Aquatic Sciences Meeting, Albuquerque 2001

CS24 Optics

Date: Tuesday, February 13, 2001, Time: 4:30:00 PM

Location: Sandia/Santa Ana

Wells, M, L, University of Maine, Walpole, USA,

SIZE CHARACTERIZATION OF COLLOIDAL CDOM IN SURFACE WATERS OFF THE MISSISSIPPI PLUME BY FLOW FIELD-FLOW FRACTIONATION

Colloidal organic phases may form both a food source to the microbial web and a vector for the aggregative removal of carbon and metals from surface waters. Cross-flow filtration has been widely applied in colloid studies, but this approach can only isolate bulk high molecular weight matter from seawater. In contrast, Flow field-flow fractionation can isolate as well as partition colloidal matter into a continuum of hydrodynamic sizes. Combined with on-line preconcentration, flow-FFF provides a novel means for characterizing the molecular weight spectrum of marine colloidal matter. Surface waters in and around the Mississippi plume were studied with Flow-FFF using UV detection (254 nm) on the system outflow. Results show a range of distinct, reproducible molecular weight spectra that appear to be characteristic of different water types and plankton community. Typical spectra for saline Mississippi plume waters show a predominance of small-sized organic colloids. However, distinct populations of low and high molecular weight matter were associated with elevated surface and sub-surface chlorophyll concentrations. Flow-FFF could be a valuable tool for assessing the character and dynamics of colloidal CDOM cycling.

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Aquatic Sciences Meeting, Albuquerque 2001

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