Reactive nitrogen (N) as a result of anthropogenic activities (e.g. fossil fuel combustion, fertiliser manufacturing and intensive agricultural practices), now dominates the global nitrogen cycle. For sensitive ecosystems across the globe, perturbation of the nitrogen cycle as a result of increased inputs of reactive N, has been seen to have a profoundly detrimental impact on biodiversity and ecosystem structure and function. Concerns surrounding the conservation and protection of both natural and semi-natural habitats from the damaging effects of N deposition, have prompted widescale research, that aims to understand and quantify ecosystem responses to elevated N inputs. Much of this research is in the experimental domain, based upon the simulation of N deposition within controlled conditions. The research outlined in this thesis, is principally focused on the findings of a long-term experimental approach on a lowland heathland system in the south east of England. N additions of 30 kg N, ha⁻¹, yr⁻¹ were seen to cause large, persistent effects on Calluna growth, phenology and chemistry, retard the development of lower plant groups and alter soil biogeochemical processes. Interactions between N inputs and climatic stress were also observed, with N additions seen to significantly modify Calluna’s response to drought conditions. Interactions between N deposition and climate were also evident at a larger scale, following a nationwide survey of UK heathlands across broad pollution, climatic and geographic gradients. Representing one of the first surveys to test both above and below ground responses to ambient N deposition across UK heathlands, the findings provide compelling evidence that many N driven changes observed within an experimental context, are also occurring at a nationwide scale. Such findings facilitate the identification of robust bioindicators of N deposition that could be successfully integrated into heathland conservation measures. Given that current emissions and deposition rates of N are predicted to double by 2050, and in regard to the future climate changes that are expected, research of the kind presented within this field of research is of the upmost importance if heathlands, and other sensitive ecosystems, are to be preserved.

Primary biological aerosol (PBA) particles include bacteria, fungal spores, pollen and animal and plant debris. They are ubiquitous in the atmosphere and form a transmission vector for animal and plant disease. Several studies also suggest PBA are important in cloud ice processes despite being present at relatively low concentrations. Biodiversity changes caused by human activity may therefore have climate impacts through cloud-aerosol interactions, and improved methods are required to characterise PBA size distributions, sources and sinks on a global scale.Natural and anthropogenic sources contribute PBA while several processes remove it from the atmosphere. It therefore exhibits strong temporal and geographical variations in concentration. Published measurements involve several collection and offline analysis techniques, which are difficult to compare directly and generally feature low time resolution. This means PBA are poorly characterised globally and specific meteorological influences are difficult to identify. Light-induced fluorescence (LIF) offers a rapid, consumable-free method of measuring PBA size distributions, however false-positive results can contribute outdoors and LIF cannot resolve specific biological species.This thesis describes the use of a Wide Issue Bioaerosol Spectrometer version 3 (WIBS-3): a novel LIF instrument that records particle diameter, shape and fluorescence following excitations at two wavelengths. Its response to samples of PBA, non-PBA and calibration particles was assessed in the laboratory, and three outdoor studies are discussed at length: Below and above a tropical rainforest canopy (Malaysia); in an urban location (Manchester); and at a high-altitude background site (Puy de Dôme, France). The likely sources of fluorescent aerosol are identified at each site: Fungal spore release was triggered by rainfall in Borneo; increased fluorescent concentrations were linked to traffic activity in Manchester and a strong diurnal cycle in France was attributed to boundary layer depth. The limitations and benefits of the different WIBS-3 measurement channels are also discussed, along with comparisons of fluorescent particle concentrations with published and in-situ PBA measurements.False-positives are found to play a strong role outdoors away from PBA sources such as tropical forest, and a ubiquitous background of fluorescent non-PBA was detected using one excitation wavelength. A shorter excitation wavelength appears more capable of discriminating between PBA and false-positives. Basic PBA emission rates are calculated using data from these studies and tropical rainforests are concluded to be the largest source of PBA mass globally.

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This thesis IS divided into two parts. Part I provides a detailed discussion of the design ami construction of a highly instrumented reactor for atmospheric chemistry (HlRAC). The main analytical tool'constraining HlRAC's design is its multipass FTIR absorption spectroscopy optical system. Apart from the FTIR system, HIRAC features an extensive suite of instrumentation en'abling simultaneous measurement of several different atmospheric trace gases. This capability allows experimental flexibility, and potentially provides multiple constraints in the development and testing of atmospheric oxidation mechanisms. The initial experimental results obtained from the system show HlRAC's capacity to facilitate atmospheric chemistry research at Leeds, linking laboratory and theoretical investigations of elementary reactions with VOC mechanism development. Part II discusses theoretical work conducted in order to -explore reaction kinetics and product yields of elementary reactions that are significant to the chemistry of planetary atmospheres. The tools for theoretical analysis include: (1) electronic structure theory, (2) statistical theories for describing reaction rates and product energy partitioning, (3) the energy grained master equation (EGME), and (4) trajectory simulations. In conjuction with experimental data, .these techniques permit a detailed' understanding of reaction mechanisms under a range of conditions that are relevant to the chemistry of planetary atmospheres. They also facilitate experimental design in: (1) laboratory studies of elementary reactions and (2) chamber studies of more complex oxidation systems, such as may be carried out in HIRAC.

Radioactive particles have been released into the environment from different sources (e.g. nuclear weapon tests, nuclear accidents, nuclear reprocessing plants, and use of depleted uranium (DU) munitions). Nuclear fuel particles have been released from authorised discharges of low-level radioactive effluent into the Irish Sea sediments from the nuclear fuel reprocessing plant at Sellafield, UK. Following the use of depleted uranium munitions in the Gulf wars and the Balkan conflicts, the environmental impact of depleted uranium and its behaviour in the environment have been of great concern. In this thesis, nuclear fuel particles released from Sellafield and retained in the intertidal Irish Sea salt marsh sediments, and DU particles arising from testing of DU munitions against hard targets and corrosion of DU metal buried in soil at Eskmeals firing range, UK, were investigated using a range of microanalytical, analytical and radiometric techniques. The particles were characterised in terms of size and morphology, elemental and radionuclide compositions, isotopic composition of associated radionuclides and, crystalline structure of uranium forms. The results demonstrate the usefulness of the applied techniques in characterising environmental radioactive particles, and lead to better understanding of the origin, behaviour and fate of these particles in the environment. The nuclear fuel particles were 1-20 µm in size, composed mainly of uranium and irradiated in the reactor as the transuranium elements (Np, Pu, Am and Cm) can be identified. The isotopic composition of uranium and plutonium suggest that these particles are derived from reprocessing of spent fuel. The results demonstrated the persistence for some decades of irradiated fuel particles in estuarine marine environment.DU particles from firing impacts were oxidized uranium forms (UO2 and U3O8) and composed mainly of uranium with few molten particles composed of a mixture of uranium and iron. DU particles from corrosion processes were mainly sand grains coated with metaschoepite corrosion product. The results showed the diversity of particles which can be produced through the use of DU munitions and the potential for these to persist in the environment for many years.

The research for this thesis led to the development of two environmental detectors, whose function was to identify predetermined threshold levels of the analyte. The research centred onto two types of analyte; immiscible and dissolved, both occurring in water based locations. The first detector was developed to detect the accumulation of oil within an oil/water interceptor. Pollution from oil spillages is a major contaminate of water systems and the control of this potentially hazardous material has legal obligations. This liquid, which naturally separates from water, accumulates within the interceptor enclosure and can be removed once the quantity of oil reaches the desired level. However, the often unpredictable nature of oil leaks and spillages means that the accumulation of oil within an interceptor is an irregular occurrence. Interceptor detectors based upon electrical techniques already exist. This research specifically developed a detection system that operated without any electrical devices within the interceptor. The research explored several possible avenues, eventually pursuing a technique based upon pressure change, based on the density differential between water and oil. The final system was capable of identifying when the oil had reached a depth of 200 to 250 mm within the interceptor. The second detection system, a portable microfluidic fluorimeter, was intended for placement in locations for the direct analysis of water. Glutathione was chosen as a model analyte, associated with a sex pheromone and prior to the onset of spawning may be found in high concentrations. The system that has been developed is capable of selectively sensing glutathione to below 10 μM. However, the threshold concentration in the proximity of its release as a pheromone is greater than 100 μM and within this range the fluorimeter produced a linear response. The fluorimeter used an LED light source with a PMT detector. An analysis could be made every seven minutes, using 150 μL each of analyte and reagent for every cycle. Through assessment of a pre-made standard, the viability of the microfluidic system could be assured with regards to blockages or other malfunctions of the system.

Pectin methyl esterase (PME) enzymes are produced by bacteria, fungi and higher plants, and hydrolyse methyl ester groups present on the backbone of pectic polysaccharides found in the primary cell wall of plants. Pectic polysaccharides are required for intercellular adhesion in dicotyledonous plants. To fulfil this function, they need to be cross-linked, covalently or non-covalently. The texture of plant-based foods is affected by the location and extent of these linkages, ultimately determined by chemical and subsequent structural modifcations undergone by the methyl ester groups on the pectic polysaccharide backbone during growth, ripening, storage, cooking and processing. These processes result in spatial variations in cell separation and adhesion betwen the walls of adjacent cells. These modifications are due to the action of PME enzymes. It has been suggested that covalent intercellular linkages are formed by glycosidic bonds between xyloglucan and acidic pectins. However, the presence of non-methyl esters has been confirmed and these linkages are candidates for the role of intercellular adhesion. The correlation between the quantity of these non-methyl ester groups and the deterioration of potato tuber texture during the period of storage following harvest was explored in two potato cultivars using titrimetric techniques and atomic absorption spectrometry. Pectic methyl ester groups in plant material are a major reservoir of methanol in the biosphere. PME enzymes are responsible for the cleavage of the ester bond between theses methyl groups and the pectic polysaccharide backbone, resulting in the release of methanol and acidic pectin. Methanol from both anthropogenic and biogenic sources is an important precursor of the gaseous pollutant, tropospheric ozone. Thus the accurate quantification of methanol emitted to the troposhere from both growing and decaying plant material is essential as the global balance of gases in the Earth's atmosphere is continuously skewed as a result of anthropogenic activities. Particular principles and techniques used in the quantification of methyl ester groups in potato tubers were developed and utilised in order to quantify the amount of methanol contained in the leaves from tree species native to Great Britain, in the form of pectic methyl esters, that could potentially be emitted to the troposphere as a consequence of the senescence of these leaves. The potential impact on the quantity of methanol in the troposphere of the growth of certain crop species grown commercially in the UK was investigated. A modified bell jar headspace capture and purge emthod and thermal desorption technique, in conjunction with gas chromatographic (GC) quantification, were developed and used to quantify methanol emitted from the developing tissues of plant species with significant agronomical importance, both in the UK and globally. Results obtained from the determination of pectic methyl esters contained in mature leaves of tree species, native to Great Britain and growing sites in Scotland, were extrapolated using available leaf litterfall and leaf area index (LAI) data to account for total area of trees of the same species growing across Great Britain and the globe. The results obtained following the quantification of methanol emitted from growing plant species of agricultural significance were extrapolated to ultimately estimate the quantity of methanol being emitted from these plant species on a global scale annually.

Glasgow contains many buildings made from local ‘blond’ sandstones that are showing the legacy of 150 years of urban weathering and this decay may accelerate as climate changes in the future. Most of the blond sandstones are Carboniferous in age and comprise of micaceous quartz arenites with varying amounts of diagenetic minerals including ankerite and kaolinite. Chemical decay can be visually identified in the carbonate minerals, but the combination of quantitative X-ray microanalysis (chemistry of mineral) and Raman spectroscopy (structure of mineral) also allows chemical decay to be observed in both kaolinite and muscovite. The Raman spectroscopy shows a variation in the muscovite minerals between the outermost surface and internal region (20 mm depth), demonstrating that structural decay is occurring within the micas and reduces them to an “ionic slurry state” in a relatively short time frame. The impact of microbial colonisation on the stones was also investigated. Using osmium stained polished blocks, complimented by scanning electron microscope imaging, microorganisms were found to be living cryptoendolithically in a few samples but at very shallow depths (<2 mm). Light penetration results revealed that a thin weathered crust (<1 mm) on the surface of sandstone will restrict the transmission of light into the rock, thereby preventing the colonisation of photosynthetic microbes. As a result, most microbial communities are restricted to the stone surface but only where they will not be subjected to photo-oxidative damage, which frequently occurs during summer months. Consequently, the most extensive microbial colonisation is restricted to the sandstone’s surface and during the winter. Using novel internal microclimate monitoring technologies it was found that stone temperature and humidity is decoupled from ambient conditions. During the summer the stone interior is considerably hotter than air temperature, whilst relative humidity is generally comparable to external conditions, whereas in the winter interior temperatures are closely related to ambient conditions and relative humidity is generally much higher. To understand how sandstone buildings will react to a change in climate, current conditions were extrapolated to 2080 using predictive models for the Glasgow region and the impact of these conditions was investigated by accelerated weathering experiments in a climate chamber. Results reveal rapid granular disintegration, the rates of which are independent of grain size. Overall, this study concludes that rates of chemical decay will increase as the climate warms and becomes wetter overall, primarily iii through dissolution, decay and loss of diagenetic minerals, and the extent of microbial activity will change, but these effects will be strongly dependent on local microenvironment. Implications of these findings are that more work on conservation and preservation techniques will be very important to protect the stone-built heritage of Scotland.

Climate change presents a major threat to global health and will further exacerbate the health inequalities that exist internationally. However, the provision of healthcare results in considerable greenhouse gas (GHG) emissions and is therefore contributing to climate change itself. Meanwhile, the integration of strategies to address climate change into global health efforts will realise health co-benefits. Meeting the challenging carbon reduction targets set within the NHS will require an improved understanding of the GHG emissions association with different forms of healthcare. This thesis explores the environmental impact of the provision of renal medicine services within the United Kingdom, placing a particular emphasis upon GHG emissions. The approach required, and the opportunities that exist, to reduce the environmental impact of renal medicine services are first explored through a review of the existing literature and a survey of the current practices of renal services in England, Scotland and Wales. A study, adhering to the principles of PAS2050, of the GHG emissions attributable to an individual renal service is then reported. This is the first assessment of the carbon footprint of an individual specialty service to include both direct and indirect GHG emissions. Consideration is given to how the results might inform carbon reduction strategies. Indicative carbon burdens for outpatient appointments and inpatient admissions are derived in order to facilitate future modelling of the emissions attributable to different clinical pathways of care. A second study, in which the GHG emissions attributable to different forms of an individual treatment (haemodialysis) are determined, is then presented. Finally, four case studies of good environmental practice within renal medicine, identified from the earlier literature search and survey, are presented in the context of the results of these studies.

Tropical peatlands play an important role in the global carbon cycle, but little is known about the factors which regulate carbon dioxide (CO2) and methane (CH4) fluxes from these ecosystems. To improve our understanding of the potential impact of future changes in climate and/or land-use, this study aimed to quantify current fluxes of these gases from a large domed peatland, San San Pond Sak, in Panama and assess the influence of environmental factors. Three sites with differing dominant vegetation species (Raphia taedigera, Campnosperma panamensis and Cyperus species) and nutrient status were investigated between February 2007 – September 2009 using a combination of in situ closed chamber gas sampling and ex situ headspace gas sampling to quantify current and potential gas fluxes from the peat surface and at depths of 2 m from the surface. Physical and chemical properties of the peat were determined concurrently. Laboratory experiments were carried out to investigate patterns of litter decomposition and microbial activity. Gas fluxes differed significantly between sites. CO2 fluxes were greatest at the C. panamensis site (100–400 mg m-2 h-1), followed by the R. taedigera (74–352 mg m-2 h-1) and Cyperus sp. (59–294 mg m-2 h-1). The seasonal patterns associated with rainfall were similar for all sites, with the release of CO2 being greatest during the dry season. CH4 fluxes also varied between sites, but no seasonal variation was evident. CO2 flux varied diurnally at the C. panamensis and Cyperus sp. sites, perhaps due a circadian rhythm in vegetation processes. CO2 and CH4 production occurred throughout the upper 2 m of the profile, both in situ and ex situ, with potential CO2 fluxes of up to 1,000 mg m-2 h-1 being found in the surface layer. The peat became increasingly recalcitrant and P-limited with increasing depth. Measurements of litter decomposition and microbial activity indicated that the availability of labile substrates and nutrients differed between sites. In conclusion, CO2 and CH4 fluxes differed between sites experiencing similar environmental conditions, and were influenced by variation in environmental factors. Fluxes varied on both short- and long- timescales, but not at all sites. The magnitude of the gas fluxes was influenced by different environmental factors at each site, indicating that fluxes and the most important driving variables vary dependent on surface vegetation even within a single peatland system. With regard to climate and/or land-use change, it was concluded that San San Pond Sak peatland would be sensitive to water table drawdown, with the likely outcome of increased CO2 releases and the potential for CH4 uptake, rather than release.