Remote acoustic sensing of the particulate phase of industrial chemical wastes and sewage sludge : report on the seasonal variability of the dispersion of the particulate phase as observed from three cruises, July 1977, January-February 1978, and April 1978

Abstract

The seasonal variability of the dispersion of the particulate phase of industrial chemical waste has been studied with acoustic backscattering techniques at Deep Water Dumpsite 106 (DWD 106). The vertical dispersion of the particulates has been found to be strongly dependent on the depth of the mixed layer and the magnitude of the density gradient associated with the seasonal thermocline. The horizontal dispersion of the particulates as a function of depth has been found to be strongly dependent on the shear present in the water column. Entire waste plumes have been found to be advected out of the dumpsite in less than 24 hours when the area is occupied by a warm core ring. Simple calculations based upon Stoke's law are presented to reveal the impact of variable oceanic density structure on the sink rate of particles and to indicate the need for incorporating these considerations into numerical models. A short discussion is presented on (1) the need to make field measurements on the magnitude of both turbulence and shear in the water column and (2) the need to incorporate shear and turbulence-dependent calculations for the sink rates of particles into those numerical models which may be used to predict the particulate and effluent dispersion rates at DWD 106.