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GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L09308, doi:10.1029/2004GL019581, 2004

Light-driven cycling of dimethylsulfide (DMS) in the Sargasso Sea: Closing the loop

Dierdre A. Toole

Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, California, USA


David A. Siegel

Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, California, USA


Abstract

The factors driving dimethylsulfide (DMS) cycling in oligotrophic environments are isolated using a time-series of DMS sampled in the Sargasso Sea. The observed distribution of DMS is inconsistent with bottom-up processes related to phytoplankton production, biomass, or community structure changes. DMS concentrations and estimates of net biological community production are most highly correlated with physical and optical properties, with the dose of ultraviolet radiation (UVR) accounting for 77% of the variability in mixed layer DMS concentrations. Physiological stresses associated with shallow mixed layers and high UVR are the first order determinant of biological production of DMS, indicating that DMS cycling in open-ocean regions is fundamentally different than in eutrophic regions where phytoplankton blooms provide the conditions for elevated DMS concentrations. The stress regime presented here effectively closes the DMS-climate feedback loop for open-ocean environments. This response may also provide a climatic role for phytoplanktonic processes in response to anthropogenic forcing.

Received 26 January 2004; accepted 9 April 2004; published 6 May 2004.

Index Terms: 4805 Oceanography: Biological and Chemical: Biogeochemical cycles (1615); 1635 Global Change: Oceans (4203); 1615 Global Change: Biogeochemical processes (4805); 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 4842 Oceanography: Biological and Chemical: Modeling.

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Citation: Toole, D. A., and D. A. Siegel (2004), Light-driven cycling of dimethylsulfide (DMS) in the Sargasso Sea: Closing the loop, Geophys. Res. Lett., 31, L09308, doi:10.1029/2004GL019581.