Organic solar cells have caught considerable attention in the past few years due to their potential for providing environmentally safe, flexible, lightweight, inexpensive, and roll-to-roll feasible production solar cells. However, the efficiency achieved in current organic solar cells is quite low, yet quick and successive improvements render it as a promising alternative. A hopeful approach to improve the efficiency is by exploiting the tandem concept which consists of stacking two or more organic solar cells in series. One important constituent in tandem solar cells is the middle electrode layer which is transparent and functions as a cathode for the first cell and an anode for the second cell. Most studies done so far have employed noble metals such as gold or silver as the middle electrode layer; however, they suffered from several shortcomings especially with respect to reproducibility. This thesis focuses on studying a new trend which employs an oxide material based on nano-particles as a transparent cathode (such as Zinc-oxide-nano-particles) along with a transparent anode so as to replace the middle electrode. Thus, this work presents a study on solution processable zinc oxide (ZnO) nanostructures, their proper handling techniques, and their potential as a middle electrode material in Tandem solar cells in many different configurations involving both polymer and small molecule materials. Moreover, the ZnO-np potential as a candidate for acceptor material is also investigated.

This thesis improves the understanding of the fate and transport of aerosols in North America. Aerosols play an important role climate modification, visibility, human health, and regulatory compliance. Through multiple aircraft-based and ground-based field campaigns, in situ ambient bulk aerosol concentrations will be determined across geographically diverse regions of the United States. By examining aerosol composition - specifically, inorganic ions and water-soluble organic carbon - as they are transported across the Pacific Ocean, we can observe background concentrations that may contribute to aerosol loading observed in many US communities. Furthermore, the aerosol continues to be modified by anthropogenic and biogenic emissions, dry and wet deposition, and secondary formation and transformation as it is transported across the continent. To capture some of these dynamic changes, aerosol will be extensively measured near the east coast of the US and Canada, and results may show significant anthopogenic, biogenic, and secondary transformation. Many results from the Northeastern United States and Southeastern Canada will be presented, and a special case study discussing acid-catalyzed formation of secondary organic aerosol in the region of northern Georgia, US is discussed. Lastly, through laboratory- and field-based instrument development, a commonly-deployed instrument is modified for improved measurement of organic carbon and results are presented herein.

<p>Organic solar cells have caught considerable attention in the past few years due to their potential for providing environmentally safe, flexible, lightweight, inexpensive, and roll-to-roll feasible production solar cells. However, the efficiency achieved in current organic solar cells is quite low, yet quick and successive improvements render it as a promising alternative. A hopeful approach to improve the efficiency is by exploiting the tandem concept which consists of stacking two or more organic solar cells in series.</p><p>One important constituent in tandem solar cells is the middle electrode layer which is transparent and functions as a cathode for the first cell and an anode for the second cell. Most studies done so far have employed noble metals such as gold or silver as the middle electrode layer; however, they suffered from several shortcomings especially with respect to reproducibility.</p><p>This thesis focuses on studying a new trend which employs an oxide material based on nano-particles as a transparent cathode (such as Zinc-oxide-nano-particles) along with a transparent anode so as to replace the middle electrode.</p><p>Thus, this work presents a study on solution processable zinc oxide (ZnO) nanostructures, their proper handling techniques, and their potential as a middle electrode material in Tandem solar cells in many different configurations involving both polymer and small molecule materials. Moreover, the ZnO-np potential as a candidate for acceptor material is also investigated.</p>

The two objectives of this work were to develop a simplified method for the analysis of chlorinated organics in water samples and to improve an existing soil remediation technology. The contaminants considered for these studies were chlorinated hydrocarbons because of their relative frequency of appearance at contaminated sites. The first half of this study involved the analysis of chlorinated ethenes by gas chromatography with flame ionization detection (GC-FID). I tested the hypothesis that the FID response factor is the same for all chlorinated ethene compounds. The rationale for this investigation is that if the hypothesis is correct, a single calibration curve can be used for GC/FID analysis of all chlorinated ethene compounds, saving time and money during sample analysis. Based on my measurements, a single calibration curve fits PCE, TCE, and cis-DCE (R2=0.998). However, the apparent slope of the calibration curve for vinyl chloride is approximately 45% lower, indicating that a separate calibration curve must be used to quantify vinyl chloride. I believe this difference in vinyl chloride is due to loss of analyte mass due to volatilization. The second half of the study considered the effect of solvent composition for a soil remediation technology, entitled remedial extraction and catalytic hydrodehalogenation (REACH), developed by Dr. Hun Young Wee and Dr. Jeff Cunningham (Wee and Cunningham, 2008). The objective of this thesis is to convert 1,2,4,5-tetrachlorobenzene (TeCB) to cyclohexane, thus improving on the work of Wee (2007). Recent work by Osborn (2011) tested successfully the use of palladium and rhodium catalysts for this conversion, though it took twelve hours for full conversion. Osborn (2011) performed her experiments in a 50:50 water-ethanol solvent; previous work by Wee and Cunningham (2008) suggests that using a 67:33 water-ethanol composition may dramatically reduce the reaction time. Therefore, the goal of this research was to use palladium and rhodium catalysts with a 67:33 water-ethanol solvent composition, with an aim of reducing the reaction time required to fully convert benzene to cyclohexane. The data suggest that the time required for conversion of the analyte to its product was improved dramatically compared to previous experiments. However, powdered palladium catalyst was used in this study instead of pellet form as in previous studies. The powdered palladium allowed for full conversion of the target chemical, TeCB, to benzene in less than 5 minutes. Benzene was fully converted to cyclohexane within 45 minutes in the batch reactor when a rhodium catalyst was used jointly with palladium. This study suggests that the 67:33 water-ethanol solvent composition be utilized in continuous flow tests in the future to improve the efficiency of the REACH system. The results also suggest that powdered palladium catalyst be considered because of its ability to force the reaction to completion in significantly less time than previous experiments.

Zero-valent metals such as bulk iron and zinc are known to dechlorinate toxicorganic compounds. Enhancement in reaction rates has been achieved through bimetallicnanosized particles such as nickel/iron (Ni/Fe) and palladium/iron (Pd/Fe). Batchdegradation of model compounds, trichlroethylene (TCE) and 2,2'-dichlorobiphenyls(DCB), were conducted using bimetallic Ni/Fe and Pd/Fe nanoparticles. Completedegradation of TCE and DCB is achieved at room temperature. Zero-valent iron, as themajor element, undergoes corrosion to provide hydrogen and electrons for the reductivecatalytic hydrodechlorination reaction. The second dopant metals of nickel and palladium(in nanoscale) act as catalyst for hydrogenation through metal hydride formation thatproduces completely dechlorinated final product. Different compositions of bimetallicNi/Fe and Pd/Fe nanoparticles were synthesized and their reactivity was characterized interms of reaction rate constants, hydrogen generation through iron corrosion, andproducts formation. The observed TCE degradation rate constant was two orders ofmagnitude higher than the bulk iron and nanoiron, indicating that the bimetallicnanoparticles are better materials compared to the monometallic iron systems. Longevitystudy through repeated cycle experiments showed minimum loss of activity. The surfacearea-normalized rate constant was found to have a strong correlation with the hydrogengeneration by iron corrosion reaction. A mathematical model was derived thatincorporates the reaction and Langmuirian-type sorption terms to estimate the intrinsicreaction rate constant and rate-limiting step in the degradation process. Bimetallicnanoparticles were also immobilized into the chitosan matrix for the synthesis of ananocomposite membrane reactor to achieve membrane-phase destruction of chlorinatedorganics under convective flow condition. Formation of uniformly distributed nanosizedparticles is confirmed by high resolution transmission electron microscopy. Themembrane-phase degradation results demonstrated similar trends with the previoussolution phase analysis with the observed enhanced reaction rates. The advantage of themembrane system is its ability to prevent the agglomeration of the nanoparticles in themembrane matrix, to minimize the loss of precious metals into the bulk solution phase,and to prevent the formation of precipitated Fe(III) hydroxide. These are due to thechelating effect of the amine and hydroxyl functional groups in the chitosan backbones.

The synthesis of highly ordered carbonaceous materials, including carbon nanofibers, has been the subject of a disparate and burgeoning literature over the past decade. Growth of carbon nanotubes via an atypical catalytic route, the decomposition of halogenated reactants as chlorobenzene (CB) over 10% (w/w) Ni/SiO2 is investigated. The C (carbon) yield and structural order are a function of reaction time and temperature. Greater degree of structural order and C yield is observed from CB relative to benzene, suggesting Cl/catalyst interaction(s) and metal site restructuring. Evaluation of the effect of H2 on C growth from CB reveals that C yield is sensitive to % (v/v) H2 with selectivity maxima at 40% (v/v) H2. Further, C yield is significantly influenced by the nature of the heteroatom substituent on the benzene ring; presence of strong electron withdrawing groups favors C yield and weak electron withdrawing or donating groups favors competing side reactions. The effect of the strong electron withdrawing group, Cl, varies with the chemical structure of the carbon source. Presence of Cl promotes C yield in the case of aromatic and straight chained (aliphatic) compounds whereas it promotes formation of benzene in the case of cyclic (aliphatic) compounds. Results are interpreted in term of substituent/ catalyst interaction and the mechanism of solid C formation. Further, effect of % (v/v) H2 on C growth characteristics varies significantly with the precursor. The C growth characteristics are strongly dependent on the nature of the support used, as demonstrated for the following supports: SiO2, Ta2O5, Al2O3, NaY, activated carbon and graphite at 10% (w/w) Ni loading. Ni/SiO2 results in maximum C yield. Variation in Ni loading significantly influences the C yield; higher loading favors greater C yield. C grown on Ni/NaY was found to be relatively more structured to C obtained on the other supports. EDX analysis of the carbon product was used to assess the possibility of Cl intercalation and it reveals presence of 0.4 at% Cl on carbon grown on Ni/Al2O3.

The increased proliferation of benthic marine cyanobacteria of the Lyngbya genus in many tropical and subtropical systems worldwide is a concern due to the detrimental impacts these blooms can have on ecosystems, local economies and public health. While increasing nutrient loads from anthropogenic sources/activities has been hypothesised as the main cause, evidence to support this is limited. This hypothesis was explored by investigating blooms of the toxic, benthic cyanobacterium Lyngbya majuscula in a sub-tropical shallow coastal embayment (Moreton Bay) in southeast Queensland, Australia—where blooms have increased in frequency and severity. More specifically, the thesis aimed to investigate the role of nutrients in the physiology and growth dynamics of L. majuscula in Moreton Bay through examination of three main research questions. Examination of the spatial and temporal variations in the growth and nutritional status of L. majuscula in Moreton Bay (Research Question 1) was investigated by tracking natural summer blooms in northeastern Moreton Bay (Deception Bay) over two successive years. Detailed field observations, extensive biomass and tissue nutrient sampling (every 10–14 days) and a three-dimensional model were used to map the change in areal extent, biomass and tissue nutrients over the course of the blooms. The results demonstrated the innate ability of L. majuscula to rapidly spread and generate massive amounts of biomass, with the peak biomass calculated at 5057 tww in the 2005–2006 and 10 213 tww in the 2006–2007 seasons. A sequence of phases showing differing appearance, biomass growth and tissue nutrient changes were identified and documented. The role of nutrients (individually and collectively) in the enhancement of L. majuscula growth (Research Question 2) was investigated using a combination of comprehensive laboratory experiments (filament growth, 14C-bicarbonate uptake rate and biomass increase) and in-situ field experiments. Addition of nutrients to the water column were shown to promote prolific L. majuscula growth in the laboratory; this was confirmed in field experiments at two locations in Moreton Bay—showing nutrients can be a major causal factor in bloom formation. Additions of phosphorus (macronutrient) and iron (required for photosynthesis and nitrogen-fixation) caused the greatest stimulation of L. majuscula in both laboratory and field experiments. The form of iron was shown to be important —organically complexed iron (FeEDTA) was substantially more effective in promoting L. majuscula growth under laboratory conditions than inorganic iron (FeCl3). This is important as FeEDTA mirrors the naturally occurring iron organic complexes (which increase the solubility of iron) in waters from the region. The effect of nitrogen additions was more complex—likely due to the capacity of L. majuscula to fix atmospheric nitrogen reducing reliance on an inorganic nitrogen source. In the high light conditions experienced in this study, L. majuscula appeared to acquire nitrogen: (i) directly from the dissolved inorganic nitrogen in the water column—evidenced by a positive response to the nitrogen treatments; and, (ii) through enhanced nitrogen-fixation rates when iron and/or phosphorus were added in the absence of nitrogen—inferred from a substantial increase in the total nitrogen content of the L. majuscula biomass (nitrogen-fixation was not measured directly). The main sources of naturally occurring nutrients likely to promote L. majuscula blooms in Moreton Bay (Research Question 3) were investigated using laboratory experiments, soil and water analyses, and GIS-based modelling. The potential for groundwater/surfacewater from different vegetation, soils, geology and landuses within the study area catchments to stimulate L. majuscula response (14C-bicarbonate uptake rate) was tested in laboratory bioassays. Areas with acid sulfate soils (ASS), Melaleuca vegetation, pine plantations and Casuarina on ASS all had waters that enhanced L. majuscula growth. To investigate causal agents, bioassay response data and water analyses were subject to multiple regression and correlation analysis; this confirmed the importance of iron, phosphorus and nitrogen to L. majuscula growth and the roles of low pH and dissolved organic carbon, the latter two appearing to influence the chemical state and enhance the solubility of nutrients to L. majuscula. This information was incorporated into a GIS-based model to identify areas of hazard which were most likely to supply/export nutrients to Moreton Bay. These hazard maps, with further local verification, will be used as planning and decision support tools to assist government and landuse managers to limit the mobilisation and transport of key nutrients to potential bloom sites. The results from this thesis demonstrate that a precautionary approach to limit phosphorus, iron, nitrogen and dissolved organic carbon to waterways is necessary; otherwise the magnitude of L. majuscula blooms is likely to increase in Moreton Bay as coastal development intensifies with the predicted population increase. The thesis findings provide strong support for the hypothesised link between nutrients and the increased proliferation of Lyngbya and other benthic cyanobacteria blooms and are likely to be applicable to other areas where environmental conditions are suitable for their growth.

The increased proliferation of benthic marine cyanobacteria of the Lyngbya genus in many tropical and subtropical systems worldwide is a concern due to the detrimental impacts these blooms can have on ecosystems, local economies and public health. While increasing nutrient loads from anthropogenic sources/activities has been hypothesised as the main cause, evidence to support this is limited. This hypothesis was explored by investigating blooms of the toxic, benthic cyanobacterium Lyngbya majuscula in a sub-tropical shallow coastal embayment (Moreton Bay) in southeast Queensland, Australia—where blooms have increased in frequency and severity. More specifically, the thesis aimed to investigate the role of nutrients in the physiology and growth dynamics of L. majuscula in Moreton Bay through examination of three main research questions. Examination of the spatial and temporal variations in the growth and nutritional status of L. majuscula in Moreton Bay (Research Question 1) was investigated by tracking natural summer blooms in northeastern Moreton Bay (Deception Bay) over two successive years. Detailed field observations, extensive biomass and tissue nutrient sampling (every 10–14 days) and a three-dimensional model were used to map the change in areal extent, biomass and tissue nutrients over the course of the blooms. The results demonstrated the innate ability of L. majuscula to rapidly spread and generate massive amounts of biomass, with the peak biomass calculated at 5057 tww in the 2005–2006 and 10 213 tww in the 2006–2007 seasons. A sequence of phases showing differing appearance, biomass growth and tissue nutrient changes were identified and documented. The role of nutrients (individually and collectively) in the enhancement of L. majuscula growth (Research Question 2) was investigated using a combination of comprehensive laboratory experiments (filament growth, 14C-bicarbonate uptake rate and biomass increase) and in-situ field experiments. Addition of nutrients to the water column were shown to promote prolific L. majuscula growth in the laboratory; this was confirmed in field experiments at two locations in Moreton Bay—showing nutrients can be a major causal factor in bloom formation. Additions of phosphorus (macronutrient) and iron (required for photosynthesis and nitrogen-fixation) caused the greatest stimulation of L. majuscula in both laboratory and field experiments. The form of iron was shown to be important —organically complexed iron (FeEDTA) was substantially more effective in promoting L. majuscula growth under laboratory conditions than inorganic iron (FeCl3). This is important as FeEDTA mirrors the naturally occurring iron organic complexes (which increase the solubility of iron) in waters from the region. The effect of nitrogen additions was more complex—likely due to the capacity of L. majuscula to fix atmospheric nitrogen reducing reliance on an inorganic nitrogen source. In the high light conditions experienced in this study, L. majuscula appeared to acquire nitrogen: (i) directly from the dissolved inorganic nitrogen in the water column—evidenced by a positive response to the nitrogen treatments; and, (ii) through enhanced nitrogen-fixation rates when iron and/or phosphorus were added in the absence of nitrogen—inferred from a substantial increase in the total nitrogen content of the L. majuscula biomass (nitrogen-fixation was not measured directly). The main sources of naturally occurring nutrients likely to promote L. majuscula blooms in Moreton Bay (Research Question 3) were investigated using laboratory experiments, soil and water analyses, and GIS-based modelling. The potential for groundwater/surfacewater from different vegetation, soils, geology and landuses within the study area catchments to stimulate L. majuscula response (14C-bicarbonate uptake rate) was tested in laboratory bioassays. Areas with acid sulfate soils (ASS), Melaleuca vegetation, pine plantations and Casuarina on ASS all had waters that enhanced L. majuscula growth. To investigate causal agents, bioassay response data and water analyses were subject to multiple regression and correlation analysis; this confirmed the importance of iron, phosphorus and nitrogen to L. majuscula growth and the roles of low pH and dissolved organic carbon, the latter two appearing to influence the chemical state and enhance the solubility of nutrients to L. majuscula. This information was incorporated into a GIS-based model to identify areas of hazard which were most likely to supply/export nutrients to Moreton Bay. These hazard maps, with further local verification, will be used as planning and decision support tools to assist government and landuse managers to limit the mobilisation and transport of key nutrients to potential bloom sites. The results from this thesis demonstrate that a precautionary approach to limit phosphorus, iron, nitrogen and dissolved organic carbon to waterways is necessary; otherwise the magnitude of L. majuscula blooms is likely to increase in Moreton Bay as coastal development intensifies with the predicted population increase. The thesis findings provide strong support for the hypothesised link between nutrients and the increased proliferation of Lyngbya and other benthic cyanobacteria blooms and are likely to be applicable to other areas where environmental conditions are suitable for their growth.

The increased proliferation of benthic marine cyanobacteria of the Lyngbya genus in many tropical and subtropical systems worldwide is a concern due to the detrimental impacts these blooms can have on ecosystems, local economies and public health. While increasing nutrient loads from anthropogenic sources/activities has been hypothesised as the main cause, evidence to support this is limited. This hypothesis was explored by investigating blooms of the toxic, benthic cyanobacterium Lyngbya majuscula in a sub-tropical shallow coastal embayment (Moreton Bay) in southeast Queensland, Australia—where blooms have increased in frequency and severity. More specifically, the thesis aimed to investigate the role of nutrients in the physiology and growth dynamics of L. majuscula in Moreton Bay through examination of three main research questions. Examination of the spatial and temporal variations in the growth and nutritional status of L. majuscula in Moreton Bay (Research Question 1) was investigated by tracking natural summer blooms in northeastern Moreton Bay (Deception Bay) over two successive years. Detailed field observations, extensive biomass and tissue nutrient sampling (every 10–14 days) and a three-dimensional model were used to map the change in areal extent, biomass and tissue nutrients over the course of the blooms. The results demonstrated the innate ability of L. majuscula to rapidly spread and generate massive amounts of biomass, with the peak biomass calculated at 5057 tww in the 2005–2006 and 10 213 tww in the 2006–2007 seasons. A sequence of phases showing differing appearance, biomass growth and tissue nutrient changes were identified and documented. The role of nutrients (individually and collectively) in the enhancement of L. majuscula growth (Research Question 2) was investigated using a combination of comprehensive laboratory experiments (filament growth, 14C-bicarbonate uptake rate and biomass increase) and in-situ field experiments. Addition of nutrients to the water column were shown to promote prolific L. majuscula growth in the laboratory; this was confirmed in field experiments at two locations in Moreton Bay—showing nutrients can be a major causal factor in bloom formation. Additions of phosphorus (macronutrient) and iron (required for photosynthesis and nitrogen-fixation) caused the greatest stimulation of L. majuscula in both laboratory and field experiments. The form of iron was shown to be important —organically complexed iron (FeEDTA) was substantially more effective in promoting L. majuscula growth under laboratory conditions than inorganic iron (FeCl3). This is important as FeEDTA mirrors the naturally occurring iron organic complexes (which increase the solubility of iron) in waters from the region. The effect of nitrogen additions was more complex—likely due to the capacity of L. majuscula to fix atmospheric nitrogen reducing reliance on an inorganic nitrogen source. In the high light conditions experienced in this study, L. majuscula appeared to acquire nitrogen: (i) directly from the dissolved inorganic nitrogen in the water column—evidenced by a positive response to the nitrogen treatments; and, (ii) through enhanced nitrogen-fixation rates when iron and/or phosphorus were added in the absence of nitrogen—inferred from a substantial increase in the total nitrogen content of the L. majuscula biomass (nitrogen-fixation was not measured directly). The main sources of naturally occurring nutrients likely to promote L. majuscula blooms in Moreton Bay (Research Question 3) were investigated using laboratory experiments, soil and water analyses, and GIS-based modelling. The potential for groundwater/surfacewater from different vegetation, soils, geology and landuses within the study area catchments to stimulate L. majuscula response (14C-bicarbonate uptake rate) was tested in laboratory bioassays. Areas with acid sulfate soils (ASS), Melaleuca vegetation, pine plantations and Casuarina on ASS all had waters that enhanced L. majuscula growth. To investigate causal agents, bioassay response data and water analyses were subject to multiple regression and correlation analysis; this confirmed the importance of iron, phosphorus and nitrogen to L. majuscula growth and the roles of low pH and dissolved organic carbon, the latter two appearing to influence the chemical state and enhance the solubility of nutrients to L. majuscula. This information was incorporated into a GIS-based model to identify areas of hazard which were most likely to supply/export nutrients to Moreton Bay. These hazard maps, with further local verification, will be used as planning and decision support tools to assist government and landuse managers to limit the mobilisation and transport of key nutrients to potential bloom sites. The results from this thesis demonstrate that a precautionary approach to limit phosphorus, iron, nitrogen and dissolved organic carbon to waterways is necessary; otherwise the magnitude of L. majuscula blooms is likely to increase in Moreton Bay as coastal development intensifies with the predicted population increase. The thesis findings provide strong support for the hypothesised link between nutrients and the increased proliferation of Lyngbya and other benthic cyanobacteria blooms and are likely to be applicable to other areas where environmental conditions are suitable for their growth.

The increased proliferation of benthic marine cyanobacteria of the Lyngbya genus in many tropical and subtropical systems worldwide is a concern due to the detrimental impacts these blooms can have on ecosystems, local economies and public health. While increasing nutrient loads from anthropogenic sources/activities has been hypothesised as the main cause, evidence to support this is limited. This hypothesis was explored by investigating blooms of the toxic, benthic cyanobacterium Lyngbya majuscula in a sub-tropical shallow coastal embayment (Moreton Bay) in southeast Queensland, Australia—where blooms have increased in frequency and severity. More specifically, the thesis aimed to investigate the role of nutrients in the physiology and growth dynamics of L. majuscula in Moreton Bay through examination of three main research questions. Examination of the spatial and temporal variations in the growth and nutritional status of L. majuscula in Moreton Bay (Research Question 1) was investigated by tracking natural summer blooms in northeastern Moreton Bay (Deception Bay) over two successive years. Detailed field observations, extensive biomass and tissue nutrient sampling (every 10–14 days) and a three-dimensional model were used to map the change in areal extent, biomass and tissue nutrients over the course of the blooms. The results demonstrated the innate ability of L. majuscula to rapidly spread and generate massive amounts of biomass, with the peak biomass calculated at 5057 tww in the 2005–2006 and 10 213 tww in the 2006–2007 seasons. A sequence of phases showing differing appearance, biomass growth and tissue nutrient changes were identified and documented. The role of nutrients (individually and collectively) in the enhancement of L. majuscula growth (Research Question 2) was investigated using a combination of comprehensive laboratory experiments (filament growth, 14C-bicarbonate uptake rate and biomass increase) and in-situ field experiments. Addition of nutrients to the water column were shown to promote prolific L. majuscula growth in the laboratory; this was confirmed in field experiments at two locations in Moreton Bay—showing nutrients can be a major causal factor in bloom formation. Additions of phosphorus (macronutrient) and iron (required for photosynthesis and nitrogen-fixation) caused the greatest stimulation of L. majuscula in both laboratory and field experiments. The form of iron was shown to be important —organically complexed iron (FeEDTA) was substantially more effective in promoting L. majuscula growth under laboratory conditions than inorganic iron (FeCl3). This is important as FeEDTA mirrors the naturally occurring iron organic complexes (which increase the solubility of iron) in waters from the region. The effect of nitrogen additions was more complex—likely due to the capacity of L. majuscula to fix atmospheric nitrogen reducing reliance on an inorganic nitrogen source. In the high light conditions experienced in this study, L. majuscula appeared to acquire nitrogen: (i) directly from the dissolved inorganic nitrogen in the water column—evidenced by a positive response to the nitrogen treatments; and, (ii) through enhanced nitrogen-fixation rates when iron and/or phosphorus were added in the absence of nitrogen—inferred from a substantial increase in the total nitrogen content of the L. majuscula biomass (nitrogen-fixation was not measured directly). The main sources of naturally occurring nutrients likely to promote L. majuscula blooms in Moreton Bay (Research Question 3) were investigated using laboratory experiments, soil and water analyses, and GIS-based modelling. The potential for groundwater/surfacewater from different vegetation, soils, geology and landuses within the study area catchments to stimulate L. majuscula response (14C-bicarbonate uptake rate) was tested in laboratory bioassays. Areas with acid sulfate soils (ASS), Melaleuca vegetation, pine plantations and Casuarina on ASS all had waters that enhanced L. majuscula growth. To investigate causal agents, bioassay response data and water analyses were subject to multiple regression and correlation analysis; this confirmed the importance of iron, phosphorus and nitrogen to L. majuscula growth and the roles of low pH and dissolved organic carbon, the latter two appearing to influence the chemical state and enhance the solubility of nutrients to L. majuscula. This information was incorporated into a GIS-based model to identify areas of hazard which were most likely to supply/export nutrients to Moreton Bay. These hazard maps, with further local verification, will be used as planning and decision support tools to assist government and landuse managers to limit the mobilisation and transport of key nutrients to potential bloom sites. The results from this thesis demonstrate that a precautionary approach to limit phosphorus, iron, nitrogen and dissolved organic carbon to waterways is necessary; otherwise the magnitude of L. majuscula blooms is likely to increase in Moreton Bay as coastal development intensifies with the predicted population increase. The thesis findings provide strong support for the hypothesised link between nutrients and the increased proliferation of Lyngbya and other benthic cyanobacteria blooms and are likely to be applicable to other areas where environmental conditions are suitable for their growth.