A growing body of evidence indicates that oceanic particulate organic matter (OM) is subject to extensive redistribution by bottom currents so that material at a given depositional location may be substantially pre-aged and remote from its site of formation. Processes that impart spatial and temporal decoupling of OM sources and sinks may be particularly prevalent on continental margins where particles can be laterally advected down- and along-slope, and ultimately exported to the ocean interior.
Researchers at Woods Hole Oceanographic Institution have pooled their expertise in geochemistry, sedimentology and physical oceanography to document these processes on the N.W. Atlantic margin. Beginning in Spring 2004, an array of moored physical oceanographic instrumentation and coordinated shipboard measurements will establish in the dynamics of the Deep Western Boundary Current and its interactions with the Gulf Stream in unprecedented detail. For this project, the researchers will augment the moorings with transmissometers and collect sediments, sediment trap samples and suspended particles for detailed geochemical, isotopic and mineralogical analyses, permitting them to constrain the nature, provenance, age and fluxes of particles and organic matter transported via lateral advection and to help establish its ultimate depositional fate.
A broader impact will be a better ability to identify other areas that may be similarly affected, and hence to establish its global significance. If these processes are widespread, this finding would have important implications for our understanding of the global carbon cycle since the hypothesized transport mechanism of benthic "storms" is climatically controlled. An ability to recognize diagnostic sediment and OM accumulation patterns could also be identified in the sedimentary record and unambiguously interpreted in the context of climate change.
