A differentiation method for separating a mixture of suspended particle size distributions

摘要

A simple method is proposed to partition a mixture of two populations insuspended particle size data. The method, termed here "the differentiationmethod" is based on the function of the lognormal distribution. Suspendedmaterial in marine or estuarine situations often consists ofdifficult-to-interpret complex populations. The treatment of particle size databy the method described enables the confirmation of the lognormal law and alsothe demonstration of the occurrence of a combination of a number of populationswhich may not be distinguished by the classical Gaussian transformation orautomatic methods. A simple combination of graphical and numerical techniquespermits the decomposition and the easy determination of the various statisticalparameters (median diameter, mean diameter, etc...). The method is applied tointerpret observed size distributions of suspended particulate matter in theSeine estuary. The method enables the determination of the relative sizes of theconstituent sub-populations that comprise the total suspended matter. In theexample used to illustrate the method, particles are shown to be resuspended asa function of different hydrodynamic parameter.