Cadmium (Cd) is a potentially toxic trace element. Two growth chamber studies were conducted to understand how: i) mono-ammonium phosphate affects durum wheat, flax or canola Cd uptake due to fertilizer induced changes in soil solution and plant; ii) preceding canola and barley affect the Cd uptake of subsequent durum wheat or flax. Durum wheat and flax shoot Cd concentrations were greater when grown on previous crop canola soil than when grown on previous crop barley soil regardless of what type of crop residue, if any, was added. The increase in Cd uptake for durum wheat and flax when on canola soil was probably due to increased availability of Cd in soil. Conversely, the application of mono-ammonium phosphate – reagent grade and the incorporation of preceding crop residue did not increase the crop Cd uptake of canola, durum wheat or flax and durum wheat or flax, respectively.

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Shellfish are an important food source however they are known to harbour bacteria, viruses and toxic chemicals that can be detrimental to their human consumers. Oysters have been associated with the gastroenteritis virus Norovirus. New Zealand has some of the highest cases of foodborne illness in the western world. This study investigated a possible link between periods of high rainfall and reported Norovirus outbreaks in four major cities in New Zealand (Auckland, Wellington, Christchurch and Dunedin) as well as national data. Norovirus is a highly infectious foodborne illness. Outbreaks of norovirus have been linked to the consumption of shellfish, and in particular oysters. Norovirus virions can enter the aquatic environment via sewage as a result of human shedding of the virus. This investigation into rainfall and Norovirus outbreaks found no statistically significant relationship, in a monthly or season setting. In addition the relationship between environmental cadmium levels and exposure levels in New Zealand was investigated through meta-analysis. Cadmium is a heavy metal commonly associated with the mining of copper and zinc ores. It is found naturally in the environment, in air land and oceans Increased exposure to cadmium is known to have a number of serious detrimental health effects, in particular this study investigates cadmiums immunosuppressive properties. Concentrations in New Zealand were compared with Canada, Italy and the UK to determine if New Zealand has a relatively high cadmium intake. Interestingly environmental levels (soil and oceanic) in New Zealand were low. Cadmium levels were higher in oysters than in mussels, with New Zealand oysters containing the highest concentration of cadmium presented. New Zealanders also had the highest cadmium burdens in the kidneys and the highest daily intakes. A No Observable Effect Level (NOEL) was calculated from mice data and compared to the daily intakes of the four countries. Both Canada and New Zealand were above this level. Shellfish are a common mechanism for exposure to both Norovirus and cadmium. The levels of cadmium present in the diet of New Zealanders may be sufficiently high to suppress the immune system, making it more vulnerable to infections of enteric diseases such as Norovirus.

A series of acute (96h) toxicity tests were conducted on six species of crayfish inthe family Cambaridae. Toxicity values fell into a sensitive group comprising Orconectesplacidus and Procambarus acutus (LC 50= 0.368mg Cd/L - 0.487mg Cd/L; LC10= 0.048mg Cd/L - 0.092 mg Cd/L) and tolerant group comprising O. juvenilis, O. virilis, P.alleni, and P. clarkii (LC 50= 2.44 mg Cd/L - 3.30 mg Cd/L; LC10= 0.386 mg Cd/L -0.947 mg Cd/L). For juvenile crayfish, the LC50 and LC10 values were as follows: O.juvenilis, 0.060 and 0.014 mg Cd/L; O. placidus, 0.037 and 0.002 mg Cd/L; P. clarkii,0.624 and 0.283 mg Cd/L. Cd exposure decreased molting success highlighting theimportance of this sensitive process. Behavioral responses were assessed in O. placidus,O. virilis, P. acutus, P. alleni, and P. clarkii. The tail-flip predator avoidance behaviorwas significantly reduced by cadmium exposure. In most species tested, the claw raisedefensive behavior was significantly increased by Cd exposure. Between species, as bodymass increased, the tail-flip response frequency decreased, and the claw-raise responseincreased in frequency. P. clarkii was also analyzed for the effect of Cd exposure onheart rate and response to two stimuli. The data indicate that heart rate may be a usefulphysiological marker of Cd toxicity. The major organ systems were dissected fromsurvivors of four adult crayfish toxicity tests (O. juvenilis, O. placidus, P. acutus, P.clarkii) and analyzed for metal content. Cadmium tissue content correlated with Cdexposure. Cadmium accumulated more in the hepatopancreas, gills and green glands ofsensitive species than in tolerant species. Zn showed negative correlations with Cdexposure in the hepatopancreas. Cu increased in green glands, gills, and hemolymph and,in some cases, decreased in the hepatopancreas. Ca, Fe, Mg, and Zn also showedsignificant trends. Zn accumulated in the exposure water over 24h. These data indicatethat Cd may displace Cu and/or Zn in the hepatopancreas and the displaced metal thenmay move into other tissues, especially the gills and green glands, possibly to beexcreted.

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This thesis present photoluminescence spectroscopy and X-ray diffraction analyses of four different cadmium zinc telluride samples with different quality and features and similar zinc molar concentration of 10%. Photoluminescence spectroscopy of the samples let us obtain several physical parameters of the samples which are indicators of quality, composition, structure, and impurity levels of the samples. The band gap energy of the samples obtained from the photoluminescence spectra at low temperatures helped us to estimate zinc molar concentration of the samples. Temperature dependence of band gap energy in these samples has been analyzed and exciton-LO phonon interactions in the samples has been analyzed. From temperature dependence of full width at half maximum of the photoluminescence peak several parameters including concentration of impurity centers and inhomogeneity of the samples are determined and compared in order to check the quality of the samples. Thermal quenching of the photoluminescence peak has been analyzed and the processes which are associated with each parameter are determined and discussed. X-ray diffraction analyses of the sample for the location and width of the peaks have been analyzed and several characteristics of the samples including quality, lattice constant and zinc molar concentration of the samples are determined and compared. The parameters that are obtained from these analyses are compared with the ones from the photoluminescence spectra and showed a good agreement between the results of these two non-destructive characterization techniques. / Graduate / 0605 / 0544 / 0794

Cadmium (Cd) is a potentially toxic trace element. Two growth chamber studies were conducted to understand how: i) mono-ammonium phosphate affects durum wheat, flax or canola Cd uptake due to fertilizer induced changes in soil solution and plant; ii) preceding canola and barley affect the Cd uptake of subsequent durum wheat or flax. Durum wheat and flax shoot Cd concentrations were greater when grown on previous crop canola soil than when grown on previous crop barley soil regardless of what type of crop residue, if any, was added. The increase in Cd uptake for durum wheat and flax when on canola soil was probably due to increased availability of Cd in soil. Conversely, the application of mono-ammonium phosphate – reagent grade and the incorporation of preceding crop residue did not increase the crop Cd uptake of canola, durum wheat or flax and durum wheat or flax, respectively.

This thesis present photoluminescence spectroscopy and X-ray diffraction analyses of four different cadmium zinc telluride samples with different quality and features and similar zinc molar concentration of 10%. Photoluminescence spectroscopy of the samples let us obtain several physical parameters of the samples which are indicators of quality, composition, structure, and impurity levels of the samples. The band gap energy of the samples obtained from the photoluminescence spectra at low temperatures helped us to estimate zinc molar concentration of the samples. Temperature dependence of band gap energy in these samples has been analyzed and exciton-LO phonon interactions in the samples has been analyzed. From temperature dependence of full width at half maximum of the photoluminescence peak several parameters including concentration of impurity centers and inhomogeneity of the samples are determined and compared in order to check the quality of the samples. Thermal quenching of the photoluminescence peak has been analyzed and the processes which are associated with each parameter are determined and discussed. X-ray diffraction analyses of the sample for the location and width of the peaks have been analyzed and several characteristics of the samples including quality, lattice constant and zinc molar concentration of the samples are determined and compared. The parameters that are obtained from these analyses are compared with the ones from the photoluminescence spectra and showed a good agreement between the results of these two non-destructive characterization techniques. / Graduate / 0605 / 0544 / 0794

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