Ligand I- along with nonionic surfactant, Triton X-100 or anionic surfactant, sodium dodecyl sulfate (SDS) were applied as soil washing agents to desorb Cd from both naturally and artificially contaminated soils. After seven consecutive washings, up to 90% of Cd was desorbed from both soils. Triton X-100 with I- showed a higher capacity to desorbing Cd than did SDS with I-. The increase of ligand concentration was a critical factor for increasing leaching capacity. Without the ligand, surfactant alone could not desorb Cd effectively from either soil. After seven consecutive washings, a sequential extraction experiment was performed for soil residuals to define the soil fraction of Cd removed by the washing agent. Among the washing agents, only Triton X-100/I- could remove Cd from the exchangeable fraction of both soils. / Various ligands including I-, SCN-, and I-/SCN- in combination with Triton X-100 were tested for their efficacy in desorbing heavy metals such as Cd, Zn, Cu, and Pb from a field contaminated soil. Cadmium was preferentially desorbed by Triton X-100/I- whereas Zn and Cu were preferentially desorbed by Triton X-100/SCN-. The mixture of I- and SCN- with Triton X-100 desorbed the most Cd and Cu, but not for Zn, as I- inhibited Zn desorption. Sequential extraction experiments after seven washings showed that metals held in the exchangeable fraction can be desorbed only by a combination of ligand and surfactant. / Nonionic surfactants having different alkyl chain lengths in combination with ligand I- were tested for the desorption of Cd and PCBs from soil. Cadmium desorption was increased at the lower surfactant concentration and higher ligand concentration. The increase in the hydrophilic alkyl chain length of the surfactant adversely affected Cd desorption. Up to 100% of PCBs were successfully removed by most of surfactant-ligand combinations and the desorption was less dependent, compared to heavy metals, on the concentration of washing agents and length of alkyl chain. The linear relationships between number of washings and Cd desorption, and between alkyl chain length and Cd desorption was defined. (Abstract shortened by UMI.)

In this research, it is aimed to remove toxic heavy metals in waste water with the help of fly ash from &Ccedil / ayirhan thermal power plant. The chemical and physical properties (size distribution, specific surface area, porosity, chemical composition, etc.) of fly ash were determined. The experiments were carried out in synthetic waste water containing lead, zinc and copper metals at different concentrations with the addition of fly ash. The effects of metal concentration, agitation time, particle size, ash amount, and pH in the metal removal were examined. With the addition of even very small amount of fly ash, heavy metal removal from waste water was attained at up to 99%. Fly ash particle size has no significant effect on removal of heavy metal ions from solutions. Higher solution pH and longer treatment time were resulted better metal removal. The results also indicated that the main mechanism for metal removal was precipitation due to alkaline characteristics of fly ash and more than 90 % of metals in solutions were removed by precipitation. The pH ranges for maximum metal precipitation were 10-11, 8-10, and 10-11 for copper, zinc, and lead respectively. Very small percentages of adsorbed metal was released during the desorption test.

In the recent years, environmental pollution becomes a health threatening issue for human beings. Technological developments introduce industrial wastes and heavy metals, and developments in agriculture introduce pesticides into the world that we live. All these toxic wastes accumulate in drinking water and food consumed by humans. Therefore, detection of toxic wastes in all kinds of environmental samples, and development of new detection techniques become an important issue. In this study, development of a protein-based biosensor for detection of heavy metals in environmental samples, by expressing genetically modified glutathione S-transferase (GST-(His)6) protein in E.Coli BL21 (DE3) expression system, was designed. Recombinant GST proteins was expressed in E.Coli BL21 (DE3) expression system and purified with Glutathione Sepharose 4B affinity column and Ni-NTA spin kit. GST activities were determined using the GST substrate 1-chloro-2,4-dinitrobenzene (CDNB). Protein expression was tested by SDS-PAGE and Western blot analysis. Product formation linearly increased up to 1 mM CDNB, 1 mM GSH, 1.7 &micro / g proteins in 0.05 M, pH 6.9 phosphate buffer in the final volume of 1.0 ml at 25&amp / #9702 / C. The Vmax and Km values for GST-(His)6 towards CDNB and GSH were calculated with Lineweaver-Burk as CDNB Vmax / 22.88 &micro / mol/min/mg, Km / 4.29 mM,and as GSH Vmax / 6.42 &micro / mol/min/mg, 24.45 &micro / mol/min/mg, Km / 3.69 mM, respectively. Biosensor working electrode was prepared by immobilizing the GST-(His)6 by 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride (EDC) coupling on the gold surface. Electrode preparation was confirmed by cyclic voltammetry measurements. The biosensor was inserted as the working electrode in the constructed three(four)-electrode flow cell. The conformational change resulting from the binding of the metal ions to the recombinant protein causing a capacitance change proportional to the concentration of the metal ions was determined. After the working electrode is standardized and calibrated, the heavy metal concentration in water samples was measured. The GST-(His)6 biosensor has a large operational range between 1 fM and 10 mM and a storage stability of approximately 2 weeks. The GST-(His)6 biosensor is very sensitive to, Cu+2&gt / Cd+2&gt / Zn+2&gt / Hg+2 metal ions, at low concentrations.

The research described in the thesis details the investigation of build-up and wash-off process kinetics of Polycyclic Aromatic Hydrocarbons (PAHs) and heavy metals in urban areas. It also discusses the design and development of a rainfall simulator as an important research tool to ensure homogeneity and reduce the large number of variables that are usually inherent to urban water quality research. The rainfall simulator was used to collect runoff samples from three study areas, each with different land uses. The study areas consisted of sites with typical residential, industrial and commercial characteristics in the region. Build-up and wash-off samples were collected at each of the three sites. The collected samples were analysed for a number of chemical and physico-chemical parameters. In addition to this, eight heavy metal elements and 16 priority listed PAHs were analysed in five different particle size fractions of the build-up and wash-off samples. The data generated from the testing of the samples were evaluated using multivariate analysis, which reduced the complexity involved in determining the relative importance of a single parameter in urban water quality. Consequently, variables and processes influencing loadings and concentrations of PAHs and heavy metals in urban stormwater runoff from paved surfaces at any given time were identified and quantified using Principal Component Analysis (PCA). Furthermore, the process kinetics found were validated using a multivariate modelling approach and Partial Least Square (PLS) regression, which confirmed the transferability of chemical processes in urban water quality. Fine particles were dominant in both the build-up and wash-off samples from the three sites. This was mirrored in the heavy metal and PAH concentrations at the three sites, which were significantly higher in particles between 0.45-75μm than in any other fraction. Thus, the larger surface area and electrostatic charge of fine particles were favourable in sorbing PAHs and heavy metals. However, factors such as soil composition, total organic carbon (TOC), the presence of Fe and Mn-oxides and pH of the stormwater were all found to be important in partitioning of the metals and PAHs into different fractions. Additionally, PAHs were consistently found in concentrations above their aqueous solubility, which was attributed to colloidal organic particles being able to increase the dissolved fraction of PAHs. Hence, chemical and physico-chemical parameters played a significant role in the distribution of PAHs and heavy metals in urban stormwater. More importantly, the research showed the wide range of factors that distribute metals and PAHs in an urban environment. Furthermore, it indicated the need for monitoring these parameters in urban areas to ensure that urban stormwater management measures are effective in improving water quality. The build-up and wash-off process kinetics identified using PCA at the respective land uses were predicted using PLS and it was found that the transferability of the governing processes were high even though the PAHs and metal concentrations and loads were highly influenced by the source strength at each site. The increased transferability of fundamental concepts in urban water quality could have significant implications in urban stormwater management. This is primarily attributed to common urban water quality mitigation strategies relying on studies based on physical concepts and processes derived from water quantity studies, which are difficult to transfer between catchments. Hence, a more holistic approach incorporating chemical processes compared to the current piecemeal solutions could significantly improve the protection of key environmental values in a region. Furthermore, urban water quantity mitigation measures are generally designed to reduce the impacts of high-flow events. This research suggests that fairly frequent occurring rainfall events, such as 1-year design rainfall events, could carry significant heavy metal and PAH concentrations in both particulate and dissolved fractions. Hence, structural measures, designed to decrease quantity and quality impact on receiving waters during 10 or 20-year Average Recurrence Interval (ARI) events could be inefficient in removing the majority of PAHs and heavy metals being washed off during more frequent events. The understanding of physical and chemical processes in urban stormwater management could potentially lead to significant improvements in pollutant removal techniques which in turn could lead to significant socio-economic advantages. This project can serve as a baseline study for urban water quality investigations in terms of adopting new methodology and data analysis.

The release of toxic metal species is of concern due to their detrimental effects on the environment and human health. Industrial effluents are a major source of mobilised metal species. Suitable technologies are needed to sequester toxic metal species at the point of source. Biosorption, which is based on the passive adsorption of contaminants onto biological materials, promises to offer an effective alternative or complementary step to existing treatment methods. However, to date there has been no widespread commercialisation of the technique. This is partly due to an insufficient understanding of the complex underlying mechanisms which makes it difficult to select suitable biomass for specific remediation problems and to predict process performance. This study characterised two gram-positive, thermophilic bacteria, Anoxybacillus flavithermus (BF) and Geobacillus stearothermophilus (BS), harvested at two different growth times, with regard to their acid-base and Cd�⁺ adsorption behaviour. The aim was to investigate the metal cation adsorption properties of thermophilic bacteria which has not been studied previously, and to gain a better understanding of the interactions responsible for bacterial metal cation adsorption. Experimental techniques employed in this study included microscopy to establish cell and cell wall morphology, batch acid-base and Cd�⁺ adsorption experiments to quantify proton active surface functional groups and Cd�⁺ adsorption, electrophoretic mobility measurements to assess the overall surface charge of the bacteria and in situ attenuated total reflection infrared (ATR-IR) spectroscopy to reveal the chemical identities of functional groups. Chemical equilibrium models based on batch acid-base titration and electrophoretic mobility data were developed to quantitatively describe proton active surface functional groups. These groups can also interact with metal cations. It was found that growth time was an important factor in all experiments with the differences between growth times often being more pronounced than the differences between the two bacterial strains. Microscopy revealed a gram-positive cell wall structure with different widths and staining behaviour for exponential phase cells of BF and BS. Stationary / death phase cells showed disintegrating cell walls. Acid-base titrations indicated that all cells possessed buffering capacity over the whole investigated pH range (pH 2 - 10). From electrophoretic mobility measurements, isoelectric points of ~ 3.2 for BF and < 1.8 and ~ 4.2 for exponential and stationary / death phase cells of BS respectively were estimated. Chemical equilibrium models including a Donnan electrostatic model were derived which described both the batch acid-base titration data and the electrophoretic mobility data reasonably well, although a comparison with IR data suggested room for further improvement. In situ ATR-IR spectroscopy of hydrated bacterial cells at various pH values revealed amide and carboxyl groups and a contribution from phosphate / polysaccharide moieties. Group specific interactions with Cd�⁺ were not detected, however, a partially reversible absorbance increase of all peaks suggested conformational changes in the presence of Cd�⁺. BF and BS adsorbed ~ 70 [mu]mol Cd�⁺ (g dry bacterial)⁻� at pH 5 in 0.01 M NaNO₃. Release of major cations occurred concomitantly with Cd�⁺ adsorption. The buffering and Cd�⁺-binding capacities of BF and BS were found to be comparable to those of mesophilic bacteria and ion exchange was identified as an important adsorption mechanism.

Many brackish water aquaculture ventures in Australia and overseas have established ponds in coastal regions with acid sulfate soils (ASS). Acid sulphate soils are known to leach relatively high concentrations of metals, acid (metal and H+ ion) and sulfur, however very little is known about how these leached elements affect the water quality of aquaculture ponds. The main objective of this thesis was to describe the hydrochemical processes controlling the water chemistry in the water column and sediment pore water in the studied aquaculture ponds over time and space. Water samples providing the spatio-temporal data were collected from the ponds with the use of adapted sampling methods commonly used in the groundwater environment. A transect of five nested piesometers was installed in two prawn ponds at Pimpama, south east Queensland, Australia. Each piesometer nest contained a multilevel with eight outtakes, a mini ?? horizontal, and a slotted piesometer. Water samples were collected from each nested piesometer on a bi-monthly basis over the prawn-growing season. The unstable elements and water quality variables (pH, Eh, DO, EC, water temperature) were measured in the field. Stable elements were analysed in the laboratory using ICP-OES and ICP-MS. Soil samples were collected at the end of the season for elemental analysis. A number of key sediment/water interactions and processes such as precipitation/dissolution reactions, oxidation-reduction reactions, photosynthesis, adsorption and seawater buffering were identified as important controls on pond water conditions. This is the first study to provide detailed hydrochemcial analysis of the pond water over time and space and aided in identifying that even shallow water bodies can be chemically heterogeneous. Analysis of the water and sediment highlighted the selection of metals that can be associated with ASS and that are mobilised from pond sediments under certain chemical conditions. In Pond 7 Al, As, Ni and Zn concentrations were generally higher at the beginning of the grow-out season. Variability of the metal concentration was observed between the water column (0 ?? 1500 mm) and the pore-water (0 - -1000 mm). The highest concentration of Al (1044 ??g/L) and Zn (104 ??g/L) were sampled in the water column (approximately 400 mm from the surface of the pond). The highest concentration of As (130 ??g/L) and Ni (73 ??g/L) were sampled in the pore water sediment (associated with ASS). Elevated Mn and Fe2+ concentrations were also associated with the sediment pore water. The highest concentrations of Mn and Fe2+ were 4717 ??g/L and 5100 ??g/L respectively. In Pond 10, Ni concentrations (167 ??g/L) were the highest at the beginning of the grow-out season. However, As (97 ??g/L), Al (234 ??g/L) and Zn (308 ??g/L) were most concentrated during the middle of the cycle. The highest mean concentrations of these elements are As (63 ??g/L), Al (91 ??g/L) and Zn (69 ??g/L) which are each associated with the sediment-water interface. These metals are integral in degrading the pond water quality and lead to a loss of beneficial algal blooms, a reduction in pond water pH, poor growth rates and high mortality in shrimp. It is also possible that the dissolved ions and precipitated compounds that are leached from the ASS are discharged into the adjacent coastal estuary of Moreton Bay. With knowledge obtained from this PhD study, effective management and treatment systems can be developed and implemented to minimise the impact of these soils on the pond system and the water discharging into natural coastal ecosystem.

Bibliography: leaves 153-156. / ix, 156 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis describes the experiments conducted to determine the mechanisms that cause the decline in shoot Zn concentration and the responses of the wheat plant to Zn deficiency and chlorosulfuron stress. Root tip extension is used as a measure of wheat root growth during exposure to the sulfonylurea herbicide chlorsulfuron. Wheat plants differing in Zn efficiency are grown in HEDTA chelate-buffered nutrient solution in controlled conditions. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

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Bibliography: leaves 153-156. / ix, 156 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis describes the experiments conducted to determine the mechanisms that cause the decline in shoot Zn concentration and the responses of the wheat plant to Zn deficiency and chlorosulfuron stress. Root tip extension is used as a measure of wheat root growth during exposure to the sulfonylurea herbicide chlorsulfuron. Wheat plants differing in Zn efficiency are grown in HEDTA chelate-buffered nutrient solution in controlled conditions. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references (leaves 212-219). Also available via World Wide Web.