Urban areas have well documented effects on climate, such as the urban heat island effect, reduction of wind speeds, enhanced turbulence and boundary layer heights, and changes in cloud cover and precipitation. This PhD examines the impact of the urban surface on the major agglomeration of London on local and regional climate by means of the numerical mesoscale model METRAS (Schlünzen 1988) coupled for the first time with the sophisticated urban canopy scheme BEP, developed by Martilli et al. (2002). The robustness of the new model is demonstrated through a series of simulations and sensitivity studies for an idealised urban domain. The model is then configured for the London region, and evaluated using data from a range of meteorological monitoring sites. Implementation of the urban canopy scheme results in a marked improvement in model performance. Under ideal meteorological conditions, peak urban heat island intensities of up to 2.5 K are found during night time hours, with the timing and magnitude of the peak showing good agreement with previous experimental studies for London. The new model is then used to investigate how growth of the Greater London urban area affects the urban heat island intensity. The results show that the relative fractions of urban land cover and of vegetation within the urban area have important implications for the near surface temperature, diurnal temperature range, wind speed and urban heat island intensity. The results also suggest that extensive future growth of the London urban area has the potential to increase temperatures, with significant increases for both daytime and night time. The specific forms of urban development, such as densification and spatial expansion, have an impact on these fields. These results have important implications for the design of cities and the management of urban climate.

The gas-phase reactions of ozone with alkenes can be significant sources of free radicals (OH, HO2 and RO2) in the Earth’s atmosphere. While there are a number of quantitative indirect OH and HO2 yield measurements from ozonolysis in the literature, obtained, for example, through the use of radical tracer / scavenger species, few direct observations have been reported. This thesis presents the first direct measurements of OH and HO2 by Laser Induced Fluorescence for a homologous series of alkenes. The radical and stable products from ethene, propene, 1-butene, 2 methylpropene, cis-2-butene, trans-2-butene and 2,3-dimethyl-2-butene ozonolysis have been observed. The experiments were carried out in the EUPHORE atmospheric simulation chamber, utilising various instrumentation including Fourier Transform Infrared Spectroscopy and Peroxy Radical Chemical Amplification. The alkene-ozone reaction systems were investigated with and without an OH radical scavenger and as a function of humidity. The results were interpreted through detailed chemical chamber box modelling, incorporating the Master Chemical Mechanism degradation scheme for each specific alkene, supplemented with a more explicit representation of the alkene-ozone reaction mechanism. The observed yields are interpreted in terms of branching ratios for each channel within the postulated alkene ozonolysis mechanism, and their implications for atmospheric radical production were considered.

This is the first study undertaken in a controlled environment to understand the kinetics of the release of soluble reactive phosphorus and copper from sediments of natural systems with an associated biofilm, and to identify which of the size compartments affected those fluxes most. It was found that of the sediment size fractions in the system, the stones that had a substantial biofilm growth attached had the greatest influence. Differences in the responses were observed between the sediment size fractions and the two sites, where contaminant concentrations varied. The equilibrium phosphate concentration and a phosphorus transfer index were used to establish if there was a net uptake or release of phosphorus by the sediment size at the time of sampling. The sediment having a biofilm and associated particulate material resulted in a greater flux than fine sediment, which does not support a filamentous biomass. The kinetic results imply a different mechanism than diffusion being involved. It was demonstrated that both gravel and stone substrates can have an important control over the release of soluble reactive phosphorus due to their role as firm substrate for a biofilm growth. Changes in the steady-state concentration of dissolved copper suggest that the bed sediment is responding to reduced river water concentration and setting a new steady-state. The kinetics of the reaction of the sediment to copper were of a similar order, and rate constants increased through the season, but were of a similar magnitude for both sites. The differences in the n and rate constant values indicate a difference in the mechanisms (i.e. the order of the kinetics) of uptake of copper through the seasons. The kinetics are described by a rate law which yields a method of estimating the flux to the sediment for recovery time after a pollution incident and how far downstream the copper concentration would remain elevated after a pollution incident or sediment.

This study sought to discover whether summer cutting of fenlands changes the biodiversity of invertebrates in managed areas as compared to control areas. Following preliminary sampling reedbeds were chosen for the investigation. The invertebrates studied were Mollusca, Araneae and Coleoptera. Species level changes were investigated in order to identify any specific level responses to management. All the groups studied were shown to be habitat specific and sensitive to management at the species level, for some, but not all species. Overall biodiversity and similarity, in terms of presence and absence of species within each group, and in terms of numbers of individuals, was not shown to be affected by cutting management. All three groups studied contained species which reacted positively to cutting management, increasing in abundance. There were also species in each group which responded negatively to cutting management, decreasing in abundance. Overall response was positive in the short term.

A methodology of assessment is presented of the groundwater resources available in fracture zones, within the weathered mantle of gneiss, migmatite and granite. A model of weathering is developed, and values of porosity, hydraulic conductivity and electrical resistivity assigned to the different grades of weathering. A geophysical technique is developed, based upon a combination of electrical resistivity profiling and sounding, which allows a volume estimate of the various weathering grades to be made. A finite difference algorithm is used for this estimate which enables the apparent resistivity response of an inhomogeneous resistivity distribution to be calculated. An iterative approach is then adopted, adjusting the resistivity model until the calculated response agrees with the field data. An analysis of recharge in a savanna climate is developed based upon the Monteith equation for predicting evapotranspiration, and upon a model of unsaturated zone soil moisture movement. The recharge function developed is included in a one dimensional catchment water balance model. The results from this model are compared with observed runoff and groundwater hydrographs. The estimate of recharge is combined with the estimate of aquifer storage to produce an assessment of available groundwater. Optimal methods for the development of the resource are discussed. While developed in Northern Nigeria, the methodology of assessment is applicable to any similar geological and climatological environment.

Over the past decade, there has been an ever increasing interest in the relationship between weather and climate and how they are portrayed artistically. The representations of skies, atmosphere, weather, climate and climate change through a variety of artistic media have been considered thus far (Eliasson 2003; Olson et al 2004, Kunz et al 2005; Thornes 1999, 2008a, 2008b). Furthermore, there have been a number of studies that have contemplated the use of environmental art as a form of proxy data for past weather, air pollution and climate change (Lamb 1967; Neuberger 1970; Brimblecombe and Ogden 1977, Baker and Thornes 2006 and Zerefos et al 2007). Monet’s series paintings can be considered as another example of art representing aspects of the weather and climate, for example, when Monet painted his scenes of London, he would include the sun when it was visible or a representation of the sun when it was obscured, trying to illustrate the atmosphere, and thus the weather, in his paintings. However, Monet also reworked many of his canvases with the intention of reflecting how the atmosphere appeared on specific days from year to year, therefore it seems it could be concluded that Monet was consciously painting the climate of London as well as the weather. For this reason, the opportunity to deconstruct Monet’s representations of the skies in his London Series (1899-1905) could not have come at a better time.

Silver nanoparticles (AgNPs) are currently widely used and of special interest due to their anti-microbial properties. They have been used extensively in commercial applications and might be the most worrying of the manufactured nanoparticles because of their inherent toxicity. In this work, stable citrate and PEG stabilized AgNPs of three different core size (7, 10 and 20nm) were synthesized, the stability of citrate capped NPs was assessed in ecotoxicology media (used for OECD for Daphnia magna toxicity testing) and the stability of 20nm NPs in environmentally relevant conditions (like presence of humic substances, sunlight, different types of synthetic water, amongst other). The particles were fully characterized before and during the stability tests with a multimethod approach. The methods used were DLS, UV-vis, TEM, AFM, FI-FFF, HR-STEM, EELS, EDX. Not all methods were used for all the samples.

There is major concern that river temperature changes driven by a changing climate and associated hydrological changes will have profound impacts on freshwater ecosystems. To identify the rivers most sensitive to change and implement effective strategies to mitigate high thermal extremes, this thesis aims to improve understanding of the influences of hydrometeorology and riparian landuse on river temperature dynamics, controls and processes within a UK context. Four studies are presented within a multi-scale research design which aimed to improve understanding of: (1) spatial patterns and inter-annual variability in the shape and magnitude of annual river temperature regimes across England and Wales, and regime sensitivity to air temperature and river basin properties, (2) the effects of riparian vegetation on water temperature under a range of hydrometeorological conditions, (2) the processes by which cool water refugia are produced beneath semi-natural, deciduous forest canopies, and (4) how minimal riparian planting can be used to produce thermal refugia in reaches of differing aspect and hydraulic characteristics. The aims are achieved by combining observational, statistical and deterministic modelling techniques. The outcomes of the research contribute significant new knowledge and tools for evidence based management of river and stream temperature under present and future climates.

This Masters research took place in the Kat River Valley in the Eastern Cape, South Africa. The Kat River Valley is a semi-rural catchment that covers an area of approximately 1700km2 and is characterized by a complicated history of dispossession and resettlement. Farming is the main activity that is practiced in the area. This includes the farming of citrus at a commercial scale, rangeland stock farming and small-scale vegetable farming. The economy of the catchment is enhanced mostly by commercial citrus farming, which consumes by far the largest amount of water in the river through irrigation. Water allocation is a burning issue among water users in the catchment and needs to be negotiated taking into consideration social, economic and environment impacts. The aim of this study is to describe, discuss and evaluate the Companion Modelling (ComMod) approach, which used a simulation model and a role-playing game related to the model in order to facilitate and develop negotiating skills as well as build capacity in decision-making amongst local stakeholders for water resource management in the Kat River Valley. The ComMod approach, developed by a group of Companion Modellers, is a community-based science approach that emerged in the 1990s. The ComMod approach is used in order to facilitate collective learning, negotiation and institutional innovation in dealing with resource management complexities faced by rural communities. Through ComMod, the model (KatAWARE) and its related role-playing game was developed by having the contact with local stakeholders. The information to feed the model and the role-playing game came from informal interviews, surveys, geographic information systems (GIS), workshops and focus groups. The use of workshops in the implementation of ComMod was a success. Results show that (1) new knowledge was acquired, which allowed stakeholders to have a broad understanding of a catchment system. (2) Awareness was created about complex systems and enabled stakeholders to see an individual action into to the broader system. (3) Strong interrelationships were fostered amongst different water users, which allowed stakeholders to share their view points. The ComMod process was however associated with a number of limitations, many of which resulted from the constraints that were imposed by the socio-economic background of the study area. Nevertheless, the outcome of the study shows that the ComMod process was useful in helping the Kat River Water Users Association (KRWUA) stakeholders develop negotiating skills regarding water allocation strategies for the development of the Catchment Management Plan.

This thesis aims to determine the colonisation rates of house dust mites in different types of flooring materials and how this is influenced by vacuum cleaning, to assess the common fungal taxa present within carpets and how differing environmental determinants influence this, to develop more efficient cleaning regimes for the removal of house dust mite allergens from smooth and carpeted floors, and to assess the influence of vacuum cleaning on the airborne concentrations of Der p I and fungal spores from rooms with smooth and carpeted floors. The colonisation behaviour of two house dust mite species in three flooring types was compared and the differences noted. Significant differences were found in the colonisation of the same three flooring types by house dust mites and significant differences were found between controls and vacuum cleaned flooring. In the home environment, a number of variables were found to influence both the concentration of the house dust mite allergen Der p I and the level of fungal contamination of carpeted floors. Substantial differences in Der p I allergen concentrations were found between smooth and carpeted flooring and the process of intensive vacuum cleaning showed significant reductions in allergen concentrations for specific cleaning times. Significant differences occurred in airborne allergen concentrations and fungal spore counts both before and after vacuum cleaning, with significant differences found between rooms with carpeted and smooth floors. The general conclusion was that cleaning frequency and flooring type are two of the major variables to control in order to minimise exposure to house dust mite allergens and fungi in the home.