Keeling sm, Stewart rb, Anderson cw

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Int J Phytoremediation. 2003;5(3):235-44.
International Journal of Phytoremediation,
5(3):235–244 (2003)

Nickel and cobalt phytoextraction by the hyperaccumulator Berkheya coddii: implications for polymetallic phytomining and phytoremediation.

Keeling SM, Stewart RB, Anderson CW, Robinson BH.

Soil and Earth Sciences, Institute of Natural Resources, PB 11-222, Massey University, Palmerston North, New Zealand.

We investigated the potential of the South African high-biomass Ni hyperaccumulator Berkheya coddii to phytoextract Co and/or Ni from artificial metalliferous media. Plant accumulation of both metals from single-element substrates indicate that the plant/media metal concentration quotient (bioaccumulation coefficient) increases as total metal concentrations increase. Cobalt was readily taken up by B. coddii with and without the presence of Ni. Nickel uptake was, however, inhibited by the presence of an equal concentration of Co. Bioaccumulation coefficients of Ni and Co for the single element substrates (total metal concentration of 1000 micrograms g-1) were 100 and 50, respectively. Cobalt phytotoxicity was observed above a total Co concentration in plant growth media of 20 micrograms g-1. Elevated Co concentrations significantly decreased the biomass production of B. coddii without affecting the bioaccumulation coefficients. The mixed Ni-Co substrate produced bioaccumulation coefficients of 22 for both Ni and Co. Cobalt phytotoxicity in mixed Ni-Co substrate occurred above a total Co concentration of 15 micrograms g-1. When grown in the presence of both Ni and Co, the bioaccumulation coefficients of each metal were reduced, as compared to single-element substrate. This may indicate competition for binding sites in the root zone. The interference relationship between Ni and Co uptake demonstrated by B. coddii suggests a significant limitation to phytoextraction where both metals are present.

Phytomining for nickel, thallium and gold
Anderson, C.W.N. | Brooks, R.R. | Chiarucci, A. | LaCoste, C.J.; Leblanc, M. | Robinson, B.H. | Simcock, R. | Stewart, R.B. |
Journal of Geochemical Exploration. Vol. 67, no. 1, pp. 407-415. 1999

The technique of phytomining involves growing a crop of a metal-hyperaccumulating plant species, harvesting the biomass and burning it to produce a bio-ore. The first phytomining experiments were carried out in California using the Ni-hyperaccumulator Streptanthus polygaloides and it was found that a yield of 100 kg /ha of sulphur-free Ni could be produced. We have used the same technique to test the phytomining potential of the Ni-hyperaccumulators Alyssum bertolonii from Italy and Berkheya coddii from South Africa. The effect of different fertilizer treatments on growth of Alyssum bertolonii was established in situ in Tuscany and showed that the biomass of the plant could be increased by a factor of nearly 3 (4.5 t/ha to 12 t/ha) without significant loss of the Ni concentration (7600 mg/kg) in the plant. Analogous experiments have been carried out on Berkheya coddii where a biomass yield of over 20 t/ha can readily be achieved though the Ni concentration is not as high as in A. bertolonii. The total yield is, however much greater. We have also been able to induce plants to hyperaccumulate Au by adding ammonium thiocyanate to the substrate. Up to 57 mg/kg Au (dry mass) could be accumulated by Indian mustard (Brassica juncea). Unusual hyperaccumulation ( > 500 mg/kg dry mass) of Tl has been determined in Iberis intermedia and Biscutella laevigata (Brassicaceae) from southern France. The Iberis contained up to 0.4% Tl (4000 mg/kg) in the whole-plant dry matter and the Biscutella over 1.5%. This unusually high accumulation of Tl has significance for animal and human health, phytoremediation of contaminated soils, and phytomining for Tl. We calculate that using Iberis, a net return of $US 1200/ha (twice the return from crop of wheat) would be possible with a biomass yield of 10 t/ha containing 0.08% Tl in dry matter. The break-even point (net yield of $US 500/ha) would require 170 mg/kg (0.017%) Tl in dry matter. A model of a phytomining operation and its economics is presented and its advantages and disadvantages discussed.

Descriptors: Environmental Engineering | Phytomining | Phytoremediation; Remediation | Biomass | Plants (botany) | Crops | Nickel | Thallium; Gold | Soil pollution control |

Studies on serpentine flora: Preliminary analyses of soils and vegetation associated with serpentinite rock formations in the south-eastern Transvaal.
Morrey, DR | Balkwill, K | Balkwill, M-J |
S. AFR. J. BOT./S.-AFR. TYDSKR. PLANTKD. Vol. 55, no. 2, pp. 171-177. 1989.

Soils sampled from sites adjacent to two disused mines in the Barberton district were found to be derived from ultrabasic rocks. The soils contained elevated concentrations of Ni and Cr. Although potentially phytotoxic, the soils supported a relatively diverse flora. Samples of six species collected from both sites had unusually high root and leaf tissue concentrations of Ni, suggesting physiological tolerance of the metal. Berkheya coddii Roessl. showed hyperaccumulation of Ni in leaves and is likely to be endemic to nickeliferous serpentine; it may also have value as a geobotanical indicator species. Only Sporobolus pectinatus Hack. and Sutera sp. aff. S. silenoides Hilliard absorbed Cr from soil solution and translocated it to leaves.

Descriptors: bioaccumulation | South Africa, Transvaal |

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