title: An Integrated Experimental and Modeling Approach to Predict Sediment Mixing from Benthic Burrowing Behavior.
abstract: Bioturbation is the dominant mode of sediment transport in many aquatic environments and strongly influences both sediment biogeochemistry and contaminant fate. Available bioturbation models rely on highly simplified biodiffusion formulations that inadequately capture the behavior of many benthic organisms. We present a novel experimental and modeling approach that uses time-lapse imagery to directly relate burrow formation to resulting sediment mixing. We paired white-light imaging of burrow formation with fluorescence imaging of tracer particle redistribution by the oligochaete Lumbriculus variegatus. We used the observed burrow formation statistics and organism density to parametrize a parsimonious model for sediment mixing based on fundamental random walk theory. Worms burrowed over a range of times and depths, resulting in homogenization of sediments near the sediment-water interface, rapid nonlocal transport of tracer particles to deep sediments, and large areas of unperturbed sediments. Our fundamental, parsimonious random walk model captures the central features of this highly heterogeneous sediment bioturbation, including evolution of the sediment-water interface coupled with rapid near-surface mixing and anomalous late-time mixing resulting from infrequent, deep burrowing events. This approach provides a general, transferable framework for explicitly linking sediment transport to governing biophysical processes.
authors.affiliation: Department of Civil and Environmental Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Roche
authors.affiliation: Lyles School of Civil Engineering, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907-2051, United States.
authors.forename: Antoine F
authors.initials: AF
authors.lastname: Aubeneau
authors.affiliation: Department of Civil and Environmental Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States.
authors.forename: Minwei
authors.initials: M
authors.lastname: Xie
authors.affiliation: Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors.forename: Tomás
authors.initials: T
authors.lastname: Aquino
authors.affiliation: Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors.forename: Diogo
authors.initials: D
authors.lastname: Bolster
authors.affiliation: Department of Civil and Environmental Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States.
authors.forename: Aaron I
authors.initials: AI
authors.lastname: Packman
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D019015:Geologic Sediments / Q000737:chemistry*; D008962:Models, Theoretical; D009068:Movement; D009835:Oligochaeta; D014867:Water; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water