1 Plutonium, as you know, is an isotope that has been introduced to 



2 the atmosphere due to atmospheric nuclear weapons testing. It began, of 



3 course, in 1945 and the peak activity was in the early 1960s. 



4 This material is introduced to the surface waters of the ocean. 



5 It is a fairly reactive element with respect to biological and inorganic 



6 particles. It finds its way to sea floor in areas of enhanced 



7 scavenging. 



8 A measure of that scavenging, I think, is seen in a comparison 



9 with the Lydonia Canyon axis versus the continental slope, showing the 



10 open triangles here. You can see at all depths the activity of the 



11 Plutonium, recorded in dpm's per gram is considerably higher. 



12 The inventories, if you were to just determine the amount of 



13 Plutonium on an area basis, is about two and a half times greater in the 



14 axis of the canyon than it is on the continental slope. 



15 The other important point to make here is if I explain that our 



16 best estimates of sediment accumulation on the continental slope is 



17 quite low, on the order of 13 cm/1,000 years or .013 cm/year, the life 



18 that that plutonium has been in existence would be constrained to the 



19 upper half centimeter or so, if there was not biologic reworking and 



20 just accumulation was accounting for this profile. 



21 I was real glad that Jim made a comment about bioturbation and the 



22 effect of bioturbation on reworking contaminants into the sediments. 



23 This, I think, is a clear example of that type of bioturbation. 



24 Not only on this core do you find a subsurface peak, which could 



25 very well be the bottom of a certain deposit-feeder who moves material 



26 from the surface to depth, but the fact is you find plutonium to 



27 tremendous depths--tremendous--down to 20 or 25 centimeters almost. 



28 In fact, that core isn't long enough to really determine where the 



29 maximum exists. I think this is a good illustration of the fact that 



30 contaminants are moved into these sediments. 



31 I'd like to make a point right here that I believe that in areas 



32 of Lydonia Canyon where a small percentage of fine-grained sediments 



33 exist--emits a coarse-grained sediment, that this type of reworking, 



34 where organisms exist, may, in fact, be important in scavenging 



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