Reassessment of dissolved DMSP concentrations and turnover flux in the ocean

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"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Researchers at the University of South Alabama will evaluate new approaches for measuring the biologically available pool of dimethylsulfoniopropionate (DMSPd) and its turnover rate in a variety of marine systems. DMSPd is rapidly cycled in the upper ocean and is thought to be a source of carbon and sulfur for microbial communities. In addition, it is believed to be a major precursor for DMS, which is a volatile sulfur compound that is involved in the atmospheric sulfur cycle and DMS is a climate-active gas. However, conclusions regarding certain components of the DMSPd cycle that are based on prior research might be in error because of inaccurate determinations of its dissolved concentration. The new information that will be developed during this project will be used to reevaluate the role of DMSPd in the carbon and sulfur cycles of the surface ocean and as a precursor of DMS. The first objective of the work includes determining the biologically available fraction of the dissolved DMSP pool in estuarine, coastal and oceanic waters. The second objective will be to assess the existing analytical procedure to determine if it overestimates the biologically available fraction of DMSPd. The third and fourth objectives focus on the methods for, and quantifying the turnover rates of, this compound, and the fifth objective is focused on utilizing this rate information to assess whether DMSPd is a significant source of carbon and sulfur for marine microbiological communities.DMSP may have some of the highest mass fluxes through the ocean system of any single known compound. However, knowledge of those fluxes is uncertain and this work will remove a lot of that uncertainty. DMSP cycling is of interest to scientists from a broad range of disciplines including biogeochemisty, ecology and atmospheric science. Oceanic-atmospheric trace gas exchange is important to the climate feedbacks, and DMS is an important example of ocean-produced gases that can influence the atmosphere. One graduate student, one undergraduate student and one research technician will be trained as part of this project, and several activities involving public outreach and education will be initiated.