Environ. Sci. Technoi. 1982, 16, 579-581
Strachan, W. M. J.; Huneault, H. J. Great Lakes Res. 1979, 5,61-68. Rodgers, P. W.; Salisbury, D. K. “Modeling of Water Quality in Lake Michigan and the Effect of the Anomalous Ice Cover of 1976-1977”; Great Lakes Environmental Planning Study, Contribution No. 44,Great Lakes Basin Commission, Ann Arbor, MI, 1981. Thomann, R. V.; DiToro, D. M.; Winfield, R. P.; O’Connor, D. J. “Mathematical Modeling of Phytoplankton in Lake Ontario. Part 1: Model Development and Verification”; EPA-660/3-75-005, U.S. Environmental Protection Agency, Washington, D.C., 1975. DiToro, D. M.; Matystik, W. F., Jr. “Mathematical Models of Water Quality in Large Lakes. Part 1: Lake Huron and Saginaw Bay“; EPA-600/3-80-056, U.S. Environmental Protection Agency, Washington, DE., 1980. DiToro, D. M.; Connolly, J. P. Mathematical Models of Water Quality in Large Lakes. Part 2: Lake Erie”; EPA600/3-80-065, U.S. Environmental Protection Agency, Washington, D.C., 1980. Wahlgren, M. A.; Robbins, J. A,; Edgington, D. N. Argonne National Laboratory, Radiological and Environmental Research Division, ANL/ERC 78-42, 1978. Edgington, D. N.; Robbins, J. A. Environ. Sci. Technol. 1976, 10, 266-274. Leland, H. V.; Bruce, W. N.; Shimp, N. F. Environ. Sci. Technol. 1973, 7, 833-838. Mackay, D. Enuiron. Sci. Technol. 1979,13, 1218-1223. Mackay, D.; Shiu, W. Y.; Sutherland, R. J. In “Dynamics,
Exposure, and Hazard Assessment of Toxic Chemicals”; Haque, R., Ed.; Ann Arbor Science: Ann Arbor, MI, 1980; Chapter 11. Great Lakes Water Quality Board, “1981 Report on Great Lakes Water Quality”; International Joint Commission: Windsor, Ontario; Appendix-Great Lakes Surveillance. Hendersen, J. C.; Inglis, A.; Johnson, W. L. Pestic. Monit. J. 1971, 5, 1-5. Federal Food and Drug Administration, Minneapolis, MN, 1978, unpublished data. Swain, W. R.; Wilson, R. J.; Neri, R. P.; Porter, G. S. U.S. Environmental Protection Agency, 1977, unpublished data. Armstrong, D. E., University of Wisconsin, Madison, WI, 1981, personal communication. Eisenreich, S. J., University of Minnesota-Minneapolis, MN, 1981, personal communication. Mackay, D.; Leinonen, P. J. Environ. Sci. Technol. 1975, 9, ii7a-iiao. Robbins, J. A. “Sediments of Southern Lake Huron: Elemental Composition and Accumulation Rates”; EPA600/3-80-080, U.S. Environmental Protection Agency, Washington, D.C., 1980.
Received for review October 19, 1981. Accepted April 12, 1982. This paper was based in part on material presented a t the 21st Conference on Great Lakes Research, University of Windsor, Windsor, Ontario, May 9-11, 1978.
Bioaccumulation of Technetium by Marine Phytoplankton Nicholas S. Fisher
International Laboratory of Marine Radioactlvlty, IAEA, Oceanographic Museum, Principality of Monaco ambient Tc levels in seawater, and only a few studies have been conducted to examine interactions of this element with marine biota. Fowler et al. (4), Pentreath (5), and Beasley et al. (6) have initiated studies on uptake and retention of Tc by marine animals using the y emitter 95mT~. Experiments indicate, thus far, that Tc concentration factors (on a wet weight basis) for marine fauna tend to be low (typically less than 10 for whole organisms) but biological half-lives tend to be high (often greater than 100 days). Few reports document uptake of Tc by marine microorganisms, and no studies have systematically compared the Tc uptake kinetics of marine phytoplankton species from different taxa. In a study focusing on biochemical effects of Tc on marine microorganisms, Gearing et al. (7) noted low uptake by one species of green and one species of blue-green algae. On the other hand, Gromov (8)reported considerably greater uptake of Tc by a natural phytoplankton community, though Ru and Pu proved even more reactive. It is possible that the difference between Gearing et ale’s and Gromov’s results is attributable to differences in algal taxa employed and/or their physiological states, but this remains unresolved. Introduction Phytoplankton are thought to play prominent roles in Technetium-99, with a half-life of 2.1 X lo5 years, is the geochemical cycling of some elements in marine sysregularly produced in nuclear reactors by fission of 236U, tems and in the introduction of many pollutants into making up more than 1%of total fission products. There marine food chains. Their interactions with potentially are no stable isotopes of Tc. Grimwood and Webb (I) important, long-lived contaminants like Tc clearly warrant project world Tc inventories at ~2 X 1014kBq (5-6 X lo6 study. This radiotracer study therefore examined uptake Ci) for the year 2000. While the chemistry of this element by marine phytoplankton species maintained in monois well studied (2)its behavior in the environment remains culture to assess the relative degree of Tc bioaccumulation little known despite the fact that it may be released in large by representatives of the major phytoplankton phyla and quantities via waste disposal, fuel reprocessing, and fallout to see whether Gromov’s (8) high Tc bioaccumulation from weapons testing (3). Published data do not exist on observations could be repeated. g 5 m T in ~ , the IV and VI1 oxidation states, was added in picomolar quantities to monocultures of seven species of marine phytoplankton, including a green alga (Dunaliella tertiolecta), a diatom (Thalassiosira pseudonana), a blue-green alga (Oscillatoria woronichinii), a prasinophyte (Tetraselmis chuii), two haptophytes (Emiliania huxleyi and Cricosphaera carterae),and a dinoflagellate (Heterocapsa pygmaea). Cultures were incubated for 4 days, and uptake of Tc was periodically determined by y spectroscopy of filtered and unfiltered samples. All the Tc remained in the water column in all flasks, but none of the species appreciably concentrated the element in either oxidation state. Mean uptake (measured as the fraction retained on filters) for all species was 0.029% for Tc(1V) and 0.023% for Tc(VII), neither of which was significantly different from the uninoculated control cultures. Wet weight concentration factors never exceeded 20 for any species, 3 orders of magnitude lower than previously reported for phytoplankton and Tc. The results indicate that phytoplankton are likely to have negligible influence on the cycling of Tc in marine systems.
0013-936X/82/0916-0579$01.25/0
0 1982 American Chemical Society
Environ. Scl. Technoi., Vol. 16, No. 9, 1982
579
Table I. Percent of Tc in Water Column Removed by Nuclepore Filtration, * l a Propagated Counting Error. Means t SD of All Species and at All Times and Wet Weight Concentration Factors at 91 h Are Also Shown oxidation species state added no cells IV VI1 T . pseudonana IV VI1 D. tertiolecta IV VI1 T . chuii IV VI1 H. pygmaea IV VI1 E . huxleyi IV VI1 C. carterae IV VI1 0. woronichinii IV VI1 IV VI1
19 h uptake t l u , %
uptake t l u , %
uptake
0.029 i 0.003 0 c 0.002 0.028 t 0.003 0.029 * 0.002 0.031 t 0.003 0.007 ?r. 0.002 0.045 t 0.003 0.002 i 0.002 0.068 t 0.003 0.023 t 0.002 0.036 t 0.003 0 i 0.002 0.062 * 0.003 0.038 * 0.002 0.024 t 0.002 0.031 i 0.003 0.040 * 0.017 0.016 i 0.016
0.036 0.004 0.020 0.043 0.039 0.006 0.059 0.008 0.042 0.022 0.040 0.012 0.025 0.005 0.027 0.022 0.036 0.015
0.006 ~t0.003 0.004 f 0.002 0.015 t 0.003 0.082 t 0.003 0.006 ~t0.003 0.007 i 0.002 0.008 t 0.003 0.014 i 0.002 0.009 t 0.003 0.109 t 0.002 0.021 t 0.003 0.011 i 0.002 0.005 ~t0.003 0 i 0.002 0 f 0.002 0.020 ?r 0.003 0.009 i 0.006 0.031 i 0.041
43 h
Materials and Methods Organisms. Axenic, clonal cultures of the chlorophyte Dunaliella tertiolecta (clone DUN), the diatom Thalassiosira pseudonana (clone 3H), the cyanophyte Oscillatoria woronichinii (clone OSC N4), the prasinophyte Tetraselmis chuii (clone Tet C2), the haptophytes Emiliania huxleyi (clone MCH no. 1) and Cricosphaera carterae (clone Crico Nl), and the dinoflagellate Heterocapsa pygmaea (clone GYMNO) were batch cultured in sterile-filtered (0.2-pm Sartorius filters) Mediterranean surface water enriched with f / 2 nutrients (9) minus the Cu, Zn, and EDTA additions. Cultures were maintained at 18 f 1 "C and received -200 peinsteins m-2 s-l of illumination from cool-white fluorescent lamps for 14 h/day. Isotope. The oxidation state of the Tc added to the cultures was controlled so that Tc(VI1) and Tc(1V) were compared for each species. (The reduced forms of Tc in seawater are not well known, but probably exist as Tc(IV), perhaps as the oxychloro or chloro anions (IO).) The yemitting isotope 96mT~, produced in a cyclotron, was used to facilitate sample preparation and Tc counting procedures. Moreover, use of 9 6 m Tallows ~ practical experimentation using atom levels (pM) approximating those likely to be found in the environment. The Tc was supplied by New England Nuclear Co. dissolved as the pertechnetate ion, Tc04- in distilled water acidified to pH 4 with HN03. An aliquot of Tc(VI1) stock solution was reduced to produce Tc(1V) stock prior to the experiment by adding 10 mg of hydrazine sulfate to 1.375 mL of solution containing 17 X lo3 kBq of Tc. Experimental Procedure. Surface Mediterranean seawater was filtered through sterile 0.2-pm Sartorius filters and then decanted, 600 mL/vessel, into sterile l-L Erlenmeyer flasks stoppered with autoclaved polyurethane plugs. Each flask recieved 200 pL of a g 6 m T stock ~ solution (via Eppendorf automatic pipet) containing 207 kBq (corresponding to 4.3 pM of Tc in the flasks at the start of the experiment) of Tc in either the Tc(1V) or Tc(VI1) (pertechnetate) state. The Tc was allowed to equilibrate in each flask for 22 h before log-phase cells were introduced. The cell densities at the start of the experiment were 3 X lo4 mL-l (clones DUN, 3H and MCH no. l),lo4 mL-l (clones Crico N1 and Tet C2), 8.5 X lo3mL-l (clone GYMNO), and 1.43 X lo3filaments mL-l (clone OSC N4). The initial cell densities were adjusted to give approximately equivalent biomasses (wet weights) for all species. 580
Environ. Sci. Technol., Vol. 16, No. 9, 1982
t 0.003 ~t 0.002
t 0.003 t 0.002
* 0.003 * 0.002 ~t0.003
* 0.002 t i i
*
t t i t
t t
0.003 0.002 0.003 0.002 0.003 0.002 0.003 0.002 0.012 0.013
91h
CF
tlu, %
0.024 i 0.016 0.003 t 0.002 0.021 t 0.007 0.051 * 0.027 0.025 ~t 0.017 0.007 t 0.001 0.037 t 0.026 0.008 t 0.006 0.040 t 0,030 0.051 * 0.050 0.032 -L 0.010 0.008 t 0.007 0.031 t 0.029 0.014 f 0.021 0.017 i 0.015 0.024 t 0.006
4 10 0
