Packman, A.I., J.-F. Gaillard, and G.A. Burton, Jr. SERDP Project ER-1745, 120 pp, 2016

In lab experiments performed to determine the coupled effects of hydrodynamics, bioturbation, and biogeochemical processes on the transformation, mobility, bioavailability, and toxicity of metals in contaminated sediments, oxidation of surficial sediments liberated metal species that were then mobilized to both porewater and overlying water. Liberation of metals generally increased with hydrodynamic shear on the sediment-water interface, even in some low-permeability sediments. Sediment resuspension transitorily mobilized particulate metals but did not significantly mobilize dissolved metals or increase contaminant bioavailability or toxicity. Bioturbation and bioirrigation by burrowing worms, however, greatly increased sediment heterogeneity, oxygen delivery into sediments, and efflux of metals to both porewater and overlying water. Bioturbation also destabilized sediments, resulting in greater particle resuspension and metals efflux following flow perturbations. Based on these findings, the authors recommend including measurements of the effects of flow forcing and sediment resuspension in concert with biological perturbations during assessments of metals bioavailability and toxicity in contaminated sediments. https://www.estcp.com/content/download/40096/384816/file/ER-1745%20Final%20Report.pdf