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    Biogeochemical studies on some nickel accumulating plants from New Zealand and New Caledonian serpentine areas : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University
    (Massey University, 1974) Lee, Julian
    Serpentine areas in New Zealand and New Caledonia are described. A study was made of soil factors controlling the distribution of five species from a serpentine flora in the Dun Mountain area, South Island, New Zealand. Samples of soil were taken from sites of each of the species, and each sample was analysed for calcium, chromium, cobalt, copper, magnesium, manganese, nickel, potassium and zinc. On the basis of the species growing on them, the soil samples were divided into five groups: group 1, Pimelea suteri; group 2, Myosotis monroi; group 3, Lebe odora; group 4, Cassinia vauvilliersii; group 5, Leptospermum scoparium. Discriminant analysis was used to characterise each group of soils on the basis of chemical composition. The results showed that the two endemic plants (P. suteri and M. monroi) were much more commonly found in localities of highest magnesium concentration. These two species were strongly differentiated by the potassium and copper levels in their soils. No strong elemental discrimination was found among the non-endemic species. Correlation coefficients were calculated for the relationships between pairs of elements and highly-significant correlations (P 0.001) are reported. A nickel accumulating species from New Caledonia, Homalium kanaliense is compared with the New Zealand nickel accumulator, Pimelea suteri. The very high accumulation of nickel in the New Caledonian species, presents interesting questions in plant physiology. Purification of nickel complexes from an aqueous extract of B. kanaliense leaves was achieved and preliminary identification methods employed. None of the nickel was associated with amino acids and the present evidence suggested possible complexing of the nickel to simple carboxyllic sugars.
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    Ecological and phytochemical studies on nickel accumulating plants from the Pacific Basin region : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University
    (Massey University, 1979) Kersten, William J
    The distribution of species and genera contained in the floras of the Pacific Basin region is discussed. The outstanding feature of these floras is the high degree of specific endemism. A survey of the 53 species of Flacourtiaceae known in New Caledonia was successful in identifying a tital of 19 nickel hyperaccumulating species. The seven previously recorded in the Homalium genus were re-identified using fresh material and a further ten were located in the Xylosma genus with one in each of Casearia and Lasiochlamys. A similar survey of the Phyllanthus revealed a further ten hyperaccululating species out of the 51 studied. It was also possible to characterise and identify a number of species from their nickel and/or cobalt contents. This was particularly true for the taxonomically-difficult section Heteroglochidion. It appears that many nickel accululating plants are exclusive to ultrabasic substrates and as well as being able to tolerate high concentrations of the non-essential heavy metals they are also able to withstand extremely low levels of the essential elements. Pot trials showed that a strong relationship existed between soil and leaf nickel concentrations in Psychotria douarrei. Elemental concentrations were determined in several specimens of Rinorea bengalensis growing over a wide variety of substrates throughout the Pacific Basin region. It appears that soil conditions determine the extent to which an element is accumulated. Statistical considerations suggested a dependency on the organic constituents in the plant for the translocation of nickel. The nature of nickel complexes in several hyperaccumulating plants was investigated using gel filtration, ion exchange chromatroraphy, high pressure liquid chromatography and gas-liquid chromatography - mass spectrometry. Aquo, citrate and malate complexes of nickel were identified. Gel-filtration, electrophoretic and spectrophotometric comparisons with synthetic compounds suggested a 1:1 nickel/organic acid ratio exists in vivo. All species studied contained aquo and citrate complexes, but Psychotria douarrei and Phyllanthus serpentinus also have a large portion of their nickel bound in a malate complex. Possible factors determining the formation of a particular nickel complex are considered as is a possible pathway for the translocation of such a complex within the plant.
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    Studies on plants that hyperaccumulate copper, cobalt and nickel : their potential for use in phytomining and phytoremediation : a thesis presented in partial fulfillment of the requirements for the degree of Masterate of Science in Soil Science at Massey University
    (Massey University, 1998) Bennett, Frances Anneli
    This thesis reviews three lines of research on hyperaccumulators to examine their potential for phytoremediation and phytomining. The first line of research was to test the affect of nutrient addition on biomass and nickel uptake by two nickel hyperaccumulators, Alyssum bertotonii and Streptanthus polygaloides. Addition of fertiliser increased the biomass although the maximum amount added was found to be suboptimal. Nutrient addition did not affect the rate of nickel uptake. Larger plants contained a more dilute nickel content but still had an overall larger amount than smaller plants. The second line of research was to test the affect of chelates on metal uptake by copper and cobalt flora of the Democratic Republic of Congo (formally Zaïre) and a copper tolerant plant from Spain, Erica andevalensis. EDTA and Citric Acid increased uptake of copper in these plants but had no effect on the uptake of cobalt and nickel. EDTA increased the uptake of lead by Alyssum bertotonii but did not affect the uptake of zinc and cadmium. The third line of research was to examine the reality of hyperaccumulators of copper and cobalt. Copper and cobalt hyperaccumulation does in fact exist but not to the extent reported previously. There is a good possibility that the previously reported values for copper and cobalt hyperaccumulation are in some cases erroneous due to high iron levels indicating contamination of plant samples by soil.
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    Environmental implications of phytoextraction for mercury and gold : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Science
    (Massey University, 2000) Msuya, Fletcher Abduel Msami
    The overall objective of this study was to investigate how plants could be used to harvest gold (phytomining) and at the same time remove mercury (phytoremediation) from auriferous mercury-contaminated soils. This study was undertaken to find appropriate plants that could be used to harvest gold, residual in mine tailings or in uneconomic low-grade ore, and at the same time remove residual mercury, commonly used to extract the gold in artisanal mining areas. Different procedures involving analytical methodology, leaching of acid mine tailings and the growing of plants in both gold and mercury-bearing substrates were undertaken. The analytical methods involved in the analysis of gold in the laboratory using the modern instruments were Flame Atomic Absorption Spectrometry (FAAS) and Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The determination of mercury involved using Flameless Atomic Absorption Spectrometry. To understand the induced solubility of metals in phytoextraction, Tui mine tailings were leached with several chemicals known to solubilise gold: ammonium thiocyanate, ammonium thiosulphate and urea. The pH of the tailings material was varied through amendment with lime to examine the effect of this geochemical parameter on metal solubility and thus the potential for both plant uptake and leaching. The Tui mine tailings were chosen because of their geochemistry; these are highly weathered sulphide-ore tailings that leach heavy metals into adjacent water systems. The induced-phytoextraction potential of root crops was also examined in this thesis. Five root crops were grown in an artificial substrate consisting of 3.8 mg/kg (ppm) of elemental gold dispersed in sand. The possibility of using these root crops for phytomining was determined by separately adding chelating agents ammonium thiocyanate and ammonium thiosulphate to the substrate. In most cases there was a higher gold concentration in the roots than in the shoots. The highest mean gold concentrations were found in carrot roots and in roots of two radish cultivars. It was concluded that there was some potential for the use of carrot to grow an economic crop of gold from mine tailings. Results obtained from experiments where plants were grown in Tui tailings indicated that both chicory and Brassica juncea could be used for the phytoextraction of gold and mercury in the same crop. Under acidic conditions thiocyanate induced the uptake of gold by Brassica juncea and the uptake of mercury by chicory; and thiosulphate induced the uptake of mercury by chicory, but it did not induce the uptake of gold by the same plant. Under alkaline conditions, treatment with ammonium thiosulphate induced the uptake of gold and mercury by Brassica juncea; and treatment with thiosulphate induced the uptake of mercury by chicory but it did not induce the uptake of gold. It was therefore concluded that, Brassica juncea could be used for phytoextraction of gold and mercury when ammonium thiosulphate is applied to the substrate. Results from the root-crop experiment indicate that, carrots could supersede most of the plants used due to the greater apparent metal-uptake potential. Finally, a model is proposed for field trials to examine the potential of phytoextraction for gold and mercury in Tanzania. The aim of this model is to examine how the positive results obtained from research conducted in the laboratory and greenhouse can be put into practice. The use of similar plants as well as traditional tropical species (e.g. wild cassava - a known accumulator of cyanide) is suggested along with suitable chemical amendments.