ANALYSIS OF SUSPENDED-PARTICLE-SIZE DISTRIBUTIONS OVER THE NOVA SCOTIAN CONTINENTAL RISE
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The relationships of particle-size distributions to particle concentrations, silicate content and process of bottom boundary layer formation on the Nova Scotian Continental Rise were examined to analyze the dynamics of the benthic nepheloid layer. High particle concentrations (> 400 g 1-1) in the intense benthic nepheloid layers are nearly always associated with a coarse ({reversed tilde equals} 8 m) particle mode. These coarse particles must be renewed on a time scale of weeks in order to be maintained in suspension. No unique type of particle-size distribution in the benthic nepheloid layer is associated with water masses distinguished on the basis of silicate content. However, the method of formation of the bottom boundary layer does influence the particle-size distributions. Locally mixed bottom boundary layers are dominated by a coarse particle mode ({reversed tilde equals} 8 m). Bottom boundary layers composed of hydrographically distinct filaments of bottom water mainly contain fine particles ({reversed tilde equals} 2-3 m) obtained upstream. Where the filament has extremely high particle concentrations (> 1 mg 11), the fine particle mode is masked by a locally resuspended coarse mode indicating that the filament must occasionally (within 200-300 km) be accelerated by some external energy to the point that the critical shear stress for erosion is exceeded. 1985.
