Ammonia is the most prevalent alkaline gas in the atmosphere and plays an important role in environmental pollution through acidification and eutrophication. Livestock are the largest source of ammonia in the UK, mainly originating during storage and spreading of animal manure. The aim of this study was to validate the collection efficiency of recurved passive ammonia flux (PAF) samplers and the flux frame method to provide a robust methodology for measurement of distributed agricultural sources of ammonia outdoors. The collection efficiency of recurved PAF samplers was determined in a wind tunnel under controlled conditions of ammonia flux (0.771 - 13.49 mg NH3 m-2 s-1), and at angles of orientation to the flow direction (0, 30, 60, 70, 80, 90°). The samplers were effective up to a wind speed of 7 m s-1 and an angle of 80°, with a mean collection efficiency of 71%. The flux frame method had a mean collection efficiency of 87.4% when used with ground level point sources under controlled conditions in the Atmospheric Flow Laboratory. However, in controlled field releases, the efficiency fell to 56.4%. The flux frame method was also suitable for line sources, although assumptions must be made about the source homogeneity and plume dispersion. ADMS modelling was used to predict the collection efficiencies for the flux frame method and these agreed with measured collection efficiencies to within 37.3%. A comparison of source strengths determined using a full size flux frame and portions of the flux frame showed that a full size flux frame was unnecessary as one column of samplers produced a very similar estimate to that of the whole frame. The validated method was then used to measure ammonia emissions from free-range pigs. The amount of ammonia emitted from this source was very low and less than 0.16 g (kg of sow)-1 day-1.

In assessing the health risks posed from heavy metals in a contaminated site, it is important to determine when the contamination occurred and when the metals become available to the surrounding biota. Trees and plants growing in the vicinity of a contaminated site may provide such a historic record. There have been few studies on their role as biomarkers to identify metal mobility or bioavailability for continuous monitoring purposes. The aim of the study was to evaluate the role of plants as biomonitors for site characterisation and risk assessment purposes and to see if there was any selectivity between metal uptake in leaves and roots. Tree cores were also collected as metals in soil or ground water and may be drawn up via tree roots and deposited in the growth rings. This was examined using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LAICPMS) and Proton Induced X-Ray Emission (PIXE). From the plant analysis, the elements present in highest amount were lead, zinc and cooper. The mobility of lead could be monitored by bramble and nettle leaves; that of copper by nettle roots and bramble leaves and that of zinc by nettle roots, bramble and sycamore leaves. Analysis of tree cores by LAICPMS and PIXE showed a contrasting contaminant signature between the sampled trees, as there was inconsistency of metal concentrations within the same segment of growth ring. This variability may offer an insight into labile metal function within the tree physiology. The utility of using the dendrochemical record may best serve as an indicator of macro-environmental perturbations, rather than an indicator of labile metal chronologies, for which only lead showed a reasonably consistent decline through time, across the tree core record.

This project looks at the potential for re-use of quarry wastes, in particular, Hassock, from the Lower Greensand, Hythe Beds, which in one Ragstone quarry alone, amounts to 100,000 tonnes of material annually. Quarry wastes have been solidified with a range of other waste products including Cement Kiln Dust, Ground Granulated Blast-furnace Slag and Pulverized Fuel Ash. The mixes were subjected to a CO2 atmosphere for varying lengths of time, to determine their carbonation potential and optimum CO2 exposure time, in order to produce pellets with optimum strength, measured by Aggregate Impact Value. Pellets that had been hydrated before carbonated were stronger than those carbonated immediately. However, carbonating the mixes during pelletization was found to have a beneficial effect on final pellet strength. After further hydration in air for 6 weeks, the pH of these pellets was reduced considerably, when they were further carbonated for 24 hours in the CO2 chamber. Furthermore, strength was found to be substantially increased. The manufacture of these carbonated pellets will recycle CO2 and up to 4 waste streams and modify the quarry waste by reducing the dust component to a mere trace. The Aggregate Impact Value of pellets ranges from 14 to 19 and they have a bulk density of 1030 to 1100 kg/m3, making them potentially suitable for use as Light Weight Aggregates.

Siphonic roof drainage systems are finding increasing acceptance amongst architects and builders of large commercial buildings in Australia. The benefits of siphonic roof drainage over conventional roof drainage systems include underground excavation savings, higher flow volumes, fewer outlets and stormwater harvesting and reuse potential. Siphonic roof drainage systems are generally designed using the steady state Bernoulli and the Colebrook-White equations. Both of these equations assume a full bore flow regime which only occurs for short periods in siphonic systems. This means that the majority of storm events do not cause the system to run at its full capacity or efficiency. In Australia, systems are designed to cope with a maximum design rainfall intensity, usually the 1 in 100 year storm event. While the performance of siphonic roof drainage systems at this rainfall intensity is well understood, the system performance at lower rainfall intensities and unsteady flow regimes is largely unknown. This research aims to investigate and identify the improvements which can be effected to the overall performance of siphonic roof drainage by the removal of air from the system. The research will also investigate the effect the air entrainment has on siphonic flows. / PhD Doctorate

No description available.

Thesis (PhD(Civil Engineering)(Engineering, Built Env. and Inf. Tech.)) -- University of Pretoria, 2007. / Summary in English. Includes bibliographical references.

Thesis (M.P.A.)--University of Hong Kong, 2003. / Includes bibliographical references. Also available in print.

Rapid urbanization of cities has greatly modified the thermal and dynamic profile in the urban boundary layer. This thesis attempts to study the effect of urban heating on the local climate and air quality for a tropical coastal urban agglomeration, Greater Kuala Lumpur (GKL) in Malaysia. A state-of-art numerical model, Weather Research and Forecast Model (WRF) is used to identify the influence of urbanization through modification of urban surfaces. In order to thoroughly study the environmental impact of land use change in GKL, this thesis begins with the local urban heating on the surface layer before extending to the influence on the boundary layer circulation and its atmospheric composition. The WRF model is tested for its applicability to reproduce the urban heating condition. The model verification hence incorporates sensitivity analysis of physics pertinent to the simulation of land surface and boundary layer dynamics condition, namely the land use map, urban canopy model (UCM) and planetary boundary layer (PBL) physics options. Result shows that the urban surface representation and parameterization models in WRF are of great importance for the high resolution urban climate in the region. The locally calibrated land use map and urban parameters have substantially improved the near-surface weather and urban heating prediction. The local PBL scheme also predicts a generally good agreement for the studied region in terms of near-surface environment and vertical profile during the morning and evening transitional period. Incorporating the optimum physics settings, the control study found that urbanization due to land use change has induced a modelled daily mean urban heat island intensity (UHII) of 0.9 °C with a more severe heating of 1.9 °C at night. The heating condition induces urban thermal circulation that interacts with the local topographic flow, namely sea/land breeze and downhill/uphill breeze for the coastal urban agglomeration sheltered by the mountain ranges on the other side. Depending on the cloud cover and prevailing synoptic flow, the immense heat forcing on the surface accelerates/decelerates the moisture-bearing sea breeze during the day. It also induces vertical lifting which creates a conducive environment for convective precipitation on the upwind region. The subsequent control study with chemical weather prediction model (WRF-Chem) shows that the urban heating condition reduces the ground ozone level by around 20 ppbv throughout the day. Analysis shows that the reduced ozone level is closely correlated to the stronger horizontal sea breeze front (SBF) advection in the morning and urban-enhanced vertical mixing during the night which disperse the ground ozone and its precursors. Despite the reduction of ozone level, the air quality monitoring result identifies GKL as NOx-sensitive region which is prone to higher level of ozone with the continuous expansion of urban. The thesis explores the ability of WRF software to reproduce the high resolution urban climate. The model evaluation has realistically discovered that WRF is able to produce good approximation of the near-surface weather condition and fairly reasonable vertical boundary layer profiles. However, the atmospheric chemistry composition of the local surface pollutants is greatly underestimated. Continuous effort is required to improve the regional prediction on the chemistry weather prediction tool.

Non-degradable waste tire generation around the world is growing at an alarming rate. Diversifying the recycling route of these waste tires is essential to solve the problem. One way is to incorporate them into polymers and convert them into new products. However, incorporation of ground tire rubber into thermoplastics has been hampered due to lack of toughness and adhesion between phases. To address the issue, this study utilized reclaimed waste tire rubber (RTR) instead; and evaluated the properties of RTR and poly(ethylene-co-vinyl acetate) (EVA) blends. The properties of the RTR/EVA blends were further enhanced by compatibilization and electron beam irradiation. Processing, mechanical, thermal and dynamic mechanical properties of RTR were tremendously improved by blending with EVA. However, the interfacial adhesion was found to lack in the blends. Compatibilization by reactive, physical and combination strategies were explored utilizing (3-Aminopropyl)triethoxy silane (APS), liquid styrene butadiene rubber (LR) and maleated EVA (MAEVA), respectively. APS and MAEVA were found to be the most and least favourable compatibilizer, respectively. Apart from functioning as reactive compatibilizer, APS also reclaimed the RTR phase further. These lead to improved dispersion of smaller RTR phase in EVA matrix and enhanced the interfacial adhesion. Electron beam irradiation revealed the presence of radical stabilizing and scavenging additives within RTR which retards the crosslinking process in RTR and RTR/EVA blends. Though chain scissions were predominant; study showed the replacement of S-S and S-C bonds with stronger and stiffer C-C bonds ensures the retention of RTR and RTR/EVA blends properties upon irradiation. Compatibilization of RTR/EVA blend by APS (50RTR/5APS) also improved the crosslinking efficiency. However, the blend still suffered from oxidative degradation from irradiation in air. Radiation sensitizers, trimethylol propane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA) and N,N-1,3 Phenylene Bismaleimide (HVA2), were used to accelerate the irradiation induced crosslinking in RTR and 50RTR/5APS blends. Presence of radiation sensitizers leads to simultaneous improvement in toughness and tensile strength of RTR and 50RTR/5APS blends. Elastic capacity of RTR phase was restored and interfacial adhesion enhanced in the presence of radiation sensitizers.

Urban air quality has been a topic of major public concern and scientific research in recent years. Several theoretical and experimental studies have focused on the assessment of air quality within street canyons and other microenvironments (intersections, motorways, parking spaces, etc.), where population exposure to traffic-related pollutants is relatively high. The aim of this study was to develop a practical methodology for assessing traffic-related air pollution in urban streets, after testing available monitoring and modelling techniques. To meet this objective, a large amount of original air quality, meteorological and traffic data were collected during four intensive short-term and one long-term monitoring campaigns carried out in the region of Paris from December 1998 to December 2001. These campaigns covered three representative street canyon sites (Bd. Voltaire, Rue de Rennes, Av. Leclerc - PI. Basch) as well as a motorway service station (RN10 petrol station). Passive and active monitoring techniques were used to sample a wide range of inorganic (CO, NO X and Os) and organic gases (benzene, toluene, xylene, ethylbenzene, formaldehyde, acetaldehyde, etc.) at different heights and distances from the kerb. Indicative background measurements were also taken during the same sampling periods. Furthermore, relevant meteorological (synoptic and local) and traffic information was obtained on each site. The analysis of the data gave insights into the dispersion and transformation processes taking place within the streets. Channelling effects induced by parallel to the road axis winds gave rise to relatively high kerbside pollution levels. On the other hand, perpendicular synoptic winds generated air vortices within the canyons, which resulted in steep crossroad concentration gradients. In that case, higher pollution levels were observed on the leeward than on the windward side of the streets. A significant reduction of concentrations with height above the ground was also observed within two of the street canyons (Bd. Voltaire and Av. Leclerc). In all cases, roadside concentrations were several times higher than the corresponding urban background values. This spatial variability indicates a strong transport effect on the pollutant distribution within urban canyons, caused by the synoptic wind and influenced by the geometry of the street. That may have serious implications in terms of population exposure and compliance with air quality legislation. In this context, the siting of permanent monitoring equipment becomes crucial. A relationship between CO and benzene as well as an exponential expression linking pollutant concentrations at different heights within the canyons were empirically deduced. Five dispersion models of different levels of complexity (STREET-SRI, OSPM, AEOLIUS, CAR-International, and CALINE4) were used to calculate CO and benzene concentrations at the campaign sites. The Computational Fluid Dynamic code PHOENICS was also tested for one location. The comparison between observed and predicted values revealed the advantages and drawbacks of each model in association with the configuration of the street and the meteorological conditions. Furthermore, a sensitivity and uncertainty analysis involving three of the available models (STREET-SRI, OSPM and AEOLIUS) was carried out. OSPM was slightly modified in order to allow user access to certain internally coded parameters. An operational method combining multi-site sampling and dispersion modelling was finally proposed for assessing air quality in urban streets, taking into account the pronounced spatial and temporal variability of traffic-related air pollution, the modelling uncertainty, the practical constraints related to measurements and models, and the needs of decision makers. This methodology may find wider application in air quality management, urban and transport planning, and population exposure studies.