This thesis outlines results from an investigation of radon and radon daughter concentrations in limestone caves, from a geographical and geological perspective Investigations were conducted at all geographical scales, ranging from a national investigation in the four major caving regions of England and Wales to a detailed survey within a single cave in the Peak District. The measured radon concentrations in some limestone caves in England and Wales are amongst the highest ever recorded in the world Significant spatial and temporal variations were recorded m concentrations at all scales, within a single cave, between caves in the same region and between different regions Additionally, seasonal and diurnal variations in concentrations were highlighted. External climatic variables and the cave radon budget were demonstrated to account for variations in cave radon concentrations Within limestone caves seven primary sources of radon were identified and the relative importance of each to the overall radon budget was determined Sediments and the contaming limestone rock were the major sources although in certain cases water and the soil were demonstrated to be influential Models were developed to predict cave radon concentrations within a single cave However, these could not be transposed to predict radon concentrations in other caves in the same region or other regions The users of limestone caves were identified, their potential exposure times were examined and legislation concerning their exposure was discussed Four groups were identified as being at risk from radon while underground, and three groups were identified as bemg at little risk Methods by which the risk from radon exposure can be reduced were examined

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As a result of damage caused during the First Gulf War in 1990-1991, the Kuwaiti environment suffered from drastic pollution caused by massive petroleum hydrocarbon contamination resulting from the destruction and burning of 700 oil wells across Kuwait. A range of types of polluted soils, including fresh oil lakes, dry oil lakes, and tarcretes, damaged desert wildlife. The idea of phytoremediaton using native plants was introduced and concluded that the native species Haloxylon salicornicum (Amaranthaceae) had potential as a phytoremediator. In the initial phase of this study a follow-up survey of clean and polluted sites in 7 areas in Kuwait was undertaken: Bahra, Sabah Alahmad protected area, Burgan oil field, Um Alaish oil field, Um Alrros Military Base, Sabriya oil field, and Um Ghadaier oil field where 41 plant species were found to be present. TWINSPAN classification of the dataset identified four assemblages of plant species, occurring in four ecologically-distinguishable habitat types (represented by 7 sample-groups produced by the classification procedure); one of them is mostly north of Kuwait where Sabah Alahmad protected area is and Bahra and Um Alaish oil fields and tends to be more in the oil damaged areas and characterized by the presence of the Haloxylon salicornicum; the other one is in both the north (Um Alaish oil field) and south of Kuwait (Burgan oil fields) and is characterized by the presence of both Cyperus conglomeratus and Rhanterium epapposum while the third and fourth assemblages can be mostly considered variant and characterized by the presence of Pennisitum divisum. These native species (former 3) were hence selected as the focus for subsequent investigation. The survival of Haloxylon salicornicum plants in weathered oil-polluted soils was experimentally investigated under greenhouse conditions, using a random block design with 4 replicates and 5 treatments: pots containing 100%, 75%, 50%, and 25% polluted soil, mixed with clean soil, and clean soil only as a control. The results indicated that the plants could grow successfully even in 100% oil-polluted soil. The experimental results also provided evidence that water applied to the surface (simulating rainfall) could reach the root system in all of the treatments (even for the 100% oil contamination treatment). Following on from the greenhouse study, a field trial was undertaken to examine the survival and growth of Haloxylon plants introduced into clean and oil-polluted soils (in and adjacent to a weathered dry oil lake) under field conditions. Three replicate two-year old iii (nursery-grown) Haloxylon plants were planted at each randomly-chosen location in the dry oil lake soil, and the design was repeated at 10 random locations in clean soil close to the lake boundary. The experiment was set up in two different locations (Bahra area in the north; and in Burgan oil field in the south of Kuwait). there was no significant difference in growth rates between plants in clean and polluted soil, in either area. The biomass data showed a significant difference in fresh weight between plants from clean and polluted soils, with those growing in clean soil having higher moisture content (possibly less woody than those from the polluted sites). However there was no significant difference in either fresh or dry biomass between the two experimental areas in the north and south. Data produced by analysis of amount of TPH in the polluted soils in both experimental areas showed some variability, but overall there was no significant difference between the two polluted areas, in terms of their weathered petroleum hydrocarbon content. Successful phytoremediation usually, if not always, is a function not only of phytoremediator plant physiology, but also the activity of the phytoremediator species associated rhizosphere microflora. In order to gain some insight into the hitherto unknown rhizosphere microflora of Haloxylon salicornicum plants, bacterial and fungal isolation procedures were carried out on samples taken from the roots of wild Haloxylon salicornicum plants, and from cultured plants growing in oil-contaminated soils in the greenhouse experiment, using media enriched with petroleum hydrocarbons to encourage the culture to survive in such conditions. Bacteria organisms found to be associated with the rhizosphere of wild Haloxylon are Streptomyces spp. and Inquilinus sp., while in 100% oil contaminated soil Rhodococcus manshanensis, Agrobacterium tumefaciens, Nocardia cyriacigeorgica, Gordonia lacunae / Gordonia terrae and Lysobacter spp., occurred. In the 50% oil contamination treatment soil, around the roots of Haloxylon plants contained Gordonia lacunae / Gordonia terrae and Agrobacterium tumefaciens and finally the clean soil Sphingopyxis spp. was present. Fungi found in the Haloxylon rhizosphere included organisms known to be associated with petroleum hydrocarbon degradation, including Penicillium spp. in wild Haloxylon (and also 50%, 100% and clean soil from the greenhouse trial), as well as Trichoderma asperellum in the clean soil. The conclusion is that Haloxylon salicornicum, together with its rhizosphere microflora it contain, offers high potential for use in phytoremediation operations designed to assist in the clean-up of oil polluted desert soils in Kuwait.

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The proposed strategy for the disposal of the United Kingdom’s nuclear waste inventory is placement within a deep geological disposal facility (GDF). The prevailing conditions of a GDF are expected to be anaerobic, with alkaline conditions (10.5 < pH > 13) over a long timescale. In these anaerobic, alkaline conditions the cellulosic components of intermediate level wastes are expected to degrade, with the major products being the α- and β-forms of isosaccharinic acid (ISA). ISAs have received particular attention because of their ability to form complexes with radionuclides, potentially influencing their migration through the GDF. The potential for microbial colonisation of a GDF means that ISAs present a source of organic carbon for utilisation. The ability of micro-organisms to utilise cellulose degradation products including ISA is poorly understood. The work presented in this thesis has shown that near surface microbial consortia are capable of the degradation of ISA under iron reducing, sulphate reducing and methanogenic conditions at circumneutral pH values expected within geochemical niches of the near field and far field of a facility, with PCR analysis suggesting groups responsible for these metabolic processes were present in each instance. The same near surface consortium studied was capable of ISA degradation up to a pH of 10 within 8 weeks. Degradation rates were retarded by the increase in pH, in particular that of the β- stereoisomer. Clostridia were the likely bacterial Class responsible for fermentation of ISA to acetic acid, carbon dioxide and hydrogen. These secondary metabolites were then used in the generation of methane by methanogenic Archaea, however the acetoclastic methanogen component of the consortium was absent at elevated pH; evidenced by the persistence of acetic acid within the microcosm chemistry. The mesophilic consortium used in these initial investigations was not capable of ISA degradation above pH 10 within the short timescales imposed within the project. As a result, a soil consortium was obtained from a hyper alkaline contaminated site, where waste products from lime burning had occurred between 1883 and 1944. Initial surveying of the site showed that ISA was present and generated through interactions between the hyperalkaline leachate and organic soil matter. Following sub-culture of the soil consortia at pH 11, complete ISA degradation was observed within 14 days where again, fermentation processes followed by methanogenesis occurred. Clone libraries showed that again Clostridia was the dominant phylogenetic Class, represented by species from the genus Alkaliphilus. As observed with the mesophilic microcosms at pH 10, hydrogenotrophic methanogens dominated the Archaeal components of the consortia. The results presented in the following body of work suggest that the microbial colonisation of a GDF is likely within the construction and operational phases of the facility. Carbon dioxide is likely to be the predominant terminal electron acceptor within the facility and here methanogenesis has been observed up to a pH of 11.0. In each case, fermentation is likely to be as a result of alkaliphilic Clostridia, where methanogenesis appears to be limited to the hydrogenotrophic pathway at elevated pH. These findings are likely to inform safety assessments through both the application of rate data and gas generation predictions.

Cold Plasma Discharges offer wide decontamination scenarios relevant to environmental, food and drink or clean room applications. The option to operate the discharge system in atmospheric or sub-atmospheric condition provides an opportunity to investigate a lowcost and simple system design. UV to NIR (200nm to 700nm) can be emitted by pulsed cold plasma discharge systems that operate at atmospheric pressure. Different wavelengths emitted from the discharge depend on the pressure and the type of gas mix used in the systems. The scope of the work involved in this research was to design and develop a prototype cold plasma system for air at atmospheric pressure. The prototype was used for air decontamination by passing seeded and unseeded air between the electrodes gap. Modelling of the discharge and pulse forming network circuit systems was carried out in MultiSim to investigate the circuit characteristic. The components values ie: capacitors, stray inductors and resistors in the model system are interchangeable which enabled simulation of individual component effects on the output pulse shape and magnitude. The optimum component properties from the modelling were used as a guide to designing the system. The main discharge system contained a pair of Chang Uniform Field Electrodes which were manufactured in-house, and provided a discharge area of 1.0cm x 60.0 cm. The discharge volume is varied depending on the gap between of the anode and cathode. Preionisation was achieved via trigger wire, built within the discharge system. This promotes the ionisation of the gas in between the electrodes in enhancing uniform discharge characteristics. Different types of electrodes were made from aluminium with the discharge size 300mm x 200mm, laser marked and unmarked surface were also used in the system in order to obtain wider discharge surface and reduce manufacturing costs.

Soil samples originating from the Chernobyl Exclusion Zone and Vetka region of Southern Belarus, which are contaminated by radioactive Chernobyl fallout were analysed using three analytical procedures which were developed for this work: 1. A Differential Autoradiographic Imaging (DAI) procedure which allows the non destructive isotopic classification of radioactive contamination in soil. This technique enabled differentiation of certain isotopes, including Cs-I37, Sr-90 and Am-241. Images were generated from one fallout contaminated sample in which areas were assigned to the dominant isotopes, Sr-90 and Cs-137. The technique allowed an interpretation of the activity distribution in terms of "homogeneous" and "particulate" contamination. 2. A gamma spectroscopic measurement procedure which enables the identification of the presence of hot particles (insoluble radioactive clusters) in large quantities of soil, dirt or dust. In 100 g of a sandy soil originating from 15 km North of the Chernobyl reactor, approximately 500 hot particles were found present, with an estimated Cs-l37 of 20 Bq each. 3. A titration-extraction procedure which identifies radionuclides associated within the humic acid fraction, and their solubility in a range of different extraction solutions. Radiocesium present in peat and sand originating from the Vetka region, was found to have markedly different and lower solubility characteristics compared to similar soil types which were laboratory contaminated using radiocesium in an ionic form. High solubility was found only in fallout contaminated peat, in which 25% of the radiocesium was found to be associated with the humic acid fraction. Depth distributions of gamma emitting radionuclides were determined in soil from the above mentioned locations in Belarus. In peat an exponential depth distribution was obtained, whereas in sandy soil the migration velocity was found to be slower and the depth distribution could not be fitted by a single exponential function. The work presented here supports the hypothesis that the pattern of the activity depth distributions, at distances up to 150 km from the Chernobyl reactor, can substantially arise from hot particle contamination. However, other forms of radioactive insoluble clusters may exist. The development of such clusters or hot particles was observed in a pure quartz sand as well as in an "Ea" horizon material from a humo ferric podzol, after treatment with radiocesium in an ionic form.

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No description available.