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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #295199
Title: Colloid filtration in surface dense vegetation: Experimental results and theoretical predictions

Author
item WU, LEI - University Of Florida
item MUNOZ-CARPENA, RAFAEL - University Of Florida
item GAO, BIN - University Of Florida
item WENG, YAN - University Of Illinois
item Pachepsky, Yakov

Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2014
Publication Date: 7/20/2014
Citation: Wu, L., Munoz-Carpena, R., Gao, B., Weng, Y., Pachepsky, Y.A. 2014. Colloid filtration in surface dense vegetation: Experimental results and theoretical predictions. Environmental Science and Technology. 48(7):3883-3890.

Interpretive Summary: Vegetative filter strips are routinely recommended as a best management practice for the removal of colloidal size particles, including microorganisms, from runoff. It is generally assumed that the primary mechanism of colloid retention is infiltration into the soil column or deposition onto the soil surface. Another potential mechanism of colloid retention by vegetation is attachment or entrapment on plant stems due to the presence of trichomes, which are hair-like protuberances on the stem surface. In experiments with colloidal suspension flowing through densely planted Browntop millet seedlings, we observed substantial retention of colloids. Since the soil was sealed, the results could not be accounted for using by filtration. The results could only be explained by retention onto the millet seedlings. The results of this work should be of interest to environmental scientists and engineers dealing with the fate and transport of biological and abiotical colloidal particles in runoff affecting water quality.

Technical Abstract: Understanding colloid and colloid-facilitated contaminant transport in overland flow through dense vegetation is essential to protect water quality for the environment. In previous studies, a single-stem efficiency theory for rigid and clean stem systems has been developed to predict colloid filtration by plant stems of vegetation in laminar overland flow. Hence, in order to improve the accuracy of the single-stem efficiency theory to real dense vegetation system, a new dimensionless number was incorporated into that accounts for the effect of plant surface properties on the filtration of colloids by stems. Laboratory dense vegetation flow chamber experiments and model simulations were used to determine the kinetic deposition (filtration) rate of colloids in the vegetation system under various conditions. The results showed that, in addition to flow hydrodynamics and solution chemistry, steric repulsion afforded by biopolymer brush player on the plants stem surface could also play a significant role in controlling colloid deposition on vegetation in overland flow. For the first time, an extended single-stem efficiency theory which considers the steric repulsion effect and describes the experimental data with good accuracy is developed. The extended theory can be used to not only help construct and refine mathematical models of colloid transport in real vegetation systems in overland flow but also inform the development of theories of colloid deposition on various polymer brush surfaces in natural, engineered, and biomedical systems.