COLLOID PARTICLE SIZES IN THE MISSISSIPPI RIVER AND SOME OF ITS TRIBUTARIES, FROM MINNEAPOLIS TO BELOW NEW-ORLEANS

An on-board technique was developed that combined discharge-weighted p umping to a high-speed continuous-flow centrifuge for isolation of the particulate-sized material with ultrafiltration for isolation of coll oid-sized material. In order to address whether these processes change d the particle sizes during isolation, samples of particles in suspens ion were collected at various steps in the isolation process to evalua te changes in particle size. Particle sizes were determined using lase r light-scattering photon correlation spectroscopy and indicated no ch ange in size during the colloid isolation process. Mississippi River c olloid particle sizes from twelve sites from Minneapolis to below New Orleans were compared with sizes from four tributaries and three seaso ns, and from predominantly autochthonous sources upstream to more allo chthonous sources downstream. (C) 1998 John Wiley Sons, Ltd.