The ecology of ponds is threatened by urbanisation and as cities expand pond habitats are disappearing at an alarming rate. Pond communities are structured by local (water quality, physical) and regional (land-use, connectivity) processes. Since ca1904 >80% of ponds in Birmingham, U.K., have been lost due to land-use intensification, resulting in an increasingly diffuse network. A survey of thirty urban ponds revealed high spatial and temporal variability in water quality, which frequently failed environmental standards. Most were eutrophic, although macrophyte-rich, well connected ponds supported macroinvertebrate assemblages of high conservation value. Statistically, local physical variables (e.g. shading) explained more variation, both in water quality and macroinvertebrate community composition than regional factors. Nonetheless, habitat availability within the wider landscape was important. Ecosystem functioning (leaf-litter breakdown) along a rural-urban gradient was confounded by habitat area, despite a decrease in functional redundancy. Ponds are identified that promote network connectivity and management of land-use within 100m may buffer against diffuse pollution with reductions in riparian shading required to improve growth conditions for oxygenating vegetation and to reduce nutrient levels. The results indicate that many urban ponds are threatened habitats that require active management to protect and restore water quality, biodiversity and ecosystem functioning.

Perfluorooctane sulfonate (PFOS) is a pertluoroalkyl substance with extensive historical use. Its persistence, bioaccumulation, toxicity and health concerns led to its incorporation in the Stockholm Convention as a persistent organic pollutant in 2009. Direct exposure to PFOS has been reported in different environmental and biological samples, and recent human biomonitoring studies indicate that levels are in decline. However. certain uncertainties remain when estimating its body burdens: indirect exposure to so called PFOS-precursor compounds - such as perfluorooctane sulfonamides and petfluorooctane sulfonamidoethanols - , followed by in vivo metabolism could contribute to the current levels of PFOS in human biological samples. To evaluate the direct and the indirect contribution to PFOS exposure, sample preparation and instrumental HPLC-MS/MS methods for the analysis of PFOS - linear and sum of branched isomers - and PFOS precursors - three FOSAs, two FOSEs and three FOSAAs - in dust, food and serum samples were developed and validated. Daily intakes for total PFOS and PFOS precursors via dust and food ingestion were estimated under different scenarios, and compared with reported internal exposure levels of PFOS. Finally. for a better understanding of the link between external and internal exposure, a qualitative study of the in vitro metabolism of two PFOS precursors was conducted.

Physico-chemical characterisation of atmospheric metallic particles collected at six roadside, background and rural sites has been undertaken by multiple methods. Mass-size distributions of total PM mass have been compared between multiple sites and roadside increments calculated in Birmingham, which are found to occur in the size ranges 100-180 nm, 320-560 nm and >1000 nm. Good correlations are observed between Ba, Cu and Fe, but some divergence of sources is evident in small particles. Single-particle analysis by TEM-X-EDS and EELS has classified Fe-dominated particles into two main groups; Fe content >90%/wt and Fe-Mn alloys (Fe ~75%/wt). Both classes are mainly γ-Fe\(_2\)O\(_3\) and α-Fe\(_2\)O\(_3\). Pb-dominated particles have been detected with Zn and Sb. Ce particles have been found as nanoparticles attached to large soot agglomerates. TEM and ICP-MS samples collectedfrom a static brake test rig show changes in mass distributions at different braking forces and between different elements, in particular between Ba, Cu, Fe, Ni and Al. Data from TEM samples of diesel exhaust imply that particles containing Fe, Cr and Ni together may be indicative of this source and that engines are a possible source of submicrometre Cu. Use of Al-alloys in engine design contributes Al-dominated particles to the emitted exhaust.

Although the Arctic is one of the most vulnerable regions to climate change, links between hydrology and ecology in high-latitude northern river basins are not well understood. Interdisciplinary research over three summer melt seasons (2010 to 2012) in the Kongsfjorden area of northwest Svalbard identified process connections between conceptual water sources, physicochemical habitat, and ecological structure and functioning in river basins. Water source dynamics determined from hydrochemical and isotopic data indicated differences in meltwater and groundwater contributions to river flow which varied both spatially and temporally at seasonal and year-to-year timescales. Non-glacier-fed rivers were characterised by less variable flow regimes, warmer water temperature, lower suspended sediment concentration and more stable channel morphologies. Several physicochemical habitat variables, notably water temperature and channel stability, were related significantly to rates of nutrient uptake and macroinvertebrate community structure. These data suggest that a future shift towards groundwater-dominated flow regimes may increase biotic diversity and rates of nutrient cycling in some high-latitude rivers. Key research findings are synthesised in conceptual models and provide a framework to understand the hydroecological response of these Arctic river systems to climate change.

This thesis describes the development and application of a laboratory system to investigate the loss of peroxy radicals to aerosol. The laboratory system consisted of an aerosol flow tube coupled to a custom-built PEroxy Radical Chemical Amplifier (PERCA). Aerosol was generated using an atomiser and their distribution measured using a SMPS. New values of the HO2 uptake coefficient, γ , were obtained for wet and dry sodium chloride aerosol and dry ammonium sulphate aerosol. The mass accommodation coefficient, α, was also determined for NaCl. A box model was used to determine the implications of the new uptake coefficient of HO2 loss to NaCl aerosol for tropospheric chemistry in the marine boundary layer.

With the increased use of manufactured nanomaterials (MNMs) and increased environmental and human exposure, "nanosafety" has become a major research objective. This field has yet to advance due to challenges in systematically linking physicochemical properties to toxicity. The aim of this work was to develop a library of comparable NMs and study their behaviour and ageing in different scenarios. A library of metal oxide NMs based on a PVP capped ceria synthesis protocol was developed and extensively characterised. The protocol was successfully modified to produce PVP capped zinc oxide and copper oxide NMs, of comparable sizes. These NMs along with commercial uncoated ceria NMs were subjected to time and temperature dependent studies. The work studied the transformations occurring on exposure to 25, 45, 65 and 80 °C temperatures for 4 weeks. Results showed increased aggregation, changes in metal valency state and decreased stability with increasing temperature and time. Finally the potential phosphate induced environmental transformation of ceria was studied for the ceria library NMs, the commercial ceria NM and a series of zirconium doped ceria NMs. Samples were exposured to pH-adjusted phosphatisation solutions. Ceria and ceria-rich samples underwent physical and chemical transformations. Furthermore the commercial ceria was exposed to a pH-adjusted phospholipid containing phosphatisation solution where no characteristic phosphate ageing transformations were observed.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been detected across the globe in a variety of media. The toxicity of these compounds and other precursors has led to concern about human exposure. The purpose of this thesis is to investigate the presence of perfluoroalkyl compounds (PFCs) in UK indoor and outdoor microenvironments and the impact this may have on human exposure. Both PFOS and PFOA were chosen for analysis (via LC-ESI-MS/MS) because of their highly persistent behaviour. Additionally, perfluorohexane sulfonate (PFHxS), was chosen along with precursors to PFOS and PFOA; perfluorooctane sulfonamides (PFOSAs) and perfluorooctane sulfonamidoethanols (PFOSEs). An international comparison of house dust was conducted and concentrations of PFCs in the UK (except for ethyl perfluorooctane sulfonamide (EtFOSA)) were found to be similar to those from France, Germany, USA, Canada and Australia and much greater than from homes in Kazakhstan and Thailand. Concentrations of EtFOSA were significantly higher in house dust samples from Australia compared to the UK, and were raised in all other countries. The reason for this is uncertain, but is speculated to derive from the use of EtFOSA as an active ingredient in Sulfluramid, which is an insecticide used for control of ants, cockroaches and termites.

Ambient ozone, as a secondary air pollutant in the troposphere, is a major threat to human health, plants and the environment. In order to develop effective air quality policy to minimise ozone pollution, it is important to gain a quantitative understanding of the chemical factors that drive tropospheric ozone production. There are a number of limitations and uncertainties in the current models and indirect methods used to estimate chemical ozone production rates. Here, an Ozone Production Rate (OPR) instrument is developed to fulfil the demand of accurately measuring ambient ozone production rates in the atmosphere. This prototype system aims to directly measure the in situ oxidant (Ox: O3 + NO2) production rate p(Ox) in ambient air. This thesis describes the OPR experimental methodology, instrument properties and system characteristics. Two field deployments (London and India) are comprehensively discussed, and correction approaches are implemented to improve measurement accuracy. The field measurement results indicated the measured p(Ox) levels could be used to interpret modelled Ox production rates, and changes in ambient oxidant level. The OPR system could be a useful tool to determine the balance between advection and chemical production in controlling local ozone levels, and hence support ozone control policy.

This thesis investigates levels, sources, and transformation products of both legacy BFRs (LBFRs), and several novel BFRs (NBFRs). To accurately target these emerging pollutants in environmental matrices, an analytical method based on liquid chromatography coupled to high resolution mass spectrometry was developed. Sediment samples taken along the River Thames revealed the presence of both legacy and novel compounds, with concentrations of selected NBFRs approaching those of LBFRs. Tentative sources in the industrial area of London were identified, along with the presence of hydroxylated transformation products of polybrominated diphenyl ethers (PBDEs). Further, the employed technique facilitates the precise identification of metabolites and degradation products formed through in vitro and photodegradation studies. This provides valuable insight into the transformation mechanisms of NBFRs, including hydroxylation and debromination reactions. While 2,3,4,5-tetrabromobenzoic acid (TBBA) was the major metabolite of 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH) was biotransformed to monohydroxy- DBE-DBCH and monohydroxy-triDBE-DBCH in trout liver microsomes. Photolysis of investigated NBFRs resulted in the formation of lower brominated species through stepwise reductive debromination as a main pathway. In addition, the use of mass defect plots and bromine isotopic pattern assist in the identification of relevant unknown chemicals within complex mixtures of halogenated compounds in dust and sediment samples.

Currently silver nanoparticle (AgNP) is the most widely used NP. Potential hazard of AgNP to the environment, however, is largely unknown. Lack of NP characterization data in most of (eco) toxicology study, transformation of NPs in the test media and environment, etc. have challenged the attempt of presenting NP dose and toxic outcome. Therefore more control over NP ecotoxicology study need to be done. This study was aimed to synthesis a stable, fully characterized and tightly constrained PVP-capped AgNPs via bottom-up method. Modification of Mulfinger et al. (2007) synthesis protocol has been successful in generating spherical and monodisperse PVP-capped AgNPs. Another straightforward synthesis method was developed via ligand-exchanged (indirect method) from a monodisperse citrate-capped AgNPs. PEG-SH, Fulvic acid and Tween-80 polymers was also tried to recap citrate-coated AgNPs. There were no size and shape alterations as PVP and fuvic acid replaced citrate coating, while PEG-SH and Tween-80 polymer did. Ali polymers, nevertheless improved the AgNPs stability in ecotoxicology media. The stability of citrate; PEG-SH; and PVP-capped AgNPs due to incubation in several ecotoxicology media with variation in media ionic strength/concentration and composition was examined. It was seen that PVP polymer showed a better stabilization effect than citrate and PEG-SH. Shape transformation was seen for AgNPs after incubated in media without chloride (nitrate and sulphate media), especially in concentrated media. Thus type of capping agent; media ionic strength and chemical composition determined the behavior and stability of AgNPs in ecotoxicology media.