Research Location: Open ocean transects across the major ocean basins
Oceanic DOM represents one of the largest exchangeable carbon reservoirs on earth. Estimated to be 662 Pg C (Pg = 1015 g C), the global dissolved organic carbon (DOC) value is comparable to the mass of inorganic C in the atmosphere. Because of this, small perturbations in the production or sink terms of the oceanic DOC pool could strongly impact the exchange of carbon between the ocean and atmosphere. The goal of collaborative research between the Carlson Lab and Dennis Hansell's Laboratory (University of Miami) is to better resolve the distribution patterns of DOM in the various basins of the global ocean. Work conducted as part of the Joint Global Ocean Flux (JGOFS) program and most recently the Climate Variability (CLIVAR) Repeat Hydrography program has revealed striking variability of DOM in the ocean's interior.
This DOC pool contains a myriad of compounds that comprise broad pools of lability that turn over on time scales from seconds to millennia. While much of the annually produced DOM is consumed by heterotrophic microbes, approximately 20% of the global net community production escapes rapid microbial remineralization and can be vertically exported to depth by ocean mixing, thus representing an important contribution to the ocean biological carbon pump. An objective of this continuing work is to quantify the contribution of DOM export in various regions of the global ocean and to determine the fate of the DOM after export. We are interested in how microbes transform the quantity and quality of organic matter. An additional goal is to assess components of the DOM pool such as neutral aldoses and determine how they affect and are affected by microbial processes.
For a glimpse of how these oceanographic cruises are conducted, please check out this video put together by one of our students!