No description available.

No description available.

No description available.

No description available.

The purpose of this research was to determine the effects of the organophosphorothioate pesticide diazinon, its metabolite diazinon oxon and diazinon in a commercial formulation on the freshwater amphipod Gammarus pulex. It was found that diazinon in the commercial formulation was significantly more toxic to G. pulex than diazinon oxon, which in turn was significantly more toxic than diazinon. In non-lethal ecotoxicity assays, 24 h exposure to diazinon and diazinon in the commercial formulation significantly inhibited the vertical movement of G. pulex, whereas diazinon oxon had no significant effect. Inhibition of feeding was observed, with diazinon in the commercial formulation causing the most reduction, then diazinon to a lesser extent, whereas diazinon oxon had no significant effect. Only diazinon oxon caused a significant inhibition of acetylcholinesterase (AChE) activity in vitro. However, only diazinon and diazinon in the commercial formulation caused a significant inhibition of AChE activity following in vivo exposure. The levels of small heat shock protein (sHSP) and HSP 90 in post-9,000g supernatant samples were significantly increased by exposure to diazinon and the commercial diazinon formulation. Only diazinon significantly increased the level of HSP 70 in the supernatant. In contrast, diazinon and diazinon in the commercial formulation significantly increased the level of HSP 70 in 9000g pellet samples. Only diazinon in the commercial formulation significantly increased level of HSP 90 the in pellet sample. There was no significant effect of these agents on HSP 60 levels. Western blotting analysis of 10 % gels showed increased phosphotyrosine content in 51 and 75 kDa bands and increased phosphoserine and phosphothreonine content in the 75 kDa band following exposure to diazinon and diazinon in the commercial diazinon formulation. In contrast, a 51 kDa anti-phosphoserine reactive band only showed a significant increase after exposure to diazinon andIVdiazinon in the commercial diazinon. Analyses by 2D-PAGE found that a small numbers of low abundance proteins had altered levels in the 9000g supernatant sample after exposure to diazinon. However, the levels were too low to allow identification by mass spectrometry (MS). In conclusion, behavioural assays and biomarkers can be employed as useful and reliable bioindicators of environmental contamination.

In recent years the farming sector has been under growing pressure. Markets influence demand and prices, challenging farmers to improve production, business competitiveness and reduce environmental impact. Agriculture accounts for 9% of the total greenhouse gas emissions in the United Kingdom. Quantitative scientific literature provides useful strategies to reduce methane and nitrous oxide emissions from livestock farms. Their adoption may depend on their effectiveness and the influence of farmers’ perceptions of climate change on their decision-making. Adopting concepts of translational research and participatory action research, the study builds social capital among 14 livestock farmers in the South West and West Midlands, and evaluates the potential for adoption of emission mitigation strategies. The Rapid Farm Practices Appraisal (RFPA) tool was created to assess farm practices based on their mitigation potential. Practices were assessed twice over 6-9 months. Semi-structured interviews were used to assess barriers and opportunities to farmer engagement and on-farm innovation. Farmers were invited to a focus group meeting to network with other farmers and engage with researchers. All farmers participated in the 2 farm assessments. Only half the farmers adopted changes in farm management. The main difficulties related to the storage and treatment of manures due to the financial investments necessary. All farmers appreciated the RFPA tool, the clearness of the information provided and the focus of the tool on practices directly. All farmers accepted to be interviewed during the second farm visit; however, 2 farmers were unable to participate in the focus group meeting. Farmers’ main obstacles to innovation were limited financial capital, lack of trust in government action and confusion over the effectiveness of farm advice on mitigation. The lack of long-term flexibility of agricultural policies greatly influenced farmers’ decision-making. Farmers preferred practical solutions obtained through consistent, clear and transparent advisory services. The source of information greatly influenced their acceptance of advice. Farmers preferred peer-to-peer knowledge sharing and participatory activities in order to access knowledge on mitigation directly from scientists. Results provide positive grounds for the expansion of the RFPA tool to include economic assessment of farm practices and the engagement of a larger pool of farmers. Further research is needed in order to better understand how the source of information influences farmers’ acceptance of climate change science. Further studies should include a comparison between different farming systems i.e. organic v conventional, small-scale v large-scale.

Carbon dioxide, CO2, disposal into saline aquifers could reduce emissions of anthropogenic greenhouse gases into the atmosphere. To ensure that the CO2 is trapped securely and will not escape to the surface, storage in such formations must be designed carefully. The geochemical reactions involved depend on the composition of the injected fluid introduced in the aquifer and the composition of the initial minerals assemblage and the aquifer brine. This thesis studies mineral dissolution/precipitation during CO2 storage, both in the cap rock and the storage aquifer itself. The overall objective is to propose an ideal storage design for long term, inexpensive and safe CO2 disposal in saline aquifers. The rate-limiting effects of CH4 impurities in gas streams on the CO2 reactivity in the cap rock and aquifer (carbonate and sandstone) at conditions representative of storage locations are studied. Representative geochemical data of formation water and mineralogy assemblages of cap rock (Nordland shale) overlying the Sleipner field, Dogger carbonate aquifer from Paris basin, France and Frio sandstone aquifer from Texas, US, are used. Kinetic batch and one-dimensional and two-dimensional reactive transport models are run to predict mineral alteration induced in the cap rock and in the aquifer. Cap rock models are run using PHREEQC for 10,000 years. The model considers both pure CO2 and mixtures of CO2 with CH4 (1-4 (w/w)%) in the injected gas stream. The simulations demonstrate that mixtures of CO2 with CH4 suppress the porosity increase in the cap rock, leading to more secure storage. The aquifers models incorporate 1 (w/w)% organic matter and are run using TOUGHREACT. CO2 was initially injected at constant rate of 30kg/s for 25 years and the models were subsequently run for 10,000 years to study long-term storage. The simulations demonstrate that injection of CO2 in microbial-mediated aquifers enhances the precipitation of secondary carbonates minerals and decreases the porosity of both sandstone and carbonate aquifers. Overall, this study proposes two main design criteria for safe and cost-effective CO2 storage: CO2 injection with CH4 (1-4 (w/w)%) and CO2 injection into microbial-mediated aquifers to enhance mineral precipitation, rendering storage secure.

Geochemical modelling is fundamental for solving many environmental problems, and specially useful for modelling carbon storage into deep saline aquifers. This is because the injected greenhouse gas perturbs the reservoir, causing the subsurface fluid to become acidic, and consequently increasing its reactivity with the formation rock. Assessment of the long term fate of carbon dioxide, therefore, requires accurate calculations of the geochemical processes that occur underground. For this, it is important to take into account the major water-gas-rock effects that play important roles during the gas storage and migration. These reactive processes can in general be formulated in terms of chemical equilibrium or chemical kinetics models. This work proposes novel numerical methods for the solution of multiphase chemical equilibrium and kinetics problems. Instead of adapting or improving traditional algorithms in the geochemical modelling literature, this work adopts an approach of abstracting the underlying mathematics from the chemical problems, and investigating suitable, modern and efficient methods for them in the mathematical literature. This is the case, for example, of the adaptation of an interior-point minimisation algorithm for the calculation of chemical equilibrium, in which the Gibbs energy of the system is minimised. The methods were developed for integration into reactive transport simulators, requiring them to be accurate, robust and efficient. These features are demonstrated in the manuscript. All the methods developed were applied to problems relevant to carbon sequestration in saline aquifers. Their accuracy was assessed by comparing, for example, calculations of pH and CO2 solubility in brines against recent experimental data. Kinetic modelling of carbon dioxide injection into carbonate and sandstone saline aquifers was performed to demonstrate the importance of accounting for the water-gas-rock effects when simulating carbon dioxide sequestration. The results demonstrated that carbonate rocks, for example, increase the potential of the subsurface fluid to dissolve even more mobile CO2.

The work presented in this thesis is predicated upon the environmental applications of cavity enhanced absorption spectroscopy and cavity ring-down spectroscopy. These are related techniques that are highly useful for sensitive gas detection which is important in terms of anthropologically induced climate change and the detection of the changing levels of greenhouse gases. Sensitive gas detection techniques, specifically isotope ratio analysis, are useful for determining the sources and sinks of greenhouse gases and for distinguishing whether sources and sinks are natural or anthropogenic. The research involved gas detection using commercial near-infrared cavity ring-down spectrometers, made by Picarro, and highlights how well and to what environmental uses these instruments can be applied. Various gas mixtures containing methane and carbon dioxide were analysed by the CRDS instruments to try to determine the detection limits, and the effect that varying the concentrations would have upon the precision and accuracy of the measurements made. Headspace soil measurements of CH4 and C02 were also demonstrated to be made easily without processing of the gas stream.The main work described in this Thesis involved the implementation of a home-built optical feedback cavity enhanced absorption spectroscopy /cavity ring-down spectroscopy experiment which made use of a V-shaped optical cavity and a 7.8 υm quantum cascade laser for the detection of greenhouse gases in the mid-infrared. This comprised of the detection and analyses of spectral lines of methane and nitrous oxide isotopologues. Measurement in the mid-IR took advantage of the excitation of the stronger fundamental vibrational transitions occurring in this region and increased optical path lengths from the optical cavity and signal amplification from optical feedback are features that gave high signal to noise measurements. These techniques have the potential to be further developed for field usage by overcoming many of the limitations of alternative greenhouse gas detection techniques, such as instrument sensitivity and portability.

No description available.