März, C, Poulton, SW, Wagner, T et al. (2 more authors) (2014) Phosphorus burial and diagenesis in the central Bering Sea (Bowers Ridge, IODP Site U1341): Perspectives on the marine P cycle. Chemical Geology, 363. 270 - 282. ISSN 0009-2541
Abstract
To reconstruct the cycling of reactive phosphorus (P) in the Bering Sea, a P speciation record covering the last ~4Ma was generated from sediments recovered during Integrated Ocean Drilling Program (IODP) Expedition 323 at Site U1341 (Bowers Ridge). A chemical extraction procedure distinguishing between different operationally defined P fractions provides new insight into reactive P input, burial and diagenetic transformations. Reactive P mass accumulation rates (MARs) are ~20-110μmol/cm/ka, which is comparable to other open ocean locations but orders of magnitude lower than most upwelling settings. We find that authigenic carbonate fluorapatite (CFA) and opal-bound P are the dominant P fractions at Site U1341. An overall increasing contribution of CFA to total P with sediment depth is consistent with a gradual "sink switching" from more labile P fractions (fish remains, Fe oxides, organic matter) to stable authigenic CFA. However, the positive correlation of CFA with Al content implies that a significant portion of the supposedly reactive CFA is non-reactive "detrital contamination" by eolian and/or riverine CFA. In contrast to CFA, opal-bound P has rarely been studied in marine sediments. We find for the first time that opal-bound P directly correlates with excess silica contents. This P fraction was apparently available to biosiliceous phytoplankton at the time of sediment deposition and is a long-term sink for reactive P in the ocean, despite the likelihood for diagenetic re-mobilisation of this P at depth (indicated by increasing ratios of excess silica to opal-bound P). Average reactive P MARs at Site U1341 increase by ~25% if opal-bound P is accounted for, but decrease by ~25% if 50% of the extracted CFA fraction (based on the lowest CFA value at Site U1341) is assumed to be detrital. Combining our results with literature data, we present a qualitative perspective of terrestrial CFA and opal-bound P deposition in the modern ocean. Riverine CFA input has mostly been reported from continental shelves and margins draining P-rich lithologies, while eolian CFA input is found across wide ocean regions underlying the Northern Hemispheric "dust belt". Opal-bound P burial is important in the Southern Ocean, North Pacific, and likely in upwelling areas. Shifts in detrital CFA and opal-bound P deposition across ocean basins likely occurred over time, responding to changing weathering patterns, sea level, and biogenic opal deposition.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2013 Elsevier B.V. All rights reserved. This is an author produced version of a paper published in Chemical Geology. Uploaded in accordance with the publisher's self-archiving policy |
Keywords: | Integrated Ocean Drilling Program; Bering Sea; phosphorous; sequential extraction; biogenic opal; carbonate fluorapatite |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 29 Sep 2014 15:05 |
Last Modified: | 17 Jan 2018 17:07 |
Published Version: | http://dx.doi.org/10.1016/j.chemgeo.2013.11.004 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.chemgeo.2013.11.004 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:80330 |