Hyperaccumulators table – 3

This section covers radionuclides, hydrocarbures and organic solvents, and information on the plants used for their remediation.

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Hyperaccumulators table – 3

Notes
* Uranium: The symbol for Uranium is sometimes given as Ur instead of U. According to Ulrich Schmidt and others, plants' concentration of uranium is considerably increased by an application of citric acid, which solubilizes the Uranium (and other metals).
* Radionuclides: Cs-137 and Sr-90 are not removed from the top 0.4 meters of soil even under high rainfall, and migration rate from the top few centimeters of soil is slow. [http://www.springerlink.com/content/h68009j27515440m/] J.A. Entry, N.C. Vance, M.A. Hamilton, D. Zabowski, L.S. Watrud, D.C. Adriano. "Phytoremediation of soil contaminated with low concentrations of radionuclides." Water, Air, and Soil Pollution, 1996. 88: 167-176. Cited in Westhoff99.]
* Radionuclides: Plants with mycorrhizal associations are often more effective than non-mycorrhizal plants at the uptake of radionuclides.J.A. Entry, P. T. Rygiewicz, W.H. Emmingham. "Strontium-90 uptake by Pinus ponderosa and Pinus radiata seedlings inoculated with ectomycorrhizal fungi." Environmental Pollution 1994, 86: 201-206. Cited in Westhoff99.]
* Radionuclides: In general, soils containing higher amounts of organic matter will allow plants to accumulate higher amounts of radionuclides. See also note on "Lolium multiflorum" in Paasikallio 1984. Plant uptake is also increased with a higher cation exchange capacity for Sr-90 availability, and a lower base saturation for uptake of both Sr-90 and Cs-137.
* Radionuclides: Fertilizing the soil with nitrogen if needed will indirectly increase the take-up of radionuclides by generally boosting the plant's overall growth and more specifically roots' growth. But some fertilizers such as K or Ca compete with the radionuclides for cation exchange sites, and will not increase the take-up of radionuclides.
* Radionuclides: Zhu and Smolders, lab test: [http://jxb.oxfordjournals.org/cgi/content/abstract/51/351/1635] Y-G. Zhu and E. Smolders, "Plant uptake of radiocaesium: a review of mechanisms, regulation and application." Journal of Experimental Botany, Vol. 51, No. 351, pp. 1635-1645, October 2000] Cs uptake is mostly influenced by K supply. The uptake of radiocaesium depends mainly on two transport pathways on plant root cell membranes: the K+ transporter and the K+ channel pathway. Cs is likely transported by the K+ transport system. When external concentration of K is limited to low levels, le K+ transporter shows little discrimination against Cs+; if K supply is high, the K+ channel is dominant and shows high discrimination against Cs+. Caesium is very mobile within the plant, but the ratio Cs/K is not uniform within the plant. Phytoremediation as a possible option for the decontamination of caesium-contaminated soils is limited mainly by that it takes tens of years and creates large volumes of waste.
* Alpine pennycress or «Alpine Pennygrass» is found as «Alpine Pennycrest» in (some books).
*The references are so far mostly from academic trial papers, experiments and generally of exploration of that field.
* Radionuclides: Broadley and Willey [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15093373&dopt=Citation] M.R. Broadley and N.J. Willey. "Differences in root uptake of radiocaesium by 30 plant taxa". Environmental Pollution 1997, Volume 97, Issues 1-2, Pages 11-15] find that across 30 taxa studied, "Gramineae" and "Chenopodiaceae" show the strongest correlation between Rb (K) and Cs concentration. The fast growing "Chenopodiaceae" discriminate approx. 9 times less between Rb and Cs than the slow growing"Gramineae", and this correlate with highest and lowest concentrations achieved respectively.
* Caesium: In Chernobyl-derived radioactivity, the amount of contamination is dependent on the roughness of bark, absolute bark surface and the existence of leaves during the deposition. The major contamination of the shoots is from direct deposition on the trees. [http://www.springerlink.com/content/p2216nm476105868/] , J. Ertel and H. Ziegler, "Cs-134/137 contamination and root uptake of different forest trees before and after the Chernobyl accident", Radiation and Environmental Biophysics, June 1991, Vol. 30, nr. 2, pp. 147-157]

Annotated References

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