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The atmospheric flux of 7Be over a 2‐year period at a coastal site (Norfolk, Virginia) and at an inland site (Oak Ridge, Tennessee) typically supports inventories ranging from 1.0 to 2.0 pCi/cm2 (1 pCi = 0.037 Bq), with the highest inventories generally occurring in the spring and the lowest occurring in the fall. The calculated average daily fluxes required to support these inventories range from 0.013 to 0.026 pCi cm−2 d−1. Despite the different production‐source terms for 7Be and 210Pb, there is a high degree of correlation between their measured total monthly deposition reflecting the importance of washout in removing both radionuclides from the atmosphere. Beryllium 7 inventories in soil and vegetated marsh cores compare favorably with inventories calculated from the atmospheric deposition data. Lead 210 inventories in soil and vegetated marsh cores may be enriched (by 20–30%) in relation to inventories calculated from its depositional flux to bucket samplers. Possible explanations for this enrichment are that above‐ground vegetation is more efficient at collecting dry aerosols (containing short‐lived radon daughters) than buckets or that foliage is an effective trap for particles containing sorbed 210Pb which may be eroded from unvegetated surfaces by wind or water. The vertical distribution and inventory of both 7Be and 210Pb in marsh cores are affected by the presence of vegetation and the location of the groundwater table.

The atmospheric flux of cosmogenic ?Be (53.3-day half-life) and the mode of ?Be deposition in riverestuarine and coastal environments have been examined. The atmospheric flux of ?Be commonly supports inventories ranging from 1.0 to 2.0 pCi/cm 2 (1 pCi = 0.037 Bq). Beryllium 7 concentrations in water phase samples, collected across salinity gradients in several estuaries along the eastern coastline of the United States, range from 0.03 to 0.53 pCi/L and primarily reflect variations in ?Be supply and sorption kinetics. The major process controlling the concentration of ?Be on estuarine suspended particles appears to be the length of time that these particles remain in the water column. Field particle-towater distribution coefficients for ?Be have a median value of about 4 x 10 '• but range over an order of magnitude reflecting short-term variations in 7Be input, particle dynamics, and particulate iron content rather than equilibrium sorption-desorption responses to changes in water salinity or particle type.Residence times of 7Be in the water column range from a few days in estuarine areas of rapid fine-particle deposition, to several weeks in high-energy enviornments where pronounced sediment resuspension reintroduces deposited 7Be back into the water column. Inventories of ?Be in sediments range-from nondetectable to 3.3 pCi/cm 2, with the highest inventories in areas where fine particles are accumulating rapidly. Such sites are also major repositories for other particle-reactive substances. A ?Be budget for the James estuary indicates that less than 5% of the expected ?Be input is in the water column and that the short-term estuarine trapping efficiency for atmospherically derived ?Be is somewhere between 50 and 100%. the total (wet + dry) atmospheric flux of ?Be commonly supports inventories ranging from 1.0 to 2.0 pCi/cm 2 [Young and Silker, 1974; Matsunami et al., 1979; Crecelius, 1981; Robbins and Eadie, 1982; Saleh and Kuroda, 1982; Todd, 1984; Olsen et al., 1985-]. The highest inventories generally occur in the spring, when mid-latitude folding of the tropopause enhances stratospheric-tropospheric exchange, and the lowest inventories occur during periods of minimum precipitation, generally in late summer and early tall. Upon contact with "acidic" rainwater, ?Be appears to be solubilized and Be 2 + is probably the predominant species [Olsen et al., 1985]. Once deposited as a constituent of rainwater, ?Be is quickly sorbed by above-ground vegetation [Russell et al., 1981] or soil particles [Brown et al., 1981; Lundberg et al., 1983; Monaghan et al., 1983; Pavich et al., 1984] in terrestrial environments, but may remain in solution in oceanic surface waters because of the lack of suspended material [Young and Silker, 1974; Bloom and Crecelius, 1983]. The potential of 7Be as a useful tool for examining geochemical and sedimentological processes in estuarine and coastal areas (i.e., transitional zones between terrestrial and oceanic environments) has only recently been investigated [Krishnaswami et al., 1980; A...

Atmospheric depositional fluxes of 7Be and 210Pb were measured simultaneously in wet‐only and bulk deposition over a 29‐month period (October 1982 through February 1985) in Norfolk, Virginia (36°53′N, 76°18′W). Total precipitation accumulation during 1983 and 1984 was 134 and 129 cm, respectively, slightly above the normal yearly accumulation. The volume‐weighted average concentrations of 7Be in bulk deposition for 1983 and 1984 were 90 and 100 dpm/L, while those for 210Pb were 5.9 and 6.6 dpm/L, respectively. The annual depositional fluxes of 7Be and 210Pb in bulk deposition in 1983 and 1984 were 12.0 and 12.9 dpm/cm2 (for 7Be) and 0.79 and 0.85 dpm/cm2 (for 210Pb), respectively. There was a high degree of correlation between 7Be and 210Pb concentrations in wet‐only deposition. This was not anticipated, considering that the sources of these two radionuclides are different. These results suggest that 7Be and 210Pb cannot be used as two independent tracers for materials originating in the stratosphere versus those from the troposphere. Dry depositional fluxes for both radionuclides, estimated from differences in the wet‐only and bulk fluxes, were calculated to be a maximum of 12 and 11% of the bulk 7Be and 210Pb fluxes, respectively. On an annual average the washout ratio for 7Be in bulk deposition was 370, while that for 210Pb was 215. The annual average total deposition velocities for 7Be and 210Pb were estimated to be 1.3 and 0.7 cm/s, respectively. It is suggested that the apparent differences in the depositional characteristics (that is, total deposition velocity, washout ratio) for these radionuclides are mere artifacts of the manner in which they are calculated and do not necessarily reflect differential behavior in the atmospheric deposition of 7Be and 210Pb.

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