Disposal of low level radioactive liquid waste to soil is commonly practiced. Therefore, sorption of uranium from aqueous solution and fixation of uranium into soil are processes which are crucial to the attenuation of uranium and protection of groundwater. Exposure of human populations is either by direct water consumption or through crop irrigation and transfer into the food chain. In this study a range of materials, including natural materials (e.g. biochar and the natural zeolites ‘Chabazite and Mordenite’) and the synthetic zeolite ‘Faujasite-X’, were investigated as potential adsorbents for UVI from aqueous solution. A range of experiments were carried out to investigate the efficacy of using these adsorbents to successfully adsorb and fix UVI from aqueous solutions. These included sorption and desorption experiments, quantifying time-dependent fixation of UVI and applying kinetic models of this process and measuring isotopically exchangeable UVI within adsorbent materials when possible. The factors affecting adsorption processes, such as solution pH, initially added UVI concentrations and adsorption contact time, were also investigated. Speciation of U in the solution phase was investigated using the Windermere Humic Aqueous Model (WHAM-VII). Saturation indices of potential solid phases were also configured using known solubility products and the free ion activities predicted from the speciation model, WHAM-VII. Mordenite zeolite showed a poor adsorption affinity for UVI as the solution pH was continuously buffered towards high pH values > 6.5 which favours UVI ion solubilisation as a result of uranyl carbonate complex formation. Uranium (VI) ion adsorption on chabazite at pH 4.7 at 20 oC was found to fit the Freundlich adsorption isotherm but the optimised equation parameters were unique for each contact time of 1, 5, 10, 20 and 30 days. The time-dependent fixation of UVI on chabazite was found to follow an irreversible first-order kinetic equation and an intraparticle diffusion model suggesting slow penetration of chabazite porous structure following initial surface adsorption. Isotopically exchangeable 238UVI (the E-value, UE) adsorbed on chabazite showed that > 65% of initially added UVI remained isotopically exchangeable. Faujasite-X also showed time-dependent fixation of UVI over 35 days of adsorption contact time at pH values 4, 5 and 6. The adsorption kinetics were best described by an irreversible first-order equation and a spherical diffusion model. Desorption trends showed that UVI adsorption into faujasite- X was almost wholly irreversible. Saturation indices calculated from the solubility products and free ion activities of constituent ions showed that the fixation of UVI was not controlled by the precipitation of any solid phase investigated at the studied range of pH values. Bone biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of UVI from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20◦C, including pH, initial concentration of UVI and contact time. Uranium (UVI) adsorption was highly dependent on pH. However, it was found that UVI adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH> 7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of UVI within the biochar structure. Desorption experiments showed that UVI was only sparingly desorbable from the biochar with time and isotopic dilution with 233UVI confirmed the low, and time-dependent, lability of adsorbed 238UVI. Below pH 7 the adsorption isotherm trend suggested that precipitation, rather than true adsorption, may occur. Across all pH values (4.5–9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and swartzite, liebigite or bayleyite above pH 6.5 Another source of bone biochar with a fraction size of (20x 60 mesh) was investigated as candidate materials for soil remediation. Its ability both to adsorb uranium and to render it non-labile (i.e. chemically inactive) was tested by addition to a wide range of soils recently spiked with 238UVI and incubated under moist conditions. The overall aim was to recommend improved strategies for immobilisation of uranium in soils subject to application of low level radioactive waste solutions. Several measurements were made to assess possible reductions in U availability from biochar addition, including U solubility in 0.01 M Ca(NO3)2, exchangeability in 1 M Mg(NO3)2 solution and isotopic dilution with 233U and 236U. Results showed that 41.3 %, 27.6%, 28.9% and 31.7% were isotopically exchangeable on average for soil amended with 0%, 3%, 5% and 10% loading of biochar, but overall there appeared to be only marginal advantages in adding even large concentrations of biochar to soil. The major factor controlling U solubility, exchangeability and lability was soil pH and the pH value resulting from biochar, rather than the biochar itself. Therefore, while the use of biochar to effectively remove U from water is clear, its role in adsorbing U in the highly buffered soil environment is probably minimal.

Adsorption of heavy metal ions (e.g. copper, nickel and lead) onto sphagnum moss peat was investigated. The influence of pH, concentration, temperature, nature of solute, number of solutes simultaneously present, peat dose and reaction time on batch adsorption equilibria and kinetics tests were examined. Batch adsorption of copper and nickel onto peat was pH dependent, the optimum range being 4.0 to 5.0 for copper and 4.0 to 7.0 for nickel. Langmuir and Freundlich isotherms showed a single relationship between initial metal concentration, metal removal, and initial pH. The latter was found to control efficiency of metal removal. The use of peat in removal of lead from aqueous solution was studied in batch experiments. Investigations included the effect of pH and temperature of adsorption. The adsorption equilibria data followed Langmuir and Freundlich models. Efficiency of lead removal depended very little on the reaction temperatures (12 to 37°C) and initial pH values (4.0 to 6.0). The results suggested that the adsorption process is endothermic for lead-peat adsorption. Kinetic data suggested involvement of a chemical rate-limiting step, and a predictive relationship was derived relating metal removal to peat dose. In comparison with other metals, nickel removal is poor, and possible reasons are discussed. Kinetic results also indicated that pore diffusion is not the only rate determining step in peat metal adsorption. A rate equation is described for the study of the kinetics of adsorption of aqueous divalent metal ions onto sphagnum moss peat for a range of conditions. An empirical model was devised for predicting percentage metal ion adsorbed. The model showed a high coefficient of correlation, indicating its reasonableness. The last section describes the results of an examination into the simultaneous adsorption by peat of several metals. Initially copper and nickel from both single- and bi-solute systems were tested. In general, pore diffusion appeared to be the rate-controlling step. The effects of competitive adsorption in batch systems for copper and nickel system was also studied in various ratios of metal concentration. A mathematical model was used successfully and shown to be predictive for various ratio of metal ions concentration in competitive adsorption. The dose effect on the uptake of metals on moss peat was also studied for bi-solute adsorption systems. The best interpretation which could be placed on the data was that the behaviour of nickel was unusual. The results also showed that the kinetics of adsorption were best described by a second-order expression rather than a first-order model. For metal ions which are of different size but are divalent metal ions, we used lead(II) and copper(II) as well as lead(II) and nickel(II) systems. The effects of competitive adsorption in batch systems indicated that copper had a greater effect on lead adsorption than did nickel. However, lead had a greater effect on nickel than copper. A copper, lead and nickel triple-solute system was also tested. The adsorption of any single metal such as copper, lead and nickel was hindered by the presence of the other metals. The competitive effect appears to have affected the three ions in the order nickel > lead > copper with nickel affected most; the adsorption capacity for each solute from the mixed solution was 15.9, 57.4 and 71.5% of that of a single-solute system for copper, lead and nickel, respectively. The kinetic results showed that the heavy metals are adsorbed fairly rapidly, and that there is a relatively good fit between experimental data and the second order model for copper, lead and nickel.

Groundwater quality sampling guidance typically requires representative samples to be obtained. Such guidance is not always clear what this means and which sampling methods are most appropriate. The situation is complicated by increasing well screen/open interval length. Uncertainty, resulting particularly from observations of vertical flow in wells has led to calls for the use of long-screen (> 3 m) wells to be abandoned for groundwater quality monitoring. Here, four complementary field and modelling studies at various scales are used to examine appropriate groundwater quality sampling in such wells. Numerical modelling demonstrates that literature reported vertical flows in wells < 10 m in length are sufficient to bias pumped groundwater quality sampling. Bias starts for vertical well flow rates less than 50 % of the pumping rate. Vertical flow measurements explain differences and similarities in historical passive sampling between four boreholes and allow vertical aquifer concentration distributions to be quantified. However, such quantification requires per-borehole flow measurement. New technology (Active Distributed Temperature Sensing) provides a versatile alternative to existing borehole flow characterisation methods under ambient and pumping conditions. Data from contrasting field environments demonstrate that even without comprehensive flow investigation long-screen wells can still provide useful information about groundwater concentrations and trends.

High throughput analytical methods based on UPLC-APCI-HRMS and/or UPLC-ESI-HRMS were developed for the multi-residue analysis of pharmaceuticals, personal care products (PPCPs), brominated flame retardants (BFRs) and their degradation/transformation products. The PPCPs method was successfully applied to analysis of freshwater samples from Egypt. Target PPCPs were ubiquitous in the Egyptian aquatic environment and displayed relatively high concentrations in an effluent sample from a hospital wastewater treatment plant. The BFRs method was applied to screen for legacy BFRs, novel BFRs and their potential degradation/transformation products in simulated landfill leachate samples. In vitro bioassays were developed to study for the first time the metabolism of the novel BFRs TBECH by human liver microsomes and EH-TBB and FM550 by human skin S9 fractions. TBECH was metabolised by hepatic CYP450-mediated enzymes to produce a complex mixture of hydroxylated, debrominated and α-oxidation metabolites. EH-TBB and TPhP (in the FM550 mixture) underwent biotransformation by carboxylesterases in human skin S9 fractions. Kinetic modelling of the studied hepatic and dermal human biotransformation reactions revealed that exposure to multiple chemicals significantly influences the metabolic rates of target compounds. In vitro – in vivo extrapolations were also modelled to investigate the xenobiotic clearance capacities of human liver and skin.

No description available.

published_or_final_version / Public Administration / Master / Master of Public Administration

No description available.

This thesis addresses the relationship between the physical dimensions and aspect ratios of urban areas and the airflow below the urban canopy height. The aim is to investigate the link between these aspect ratios and the resulting airflow patterns, wind speed and direction, and pressure coefficients on the envelope of target buildings. The research method involves several steps which seek to explore the airflow in four urban scenarios, simplified simulation using two parallel bricks; several complex urban prototype scenarios; and two actual urban areas used as case studies situated on the Cardiff Cathays Campus and the Paulista Avenue - São Paulo. The research methods employed are: atmospheric boundary layer wind tunnel (WT), steady-state standard k-e CFD simulation and field measurements (FM). Three prevailing wind directions were investigated: parallel, orthogonal and oblique. The outputs are guiven in terms of: Cp and ΔCp data displayed as graphs, tables and/ or contour plots; airflow patterns and velocity magnitude and direction, displayed as vertical profile graphs and visualized by means of CFD pathlines or WT helium bubble pathlines; and correlation displayed as scatter diagrams and matrices. A relationship was found between the urban aspect ratios and the ΔCp results. This was demonstrated by statistical methods using the data on the variables concerned, thus verifying the strength of the correlation between them. Strong correlation was found between the investigations into similar scenarios of the urban prototypes and the two case studies as regards both the aspect ratios and the ΔCp results. On the other hand, low correlation for the same variables were identified when contrasting dissimilar urban prototype scenarios. Moreover, good levels of comparison were found between the FM and the CFD simulations in Case Study 01 for both the decrease in wind velocity magnitude and direction in urban areas.

The research outlined in this thesis is concerned with the environmental aspects of groundwater re-establishment as a consequence of surface mining. No principal effects which have been identified as being detrimental to the restored land area are as follows; i). The vertical and horizontal displacements of backfill materials following restoration, and ii). The pollution of groundwater from contact with weathered rockfill materials. The research into settlement has attempted to classify the types of movement which may occur within a backfill mass, in particular the differential movements which are of great importance to the stability of proposed structures or surface drainage. The field results from 10 opencast mine sites are presented, 3 of which were instrumented for detailed field investigations. It has been shown that backfill movements do not necessarily show similar trends under similar conditions, and reasons for this are proposed. A variety of instrumentation schemes have been devised to examine backfill displacements, both vertically and horizontally. Permeability testing has been conducted at different horizons the backfill mass in order to locate the zones of collapse settlement due to groundwater recovery. A critical review of the instrumentation utilised in the investigations is presented, with suggestions for improvement. Investigations into groundwater pollution have been devoted to examining the qualities of groundwater flowing into British surface mines and evaluating its likely reactions with fill materials. An insight into general groundwater pollution and treatment techniques is presented together with a critical analysis of their applicability, to British conditions. An investigation into water qualities in each of the six geographical regions of the opencast mining industry of Great Britain is detailed. Finally some suggestions for future research areas are indicated.

Energy consumption and Green House Gas (GHG) emissions from the UK built environment are reflective of the wider situation across Europe, where according to the Energy Performance in Buildings Directive (EPBD) "buildings account for 40% of total energy consumption in the Union" (European Commission, 2010). In December 2006 the UK Government announced a rapid transition to 'zero carbon' new buildings, as a key step forward in reducing GHG emissions from the domestic and non-domestic sectors (DCLG, 2006a; Weaver, 2007). The Passivhaus standard is the fastest growing energy performance standard in the world and in a growing number of regions across Europe it has been implemented as a mandatory minimum standard for all new buildings (iPHA, 2013). This thesis investigates the applicability of this low energy standard to the UK context, in comparison to conventional alternatives, by examining four inter-related themes: (i) in relation to climate change policy and the UK Government's plan for all new homes to be zero carbon from 2016; (ii) by addressing the limitations of the climate data currently used to design Passivhaus buildings, and developing a new methodology for creating higher resolution probabilistic climate data; (iii) by exploring the uncertainty about the future performance of Passivhaus dwellings in relation to future overheating risk and thereby proposing methods to improve whole life design optimization; (iv) by investigating the hygrothermal implications for new build and retrofit Passivhaus projects and highlighting areas where current risk assessment methods are inadequate. This thesis has argued that the transfer of the Passivhaus standard, or any advanced energy performance standard, from one country or region to another should be accompanied by an extensive programme of context specific research and application testing. The findings of this research have shown that the implementation of the Passivhaus standard, in its present format, in the UK is not without risk and uncertainty. This thesis concludes that that the majority of such risks can be substantially mitigated, through the incorporation of high resolution probabilistic climatic data, transient hygrothermal assessments and global sensitivity analysis techniques. The energy saving and thermal comfort potential of the Passivhaus approach have been shown to be substantial and therefore merit the challenges involved in addressing its successful implementation.