Investigating the role and chemical nature of dissolved organic matter in marine environments

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Marine dissolved organic matter (DOM) is an enigmatic pool of carbon-based compounds in the world's oceans, representing a pool of carbon comparable in size to the atmospheric pool of carbon dioxide. It is a complex mixture of thousands of unique chemical compounds, of which only ~10% are truly identifiable. DOM reactivity varies considerably with some fractions turning over in the order of hours to days, and others turning over on the scale of millennia. The chemical nature of DOM drives reactivity and to understand the diverse roles that DOM plays in the carbon cycle from local to global scales, it is necessary to understand the chemistry of DOM. Our research program is defined by the overarching goal of understanding the role that DOM plays in the global carbon cycle and how it impacts marine ecosystems. Three specific objectives will examine different aspects of DOM chemistry: 1.Linking Reactivity to Detailed Chemical Analysis Despite recent advances in analytical techniques, little is known about how the presence or absence of individual compounds affects the overall reactivity of DOM. It is this reactivity, however, that determines the ultimate fate of DOM in the marine system. We will use methodical approaches to bridge the structure and function of DOM; focusing on defining the chemical nature of DOM in the context of its reactivity in the marine environment. Specific emphasis will be on determining the important functional groups that drive DOM dynamics. 2.Linking Advanced Analytical Techniques to Optical Properties Combining optical measurements with detailed chemical analysis will give insight into what causes the optical properties of marine waters, with the goal of developing better chemical tracers for oceanic processes. Advanced analytical techniques will provide the detailed chemical information about DOM, and optical techniques, which are relatively rapid and low-cost, will allow for better spatial and temporal coverage of DOM properties. Developing these linkages will provide better synoptic analyses of the importance of DOM dynamics in marine systems. 3.Investigating the Dynamics of Organic Matter in Sensitive Marine Environments Marine environments play important roles in the global carbon cycle. With respect to DOM, they are both affected by and affecting how carbon cycles in the marine environment. Understanding DOM cycling in rapidly changing environments is a crucial part of understanding the effects of climate change in the global ocean. Northern and coastal regions are changing rapidly. Our research program will focus on areas such as coastal Labrador and the North Atlantic Ocean. We will investigate DOM dynamics by taking advantage of Volunteer Observing Ships to collect broad spatial and temporal datasets of DOM in the marine environment. The combination of these three complementary objectives and the results they will provide will help us to understand a challenging but crucial part of the marine carbon cycle.