Acoustical observations of anthropogenic discharge plumes

Acoustical methods such as backscatter and Doppler current measurements are gaining substantial acceptance in both point source and nonpoint source oceanic pollution studies. Using acoustical backscattered energy, chemical and biological samplers are guided to oceanic water column regions of higher contaminant concentration. In typical discharge operations, e.g., dredged material, sewage effluents, oil‐well blowouts, after‐discharge backscatter levels are initially at least three to four orders of magnitude above normal background backscatter levels and are available for tracking of plumes and guidance of sampling operations. Additionally, acoustical backscatter may also be used to map naturally occurring surfaces within the oceanic water column along which both discharged material and naturally recurring particulates may accumulate. Thus nonacoustical sampling may continue to be guided indirectly far beyond the time or distance at which plume concentration levels may be considered to have diminished to a...