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Subject: search.filters.subject.Copper in plants

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    Biogeochemical studies of nickel and copper in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
    (Massey University, 1971) Timperley, Michael Horace
    The accumulations of various metals by some indigenous trees growing on the Riwaka Basic Complex, North-west Nelson, New Zealand, were investigated by the application of statistical techniques to biogeochemical data. Particular reference was given to nickel and copper to evaluate the usefulness of plant analysis as a prospecting tool. Preliminary investigations showed that serious errors could result from the methods of sampling plants and soils and sampling procedures were adopted to minimise these errors. In addition, errors arising from atomic absorption analysis were found to be significant for some metals. Leaves and twigs from three Nothofagus species, W.racemosa and Q.acutifolia as well as their associated soils, were collected and analysed for nickel, cobalt, copper, zinc, chromium, calcium, magnesium, manganese and potassium. The plants were also analysed for iron. These results showed that each species accumulated different, but related, amounts of various metals and that they distributed these metals in different ways between their leaves and twigs. N.truncata and N.fusca which are closely related genetically, accumulated metals to similar degrees, while N.menziesii which is not closely related to the other Nothofagus species accumulated metals to differing degrees. Relationships between the metal concentrations in the plants and in the soils were evaluated by computing correlation coefficients. The best correlations for nickel were obtained for the Nothofagus genus although the other species also showed highly significant correlations. The Nothofagus genus also showed the best correlation for copper. In view of the above results, a more extensive study of the Nothofagus genus was carried out. A second survey was undertaken in the same area in which leaf samples of this genus as well as their associated soils were collected. While the metal concentrations in the soils collected in this survey compared well to those collected previously, the metal concentrations in the plants, in general, did not show good agreement. Trend analysis was used to compare in detail the nickel and copper contents in the leaves of the Nothofagus genus with the concentrations of those metals in the soils. It was shown by comparison of the trend surfaces and residuals that the accumulation of nickel was determined primarily by the concentration of nickel in the soil, whereas for copper the accumulation by the plant was a function primarily of the specific requirement of the plant for this metal. Multiple regression analysis was used to improve the prediction of the copper and nickel concentrations in the soil from the concentrations of these metals in the leaves of the Nothofagus species, by making quantitative allowance for the processes influencing the accumulation of these metals by the plants. Improvements of between 25% and 35% were obtained at the 90% confidence level. Inter-metal ratios in the leaves were considered as possible indicators of nickel and copper concentrations in the soil but the results were discouraging. Studies were made of the locations and chemical forms of nickel, copper, zinc and iron in both freeze-dried and fresh leaves from some trees growing on the Complex. Atomic absorption spectrophotometry was used to measure the concentrations of these metals in both plant extracts and on the electrophoresis and chromatography papers used to separate the metal complexes in the extracts. Results indicated that the major part of the nickel present in the leaves was not contained in cell organelles nor was it bound to cell walls, but existed as a positively charged complex in either the cytoplasm and/ or the vacuole. Copper, zinc and iron were distributed differently with varying fractions, depending on the metal, existing predominately as anionic complexes. It was concluded that the research embodied in this thesis had illustrated the application of statistical techniques to biogeochemical studies, showed that biogeochemical prospecting for nickel in New Zealand was feasible and that methods of total analysis for metals could be applied to the study of microgram amounts of metals in biological systems.
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    Botanical methods for mineral exploration in Western Australia : a thesis in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Massey University
    (Massey University, 1972) Severne, Barry Charles
    The application of vegetation to mineral exploration was investigated in the semi-desert mulga zone of Western Australia. Acacia aneura (mulga) dominated the vegetation and was employed in several biogeochemical surveys to locate subsurface copper and nickel mineralisation after successful orientation surveys over outcropping areas. Copper concentrations in A. aneura leaf were adequate for locating cupriferous zones in the Murchison Region. In the Kurrajong Region, A. aneura was employed to locate nickel sulphide mineralisation in a terrain of serpentinised and lateritised ultrabasics, characterised by high and variable nickel levels. It was possible to distinguish sulphide mineralisation from lateritic areas by consideration of coincident nickel and manganese biogeochemical anomalies. A nickel-accumulating variety of the shrub, Hybanthus floribundus, was discovered in the Kurrajong Region. Other Hybanthus varieties were also found to accumulate nickel, in more southern parts of Western Australia. Plant chemistry studies indicated thst nickel was concentrated in the leaf epidermis as a small, water-soluble positively-charged complex. The value of these nickel-accumulating shrubs in locating nickeliferous areas was demonstrated. Preliminary attempts to detect this shrub, from the air, using colour infrared photography were unsuccessful, although the potential of colour film to take advantage of the anomalous yellow colour during the summer season was realised. Three tree species, Acacia coolgardiensis, A. resinomarginea, and A. burkittii, exhibited pronounced geobotanical relationships. The first two species were restricted to metabasalt and metagabbro ridges, whilst A. burkittii characterised calcareous serpentinised pyroxenites. It was found that a usable colour infrared image could not be obtained by vertical aerial photography because of the infundibular growth-form exhibited by this xerophytic vegetation. However the application of this film to photogeology was confirmed. The possibility of using selenium as a path finder for sulphide mineralisation was investigated. A suitably-rapid instrumental method for the determination of selenium and tellurium was developed and a selenium accumulating tree, Acacia oswaldii, was subsequently discovered. A known toxic shrub, Swainsona canescens, also accumulated selenium, and the potential of this selenifereus flora in locating sulphides has yet to be demonstrated. It was concluded that the research embodied in this thesis has indicated the application of botanical methods to mineral exploration in the Eremean Province of Western Australia, and has outlined promising avenues for further investigations.
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    Mechanisms of copper uptake and transport in plants : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Soil Science at Massey University, New Zealand
    (Massey University, 2000) Liao, Mingtan
    The Cu concentration in plants varies considerably between species. This suggests different abilities to either absorb Cu from soils or translocate Cu from root to shoot. The main objective of the thesis was to provide a fuller understanding of the mechanisms of Cu uptake and transport in plants which may lead to the development the strategies to improve Cu uptake by pasture crops. Glasshouse experiments with the Cu hyperaccumulator Haumaniastrum katangense showed that Cu hyperaccumulation in shoots was not found. It was concluded that H. katangense plants tested in these experiments were Cu tolerant rather than having hyperaccumulator status. The mechanism of high tolerance to Cu could be due to the restriction of Cu transport from roots to shoots. Nutrient solution culture experiments with the Ni hyperaccumulator plants Alyssum bertolonii and Berkheya coddii showed that co-hyperaccumulation of Cu and Ni did not exist. Alyssum bertolonii was not a Cu-tolerant plant, whereas B. coddii exhibited a much greater degree of tolerance to this metal, and the tolerance of B. coddii to Cu was not at the expense of Ni uptake. It was concluded that B. coddii should be considered as a possible plant for phytoremediation of soils contaminated with both Cu and Ni and it is recommended that field trials be carried out to establish this potential. NFT nutrient solution culture experiments showed that a large proportion of total Cu uptake by chicory and tomato plants was retained by roots except when plants were grown in the basal nutrient solution (0.05 mg Cu L-1). Copper retention by roots, limited Cu translocation to xylem and shoots. Large differences between measured and predicted Cu accumulation by shoots of tomato and chicory suggested that some xylem-transported Cu is recirculated to roots via the phloem. A Cu speciation study showed that more than 99.7% of total Cu in tomato and chicory xylem sap was in a bound form. Increased Cu concentrations in the rooting media induced selective synthesis of certain amino acids which include NA, His, Asn and Gln, all of which have high stability constants with Cu. Nicotianamine and His have the highest binding constants for Cu and the concentrations of NA and His in chicory and tomato xylem saps can account for all the bound Cu carried in the sap. Copper recirculation within plants was demonstrated by an experiment with hydroponically grown tomato plants in a split-root system. Significant amounts of Cu were translocated from roots bathed in a solution of high Cu concentration to another half root system exposed to low Cu. Shoot Cu concentrations were positively correlated to plant water use (mL g-1 DM). A Cu recirculation model was suggested. Efforts have been made to develop the strategies to improve Cu uptake by pastures. The initial uptake of Cu from CuSO4-fertilised soil can be increased by 10-21 % by addition of His and casein. Casein was generally more effective at increasing plant Cu uptake than His and other amino acids. The Cu(OH)2-based fertiliser was less effective than the CuSO4-based fertilisers in supplying Cu to ryegrass grown in pots of Ashhurst stony silt loam and Wairoa pumice soil. In general, among the three CuSO4 fertilisers, Ca-caseinate-CuSO4 resulted in higher Cu uptake by ryegrass grown in both soils. The factors constraining Cu uptake by ryegrass plants from Cu-fertilised soils were elucidated. Linear relationships between ryegrass Cu uptake and total soil solution Cu concentration were soil type dependent, despite each soil having similar soil solution Cu concentrations. Between 98.5-99.5% of the soil solution Cu was in complexed forms. No relationship between the Cu2+concentration in soil solution (expressed as pCu2+) and Cu concentration in plants was found. Free Cu2+ concentrations in soil solution were sensitive to pH change. The extent of the increase in free Cu2+ concentration per unit decrease in pH was dependent on soil type. It is suggested that the rate of Cu uptake by plants is likely to be dependent on both the concentration of organically complexed Cu in the soil solution and the stability of this complex to pH change.