688 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



higher than indicated by multiplying typical near-surface suspended-load concentrations 

 times mean annual flow. The "extra" transport of particles is probably accomplished by 

 some combination of very high suspended loads coinciding with the highest freshwater 

 flow rates and bed-load transport, which in the Hudson appears to consist largely of 

 resuspension and deposition of fine particles in the lowest meter of the water column on 

 the time scale of a tidal cycle. Thus in the Hudson the total downstream transport of 

 2 3 9,240pu -g approximately a factor of 4 greater than that in the dissolved phase, which 

 indicates a half-time for removal of fallout 2 3 9,240p^ from the drainage basin, largely on 

 particles, of about 10^ years. Similar calculations for the Savannah River (Hayes and 

 Horton, this volume) and the Greater Miami River (Sprugel and Bartelt, 1978) suggest 

 drainage-basin removal times of about 2x10^ and 2 x 10"' yr, respectively. Again this 

 supply term to the coastal ocean is not significant relative to advection of deep-ocean 

 fallout 2 3 9 ,2 4 op^ Qj^^Q ^j^g ^j^gjj^ Pq^ ^j^g Hudson most of the delivery of " ^ "^ ^ °Pu on 



particles to the coastal ocean is accomplished by the dumping of dredge spoils rather than 

 by estuarine discharge of suspended particles. 



Plutonium in the New York Bight 



The concentrations of dissolved 2 3 9,240p^ ^^ ^^^ coastal waters off the New York City 

 area are two to three times those in the Hudson (Table 1). The suspended loads in the 

 New York bight are almost two orders of magnitude lower than those in the Hudson, and 

 fine-grain sediments in the bight have activities of 2 3 9.2 4 0pjj comparable to those in the 

 Hudson. Thus the transport of -3 9,2 4 0p|j ^^ ^^^ shelf environment appears to be largely 

 in the dissolved phase, in contrast to the situation in the Hudson River and estuary. 



Plutonium in Other Freshwaters 



Data for the concentration of 2 3 9.2 4 0p|j ^^ ^^^ York City tap water (Bennett, 1976) are 

 available for the period 1973 to 1975 (Table 1 ). The water supply for New York City is 

 derived from tributaries of the Hudson and Delaware rivers. The activities ranged from 

 0.08 to 0.60 fCi/liter, with a mean value of about 0.3 fCi/liter (about 2% of the average 

 rain activities during the same period). The range and mean value of the tap water 

 2 3 9,2 4 0p|j concentrations are almost identical with the values observed for the Hudson 

 River and estuary. 



Farmer et al. (1973) have reported '39,240p|^^ activities in Lake Ontario (Table 1) 

 that are in the same range as the data discussed here for the Hudson River and New York 

 bight. During the period 1971 to 1973, the average -39,240p^ activity for the entire lake 

 declined from about 0.8 fCi/liter to about 0.3 fCi/liter. The average 2 3 9,2 4 0p|j ^^tivity in 

 all five Great Lakes (Wahlgren and Marshall, 1975; WahJgren et al.. 1976) during 1972 

 and 1973 was about 0.5 fCi/liter (Table 1 ). 



Transport of Fallout Plutonium to the Oceans 



The data available indicate that the range of variation of soluble-phase 2 3 9,2 4 0p|j j^^ 

 freshwaters is relatively small. The transport by rivers of fallout 239,240p|^j j^^ "solution" 

 can thus be estimated relatively easily solely on the basis of the rate of freshwater 

 discharge. The concentrations in freshwaters appear to be "buffered" to some extent by 

 the large reservoir of fallout -^^■-''Opu jn soils and the relative uniformity of the specific 

 activity of 2 3 9,2 4 0p|j ^^^ ^^n p^^ticles and river suspended particles (^20pCi/kg). The 



