Atmospheric transported dust is a major source of iron, manganese and other nutrients to the ocean. During atmospheric transport, dust containing iron and manganese undergoes cloud processes that can increase the reactivity and solubility of iron and manganese species when they enter into seawater. Saharan sieved soils were artificially atmospherically weathered with different low pH treatments, using simple dilute acids and also cycling through a typical cloud pH range. Formation of nano-particulate iron (ferrihydrite) occurred, and was identified using high-resolution microscopy, together with a measured increase in the fraction of amorphous iron species that were leachable from the processed soil. Both treated and untreated soils were then mixed with filtered stored North Atlantic seawater in the laboratory and also with freshly collected seawater from the NE Atlantic whilst at sea. Initial release of iron from artificially treated Niger soil reached 6 nM and from artificially treated Niger Mali soil reached 3.5-10 nM (depending on the different experimental variables). This was significantly greater than from un-weathered particles ~1-1.5 nM at the soil concentrations used (10 mg). For Mn all the dissolvable metal was removed during the cloud pH cycling and was not retained on the particles due to slower oxidation and scavenging than with the Fe. However, significantly more manganese ~ 60 nM from acid treated Mali soil and ~30 nM from acid treated Niger soil was released into seawater compared to the manganese released from the untreated soil (30 nM and 22 nM for Mali and Niger soil respectively). Low pH soil treatment led to increased release of Mn in the cloud water that stayed in solution for at least 5 days. This cloud-released Mn will therefore enter the ocean surface in a soluble form. These data show the major impact of atmospheric processing on dissolution of Fe and particularly Mn from Saharan sieved soils that are transported through the troposphere to the surface ocean.

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Lead emitted into the environment, primarily from the combustion of leaded petrol and industrial activities, such as metal smelting and coal burning, retains the isotopic signature of the ores from which it is derived. Accordingly, it is possible, at least in principle, to distinguish sources of lead pollution via isotope ratio measurements. In this study, inductively coupled plasma mass spectrometry (ICP-MS) was used to characterise and investigate the extent of variation of lead isotope ratios in contemporary and historical environmental materials in Scotland. Reliable analytical methods were established for atomic absorption spec trometric measurement of lead, ICP-MS determination of stable lead isotopes, 208Pb, 207Pb and 206Pb, and gamma spectrometric assay of radioactive 210Pb in lake sediments and peat cores. Leaded petrol, atmospheric particulates and street dust sampled in central Edinburgh between February 1989 and December 1991 had mean 206Pb/207Pb ratios of 1.082±0.024, 1.092±0.011 and 1.109±0.016, respectively. These isotope ratios were found to be depleted in 206Pb compared with a mean of 1.160±0.012 for tap water in contact with lead pipes and typical ratios of 1.17-1.19 for British lead ore deposits and coal. Paint, with an observed wide range of isotopic compositions (206Pb/207Pb ratio range of 1.083-1.183 and 208Pb/207Pb ratio range of 2.363-2.592), appears to have significantly influenced house dust and some street dust isotopic signatures. Such overlaps and influences may hinder the quantitative apportionment of sources and routes of exposure in general population studies, especially for children. The identification of sources and the quantification of inputs of lead to the Scottish environment during the last 100-200 years was investigated using 210Pb-dated sediments from oligotrophic, eutrophic and acidified lochs and ombrotrophic peat cores. Pollutant lead fluxes to 210Pb-dated sediments from Round Loch of Glenhead tripled in magnitude from approximately 3mg/m2/y in the early 1800s to reach a maximum of 32mg/m2/y in the early 1940s. A similar pattern of deposition was observed in sediments from Loch Lomond and 210Pb-dated peat cores, which reveal a 10-20 fold enhancement in the fluxes of lead deposited from the atmosphere since 1800 both at rural sites near the heavily populated and industrialised central belt and on a remote island off the north-west coast of Scotland. This has been accompanied, largely during the last 50 years, by a significant reduction in the 206Pb/207Pb ratios from the 19th century values of 1.17-1.18 to 1.14-1.15, attributed to increasing contributions from car-exhaust emissions of particulate lead derived from alkyllead petrol additives manufactured from ores comparatively depleted in 206Pb. Trends in 206Pb/207Pb ratios of pollutant lead in Loch Lomond and Round Loch of Glenhead sediments were found to be consistent with atmospheric deposition records observed in peat, decreasing from 19th century values of 1.17-1.19 to 1.12-1.14. The calculated relative contribution of petrol lead to post-1950 sediments from Loch Lomond of 50-75% is considerably higher than that determined for the same period in sediment from Round Loch of Glenhead (5-30%) and for a peat core from Flanders Moss, a rural location in Scotland (27-43%), and indicates the importance of localised inputs, especially near industrial centres.

As we strive to find new technologies to dispose of our municipal solid waste, compost-like outputs (CLOs) are becoming more widely created. As a product of both aerobic and anaerobic digestion, they provide a potentially important carbon store and some have proven to enhance existing carbon stores when added to brownfield sites and agricultural land. However, the CO2 flux from this artificial soil is relatively high when compared to natural soils. The aerobic digestion process under which it is produced lasts only 9 days, producing a material which is still comparatively unstable and yet to mature. The CLO is laid in windrows where it is hoped that it will stabilise and mature; if the humification process at this stage can be optimised, would an even greater carbon store be achieved? This thesis seeks to answer this question, through the research into humification in both natural and artificial systems; through the measurement of CO2 flux to assess the stability of CLO over time; using adapted methodologies to gauge the maturity of this artificial soil by analysing the amount of humic acids present; by adding proposed catalysts to the material in fully factorial lysimeter studies; and by examining the affects of different physical environmental conditions under which CLO product humifies. The results of a series of experimental trials, undertaken over a three year period, are presented. Manganese-coated sand and char, both currently ‘waste’ products were both used as potential catalysts for the humification process of CLO. Temporal trends were seen in most samples using infra-red gas analysis, an alkali extraction technique, UV photospectrometry, fluorescence and a novel pseudo-thermogravimetric analysis. The waterlogging of the samples appeared to have an effect on the humification process and a great deal of concurrent data was seen upon the addition of Mn-coated sand and char to the CLO. Both appeared to have a stabilising effect on the CLO, reducing flux rate and increasing humification as compared to a control. An overriding theme present throughout this thesis is the heterogeneous and contaminated nature of the non-source-segregated CLO tested. It is therefore recommended that similar studies be undertaken on a purer, more homogenous CLO in order to assess whether promising results seen could be elucidated in order to gauge the efficacy of biochar and Mn in encouraging the production of humic substances. A field trial would allow the unified soil system to be considered, rather than the CLO alone.

Human exposure to weak, environmental electromagnetic fields (EMF) is widespread. Furthermore, a statistically significant association exists between residential proximity to high-voltage power lines and an increased risk of childhood Leukaemia. Most possible mechanisms involving such weak EMF are overwhelmed by the body’s own thermal ‘noise’. The radical pair mechanism (RPM), however, can circumvent thermodynamic considerations by magnetic field (MF)-induced changes in reaction rate. A ‘magnetic field effect (MFE) stopped-flow spectrophotometer’ has been successfully constructed and tested in-house to enable robust investigations with enzyme reaction systems involving RP intermediates. A commercial instrument was modified by reengineering the assembly that houses the 20 μl reaction cell from non-magnetic materials (Delrin and aluminium). Adjustable MF pulses (≤ 37 mT) are generated for a user-definable period within the cell volume by a bespoke pair of Helmholtz coils and a pulsed power supply. A previously published MFE in a horseradish peroxidase catalyzed reaction was chosen as a biological test system. However, the field-dependence, including the unique low-field feature, was not reproduced. Reanalysis of the original data uncovered a number of problems, the most significant being: 1) the method and analysis were insensitive to the reported changes; 2) the proposed RP are entirely notional. Stopped-flow MFE studies with adenosylcobalamin (AdoCbl)-dependent ethanolamine ammonia lyase (EAL), conducted by the same authors, were also revisited. The original method, used to identify the magnetically-sensitive step as C"Co homolysis, was found instead to be rate-limited by cofactor binding. The protocol was redesigned, but still no MFE observed. However, one was observed in the photolysis rate of both free AdoCbl and holo- EAL in absence of substrate. Together, these results suggest RP stabilization upon substrate binding, which has implications for the enormous catalytic power of AdoCbl-dependent enzymes. Two Human enzymes were also screened for MFEs, with negative outcomes.

Volatile organic compounds (VOCs) are ubiquitous within the Earth’s troposphere, being released both locally and globally from anthropogenic and biogenic sources. VOCs constitute an important class of reactive trace species responsible for the production and exacerbation of numerous documented atmospheric issues, including photochemical production of ozone and formation of secondary organic aerosol (SOA). Consequently, measurement of VOCs under both ambient and laboratory conditions is crucial, such that emissions controls may be affected, environment response may be monitored and scientific understanding of the atmosphere may be advanced. This thesis describes the development, characterisation and application of a novel technique for ‘real-time’ detection of atmospheric VOCs. Termed Chemical Ionisation Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS), analyte ionisation by ion-molecule interaction is employed under defined reaction conditions, followed by TOF mass spectrometric analysis. Within this work CIR-TOF-MS is comprehensively characterised for the detection of a wide range of atmospheric VOCs using the chemical ionisation reagent ions H3O+, NH4+, NO+ and O2+•. Reaction products and species-specific markers are identified for future use and ionisation mechanisms are explained. Detailed investigations into instrument performance and optimisation are described, and compound specific sensitivities and detection limits are determined. The technique is validated for quantitative atmospheric monitoring using findings from a multi-institution measurement intercomparison. It is shown that VOC measurements are made by CIR-TOF-MS with a high level of accuracy and precision. CIR-TOF-MS is also applied for the first time to urban air monitoring, where typical ‘city’ VOC pollutants are measured in high detail. The work presented culminates with a comprehensive description of the first major application of CIR-TOF-MS to the scientific exploration of a contemporary atmospheric issue: SOA formation. CIR-TOF-MS measurements provide key insight into the identity of potential SOA contributing compounds, including a number of previously unobserved molecules. Findings also provide support to current understanding of gas phase VOC degradation mechanisms.

In this thesis, the potential for the observation of acetylene (C2H2) and ethane (C2H6) from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) infrared limb emission spectra is assessed. C2H2 is primarily produced from biomass and biofuel burning with C2H6 also emitted during natural gas production. The ability to successfully observe such species at high spatial and temporal resolutions allows a detailed study of their sources and transport to be conducted, an area of uncertainty in global tropospheric chemistry. A fast detection algorithm for both C2H2 and C2H6 in the upper troposphere/lower stratosphere (UTLS) was developed (Chapter 4), capable of performing a “first look” at MIPAS data. Monthly C2H2 detection results for 2003 were analysed and shown to be well-correlated to retrieval results. This allowed African and Asian biomass burning transport, the relative influence of biomass burning to natural gas sources and the Asian monsoon anticyclone formation to be investigated. An optimal estimation retrieval was developed for both gases and successfully applied for August 2003 (Chapter 5). This enabled the vertical structure of the distributions to be examined in the context of deep convection as well as the chemical isolation of the Asian monsoon anticyclone and biomass burning export. Of particular note were the results that C2H2 was clearly isolated within the anticyclone and the observation of uplift via deep convection of C2H2 over South-East Asia (Chapter 6). Evidence for the penetration of C2H2 from the troposphere into the stratosphere above the anticyclone is also presented. Ratios of the gas concentrations were examined (Chapter 6). The C2H2/CO ratio provides information on the photochemical evolution of the biomass burning plumes. The C2H2/C2H6 ratio suggests differentiation of biomass burning and fossil fuel production sources. C2H6 enhancements observed over Mexico are attributed to the processing of natural gas.