Feedbacks between oceanic redox states and marine productivity: A model perspective focused on benthic phosphorus cycling.

Wallmann, Klaus (2003) Feedbacks between oceanic redox states and marine productivity: A model perspective focused on benthic phosphorus cycling. Open Access Global Biogeochemical Cycles, 17 (3). p. 1084. DOI 10.1029/2002GB001968.

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Abstract

A new model for the marine cycles of particulate organic carbon (POC), oxygen, nitrate, and phosphorus has been developed and applied to explore the controls and constraints on marine productivity and nutrient inventories. The coupled benthic-pelagic model uses a new approach for the simulation of the reactive phosphorus turnover (Preac corresponding to the sum of organic P, authigenic P, and adsorbed phosphate) in marine sediments. The simulated POC/Preac burial ratio in shelf, slope and rise, and deep-sea sediments increases under strongly reducing conditions in agreement with field observation. The model runs revealed that the spread of anoxia in bottom waters may enhance the productivity of the global ocean by one order of magnitude if sufficient nitrate is provided by N2-fixation. Thus anoxic bottom waters promote eutrophic conditions and vice versa. Additional model runs showed that the productivity and nutrient inventory of the glacial ocean were probably enhanced due to the falling sea level. Marine regression induced a narrowing of the depositional areas on the continental shelves and thereby an increase in the fraction of POC exported to the deep ocean. The accelerated POC delivery, in turn, decreased the oxygen contents of the deep water and thus favored the release of phosphate from deep-sea and rise sediments. Enhanced recycling of phosphate at the seafloor promoted further POC export in a positive feedback loop.

Document Type: Article
Keywords: benthic phosphate fluxes, marine productivity, paleoproductivity, nutrient inventories, redox conditions, feedbacks
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2002GB001968
ISSN: 0886-6236
Date Deposited: 18 Feb 2008 17:26
Last Modified: 15 Mar 2018 12:46
URI: http://oceanrep.geomar.de/id/eprint/5908

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