606 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



about 2 Ci was released in 1955, which was before the installation of high-efficiency 

 filters on the air exhaust system, and about 0.8 Ci in 1969 when a sand filter failed. 

 Currently, atmospheric releases average about 10 mCi/yr. Most of the plutonium from the 

 SRP operations is probably on site because analyses of soil cores from the plant perimeter 

 and off-site soils have about the same concentration, 1.96 ±0.7 mCi/km^ at the plant 

 perimeter and 1.81 ±0.58 mCi/km^ at 160 km; other values at the same latitude are 

 about 2 mCi/km^ . 



Savannah River Plant plutonium releases to surface water were estimated to be about 

 0.3 Ci for the 20-yr period from 1954 to 1974 and were fairly consistent over this 

 interval (Hayes, LeRoy, and Cross, 1976). Until 1971 plutonium releases were estimated 

 by measuring gross alpha only and by assuming that all alpha activity was from 

 plutonium. Since then plutonium has been analyzed for specifically. The water after 

 release .is subjected to cleanup by on-site streams (about 16 km in length), an on-site 

 swamp, and the Savannah River before it reaches the estuary. 



The fate of ^ ^ ^Cs released to surface water by the SRP has been extensively studied 

 and can be used to estimate the fate of plutonium released to surface waters. Plutonium 

 and cesium have similar transport properties in most environmental systems owing to 

 their strong association with the very fine suspended solids in stream water and with 

 stream-bed sediments (Simpson et al., 1976). Some 500 Ci of ^^ ^Cs has been discharged 

 to effluent streams, and only 90 Ci (about 18%) has been measured at Highway 301 

 (Fig. 1). About 58% of the 500 Ci of ^ ^ '^Cs that has been discharged is estimated to have 

 been deposited in the SRP streams before reaching the on-site swamp, and the swamp is 

 estimated to contain about 120 Ci, or about 24%, of cesium that has been discharged 

 (Marter, 1974). If these ^^^Cs data are extrapolated to plutonium, about 0.054 Ci of 

 plutonium is estimated to have left the SRP site since start-up. 



From the above data, the total amount of plutonium on the watershed is estimated to 

 be about 59 Ci. 



Results and Discussion 



Savannah River 



Plutonium concentrations in tlie Savannali River water are lower than would be predicted 

 by considering the concentration in other fresliwaters. Concentrations measured for 3 

 months in the Savannali River at Higliway 301 (Fig. 1) varied from 0.13 to 0.32 fCi/liter. 

 In comparison. Lake Michigan contains 0.6 fCi/liter (Edgington et al., 1976), the Great 

 Miami River in Oliio contains about 1 fCi/liter, and the Neuse and Newport rivers in 

 North Carolina contain abou: 1.2 and 1.7 fCi/liter, respectively (Hayes, LeRoy, and 

 Cross, 1976). Concentrations in the Savannali River appear to be greatly influenced by 

 reservoirs. Sedimentation in the two large reservoirs on the Savannali River sliould remove 

 all except some of the very small plutonium-bearing particles. About 73% of the 

 Savannah River flow originates above Clark Hill Dam. Erosion is greater in the hilly 

 Piedmont region above the reservoirs than in the coastal plains; so removal of 

 plutonium-bearing particles from the waterslied below the reservoirs would be less rapid 

 than that above the reservoirs. In contrast, the Great Miami River of Ohio and the Neuse 

 and Newport rivers of North Carolina do not have large water impoundments on them. 

 Also, the percentage of the Savannali River watershed that is under cultivation is only 

 one-third as large as that of the Great Miami River. 



