research affiliation: | OceanRep > The Future Ocean - Cluster of Excellence > FO-R05 OceanRep > SFB 754 > B5 OceanRep > SFB 754 > B4 OceanRep > SFB 754 OceanRep > SFB 754 > B1 Kiel University OceanRep > SFB 754 > B6 OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems OceanRep > The Future Ocean - Cluster of Excellence OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography |
Refereed: | Yes |
Open Access Journal?: | Yes |
DOI etc.: | 10.5194/bg-13-1367-2016 |
ISSN: | 1726-4189 |
Projects: | SFB754, Future Ocean |
Expeditions/Models/Experiments: | |
Date Deposited: | 08 Mar 2016 09:19 |
Last Modified: | 23 Sep 2019 20:36 |
URI: | http://oceanrep.geomar.de/id/eprint/31730 |
Actions (login required)
![]() |
View Item |
Document Downloads
More statistics for this item...
Copyright 2013 | GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel | All rights reserved
Questions, comments and suggestions regarding the GEOMAR repository are welcomed
at bibliotheksleitung@geomar.de !