Particle Transport and Carbon Export over the Northwest Atlantic Margin

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"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."In this project researchers at the Woods Hole Oceanographic Institute (WHOI) seek to address two primary questions regarding the transport of organic carbon over the New England continental margin. Their first question addresses the relative importance of intermediate nepheloid layers versus benthic nepheloid layers for organic carbon transport. Their second question focuses on assessing the importance of interannual variability on particle transport. The researchers will collect both settling and suspended particles along the NW Atlantic ocean margin, and they will utilize both novel and established tracers of material transport to address their primary research questions. Their assessments of particle dynamics will be coupled to an existing hydrographic observation program along an ocean section between Cape Cod and Bermuda ('Line W'). This program is focused on the physical characteristics of the region, and provides an accompanying framework for the study of carbon dynamics. The importance of the work to global carbon cycling lies in the fact that continental margins generally maintain high biological production and are physically dynamic environments. One potential fate of the biologically produced carbon is that it may be exported to the deep ocean, yet the magnitude of that exported carbon is generally not well defined. Over the Northwest Atlantic margin, large-scale currents have the potential to be an important dispersal mechanism for organic carbon to the ocean interior. In a prior research project, the investigators hypothesized that the lateral transport of particulate organic carbon occurs via a bottom nepheloid layer (BNL) maintained by the Deep Western Boundary Current (DWBC). Although their research supports the notion that the DWBC transports a significant amount of organic carbon, their observations also indicate that intermediate nepheloid layers (INLs) emanating from the shelf-slope break and upper slope of the Mid Atlantic Bight may also be important vectors for carbon export. Broader Impacts: The Line W program initiated by physical oceanographers at WHOI and involving partners at other institutions, has established a website for activities centered on this section. The researchers are in the process of uploading their biogeochemical flux data onto this website and intend to develop a link to the Ocean and Carbon Biogeochemistry (OCB) Project Office website. In addition, these researchers intend to continue to archive aliquots of materials from the sediment trap program, and make these available to other members of the research community. In addition to their synergy with the Line W program, the researchers envision that the samples and data emanating from their project will provide important context for other studies in this region, particularly those exploring tracers of water mass movement, or seeking to understand elemental boundary exchange and scavenging processes. The research will provide graduate student support for MIT/WHOI Joint Program student, David Griffith. It is anticipated that this student will work closely with Drs. Eglinton and Charette, gaining experience in both organic geochemical and radiochemical methods and will participate in several of the planned research cruises.