Collaborative Research: Resolving the processes controlling the distribution of the biogenic trace gas dimethylsulfide and related compounds in the Subarctic NE Pacific

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Researchers from the University of South Alabama and Woods Hole Oceanographic Institution will use a new method to quantify the cycling of dimethylsulfide (DMS) and its related compounds in the Subarctic Northeast Pacific Ocean. DMS is a sulfur-containing gas that is abundant in the world's oceans. Oceanic DMS emissions are the largest source of biologically-produced sulfur to the atmosphere, with important implications for atmospheric chemistry and the world's climate. Research over the last two decades has revealed that a complex web of processes is involved in the cycling of DMS in the ocean. However, many of these processes remain poorly understood. Results from this research will provide key information to a broad range of disciplines from microbiology to Earth-system science, and further develop methods and technologies useful to the broader research community. The study will also provide educational opportunities for graduate, undergraduate, K-12 students, and high school teachers. In addition, results from the study will be communicated to the general public through podcasts. Dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO) play critical roles in marine microbial ecology as metabolic substrates and as essential components of the oceanic sulfur cycle. Moreover, oceanic DMS emissions are geochemically important as the largest source of biogenic sulfur to the atmosphere and have been implicated as a contributing factor for the atmospheric radiative balance, with important climate implications. The researchers will study the dynamics of the biogenic trace gas DMS, and the related compounds DMSP and DMSO in the Subarctic Northeastern Pacific, a high-nutrient, low-chlorophyll (HNLC) region with exceptionally high DMS concentrations. They will use a novel isotope tracer method to quantify the in-situ turnover rates of these compounds in different surface water masses across frontal boundaries with contrasting DMS/phosphorus/oxygen and nutrient concentrations, and in Lagrangian experiments to investigate temporal evolution of cycling rates. Using newly-developed methods for automated underway sampling, researchers will map the surface distributions of DMS, DMSP and DMSO at unprecedented spatial resolution. Results from this study will improve our understanding of the spatial variability in oceanic DMS, DMSP, and DMSO concentrations in surface waters by accurately measuring the cycling rates of these compounds.