Modeling the Settling Velocity of Organic Settling Matter with the Consideration of Organic Properties

Estimating the settling velocity of organic settling matter (OSM) under the effects of organic properties is necessary for developing a pelagic-benthic coupled ecosystem model to evaluate the coastal environment, where OSM deposits on the sea bottom. In this study, laboratory experiments were performed with several materials, such as bentonite, OSM and suspended matter, using a particle distribution analyzer to reveal the effects of organic properties on the settling factors (e. g. effective density, fractal dimension). From the experimental results, it was found that the effective density of each material decreased in association with the increase in particle size from a certain size. Comparing these results to the organic properties of materials, it is evident that the organic properties, such as the absorption amount and the decomposition degree of organic matter, strongly affect the physical properties, such as the fractal dimension and the effective density. Furthermore, a model formula of the settling velocity, in which the effects of the organic properties are considered, has been suggested.