ERDC/EL TR-13-13 "Phytoplankton as Particles – A New Approach to Modeling Algal Blooms"

The authors investigate the hypothesis that phytoplankton blooms can be modeled by treating phytoplankton as discrete particles capable of selfinduced transport via buoyancy regulation or other behaviors. A particletracking model is inserted into the CE-QUAL-ICM eutrophication model. Phytoplankton are quantified as carbonaceous biomass attached to the particles. Kinetics are adapted from CE-QUAL-ICM. The new model is operated along with existing hydrodynamic and watershed models of the Potomac River estuary. Initial application is to the winter-spring 1994 period. The new model is compared to observations and to a conventional model of the spring diatom bloom. The particle-based model successfully computes a subsurface chlorophyll maximum. The model characteristically displays heterogeneous spatial distribution of chlorophyll with highamplitude oscillations at the semi-diurnal period. The characteristics and applicability of the particle approach are now established. The model requires optimization of parameter values to improve representation of the observed bloom in the Potomac. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/EL TR-13-13 iii