Table I. T. RESULTS Flow chart of 2397p yt4 preparation procedure. REMOVAL OF ORGANIC MATTER A. Place Pu solution in HNO, solution B. Evaporate to dryness. D. Do not bake residue. Repeat Step I C. C. E. Total organic carbon in beaker. Do not bake residue. Dissolve residue in 2 ml con. HNO,. Add 2 ml 30% H,05 to residue. Evaporate to dryness. Evaporate to dryness. Do not bake residue. II. F. G. Repeat Step I E. Add 2 ml con. HNO,. H. residue. Repeat Step I G. B. with stirring. B. Heat 30 min, (light boil, 400°C) for 30 min. Cool. Add 0.2 ml 0.5 M KMnO4. Heat for 30 min. (250°C). which contained 36% of the TOC had no significant ~ A similar trend was observed for 237py uptake by A. hydrophila (Table 4). Both F I and F II reduced 237pu uptake below that in TSB medium alone. As with S. obliguus F Ili did not significantly affect 237py uptake by A. hydrophila, plutonium was Less than 5% of the lost by plating to glass flasks with plating flasks containing organics. losses less in cells, a. Add 1 M Fe {NH2504) 4 dropwise with stirring until solution is B. Stir 30 min. Add 0.25 mi 1 M Fe (NH5503) 5. Add 4 ml 1 M’NaNO,. B. Heat for Cc. Wash into 25 ml the uptake studies. 30 min. A. Add 8 ml B. Pass solution 3 ehrough column (5 ml volumes) Dowex to solution C. 20-50 mesh resin. Collect effluent. Wash beaker with was adjusted to 4.5, which is typical of many southeastern surface waters such as Skinface Pond. While Put4 self polymerization has been observed, this phenomenon was probably not a major Pu transformation in this study. Poly- (R) 2 ml 8 N HNO,. -1lx 4, Pass washes merization is directly proportional tional to pH (Rouston et al., 1976). Wash column with 100 ml 0.5 N HNO,. 534 Collect effluent as Put’. to Pu concentration and inversely propor- Many investigators have studied the effects of humic and fulvic compounds on trace metal uptake by phytoplankton Repeat VI C, ELUTE Put4 FROM ANION EXCHANGE COLUMN A. The environmental chemistry of Pu is also pH dependant (Rouston et al., 1976), as is the complexation chemistry of humic acids (Stevenson and Ardakani, 1972). For this reason the pH of experimental media 8N HNO, - ADSORB Pu’* ONTO ANION EXCHANGE COLUMN (HNO, ) Uptake does not imply an active mechanism and no attempt was made to determine if 237pu was associated with the surface or interior of cells. Oxidation state may be important in determining the physical and chemical reactions which Pu will undergo in the environment (Rouston et al., 1976). Wahlgren et al. (1976) reported Put4 to be the predominant oxidation state in Lake Michigan water. For this reason a rigorous procedure was used to assure that all of the 237?pu was in the IV oxidation state at the beginning of Do not heat, OXIDIZE Put? To put4 D. DISCUSSION Uptake is herein defined as the association of 237py with algal or bacterial through column. VIt. Fraction III, which and (Beck et al., (Table 2). obliguus Cool to 25°. REDUCE Pu’? To Put3 A, VI. 3). Add 0.5 M KMnO, dropwise with stirring until pink color persists. clear. V. (Table No polymerization was observed in these experiments. IN HNO, to residue. Add 1 ml IM NaNO,. (Table 2), OXIDIZE Put? To put? A. IV. Add 10 mb 31.1 mg/l whileF IV Significantly increased 237 py uptake. ADJUST ALL Pu TO put4 OXIDATION STATE A. III. Do not bake in Skinface Pond was effect on 237 py uptake by S. obligquus while F Iv Significantly increased 237pu uptake. Evaporate to dryness. (TOC) is approximately four times the world average for rivers (Garreis MacKenzie, 1971) which is typical of southeastern aquatic systems 1974). More than 80% of the TOC was comprised of F ITI and F IV Fraction I and F FI both significantly reduced 237py uptake by S. (Goldberg, 1952; Shapiro, 1957; Giesy, 1976), Several investigators have reported increased trace metal uptake by Phytoplankton due to metal organic interactions (Burk, et al., 1932; Provasoli and Pinter, 1959; Johnson, 1964), while others have reported reduced uptake due to humic acids (Provasoli et al., 1957; Provasoli, 1963; Prakash and Rashid, 1968; Siegal, 1971; Giesy,1976) . Shapiro (1966) found that higher