Sediment Resuspension by Ship Traffic in Newark Bay, New Jersey
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS ENVIRONMENTAL LAB
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A frequently cited concern for potential detrimental impacts to aquatic orgamsims associated with dredging projects is sediment resuspension resulting from the excavation process, overflow, or open-water placement. However, very few attempts have been made to place dredging-induced resuspension into perspective with other natural e.g., tidal flows, high riverine discharges, storm wind and wave forces or anthropogenic e.g., commercial or recreational vessel traffic passage and maneuvering sources of resuspension. The present study examines suspended sediment plumes created by various types of vessels within Newark Bay, New Jersey. Spatial scales, total suspended solids TSS concentration gradients, and dispersion patterns were measured by a combination of acoustic Doppler current profiler ADCP surveys and collection of water samples for gravimetric analysis. Plumes varied substantially among vessel type and movement patterns. Often very large plumes, initially extending from the surface to the bottom, were associated with turning maneuvers of deep draft vessels. Plumes rapidly dissipated in the upper portion of the water column, but persisted at depth for relatively long periods. TSS concentrations above 90 mgl occurred over broad areas following vessel maneuvers. Ambient TSS concentrations ranged from 10 mgl surface to 60 mgl just above the bottom. Bottom plumes remained detectable against ambient throughout the time intervals between successive arrivals and departures, persisting for at least 50 minutes where tidal currents could disperse plumes. Residual plumes maximum 40 mgl in the lower 2 m of the water column were detectable at the point of deep draft vessel passage up to 65 minutes.
- Hydrology, Limnology and Potamology
- Marine Engineering