SEDIMENTATION FLUX OF PLUTONIUM IN A WARM, MONOMICTIC RESERVOIR

To evaluate the importance of particle settling on the behavior of Pu- 239,Pu-240 inventories in the water column of a monomictic reservoir, the sedimentation fluxes of Pu-239,Pu-240 were measured using sediment traps and compared to the Pu inventories. Sedimentation flux from sur face to deeper waters averaged 5.4 mBq Pu-239,Pu-240 m(-2) d(-1) which represented greater than or equal to 3% of the surface water inventor y of Pu per day. The fluxes were large enough to account for (1) the o bserved declines in the Pu inventories of surface waters following str atification and (2) the rapid increase in Pu inventories in deeper wat ers immediately following stratification.