Radionuclide concentrations in estuarine sediments: Comparison of measured and calculated values

Low-level radioactive effluent from the Maine Yankee Nuclear Power Reactor is discharged, through a diffuser 12 m below the surface, into Montsweag Bay in central coastal Maine. The radionuclides /sup 58/Co and /sup 137/Cs become attached to marine sediments and are dispersed under the influence of tides, the pumping of the reactor, and adsorption or attachment to the estuarine sediments as well as diffusion in the estuarine water. Transects of bottom sediment were collected using Eckman dredges and low-tide sampling on mud flats. The samples were γ-ray counted using a Ge(Li) detector with low background shield. The concentrations of γ-emitting radionuclides were contour-plotted for comparison with computer-calculated concentrations based on a dynamic estuary model. The concentrations ranged from 3.0 to 21.3 Bq kg/sup -1/ for /sup 137/Cs and from 0.2 to 5.3 Bq kg/sup -1/ for /sup 58/Co. Comparisons between the calculated and measured concentrations show that the predicted patterns of radionuclide concentration are qualitatively similar to the measured patterns