A dynamic model of oceanic sulfur (DMOS) applied to the Sargasso Sea: Simulating the dimethylsulfide (DMS) summer paradox.

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Title A dynamic model of oceanic sulfur (DMOS) applied to the Sargasso Sea: Simulating the dimethylsulfide (DMS) summer paradox.
Author Vallina, S. M.; Simo, R.; Anderson, T. R.; Gabric, Albert Jerome; Cropp, Roger Allan; Pacheco, J. M.
Journal Name Journal of Geophysical Research (Biogeosciences)
Year Published 2008
Place of publication Washington DC
Publisher American Geophysical Union
Abstract A new one-dimensional model of DMSP/DMS dynamics (DMOS) is developed and applied to the Sargasso Sea in order to explain what drives the observed dimethylsulfide (DMS) summer paradox: a summer DMS concentration maximum concurrent with a minimum in the biomass of phytoplankton, the producers of the DMS precursor dimethylsulfoniopropionate (DMSP). Several mechanisms have been postulated to explain this mismatch: a succession in phytoplankton species composition towards higher relative abundances of DMSP producers in summer; inhibition of bacterial DMS consumption by ultraviolet radiation (UVR); and direct DMS production by phytoplankton due to UVR-induced oxidative stress. None of these hypothetical mechanisms, except for the first one, has been tested with a dynamic model. We have coupled a new sulfur cycle model that incorporates the latest knowledge on DMSP/DMS dynamics to a preexisting nitrogen/carbon-based ecological model that explicitly simulates the microbial-loop. This allows the role of bacteria in DMS production and consumption to be represented and quantified. The main improvements of DMOS with respect to previous DMSP/DMS models are the explicit inclusion of: solar-radiation inhibition of bacterial sulfur uptakes; DMS exudation by phytoplankton caused by solar-radiation-induced stress; and uptake of dissolved DMSP by phytoplankton. We have conducted a series of modeling experiments where some of the DMOS sulfur paths are turned “off” or “on,” and the results on chlorophyll-a, bacteria, DMS, and DMSP (particulate and dissolved) concentrations have been compared with climatological data of these same variables. The simulated rate of sulfur cycling processes are also compared with the scarce data available from previous works. All processes seem to play a role in driving DMS seasonality. Among them, however, solar-radiation-induced DMS exudation by phytoplankton stands out as the process without which the model is unable to produce realistic DMS simulations and reproduce the DMS summer paradox.
Peer Reviewed Yes
Published Yes
Publisher URI http://www.agu.org/journals/jd/
Alternative URI http://dx.doi.org/10.1029/2007JG000415
Copyright Statement Copyright 2008 American Geophysical Union. The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Volume 113
Page from 1
Page to 18
ISSN 0148-0227
Date Accessioned 2008-05-02
Date Available 2010-11-03T07:03:28Z
Language en_AU
Research Centre Atmospheric Environment Research Centre; Australian Rivers Institute
Faculty Faculty of Science, Environment, Engineering and Technology
Subject PRE2009-Cross discipline
URI http://hdl.handle.net/10072/23703
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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