1971; Trabalka and Eyman, 1976; Elwood et al., 1976). This concept substitutes the concentrations of an element in sediment and suspended particutate matter for the concentration in water normally used in the calculation of a CF, The underlying expectation is that, due to the high Ky's, observed element accumulation in tissues of higher trophic levels will be dominated by gut absorption rather than by direct uptake which were one to two orders of magnitude greater than fish from the lake. Data on fishes from White Oak Lake show a trend of decreased concentrations of 7797?"°Pu at higher trophic levels (Table 2). Comparable concentrations in plutonium were observed in the three species which feed on bottom dwelling invertebrates (bluegill and goldfish) or on suspended particulate matter (shad}. Stomach content analysis of these three species showed significant amounts of clay material to be 482 or J = ud a = > rT = J ava S] al Zz a <a os “” WwW x a qf Oo rv) ” iw t= x = a ve) > oc ke © <1 4 = lJ = — w lw KE aq rw m7) uJ ft ra wz >a z Zz <I ~| x > al < a] ly Zz — x <{ = Tropnic Transfe r Factors (TTF) for Fresh water and Marine Environments. TIF is defined as (Puj in Organisms ( wet weight)/[Pul in Sediment or Suspended Particulate Matter (wet weight) . - 1072 = 1073 Jo Figure 2. Benthic invertebrates and rooted macrophytes (Ludwigia, Elodea, and Sagi ttoria) from White Oak Lake contained comparable concentrations of 7°°-?*°Pu tx 1074 Some of the variation in TTF values observed can be explained by the relative trophic position of the organisms analyzed. The number of intervening food chain transfers between the organism analyzed and the abiotic source of plutonium should be inversely related to the observed TTF value, This is demonstrated in Figure 2 where organisms at lower trophic levels have higher TTF values than fishes, Therefore, in assessing potential transfer of plutonium to man from aquatic ecosystems, it is important to concentrate on those food sources most closely tinked te sediment as a measure of maximum plutonium in human food. These would represent a short, single trophic transfer food chain as opposed to the traditional concept of the grazer food chains. Examples of important groups include bottom-feeding fishes, shell fish, and rooted Macrophytes such as rice. A major dietary component of a large segment of the world population is rice. Although we could find no data on accumulation of plutonium in rice, this information is important since it is representative of a single trophic transfer from sediment and/or water to man. Noshkin (1972) pointed out that marine organisms associated with the sediment-water interface, (i.e., benthic invertebrates) contain one hundred times higher plutonium burdens than marine free swimming vertebrates. “2 4979 contamination has contributed a major fraction of observed plutonium concentrations in phytoplankton materials in previous studies) the maximum possible TTF value should be on the order of one. In fact values in Figure 2 are significantly less than one, as expected. Zz uJ 4078 This term, then, serves as a realfstic measure of plutoniumdiscrimination in food chains. If our hypothesis is correct, (i.e., sediment cross- 1071 Again, we stress that external contamination with sedimentary particulate matter and gut loading are not considered to represent true uptake and should be considered separately. An example of the utility of the approach can be seen in Figure 2 where TTF is used rather than CF to express transfer of plutonium from abiotic to biotic components in various systems, This figure clearly shows that plutonium is discriminated against in food chains of aquatic systems. TIF values for fishes of ~ 107? to 107* are comparable to those observed in mammalian gavage studies (Baxter and Sullivan, 1972; Carritt et al., 1947; Weeks et al., 1956). WHITE OAK LAKE from water,