The Floc Camera: A Three-Dimensional Imaging System of Suspended Particulate Matter
In situ attributes of suspended particulate matter (SPM) in the ocean have proven difficult to ascertain. Conventional sampling of SPM, including water samplers (Folger, 1968), In situ pumps (Bishop and Edmond, 1976), monochromatic-light attenuance meters (Winters and Buckley, 1980), nephelometers (Thorndike, 1975), and high-frequency acoustic profiling (Hay, 1983), have provided proxy information on the quantity and nature of suspended particles. Each of these analytical methods has advantages over the other, yet together they have led to gross errors in estimating the flux of sediment to the ocean floor (McCave, 1975). For instance, water samplers and submerged pumps can alter the characteristics of flocculated particles through mechanical interference. The pressure wave generated during a water bottle closure, or the multilayered baffles and filters used in submerged pumps, may destroy the larger and fragile particles of marine snow. Also the coarser, or faster settling particles tend to be undersampled by water bottle samplers (Syvitski and Murray, 1981). Furthermore, the concentration of suspended particles increases in the bottom of water samplers before withdrawal, and this can cause SPM to interact in ways different than found in the unrestricted ocean. The path length of attenuance meters can be too short, or the beam too narrow, to adequately sense widely dispersed SPM. Acoustic profiles are calibrated on constant density spherical particles (Hay and Mercer, 1985), yet the shape and density of marine suspensates remain largely unknown.
KeywordsFiltration Resi Settling Xenon Photography
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