SOURCES, DISTRIBUTION AND MOBILITY OF PLUTONIUM AND RADIOCESIUM IN SOILS, SEDIMENTS AND WATER OF THE HUDSON RIVER ESTUARY AND WATERSHED (NEW YORK, NEW JERSEY)

Results of ('239,240)Pu, ('238)Pu and ('137)Cs measurements are reported for soil cores sampled within the watershed, for many sediment cores and surface dredge samples taken along the length of the Hudson River. Estuary and for water samples collected on a continuous basis in both fresh and estuarine reaches.;Plutonium-239,240 and ('137)Cs were similary distributed in sediments and water sampled from fresh water reaches of the Hudson with activity ratios (i.e., ('239,240)Pu/('137)Cs) ranging from 0.01 to 0.03. Distribution coefficients, which were determined both in vitro and in situ were similar for both nuclides (i.e., from 1 x 10('5) to 3 x 10('5) L(.)kg('-1)) in fresh water, but diverged significantly (as a result of increased ('137)Cs solubility) in brackish waters that exhibited chlorinities in excess of 1-2 g Cl('-)(.)L('-1).;The concentrations of ('239,240)Pu and ('137)Cs observed in fresh water samples were primarily functions of the suspended load. Approximately 60-70% of the annual downstream transport of ('239,240)Pu and ('137)Cs calculated during 1980 and 1981 (i.e., 4 (+OR-) 0.5 mCi and 515 (+OR-) 84 mCi, respectively) was associated with suspended particulates (GREATERTHEQ) 0.45 (mu)m.;An empirical model was developed to determine the rates of vertical migration of these nuclides in soils of the watershed. Model results were then used together with erosion rate and sediment transport estimates to reconstruct the probable delivery of these fallout-produced nuclides from the watershed to the lower Hudson River. With respect to the delivery of fallout ('239,240)Pu and ('137)Cs from watershed soils to the lower Hudson River, model results indicated effective removal half-times from the surface 2.5 cm of soil of 20 and 13 years for ('239,240)Pu and ('137)Cs, respectively. These extremely rapid removal rate estimates were governed by the calculated rates of radionuclide penetration within soils.;Accumulations of ('239,240)Pu and ('137)Cs measured within sediment cores taken from discrete regions of the river-estuary were summed to arrive at total sediment inventories of 1.6 (+OR-) 0.7 Ci and 53 (+OR-) 20 Ci, respectively. The variability observed in the sediment accumulation of radionuclides is discussed in terms of the physical and chemical characteristics of the river-estuary.;Estimates of the cumulative inputs and losses of ('239,240)Pu and ('137)Cs from all mechanisms were derived. The results of the calculated mass balance analyses compare favorably with the sediment inventories determined by core sampling techniques.