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ROLE OF BIOTURBATION IN SEDIMENT RESUSPENSION AND ITS INTERACTION WITH PHYSICAL SHEARING
Citation:
Davis, W.R. ROLE OF BIOTURBATION IN SEDIMENT RESUSPENSION AND ITS INTERACTION WITH PHYSICAL SHEARING. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/488 (NTIS PB94130192).
Description:
Marine benthic fauna play an important role in governing sediment-water relationships, including resuspension of particle-borne contaminants. onstant burrowing and subsurface deposit-feeding tend to eject sediment into overlying water, break up the cohesive structure of sediment-clay sediment, increase sediment-water content, and increase physical resuspension. xperimental evidence shows that resuspension of sediment is influenced by shear stress at the sediment-water interface and/or by the type, abundance and reworking time of infauna. esuspension by biota was investigated by monitoring the turbidity of excurrent water of deposit-feeding species. he interaction between biota and physical shear in sediment resuspension was measured using an annular flume and a flume-calibrated Particle Entrainment Simulator. ediment resuspension, in the absence of physical shear, was caused by Yoldia, Macoma, and Pectinayia during the disposal of pseudofeces (20 mg/min per individual Yoldia at 20 degrees C. The presence of otile deposit-feeders also destabilized cohesive sediment and thus increased physical resuspension. he bivalve Nucula at least doubled physical resuspension at shear values above 2 dyne/cm2. nfaunal activities such as feeding, locomotion and habitat development resulted in direct resuspension and modified physical resuspension. otal resuspension with respect to time (Rtdt) was found to equal the sum of a physical resuspension term (Rp), a biological term (Rb) and a physical-biological interaction term (Rpb). hile all terms are time-varying Rp varies as a function of currents, depth and wave height and the biological terms vary with species, abundance and activity rates (temperature).