Small-Scale Spatial Variations of Natural Radionuclide and Trace Metal Distributions in Sediments from the Hudson River Estuary
Multiple sediment cores were collected in June 1994 in the turbidity maximum zone of the Hudson River estuary off Manhattan, New York. Results from X-radiography of the sediments and measurements of natural radionuclides (234Th, 7Be, and 210Pb) and trace metals (Ag, Cd, Cu, Pb, and Zn) show significant spatial variability of sediment composition and structure and patchy distributions of radionuclides activities and trace metal concentrations in this small area (0.6 km x 0.5 km). Radionuclide and trace metal analyses confirm prior work (Olsen et al. 1978; Olsen et al. 1981; Hirschberg et al. 1996) that show the western margin area of the river acts as a repository of these chemical constituents at least for the short-term period (0.5-1 yr), and the mid-channel area is not a depositional area for sediments and associated chemical constituents. 7Be profiles reveal short-term sediment deposition rates ranging from 6 cm yr-1 to 26 cm yr-1 in the western margin area. Significant spatial variations in excess 234Th and 7Be inventories (up to a factor of 10 and 5 for 234Th and 7Be, respectively) are found in the western margin depositional area, although the inventories are balanced, on average, with in situ production in water column and atmospheric supply. The spatial variation of surficial excess 216Pb and trace metal concentrations in depositional areas of the western margin are ≤10% for Ag, Cu, Pb, and Zn and 29% for Cd. However, the variations in the transition zone range from 28% to 93%. This variability is likely related to variations in tidal current velocity, bottom shear stress, and river channel morphology.
MSU Digital Commons Citation
Feng, Huan; Cochran, J. Kirk; Hirschberg, David J.; and Wilson, Robert E., "Small-Scale Spatial Variations of Natural Radionuclide and Trace Metal Distributions in Sediments from the Hudson River Estuary" (1998). Department of Earth and Environmental Studies Faculty Scholarship and Creative Works. 535.