Deep-Sea Sediment Transport Storm

摘要

Photographs taken of the sea bottom since the 1960s suggest that sediments at great depth may be actively resuspended and redistributed. Further, it has been suspected that active resuspension/transport may be required to maintain elevated concentrations of particles in deep-sea nepheloid layers. But currents with sufficient energy to erode the bottom, and to maintain the particles in suspension, have not been observed concurrently with large concentrations of particles in the deep nepheloid layer. The high-energy benthic boundary-layer experiment (HEBBLE) was designed to test the hypothesis that bed modifications can result from local erosion and deposition as modelled by simple one-dimensional local forcing mechanics. We observed several 'storms' of high kinetic energy and near-bed flow associated with large concentrations of suspended sediment during the year-long deployments of moored instruments at the HEBBLE study site. These observations, at 4,880 m off the Nova Scotian Rise in the north-west Atlantic, indicate that large episodic events may suspend bottom sediments in areas well removed from coastal and shelf sources. Reprints. (fr)