Phytoplankton growth is sustained by the supply of essential nutrients and balanced by mortality processes such as viral infection, both of which can give rise to stress. Remod- elling of cellular lipids in response to such stresses is common in unicellular organisms. Under phosphorus (P) stress, phytoplankton substitute glycerophospholipids with non- phosphorus analogues, reducing their demand for P. Reported herein, the model marine diatom Thalassiosira pseudonana degraded only a small proportion of its original glyc- erophospholipid. Most of the P remained incorporated in glycerophospholipids, but significant changes in the individual glycerolipid species were observed. Untargeted lipidomic screening highlighted diglycosylceramides, not previously ob- served in T. pseudonana, that increase with P stress and may be useful as biomarkers. The fatty acids comprising each individual diglyceride lipid were characterised filling a conspicuous gap in our knowledge. Preliminary results suggest partitioning of diacylglyc- erol lipids between subcellular compartments. Marine diatoms, rich in lipids such as triacylglycerols are potential feedstocks for bio- fuels, where nitrogen (N) starvation is common to increase lipid yield. Quantification of individual glycerolipid species under N stress revealed that polyunsaturated glycerophos- phatidylcholine species and the predominant chemotype of sulfoquinovosyldiacylglycerol displayed large increases. Total diacylglycerol increased 3 fold under N stress, comprised of increases in saturated/monounsaturated species. This appears to form part of the cell’s adaption to N limitation that ultimately leads to the accumulation of triacylglycerides. These findings provide insight on the diatom lipidic response to nutrient stress and their adaptations to life in low nutrient environments, with additional implications upon biofuel production. Marine viruses infect phytoplankton influencing host ecology and evolution. Emilia- nia huxleyi has a biphasic life cycle with a diploid and haploid phase. Diploid cells are susceptible to infection by specific coccolithoviruses, yet haploid cells are resistant. Anal- ysis of lipids from cultures of uninfected diploid, infected diploid and uninfected haploid E. huxleyi revealed that sialic-glycosphingolipid, previously linked with susceptibility to infection, was absent from the resistant haploid cultures. Additional untargeted analyses unveiled potential biomarkers furthering our understanding of E. huxleyi host/virus lipid dynamics and highlight potential novel biomarkers for infection, susceptibility and ploidy.

This thesis uses a novel, combined mineralogical, geochemical (including stable S iso- topes), and microbiological approach to semi-quantitatively determine Scotia Sea sedi- ment formation processes. The factors that control the localisation of chemosynthetic, microbial consortia in metalliferous sediment beneath Southern Ocean vent fields is investigated along with the impact of hydrothermal venting on sediment composition. Circum-Antarctic ridges represent nearly 40 % of the Earth’s ∼58,000 km ridge crest, but remain severely understudied. In the austral summer of 2009–2010, the Royal Research Ship James Cook expedition JC42 explored the northernmost (E2) and southernmost (E9) bare-rock segments of the East Scotia Ridge, and the sedimented Kemp Caldera (a southern feature of the South Sandwich Arc), and collected >20 co-registered vent fluid, chimney sulfide and hydrothermally-influenced sediment samples using the ISIS remotely-operated vehicle. The hydrothermal materials from E9 and the Kemp Caldera are the focus of this thesis. E9 sediment composition is controlled by the simple mix- ing of >90 % local basalt that is affected by subduction-related and enriched mantle components, <10 % particulate plume fallout, which is dominated by an Fe-, Cu-, Zn-, Ba-, and Pb-rich, near-plume phase, and <1 % collapsed chimney material. The ma- jor, minor, trace, and rare earth element sediment content at E9 is largely determined by proximity to active venting. The thin sediment cover throughout E9, indicates an early stage of sediment formation and the recent onset of venting at this site. Kemp Caldera sediment components include 55–60 % phreatomagmatic shards of local basalt that were most likely deposited by a recent, volcanic event, 30–45 % crystalline elemental S derived from the magmatic disproportionation of SO2 (identified by a δ34S signature of +4.8 ‰ to +5.9 ‰), and 0–10 % buoyant plume particles (rich in P, K, Mn, Fe, and the rare earth elements). Biogeochemical Fe, Mn, and S cycling is investigated in two very different sediment systems of the Kemp Caldera: Toxic Castle and Tubeworm Field. Toxic Castle sediments are compiled from the episodic deposition of magmatic and hydrothermal components, while pore fluid composition is strongly influenced by diffuse, upwelling hydrothermal fluid. The original magmatic-hydrothermal signature is diagenetically altered in the solid phase Tubeworm Field sediments, likely initiated by dissimilatory sulfate reduction. Pore fluid Fe and Mn redox zonation in the surface sediments at Tubeworm Field is typical of biogeochemical cycling in stratified marine sediments. Microbial cell counts (identified by 4’,6-diamidino-2-phenylindole staining and fluorescent in situ hybridisation microscopy) are relatively consistent across the ma- jor Tubeworm Field redox boundaries, although there is a significant downcore shift in the microbial community structure. A dominant presence of δ-, E-, and γ-proteobacteria (which host known S metabolisers), confirms active, microbial S cycling in the deeper Tubeworm Field sediments. Sediment descriptions from modern hydrothermal (partic- ularly back-arc basin-associated) systems are relatively scarce, in comparison to those of vent fluid and chimney material, which is surprising given the potential economic im- portance of hydrothermally-derived, metalliferous, rare earth-enriched sediments. This thesis increases our knowledge of sediment formation processes and subsequent biogeo- chemical cycling, in a range of back-arc-associated bare-rock and sedimented systems, along poorly-surveyed circum-Antarctic ridges, and accentuates the requirement for continued, interdisciplinary hydrothermal surveys of the global, submarine ridge system. We must fully understand the complex interaction of geological, chemical, and biologi- cal components that constitute the complete hydrothermal system, before we allow the commercial exploitation of unique ecosystems that have forever changed our perception of life in the deep sea.

The late Palaeocene to late Eocene period of Earth's history is characterised by remarkable change. Temperate ice free poles at the beginning of this period gradually cooled until permanent ice formed on Antarctica around 33.5 million years before present (Ma) and sea ice formed in the Arctic. The intervening time was not stable and data, despite relatively low resolution, appear to show that the Eocene climate was dynamic. This period was the most recent time when atmospheric pCO2 concentrations were as high as predicted by models simulating the effects of anthropogenic fossil fuel burning on Earths' climate. The ability to understand the mechanisms of climate change in the Eocene will help to understand potential climate impacts in the future. This thesis examines 3 contrasting periods of climate change. Geochemical data indicate that a 3.5 million year period of high biogenic silica deposition during the Eocene was climatically relatively stable in the Arctic basin with only infrequent communication to the world's oceans outside. This period is correlated with high organic burial in the basin and global siliceous rich deposits which acted to gradually draw down pCO2. This period of `quiet' climate compares to two periods of warming where significant carbon isotope perturbations may indicate the forcing of the Earth's climate into an alternative quasi-stable state. The Palaeocene { Eocene Thermal Maximum (PETM) represents a significant input of exogenic carbon into the atmosphere over the course of several thousand years and significant warming of the Earth. Records of bulk carbonate isotopes from a section in NE Italy show several other Delta13C perturbations both before and after the PETM event, albeit a quarter to a half of the magnitude of the PETM, and having durations of only 40 { 60 thousand years (kyr). These events are thought to be the result of a re-arrangement of the internal carbon cycle of the Earth - atmosphere and may represent orbitally forced changes in deep water ocean ventilation similar to controls seen on modern day glacial { interglacial cycles. These rapid changes in the carbon cycle are shown to be inverse at the middle Eocene Climatic Optimum (MECO), where gradual warming over 400 kyr is ended abruptly by significant cooling. From the first marginal marine section of this event rapid organic carbon burial occurs over 50 { 100 kyr and is associated with previously unrecorded low oxygen bottom water conditions and high organic burial. We hypothesize that if this burial was extended over significant shelf areas then this could rapidly have returned the middle Eocene to the general cooling trend of the Eocene.

A baseline study has been undertaken to assess the environmental impact of heavy metals within the fluvial environment of the River Stour, E. Kent, U.K. The occurrence of metal enrichment in surface waters and bed sediments coincides mainly with areas of urbanisation and high density traffic in addition to point source discharges including STW and industrial effluent outlets. Non-tidal surface water samples exhibiting Pb, Co, Cu, Fe and Zn concentrations intermittently elevated above EQS List I and II values largely correspond with bed sediment samples exhibiting metal concentrations above background values and commonly partitioned to the mobile exchangeable/acid soluble and reducible fractions. In the tidal reaches surface water samples exhibiting As, Cd, Co, Cu, Cr, Ni, Pb, V and Zn concentrations above EQS List I and II values are generally associated with bed sediment samples exhibiting partitioning to the immobile oxidisable fraction, suggesting that estuarine processes effectively promote the liberation of elements from the sediment compartment to surface waters. Total catchment annual suspended sediment yield, (190 t/km2/yr), is consistent with previous research work detailing the annual yield of U.K. rivers which in conjunction with suspended sediment concentration data highlights the importance of the transport and distribution of associated elements throughout the river system. Research highlights a requirement to improve point source management measures and control non-point sources and dredging activities and provides an index in which to assess the future impact of anthropogenic sources of metals to the fluvial environment of the River Stour.

A baseline survey of contemporary fluvial sediments in the Kentish Stour, east Kent, England, has been undertaken to document the sources and distribution patterns of anthropogenic PGE in an attempt to constrain some of the physical and chemical parameters that may influence the distribution of these elements. Nine sedimentary rocks, four motorway-runoff sediments and twenty-one river sediments were analysed for PGE by NiS fire assay pre-concentration and ICP-MS. The highest element abundances occur in a sample of ashed sewage sludge (total PGE content of 392 ng/g), whilst the lowest values were recorded in the soils and sedimentary rocks. The total PGE content of the river sediments ranged from 0.4 to 14.2 ng/g in 1999 and from 0.6 to 167 ng/g in 2001, and exhibited significant variation along the river. This variation corresponds strongly with land use changes (urban versus rural) and with points of discharge from sewage treatment works. The PGE and trace element concentrations of the river sediments, sedimentary rocks, motorway runoff sediments and ashed sewage sludge were normalised against their average crustal abundance to identify characteristic normalisation patterns. With this technique, high Pd concentrations in the River Stour sediments were found to be indicative of sewage inputs. The partitioning of Pt, Pd and Rh was investigated in a novel combination of Tessier’s (1979) sequential extraction technique and a Te coprecipitation. The partitioning in the sediments of a sediment retention lagoon progressed from more to less mobile sediment phases. The PGE are emitted in a form (possibly particulate) that becomes predominantly associated with the silicates fraction. The behaviour of the PGE in the River Stour is predicted to be controlled predominantly by physical processes.

Chromium(VI) is a reactive and highly toxic pollutant species which is present in certain industrial effluent streams as well as sea water and polluted ground water. Chromium(III), however, is relatively inert and less toxic. Conventional methods used to eliminate Cr(VI) from aqueous phase include its reduction to Cr(III) at acidic pH by reaction with strong reducing agents such as thiosulphate, FeSO4 and SO2, followed by precipitation as hydroxide in alkaline media. However, this procedure is not suitable for Cr(VI) elimination in dilute aqueous solutions. Thus, semiconductor photocatalysis has been studied as a possible alternative. Photocatalysis is the process of using light to promote catalysis of reactions and normally involves the photoexcitation of a semiconductor catalyst. During photocatalysis, light of a wavelength corresponding to an energy greater than that of the band gap, Eg, of the material is incident on the catalyst, resulting in electrons being excited from the semiconductor valence band to its conduction band. These electrons can then reduce the Cr(VI) to Cr(III). The semi-conductor used consists of nanoparticulate iron oxide embedded in a clay matrix. Clays are micro-crystalline layered minerals. This gives rise to interlayer spaces in which the iron oxide is ‘grown’. The clay structure restricts the growth of the iron oxide, resulting in nano-particulate sized semiconductor particles. To monitor the changes in Cr(VI) concentration, a new, stable potentiometric method has been developed that involves the successful use of a gold electrode to measure Cr(VI) concentration, that has to date, not been reported elsewhere in literature. Results show that the nanocomposite does photo-reduce Cr(VI) to Cr(III) and does photo-oxidise ethanol. Modelling of the time dependence of the measured (photo-induced) potential has allowed for the extraction of key rate parameters for the Cr(VI) reduction process with a view to system optimisation.

This thesis describes a study of the distribution and behaviour of natural and manmade radionuclides in the intertidal environment of south west Scotland. This work is particularly concerned with transport processes affecting radionuclides and with the application of radionuclides as tracers of natural environmental processes. Results are presented for study sites at Ardmore Bay in the Clyde Sea Area and Skyreburn Bay, Wigtown Martyr's Stake and Netherclifton in the Solway Firth with the radionuclides investigated being 134Cs, 137Cs, 210Pb, 238Pu, 239. 240Pu 241 Am, 238U, 232Th and 230Th. The study confirms and extends an existing model for particle associated Sellafield waste radionuclide transport to the intertidal areas of the Solway Firth and the work, moreover, establishes that the same supply mechanism operates in the floodplain, or merse, areas of the Solway Firth. Inventories of the order of 10e5, 10e4 and 10e4 Bq m -2 are derived for 137Cs, 241Am and 239,240 Pu respectively in the merse sediments, indicating inventories for these nuclides of the order of 7, 1 and 1 TBq in the total area of the merse deposits of the Solway Firth. A description is provided of a study of uranium movement through the Solway floodplain silts in the vicinity of a uranium mineralization vein and it is established that uranium migration for distances of up to 55m can be observed with continuous removal from solution during transport by uptake by iron/manganese oxides and organic materials. The removal process is characterised by a 10m halving distance. The radionuclide data are considered in the context of tracer studies of various environmental processes including large scale sediment movement in the Irish Sea, local sediment movement in particular bays and, at individual sites, mixing and accumulating processes.

This thesis aims to investigate the use of two materials: rockdust and greenwaste compost for use as soil fertility amendments. A field trial was conducted over three years to investigate the impact these materials had on plant yield, plant nutrient content, soil chemistry and soil microbial communities in direct comparison with chemical fertilizer and farmyard manure. There were annual applications of compost, manure and chemical fertilizer in spring with one rockdust application in the autumn prior to the first year of the trial. Two harvests were carried out each year in summer and autumn to determine differences in plant yield. The soil was analysed prior to applications to determine the baseline chemical status then was analysed at two more points through the trial. Results from the field trial showed clear effects of organic amendments on plant yield that were attributed to nitrogen addition by compost and manure. NPK chemical fertilizer produced a yield effect at an earlier point in the trial compared to manure and compost. This, and the chemical analysis of the materials showed that the organic materials required a period of mineralization of organic-N in order to replenish soil available nitrogen. The results from the field trial also showed differences in plant nutrient content (as a measure of plant quality). The organic treatments were shown to generally produce higher plant nutrient content than the NPK fertilizer showing that the increased yields of the inorganic fertilizer treatment impacted negatively on the nutrient content. No yield effects due to rockdust addition were apparent after 3 years of the field trial. In addition, rockdust did not impact on plant nutrient content nor did it affect the soil chemistry despite 3 years of weathering that was considered sufficient time to release nutrients to the soil. Samples of soil were taken in the summer after the final year of the field trial to determine long-term changes in the soil microbial communities between the treatments. Results showed that there were fewer long-term changes than were initially expected in soil microbial communites at the end of a 3 year trial of these materials. Short-term greenhouse pot trials were also conducted using 3 different test crops to investigate the use of greenwaste compost and various types of rockdust for use as growth media in comparison with a peat based control. Results showed that while greenwaste compost supported plant growth as well as the peat based media, no rockdust type increased plant growth beyond the yield in a greenwaste compost control. The short-term supply of nitrogen in greenwaste compost was as good as that of the peat based control and while the phosphate supplied by the peat based control was shown to give excessively high plant P content. Results from the pot trials showed that greenwaste compost could wholly or partially replace peat in plant growth media without negatively impacting on plant yield or quality. The likely effects of various types of rockdust on soil chemistry were investigated by carrying out nutrient extractions using increasing extractant ‘strength’. Nutrient extractions showed that a high degree of rock weathering was required to release small quantities of trace elements from rockdust samples. Sodium, calcium and to a lesser degree potassium, magnesium, iron and phosphate were supplied in greatest quantities from most rockdust samples with basic rocktypes releasing highest quantities of nutrients. As a result of the work carried out in this thesis, it is concluded that composted greenwaste could be a valuable addition to agricultural soil and that it could replace peat in some plant growth media. There are some implications to the use of composted materials – transport and application costs and the potential addition of potentially toxic elements to soil; however the potential nutrient addition and improved plant quality could make it an attractive fertility amendment in some organic farming techniques. It was concluded that rockdust was not shown to influence plant yield or quality in the agricultural setting of the field trial, nor was it shown to be a useful addition to plant growth media. Therefore rockdust could not be proven to be a useful soil fertility amendment.

Landfill leachates contain a wide range of pollutants including potentially toxic metal(loids) e.g. arsenic. Current landfill risk assessment models predict the fate and transport of these pollutants in the environment, however they consider all species below 0.45 μm to be dissolved, thus the presence of these pollutants in colloidal form is not considered. In order to investigate the presence and distribution of metal(loids) within the nanocolloidal fraction (<100 nm), AF4 coupled with HR-ICP-MS was selected (alongside AFM and DLS) and optimised for use with landfill leachates. UV254 and Fluorescence spectroscopy were also used as detectors for AF4 to detect organic colloids. AF4-HR-ICP-MS analysis was carried out both offline (fraction collecting and subsequent HR-ICP-MS analysis) and online (interfacing the AF4 output directly with the HR-ICP-MS) with parameters optimised for lower MW particles. Online coupling provided a higher resolution analysis than the offline method. The concentration of elements within the AF4 system was found to be in flux and therefore baseline concentrations were established for each sample injection. Method repeatability and a recovery mass balance of each element were also established. The method was validated by fractionation of a MSW, an aged MSW and a MBT leachate. All three leachates were found to show the same nanocolloidal distribution with two distinct nanocolloid populations present: a low MW organic rich fraction; and a larger, less organic rich fraction consisting of a mixture of organic and inorganic particles. Metals predominated in the lower MW fraction associated with humic or fulvic-like particles. The similarities between the leachate metal distributions showed that treatment of leachate prior to landfill did not alter the colloidal characteristics. Preliminary results examining the effects of pH and ionic strength of metal distribution showed that pH had no effect; however the lowering of ionic strength appeared to cause aggregation of colloidal Fe particles, presumably due to the lower organic content, which appears to control the distribution of metals in this size fraction. This research highlights the importance for landfill risk assessments to be updated to include the presence of colloidal facilitated transport and the necessity for further particle transport studies to be conducted.

Patagonia has one of the most extensive and well preserved glacial geomorphic records of anywhere else in the world. This study provides empirical constraints of Patagonian Ice Sheet (PIS) configuration and dynamics during the last two glacial cycles and the Holocene at 49°S. In particular a chronology of palaeo-ice surface elevations, thickness changes and ice-thinning rates is developed. Cosmogenic surface exposure dating across eight mountain transects at Hielo Patagonico Sur (HPS) outlet glaciers' Viedma and Chico, and from eastern facing mountain valley glaciers, is utilised to reconstruct PIS ice-surface elevation changes through time. The earliest dated glacier ice thickness marker falls into MIS6 (Marine Isotope Stage). The last glacial cycle is characterised by continuous ice-surface elevation lowering from a maximum at MIS5a to the Antarctic Cold Reversal (ACR). Large scale PIS cover occurred between ca. 40-47 kyrs, in both the HPS outlet glaciers and the eastern mountain valleys. This regional ice-cover considerably pre-dates the global Last Glacial Maximum (gLGM). A gLGM vertical ice surface expression is absent from the study area. A minor re-advance and/or stillstand at ca. 18 kyrs is recorded by the valley glaciers, but is not evident at the HPS outlet glaciers. Glacier Viedma records a prominent ice elevation during the ACR with rapid thinning at the end of the climate perturbation. Ice-surface lowering from the ACR limit continues with acceleration toward the late-Holocene. The PIS palaeo-ice elevation and thinning record presented here is sensitive to internal PIS dynamics, local and global climate forcing acting on different timescales, with glacier response to climate perturbation strongly linked to glacier catchment size and distance from the main source of precipitation at 49°S.