polybrominated diphenyl ethers (PBDEs) are additive flame retardants that have been -widely used globally for the last 30-40 years. In their functional operation, PBDEs are released from parent products when exposed to heat and light in order to retard combustion reactions. The physiochemical properties of PBDEs coupled with widespread use and production has led to ubiquitous environmental contamination by these compounds. In recent years PBDEs have become increasingly well studied and evidence of their toxicity to biota and occurrence in remote and pristine environments has led to the - implementation of legislation to control their use and production. A great many studies have been published on PBDEs, and key concepts are introduced in Chapter 1. However, comparatively little data exists for the UK. Data is lacking on both marine and terrestrial birds of prey; this is disconcerting, given the potential toxicity of PBDEs, as predatory birds have been susceptible to the adverse effects of anthropogenic organic contaminants in the past. Utilising the eggs and livers of two predatory bird sentinel species, the northern gannet (Morus bassanus) and the sparrowhawk (Accipiter nisus), collected as pati of the activities of the Predatory Bird Monitoring Scheme (PBMS), this work aimed to detennine detailed long-term temporal and spatial trends of PBDEs in UK marine and terrestrial systems. In addition, stable isotope residues of carbon and nitrogen were used to identify if changes in the diets of these birds could influence the trends in contaminant residues in their eggs. Furthermore, other potentially confounding factors such as age, sex and body condition were assessed using sparrowhawk livers - a matrix which allowed for the PBDE contamination in male sparrowhawks to be characterised. The findings of the studies conducted as part of this thesis are presented in Papers IIV and discussed collectively in Chapter 2. Methodologies are provided in Papers I-IV and supplemented by Appendix 2. Other POPs, for which data is presented in Paper 4, are discussed in Chapter 1 and Appendix 3. Contributions to relevant studies regarding PBDE toxicity and trends in UK air are presented in Appendices 4 and 5. Key conclusions and recommendations for further work are given in Chapters 3 and 4.

No description available.

Modelling phosphorus transfers from agricultural land to receiving waters is important as part of assessingth e risk of pollution and developingm itigation strategiest o meet the demands of international legislation such as the EU Water Framework Directive (2000/60/EC). Current phosphorus models, however, are afflicted by limited experimental support of their underlying assumptions, difficulties in measuring parameters and variables, and ambiguities in calibrating parameters against observations - in other words: uncertainties in data, model structures and parameters. These uncertainties were confronted explicitly in this thesis for two case studies at the grassland field and catchment scale. A pragmatic model learning framework was proposed, which approached the modelling problem from a downward perspective. Model structures, parameterisationsa nd input data were treated as hypothesesw ithin the GeneralisedL. ikelihood Uncertainty Estimation (GLUE) framework. Model input and evaluation data uncertainties were estimated and incorporated into the model diagnostic scheme while maintaining the rigour of hypothesist; e sting. Pragmatismh ad to be retained where statistical information to characteriseu ncertainties was absent. Data uncertainty had significant effects on prediction uncertainty. Model development was approached in the order hydrology, sediment, phosphorus. At the replicated field scale, hydrology was modelled by an ensemble of lumped conceptual store formulations. Hydrological variability between fields resulted in variability of model performance and rejection. Importantly, modelling revealed a 'leaking' of the fields, which helped revise the understanding of the study site. Sediment exhibited hysteretic behaviour, exhaustion effects and flushing effects in surface and sub-surface pathways. Moderate hysteresis could be modelled by a new hysteresis model using a different parameterisation for each event. Phosphorus behaved consistently in time, space and acrossp athways. A power-law phosphorus-sedimenrte lationship simulated the observed phosphorus enrichment at low sediment concentrations. At the catchment scale, hydrology was modelled using the semi-distributed Dynamic Topmodel. Behavioural simulations at the outlet were rejected againstn estedd ischargem easurementsM. odel failure was due to a misrepresentation of drainage pipes and quick-flows as well as uncertainties about the catchment topology. An improved hysteresis model could still not simulate all sediment dynamics, presumably due to quasi-random in-stream erosion and land manakement incidents. Event parametersc orrelatedw ith antecedenwt etness,w hich led to a conceptualm odel of a dynamic transport-/source-limited regime. A constant power-law captured again the dominant phosphorus behaviour. Understanding the sediment dynamics seemed crucial for robust prediction of phosphorus transfers in space and time. However, mechanistic models covering all relevant processes of source dynamics, mobilisation, transport and land management would be difficult to conceptualise, parameterise and test, given the current understanding of processes and measurement capabilities. Caution is advised when using phosphorus models in the regulatory arena without explicit consideration of uncertainties.

The effects of zinc, lead and copper ions, at concentrations up to 10 mM, on germination and seedling vigour of wheat, barley and rice were investigated. Percentage germination was unaffected by lead and zinc ions in the three species tested. The highest concentration of copper ions (10 mM) decreased the percentage germination in rice. Rice seedlings were grown in controlled environment cabinets using a nutrient culture technique. A copper ion concentration of 8 μM in the culture solution was found to inhibit the elongation of the longest root. Seedlings were grown in nutrient solutions at pH 5.5, 5.0 and 4.5, and three concentrations of copper ions. The reduction in all the growth parameters was highest at pH 4.5 in all copper ion treatments. The amount of chlorophyll in the uppermost fully-expanded leaves of the seedlings grown at pH 4.5, was considerably less than that in comparable leaves of the control seedlings. The effect of copper ions on root plasma membranes of the seedlings was estimated by measuring K<SUP>+</SUP> leakage from intact roots. A larger amount of K<SUP>+</SUP> leaked from roots when seedlings were incubated with high (16 μM) copper ion concentrations than when seedling roots were incubated in water. Similarly, the effect of copper ions on root lipid peroxidation as measured by TBA-rm(2-thiobarbituric acid-reactive material) accumulation, showed that more TBA-rm was accumulated in copper ion treated roots than in control roots. The effect of various copper ion concentrations on the morphology and ultrastructure of the roots was studied using light and scanning electron microscopy. The results showed that copper ions caused a reduction in the length of the root hair zone and of root hair length, a reduction in the size of the root cells, and initiation of lateral root closer to the root tip, compared to seedlings grown in control solutions.

The aim of this thesis was to study the persistence of an organophosphate insecticide, chlorfenvinphos, in soil, its movement from soil to neighbouring water and its effects on terrestrial and aquatic ecosystems. Chlorfenvinphos, formulated as an emulsion and granules, persisted in soil longer than most organophosphates but less than chlorinated hydrocarbons. Intense rain soon after soil was treated with chlorfenvinphos moved the insecticide on the surface of sloping land, but no residues were detected after 23 weeks in the water and mud in a pond at the bottom of the slope. Chlorfenvinphos moved more readily than dieldrin through soil in experimental troughs. Dieldrin seemed to be more firmly bound to soil particles and less easily desorbed than chlorfenvinphos. When chlorfenvinphos emulsion was applied to the surface of a pond, it was detected in the mud at the bottom after 5 hours and only 16% of the amount applied remained in the water after 19 hours. There were too few invertebrates in samples of mud to show statistical differences after treatment. Chlorfenvinphos disturbed the ecological equilibrium in soil between predatory mites, which became·fewer, and saprophagous oribatid mites and entomobryid springtails, which often increased in numbers after treatment. Toxicity tests in the laboratory showed that predatory mites were more susceptible to chlorfenvinphos than saprophagous species of microfauna. Chlorfenvinphos reduced numbers of predators more than those of saprophagous invertebrates. Numbers of Chilopoda were reduced more than Diplopoda and the initial dosage decreased numbers of Pauropoda, Diptera larvae and wireworms. Numbers of Protura, Symphyla, Enchytraeidae and Nematoda were unaffected by chlorfenvinphos at the dosage studied. Earthworms in treated plots were reduced only little more by chlorfenvinphos than by mechanical CUltivation. They did not accumulate residues after exposure to residues. The insecticide .eeemed to " have no significant effects on numbers of adult Carabidae and Staphylinidae in field plots. The observed effects of chlorfenvinphos on ecosystems to which it is applied and those to which it may be dispersed did not persist more than a year after treatment.

Benzyldimethyl Hexadecylammonium Chloride (BDHAC) is a quaternary ammonium compound (QAC) used in corrosion inhibitor formulations. It has both corrosion inhibition and biocidal properties. Studies have suggested that QACs in produced water are often discharged to the marine environment during oil exploration and production. The fate of these compounds on release to the marine environment, especially the ones with a benzyl ring, is not well understood. On reaching the marine environment, QAC adsorb onto sediment and may become bioavailable and toxic to the benthic communities. Therefore bioremediation of sediment could be useful to help preserve the marine environment. A biodegradation study was carried out using an enrichment culture technique with marine sediment, to identify which marine bacteria degraded BDHAC and subsequent degradation products. Following enrichment in the presence of BDHAC, different strains of bacteria, isolated from marine sediments, were shown to degrade BDHAC in a minimal salts medium. The bacteria identified by 16S rDNA sequencing, were shown to belong to several genera and were identified as Marine bacterium, Bacillus subtilis, Bacillus niabensis, Sporosarcina sp., Thalassospira sp, Rhodospirillaceae and Staphylococcus equorum. Investigations revealed that these bacteria were capable of degrading BDHAC when it was present at high concentrations, in the range 2 – 4 mg/ml. In media containing BDHAC, up to 90% of the substance was degraded within 43 days. Quantification of BDHAC after biodegradation experiments were performed by Colorimetric Dye Binding Assay (CDBA) and Electrospray Ionisation Tandem Mass spectrometry (ESI-MS/MS). Preliminary analysis of samples by ESI-MS/MS produced a peak with a parent-daughter ion transition of 136.0 91.0, corresponding to N, N-dimethylbenzylamine. The presence of this potential metabolite suggested the cleavage of the C alkyl-N bond as a step in BDHAC catabolism. This research will contribute to an understanding of the potential of the isolated strains of bacteria in bioremediating BDHAC contaminated sites. It will also assist operators and regulators in the oil and gas industry to understand the fate of BDHAC in the environment when the compound is used in corrosion inhibitor formulations. This understanding will assist environmental risk assessment of oil production facilities.

This study examines the benthos within western, inner Swansea Bay, for the period before, during and immediately after the cessation of a major, sewage discharge from Mumbles Head and assesses whether any changes in the benthos affect the growth of juvenile flatfish. The results of this investigation show that there have been significant improvements in seawater quality in western, inner Swansea Bay following the cessation of the Mumbles Head sewage discharge and that there have been changes in the species composition of the benthic communities within the study area. There has been an increase in the diversity of deposit feeders, especially the amphipods, and a decrease in the diversity of the filter feeders, especially the polychaetes. These changes are not attributable either to the sediment organic matter content or to gross changes in sediment type over the study period but are related to the significant reduction in total suspended particulate organic material discharged to the Bay. There have also been changes in the diet of juvenile flatfish on the nursery grounds of western, inner Swansea Bay which can be related to the changes in species composition of the benthic communities. A recovery model has been proposed to describe how shallow water, soft sediment, sublittoral benthic communities respond to the abrupt cessation of a major sewage discharge.

This study was divided into two main sections; an examination the performance of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and attempts to use the imaging spectrometer to estimate foliar biochemical contents over an area of forest. To examine instrument performance the SNR required to estimate foliar biochemical contents from reflectance data was estimated by using laboratory reflectance spectra of vegetation and random noise. A number of methods were used to estimate the SNR of the AVIRIS based on estimates of noise from the instrument and the data. It was concluded that while in 1992 the AVIRIS had barely sufficient SNR to estimate foliar biochemical contents this was no longer a problem. The AVIRIS collected imagery of a forested study site in north central Florida in March and September 1990 and July 1992. These data were used in two attempts to estimate foliar biochemical content. The first attempt used wavebands in the reflectance data which were known to be related to foliar nitrogen, lignin and cellulose contents. This analysis identified the large noise component within the 1990 AVIRIS data and also problems with the repeatability of the AVIRIS when collecting images of the same area only a few minutes apart. It did, however, indicate that some information related to foliar nitrogen contents was being recorded by the AVIRIS. The second attempt used wavebands in the reflectance data that were selected on the basis of a statistical comparison with the foliar chlorophyll, nitrogen, lignin and cellulose contents. Prediction equations were developed which indicated strong relationships between reflectance and foliar biochemical content at the study plots but the extrapolation of the relationships across the study site was less certain. Temporal averaging of the reflectance data was required to increase the SNR before the elevated foliar biochemical contents of the study plots could be identified. From the study it was concluded that while it was possible to estimate foliar biochemical contents of vegetation canopies with reflectance data, in future instruments were required with larger SNRs and simple study sites were required where the interaction of radiation with vegetation canopies could be completely understood.

This thesis considers the problem of stream acidification in afforested catchments at Llyn Brianne, upland Wales. The main focus for study is the way in which hydrological pathways and soil chemical processes influence the acidity and aluminium levels in streamwaters. Within a 253ha experimental catchment, two small sub-catchments and study plots were instrumented to monitor the movement of water from the atmosphere, through the forest canopy and underlying soils, into streams. Water was sampled at various stages of its hydrological pathway to characterize its chemical composition. The study centred on the movement of water and solutes through Sitka spruce forest systems on two different soil types which cover large areas of upland Wales: cambic stagnohumic gleys and ironpan stagnopodzols. Precipitation at the study sites was acidified and enriched in mobile anions by enhanced atmospheric deposition on the forest canopy. The subsequent increased concentration and flux of anions in the two acid study soils was found to mobilize aluminium by cation exchange processes and leach aluminium and hydrogen ions from the soil zone. Buffering reactions in the soil parent materials were found to neutralize some acidity in the deeper groundwater zone. Hydrological pathways through the two soils controlled the transfer of acidity and aluminium to surface waters. At baseflows, streamwater draining from the gley soils was derived from the groundwater zone; this was well-buffered with a low aluminium content. During storm events, runoff was generated by saturated throughflow in the near-surface soil horizons; this was acidic with high aluminium concentrations. Water draining from the podzols was derived from the deeper soil horizons and shallow slope drifts. This also provided a source of acid, aluminium-rich runoff during storm periods. The implications of these results to the understanding and management of stream acidification in afforested catchments are evaluated.

This thesis reports on the geographical distribution of airborne metals in the South Wales environment, particularly in the Swansea region, as indicated by the analyses of Sphagnum moss samples. An initial survey in the Swansea region using natural populations of Sphaqnum moss found elevated levels of several metals - Cd, Co, Cu, Ni, Pb and Zn - in those samples growing immediately downwind of the Lower Swansea Valley. A comparison with samples from other areas is made. A subsequent survey of the same area, but using transplanted Sphagnum moss samples enclosed in nylon mesh packets (moss-bags), pinpointed several industrial sources of airborne metals. When one of these sources emitting Zn, Pb,and Cd permanently closed down, levels of these metals fell dramatically while other metals - Ni, Co and Cu - remained about the same. Also presented are the results of a comparative exercise, whereby metals retained on moss-bags are compared with corresponding results, obtained concurrently by AERE, Harwell, by three methods - a total deposit gauge, a dry deposit gauge and an air concentration gauge. The deposit gauges were found to sample the atmospheric aerosol in a conformable manner. However, because of their dependence on wind speed and their differential retention of different particle sizes, deposit gauges such as moss-bags cannot be used to indicate air concentration directly. During the winter and summer of 1973 over 400 moss-bags were exposed at sites across the whole of South Wales and subsequently analysed for Ni, Co, Cu, Cd, Pb, Zn, Fe, Mn, Ca and Mg. Three broad classes of metal levels were identified (1) low metal accumulations, in rural areas west of Swansea; (ii) higher metal accumulations in areas east of Swansea and (iii) highly elevated metal accumulations associated with individual sites or locations.