The Effects of Aggregation and Disaggregation on Particle Size Distributions and Water Clarity in the Coastal Ocean

The long-term goal of this research is to develop tools to quantitatively predict the effect of fine siliciclastics on water clarity in the coastal ocean. Scattering of light by suspended particles depends on sediment concentration, composition, and size distribution. Particle size distributions in coastal waters are dynamic because high concentrations of suspended sediment in coastal waters favor frequent encounter between particles. These encounters lead to the formation of large macroaggregate particles, or flocs, with diameters greater than 0.5 mm. While aggregation modifies the size distribution by building larger particles, variable and energetic turbulence in coastal waters can modify the size distribution by disrupting aggregates. Predictive knowledge of scattering depends on understanding of the conditions under which aggregation and turbulence-induced disaggregation alter the size distribution and of the form of the size distribution that these processes combine to produce. OBJECTIVES This research has three primary objectives. The first is to observe spatial and temporal variability in macroaggregate size distributions in situ in the bottom boundary layer (BBL) at the Coastal Mixing and Optics field site. The second is to relate observed size distributions to small particle size distributions, turbulent kinetic energy (tke), and optical properties in the BBL. The third is to extend BBL aggregation models to conditions of unsteady flow.
See also ADM002252.