Compartmental models of particle transport and storage in streams

The subject of this study Is a steady-state analysis of stream particle transport. Three compartmental models, all with storage zones (areas of nearly zero velocity), were used to model major types of particles: non-nutritive solute, sediment, and nutrient. My goal was to study steady-state particle levels as a function of many processes. Including sediment settling and resuspension rates, chemical conversion to recalcitrant forms, biotic characteristics, and physical attributes of the storage zone. General trends emerge from analysis of these models. Storage zone particle concentrations at steady state are found to be dependent on flow rate, concentration of Inflow particles, turbulence, and loss to recalcitrant forms. In the case of sediment particles. Inflow sediment concentration and stream bottom area Interact In their control of storage zone sediment concentration. Efficiency of nutrient procurement and retention by plant biomass Is found to be dependent on Inflow nutrient concentrations. A surprising result Is that In all three models there exists a threshold effect for certain parameters, such that the storage zone particle concentration (or. In the case of the biomass model, biomass nutrient concentration) either Increases or decreases with Increasing parameter values, and the factor which determines whether It Increases or decreases Is the Inflowing nutrient concentration relative to some threshold value.