Uptake of technetium by freshwater green microalgae

Garnham, Geoffrey W.; Codd, Geoffrey A.; Gadd, Geoffrey M.

doi:10.1007/bf00240749

Cited by 15 publications

(14 citation statements)

References 16 publications

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“…In contrast, very small amounts of 99 Tc were removed from solution by the other phytoplankton although they grew in the culture media. The low levels of removal observed agreed with previous studies for freshwater green microalgae (Garnham et al, 1992) and cyanobacteria (Garnham et al, 1993). These results demonstrate that E. gracilis has an ability to remove 99 Tc from solutions.…”

Section: Resultssupporting

confidence: 91%

“…S. platensis usually grows in brackish water. Since increased TcO 4 − uptake with increased external NaCl concentration was reported in freshwater microalgae (Garnham et al, 1992), there is a possibility of 99 Tc uptake by S. platensis C. pulsatilla and C. vulgaris may remove 99 Tc from solution because other species of Chlamydomonas and Chlorella removed Tc by biosorption (Garnham et al, 1992). E. gracilis does not have a cellulose cell wall.…”

Section: Methodsmentioning

confidence: 99%

“…Fisher (1982) investigated the bioaccumulation of Tc by 7 species of marine phytoplankton and reported negligible uptake of less than 0.1% of total Tc. Garnham et al (1992) reported that the freshwater phytoplankton Chlamydomonas reinhardtii , Chlorella emersonii , and Scenedesmus obliquus removed Tc by biosorption, but the removal amount was low. As a consequence of these results, it has been thought that phytoplankton are not suitable for the removal of 99 Tc.…”

mentioning

confidence: 99%

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Removal of Technetium from Solution by Algal Flagellate Euglena gracilis

Ishii¹,

Uchida²

2006

J of Env Quality

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Based on limited data for the removal of radioactive (99)Tc by freshwater phytoplankton, it has been thought that phytoplankton are unsuitable for remediation of (99)Tc-contaminated waters. This work sought to verify the validity of this assumption by studying the removal of (99)TcO(4)(-) by freshwater and brackish water phytoplankton. The phytoplankton used were Euglena gracilis, Chlamydomonas pulsatilla, Chlorella vulgaris, and Spirulina platensis. Each of them was incubated for 63 d, and the removal of (99)Tc from solution was periodically determined. Significant removal of (99)Tc was observed only for E. gracilis, and the maximum removal was 70% of the total (99)Tc added. The killed cells of E. gracilis, however, removed hardly any (99)Tc. When E. gracilis cells were washed with fresh culture medium, only 13% of the total (99)Tc was desorbed. These results suggested that intracellular uptake of (99)Tc by E. gracilis occurred. These results are the first documented example of significant removal of (99)Tc by planktonic microalgae.

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Section: Resultssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Removal of Technetium from Solution by Algal Flagellate Euglena gracilis

Ishii¹,

Uchida²

2006

J of Env Quality

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“…Correlations of the accumulation rate constants with several anions were obscure and not negatively correlated, as would be expected in case of competitive effects. In contrast, the accumulation rate constants were positively correlated with the calcium concentrations in the solution, which tend to support the role of electrostatic interactions in the cell wall [10,12]. However, based on these data solely, possible physiological or competitive effects cannot be ruled out.…”

Section: Physico-chemical Vs Physiological Interferencementioning

confidence: 81%

“…Interactions of cations with the cell wall, altering the overall cell wall potential, would be the driving force. Garnham et al [10] first suggested this mechanism for marine phytoplankton, which showed enhanced Tc uptake at increasing salinity. Similar effects were observed for Tc accumulation in L. minor in respect to dominant cations in fresh water [11].…”

Section: Introductionmentioning

confidence: 99%

Accumulation of technetium in floating aquatic plants

Hattink

Wolterbeek

2002

Radioprotection

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Abstract. Technetium ( Tc) is of radio-ecological and health-physical interest because of its long half-life and its environmental mobility, given it a potential bioavailability. Plants are able to accumulate substantial amounts of Tc. Three mechanisms are suggested to interfere with the Tc accumulation: (i) changes in the plant physiological status, (ii) competitive effects with nutrient uptake, and (iii) electrostatic cell wall interactions. This study focuses on the question whether these mechanisms apply for aquatic plants grown under natural conditions. Tc accumulation in five aquatic plant species correlated strongly with the calcium concentration in the water. Growth rate or possible competition with CF, N0 3~, P0 4 3~ or S0 4 2 " did not significantly affect, if affect at all, the Tc accumulation in submerged aquatic plants. This suggests that water hardness is the dominant factor perturbing the Tc accumulation in submerged aquatic plants, supporting the hypothesis that electrostatic cell wall interactions are associated with it.

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Influence of salinity and eutrophication on bioaccumulation of ⁹⁹technetium in duckweed

Hattink

Wolterbeek

Goeij

2001

Enviro Toxic and Chemistry

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This study concerns the bioaccumulation of the long-lived nuclear waste product 99Tc in duckweed (Lemna minor L.). 99Tc was present as the oxyanion TcO4-, being the main chemical form of technetium in aerobic water systems. In contrast with terrestrial plants, bioaccumulation in duckweed proved to be independent of the nitrate concentration in the medium. However, uptake is controlled by electrostatic effects in the cell wall, which affects the bioaccumulation of 99Tc in duckweed in natural environments. These waters are characterized by a range of salinity and hardness, and this study suggests that this may result in up to a threefold difference in 99Tc accumulation. Because of screening of negative charges in the cell wall, the highest accumulation may be expected in hard, brackish water. This behavior can be described by a general model, which includes electrostatic effects and binding of cations at the cell wall. The model also explains why cationic radionuclides are preferably taken up in soft, fresh water while anionic species are concomitantly taken up in hard, chlorine-rich waters.

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Uptake of technetium by freshwater green microalgae

Cited by 15 publications

References 16 publications

Removal of Technetium from Solution by Algal Flagellate Euglena gracilis

Removal of Technetium from Solution by Algal Flagellate Euglena gracilis

Accumulation of technetium in floating aquatic plants

Influence of salinity and eutrophication on bioaccumulation of ⁹⁹technetium in duckweed

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Uptake of technetium by freshwater green microalgae

Cited by 15 publications

References 16 publications

Removal of Technetium from Solution by Algal Flagellate Euglena gracilis

Removal of Technetium from Solution by Algal Flagellate Euglena gracilis

Accumulation of technetium in floating aquatic plants

Influence of salinity and eutrophication on bioaccumulation of 99technetium in duckweed

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Influence of salinity and eutrophication on bioaccumulation of ⁹⁹technetium in duckweed