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    Modelling and analysis of leaching of copper from volcanic ash soil : a thesis presented in partial fulfilment of the requirments [i.e. requirements] for the degree of Master of Technology in Environmental Engineering
    (Massey University, 1999) He, Dali
    Soil contaminated by heavy metal ions has become a global problem. Besides legislation to restrict the input of heavy metals, remediation of contaminated soil is also essential. The most common means of remediation is leaching. There have been many studies published in this field, some of which relate to development of mathematical models. Volcanic ash soil is common in New Zealand. Developing a model to predict the process of leaching heavy metal from volcanic ash soil is important for New Zealand. No model was found for predicting the process of leaching heavy metal from volcanic ash soil. Heavy metal soil contamination can not be remedied by microorganisms, so the heavy metals will inevitably accumulate in soils over time. Once heavy metals have accumulated in soil to exceed a threshold, they will be released and then be taken up by plants, entering the food chain or moving into the groundwater system. Therefore, it is necessary to leach the heavy metals from the contaminated soil. The batch stirred process is a fast and convenient method, and it is easily used in the field. The main purpose of this study is to develop a model that can predict the bulk liquid concentration of heavy metal in the stirred vessel. In the present study, the internal model is pore diffusion model. The explicit method is used to translate a partial differential equation to a finite difference equation. The results from thermodynamic and kinetic experiments agree with the model. With the exception of the equilibrium parameters for Freundlich isotherm derived by experiment, all other parameters were obtained from literature on volcanic ash soil. Therefore, the model can be used for leaching of other heavy metals from volcanic soil under similar conditions. The leaching of heavy metals from volcanic soil is shown to be an internal diffusion controlled process, so increasing the agitating speed in a stirred reactor is of no use for improving the mass transfer. Decreasing the size of volcanic soil aggregates by breaking them clearly increases the rate of the leaching process. The equilibrium relationships of the adsorption process and the desorption process are different for the system, and there is a hysteresis.
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    The feasibility of biogeochemical and geobotanical prospecting at Spargoville, Western Australia : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University
    (Massey University, 1972) Nielsen, Jeppe Søndergaard
    Several plant species together with their associated soils from Spargoville, Western Australia, were analysed for chromium, copper, cobalt, manganese, nickel and zinc by atonic absorption spectrophotometry. Particular reference was given to nickel and copper to evaluate the usefulness of plant analysis for biogeochemical prospecting. The nickel content in the soils gave plateaus of high values over ultrabasic rock types whereas the copper levels in the soils gave peaks over areas of mineralization at ultrabasic contacts. Consideration of the plant data showed that each species accumulated different amounts of the above elements, and that they distributed these trace elements in different ways between their leaves and twigs, or between their bark and wood. Relationships between nickel and copper concentrations in the plants and in the soils were evaluated by computing correlation coefficients; promising statistical results were checked graphically. The nickel and copper concentrations in the bark of Eucalyptus lesouefii most accurately depicted the concentrations of these metals in the soils. It was also found that the barks of Eucalyptus lesouefli, Eucalyptus longicornis and Eucalyptus torquata could be used together for prospecting purposes. In the cases where the soil-plant relationship was either very good or very poor, it seemed to make no difference whether parametric or non-parametrie correlation coefficients were used. When the relationship was intermediate between these extremes, however, the non-parametric statistic was superior. A geobotanical study was also carried out tn determine whether the distributions of the plant species was related to the geolory. Dodonaea lobulata. Pittosporum phillyraeoides and Trymaliun ledifolium were found to grow only on ultrabasic rook types, and the outer, black bark of E. lesouefii growing in mineralized ground was observed to grow to a greater height on the trunk than occurred when this species grew in non-raineralized soils. when discriminant analysis was applied to plant mapping data, the different rock types could be effectively discriminated using the relative abundances of as few as one-third of the species present. These results were markedly superior to those obtained when discriminant analysis was applied to some biogeochemical data.
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    The influence of zinc and copper fertilizer application on zinc, copper and cadmium concentration in mixed pasture : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Soil Science at Massey University
    (Massey University, 1996) Khan, Md. Afiqur Rahman
    There has been considerable debate about the accumulation of cadmium (Cd) in agricultural soils and its subsequent uptake by pasture plants due to phosphate fertilizer application. Ruminants grazing pastures absorb a small fraction of this Cd, and some of this is subsequently accumulated in the liver and kidney. Although tissue accumulation of Cd in grazing livestock is generally small (< 1 mg Cd kg-1 fresh tissue), but any reduction in plant uptake is beneficial in reducing such accumulation further, especially in the kidneys. Uptake of Cd by pasture may be affected by the concentration of other nutrient cations, such as zinc (Zn) and copper (Cu). In addition, since Zn and Cu are complexed by the same metal binding protein (metallothionein) as Cd, a change in the ratio of these nutrients in pasture may also reduce Cd accumulation rates by interfering with Cd accumulation. In order to assess the effects of Zn and Cu on Cd uptake by pasture, a field experiment was conducted, using three pairs of pasture plots with low ( 0.2 mg Cd kg-1) and high (0.6 mg Cd kg-1) background Cd status. Twelve sub-plots (l.44 m2) were laid out in each plot and increasing levels of Zn (0, 5, 15 and 40 kg ha-1) and Cu (0, 2, 5 and l0 kg ha-1) were added as ZnSO4. 7H2O and CuSO4.5H2O respectively. Pasture samples were collected at regular intervals and analysed for dry matter yield, botanical composition and Zn, Cu and Cd uptake. Soil samples were extracted with 0.01M CaCl2 and 0.lM HCl solution to measure the plant available Zn, Cu and Cd. It was found that the plots with a high background Cd status in the soil resulted in a higher Cd concentration in mixed pasture (0.22 mg Cd kg-1 DM) than those with a low background Cd status (0.10 mg Cd kg-1 DM) at the first harvest (after 73 days). The Cd concentration in the mixed pasture was higher during the summer (December) period than in the early spring (September). Application of Zn fertilizer increased the Zn concentration in pasture from 37 to 150 mg kg-1 DM at the first harvest. Excessive amounts of Zn lead to a decrease in DM yield. The growth of pasture was controlled principally by the amount of plant available Zn, which depended on the amount of both added Zn and added Cu. The effect of the added Cu was to increase the toxicity of the addd Zn. Application Cu fertilizer increased the Cu levels from 9 to 16 mg kg-1 DM at the first harvest. The Cu concentration in pasture continued to decrease with time following the addition of fertilizers. The legumes are more tolerant of Cu than grass. The Cu concentration in harvest 4 (after 159 days) ranged from 6.9 to 7.0 mg kg-1 DM in grass and 8.9 to 9.9 mg kg-1 DM in legumes. The Cd concentration in the pasture decreased with increasing Zn concentration in the pasture at the first harvest. The effect of Zn on Cd uptake was more pronounced on plots with a high background Cd status in the soil. The effect of Zn on Cd concentration depends on the external Zn concentration levels. There was no consistent effect of Cu concentration on Cd concentration. The effect of the addition of Cu and Zn in fertilizer was to lower the Cd:Cu and Cd:Zn ratios in the herbage. There was a good relationship between soil available Zn as extracted by 0.1M HCl and Zn concentration in the herbage. A similar observation was obtained for Cu. But there was no consistent relationship between 0.01M CaCl2 extractable Cd and the Cd concentration in pasture. The results indicated that pasture and soil analysis for Cd and Zn may provide useful guides to situations where Cd concentrations in pasture may be decreased by Zn applications.