| Vegetated floodplains and wetlands trap particulates, a process which is important for water quality and wetland form and function. The rate of particle removal by vegetation remains poorly characterized, especially for fine particles with a range of particle sizes. Results from a series of laboratory flume experiments with synthetic grasses that evaluated particle removal rates for a range of particle sizes and experimental treatments are presented. Suspended road dust (1.25 -- 109 microm diameter) concentration was monitored in a laboratory flume as flow velocity, initial particle concentration, plant stem density, and the presence of biofilm were varied. Particle concentration was monitored and first-order decay models were fit to the particle concentration data. The presence of vegetation was found to increase the rate of particle capture/decay compared to a bare flume. Additionally, we observed trapping of small (<30microm diameter) particles by vegetation. Particle capture by plants increased with particle size, the presence of biofilm, and stem density. Yet, the rate of particle capture was found to decrease with flow velocity. ANOVA mixed models were used to test the significance of these results; the presence of biofilm, stem density, flow velocity, and initial particle concentration were found to significantly contribute to the rate of particle capture. Additionally, we observed an increase in 3--7microm particles over time. |
