| hichest radioactivity in the old tovwm side of Eanrord along the shore with a rapidly Ciminishing activity dovwnstrcan. fate I hope you anpreciate wnat this relative activity Gersity is on all of thess slides, You mevoly take the hichest valus on tho chart as 100 porsont and express those other values 43 in tesems of pevcentates ef the most radicsetive matorial, his particular curve (indicating) is for Plankton waich has a fair short-lived conponent so that the activity Greps off 2s we go downstream due to tivo or threa major factors. Gne of theso is time for physical decay of the shorter-livod materials, Another ons is a peculiarity of crons of our sampling, af, Cs, and most of this represents in that collection along shore or in areas where the efflusnt hos not been completely dispersed -you will recall in the fivst slide we had a band of offluent which went cown the river before it became dispersed throughout the river as a waole, Of covrse, some of this fast drop-off is a result of better distribution of the effluent throughout tho river as a whole, We have these two factevs and we also have incorporation of these radionctive materials into the biolozical forn which draws them into a biological pcol and whica makes then evailable for further radioactive decay for this whole mass of radioactive material is finally moved down the rivor. This curve (inJicating) as I said, is typical of Planiton. We can draw different ones for each organism and get slightly different Slonos. at -~ If we draw this (indicating) fer the