No description available.

6. These data illustrate that acid episodes still affect stream organisms in spite of continued recovery in air and water quality and this may be a sufficient explanation for slow biological recovery in many locations. Episodic effects may impose important controls on organisms as recovering sites reach the base-flow pH range 5.5-7. The strongest recommendation is for better understanding and monitoring of the hydrochemistry and biological effects of acid episodes as acid deposition abates.

No description available.

Two chemical properties of pesticides are thought to control their environmental fate. These are the adsorption coefficient k(_oc) and soil half-life t(^soil_1/2). This study aims to demonstrate the use of Bayesian methods in exploring whether or not it is possible to discriminate between pesticides that leach from those that do not leach on the basis of their chemical properties, when the monitored values of these properties are uncertain, in the sense that there are a range of values reported for both k(_oc) and t(^soil_1/2) - The study was limited to 43 pesticides extracted from the UK Environment Agency (EA) where complete information was available regarding these pesticides. In addition, analysis of data from a separate study, known as "Gustafson's data”, with a single value reported for k(_oc) and t(^soil_1/2) was used as prior information for the EA data. Bayesian methods to analyse the EA data are proposed in this thesis. These methods use logistic regression with random covariates and prior information derives from (i) available United States Department of Agriculture (USDA) data base values of k(_oc) and t(^soil_1/2) for the covariates and (ii) Gustafson's data for the regression parameters. They are analysed by means of Markov Chain Monte Carlo (MCMC) simulation techniques via the freely available WinBUGS software and R package. These methods have succeeded in providing a complete or a good separation between leaching and non-leaching pesticides

Land pressures today and government policy-requires previously developed, 'brownfield' land to be brought back into beneficial use. The nature of these sites means that they may have been subject to some form of contamination from previous uses. The risk any pollutant has to human health and the environment must be assessed and, if deemed unacceptable, remediation must be undertaken. Risk assessment may be carried out utilising generic values for contaminant properties that can give misleading results. This thesis describes the effort to further assess the controls on adsorption of organic pollutants and its spatial variability. Spatial sampling of two brownfield sites was undertaken with generic soil parameters being measured. To better describe soil organic matter, organic extracts were prepared from soils, allowing NMR spectra to be collected. The collected soil dataset is analysed to discern any correlations between soil parameters. The nature of the organic pollutants used in this study (benzene, phenol, p-xylene and p-cresol) is described using calculated molecular descriptors. The variation in experimental adsorption results, provided by Sheffield University, were then statistically analysed using soil measures as predictors and then also adding molecular descriptors to the analysis. The percentage of black carbon may also have an influence on adsorption and so this was also measured and added to the list of predictors available for inclusion in stepwise regression. Results show that adsorption of these organic compounds can be partially described using the measured soil parameters. Molecular descriptors such as a molecule's surface area can also be used to predict adsorption. The percentage black carbon was an important predictor in only one instance for p-xylene adsorption. Soil parameters were also shown to be predicted by other soil variables from the dataset, giving good results that were improved upon by transforming all parameters to normality.

A factory in Colonie (NY, USA) emitted c. 4.8 ± 1 tonnes of depleted uranium (DU) particulates into a suburban environment during 1958 – 1984. These particulates were initially dispersed by prevailing winds. Quadrupole inductively coupled plasma mass spectrometry (ICP-MS), laser ablation multicollector (LA-MC-) ICP-MS, scanning electron microscopy (SEM) and microfocus extended X-ray absorption fine structure (μEXAFS) spectroscopy have been used to characterise soils, dusts, vegetation, and individual particles. The concentration range of natural uranium in Colonie soils is 0.7 — 2.1 μg g-1; with total uranium up to 500 ± 40 μg g-1 in DU contaminated soils. Bioturbation can account for dispersal of contaminant from the soil surface. Primary morphologies are described for uraniferous particles from soils and dusts. Polycrystalline, often hollow microscopic uranium oxide spheres are similar to particles produced by DU munitions impacting armoured targets. These survive as UO2+x and U3O8, the least bioaccessible oxides of uranium. Fruit and wood samples were contaminated by DU, demonstrating limited bioavailability. Deviation of 235U/238U from the natural isotope ratio allows detection of DU in soils to at least 5.6 km from site. The average DU ‘end-member’ composition aggregated in soil samples comprises (2.05 ± 0.06) x10-3 235U/238U, (3.2 ± 0.1) x10-5 236U/238U, and (7.1 ± 0.3) x10-6 234U/238U. Individual uranium oxide grains were analysed by LA-MC-ICP-MS, all of which were from DU, with variable isotopic compositions (236U/238U, 235U/238U & 234U/238U). There is no evidence of enriched uranium in Colonie soils and dusts. The isotopic compositions of the Colonie particles can be explained by the inhomogeneous mixing of at least seven batches of tails from the Paducah gaseous diffusion plant, which are identified as the origins of the DU feedstocks used by National Lead Industries at Colonie. LA-MC-ICP-MS is recommended for nuclear forensic applications. This case-study is an attractive analogue for battlefield contamination.

The bioavailability of polycyclic aromatic hydrocarbons (PAHs) and chlorobiphenyls (CBs) in sediments is largely dependent on the freely dissolved concentration of these pollutants. However, measuring these is challenging, due to the low concentrations of lipophilic contaminants in the environment and their strong affinity for particles and for traditional sampling (filtration and centrifugation) equipment. An equilibrium passive sampling device made of silicone rubber was developed in this research to measure the freely dissolved concentrations of lipophilic contaminants and other parameters (water extractable proportions and sediment-water partition coefficients) that describe the availability of these contaminants in the environment. Equilibration between sampler and sediment for PAHs and CBs was found to be adequately achieved after 20 days shaking of a silicone rubber sampler in sediment slurry on an orbital shaker at 200 rpm. The reproducibility of uptake was better than 5 %. Silicone rubber-water partition coefficients for 34 PAHs and 32 CBs were measured in the laboratory using a co-solvent method using methanol as co solvent. Strong linear correlations of log sr w K , with octanol-water partition coefficients (log ow K ) ( log 0.97 log 0.01; 2 0.94 , K = K − r = sr w ow & log 1.17 log 1.82; 2 0.90 , K = K − r = sr w ow ) were found for PAHs and CBs, with a systematic difference in correlations observed for the different classes of compounds which was attributed to structural differences of the compounds. The silicone rubber samplers were then used to measure concentrations of PAHs in the pore water of sediments from the Fladen Ground of the North Sea, Loch Shell, Firth of Forth, Firth of Clyde, Loch Etive and Aberdeen Harbour in Scotland and the Vefsn fjord, Norway. A proportion of the PAHs were found to be unavailable for exchange into the aqueous phase, and this was reflected in the high log oc K measured in all the sediments studied. The sediment-water partition coefficients also correlated positively with the octanol-water partition coefficients. Accumulation of PAHs in Nereis virens from sediments was better predicted from literature bio concentration factors and pore water concentrations obtained using the silicone rubber samplers than from sediment concentrations traditionally used in risk assessments. Participation in an International Council for the Exploration of the Seas (ICES) passive sampling trial survey using silicone rubber in sediments and water is described, and demonstrated the potential of passive sampling in monitoring environmental pollution. The log BCF (bio concentration factor) for PAHs in mussels increased with increasing log ow K at both Loch Etive and Aberdeen Harbour locations, and could be used to estimate concentrations in mussels directly. The survey data also showed the use of silicone rubber in assessing the diffusive exchange of PAHs across sediment-water interfaces.

This thesis firstly investigates the effect of the cestode parasite Schistocephalus solidus on the reproduction of its intermediate host, the three spined stickleback. The results indicated that the parasite reduced host reproduction and the physiological basis behind this was established. In males, parasite infection reduced the fish’s ability to produce 11-ketotestosterone which resulted in reduced reproductive behaviour and sexual development. In infected females, vitellogenin production was reduced which prevented egg maturation. The adaptive nature of these changes seemed to be variable among different populations. This variation may result from genetic differences in the host or parasite population, co-evolutionary processes or reflect differences in the environmental conditions experienced by populations. The second part of this thesis investigates the effect of two types of anthropogenic stressors – endocrine disrupting chemicals and temperature change as an outcome of global climate change – on disease progression in the stickleback-Schistocephalus system. The results indicated that the natural steroid 17β estradiol (E2) had a significant impact on disease progression in a sex and dose dependent manner, with males exposed to the high 100ngLˉ¹ E2 treatment harbouring significantly larger parasites compared to females in this treatment and fish from the lower E2 and solvent control treatment. Elevated temperatures were also found to significantly increase parasite growth and reduce host growth. In addition, a behavioural study showed that fish harbouring infective parasites seek out high temperatures which could be adaptive on the part of the parasite as it would allow them to grow faster and potentially increase their reproductive output. The clear outcome of this thesis is that anthropogenic stressors increase disease progression in the stickleback-Schistocephalus system and this is likely to lead to reduced host reproduction and increased parasite transmission and reproduction, potentially leading to the evolution of higher virulence in this host-parasite interaction.

In this thesis, the measurements of carbon monoxide (CO) obtained from an nadir sounding Measurement Of Pollution In The troposphere (MOPITT) instrument are used. Atmospheric CO is one of the most abundant and widely distributed air pollutant and is a very important indirect greenhouse gas via its reaction with the OH radical which in turn controls the oxidising capacity of the troposphere. In this thesis, the MOPITT Level 2 Version 3 (L2V3) retrieved CO data is primarily used and compared with recently released (April 2009) Level 2 Version 4 (L2V4) retrieved CO data to examine the potential of the MOPITT instrument to differentiate emission features in the lowermost troposphere including mega-cities. This study develops a novel robust methodology using day-night difference profile simulations to examine the ability of the instrument to identify CO enhancements in the lowermost layer of the atmosphere using ‘typical’ averaging kernels. More realistic CO profiles from the TOMCAT model are then used to validate this methodology. The day-night difference simulations are performed for the Indian subcontinent. It is shown that for L2V3, the daytime and nighttime degrees of freedom for a signal (DOFS) exhibit a bi-modal distribution for all selected Indian regions. The L2V3 simulation study clearly demonstrates, for higher DOFS, that day700-night700 differences give a closer differentiation of lowermost CO than other measures for MOPITT data, the first time that this has been processed. For L2V4, similar DOFS distributions are observed for the Indian subcontinent. The L2V4 simulation study also demonstrates for the first time that day850-night700 CO differences give a closer differentiation of lowermost CO by taking account of L2V4 day and night a priori mixing ratios. Finally, the methodologies developed in chapter 3 and 4 are applied to identify spatially isolated signals of lowermost CO for one year of data i.e. 2007. Features associated with nearly 100 cities are identified, the use of thresholds for higher DOFS retrievals and the use of non-surface retrieval levels with less tie to a priori. The significant step forward being consistent day-night differences for two different analyses (L2V3, L2V4).

An increasing number of pharmaceuticals have been found in the aquatic environment and the issue has become a human and environmental health concern. Many pharmaceuticals are not fully degraded in wastewater treatment plants (WWTPs) and are continuously released in the aquatic environment resulting in concentrations in the low µg/l range in the receiving waters. Diclofenac is a widely used non-steroidal anti-inflammatory drug (NSAID) and is persistent in the aquatic environment. This pharmaceutical has been frequently reported in wastewater effluents, surface waters, groundwaters and even drinking water. NSAIDs are known to inhibit the cyclooxygenase activity, an enzyme present in many species of the animal kingdom responsible for the synthesis of prostanoids, and chronic exposure to environmental diclofenac may have detrimental effects on metabolism of non-target organisms including microbes and fish. In this thesis, microbiology, genomics and metabolomics approaches were used to investigate the effects of diclofenac on aquatic microbes and fish. In the first study of the thesis (chapter 3), the biodegradation of selected NSAIDs was investigated, together with their potential toxicity to aquatic microbes. Aerobic biodegradation experiments were conducted using activated sludge and wastewater effluents as microbial inocula and diclofenac, ketoprofen or naproxen as sole carbon source (1-10 mg/l) in order to isolate and identify the bacterial degraders. Changes in the bacterial populations were monitored by optical density and PCR-DGGE. The analytical techniques solid phase extraction (SPE) and ultraperformance liquid chromatography-mass spectrometry (UPLC-TOF-MS) were optimised to quantify the pharmaceuticals in environmental samples. High recovery rates were obtained with 94% for diclofenac; 92% for ketoprofen and 85% for naproxen and with detection capabilities down to 3-7 ng/l. Results from the biodegradation experiments showed that ketoprofen and naproxen were eliminated at up to 99 and 55% respectively over a 40 days period. Consistently with previous studies, diclofenac showed no significant degradation. In all the enrichments, a significant decrease in the bacterial abundance was observed as a consequence of NSAIDs exposure and attempts to isolate the bacterial degrading populations were unsuccessful. Given the apparent micro-toxicity of these NSAIDs, the standardised test Microtox@ was carried out with Vibrio fischeri. The EC50 (15 min) estimated ranged from 13.5 mg/l + 2.3 for diclofenac to 42.1 mg/l + 3.9 for naproxen. Further toxicological tests were performed with diclofenac on bacterial strains isolated from activated sludge. Growth inhibitory effects were observed from 50-70 mg/l for Micrococcus luteus, Zoogloea ramigera and Comamonas denitrificans. Pseudomonas putida seemed more tolerant to diclofenac exposure and toxic effects were observed from 90 mg/l. These studies showed that diclofenac was the most toxic NSAID but toxicological effects in bacteria only occurred at concentrations at least 1,000 times higher than those found in the environment. However, chronic exposure to lower concentrations may cause similar interferences and affect the degradation potential of naturally occurring microbial populations. The second study (chapter 4) investigated the biological effects of sub-chronic exposure to waterborne diclofenac (0.5, 1, 5 and 25 µg/l) in female juvenile rainbow trout Oncorhynchus mykiss. After 21-day exposure, mRNA expression levels of cytochrome p450 1a1 (cyp1a1), cyclooxygenase (cox) 1 and 2, and p53 were investigated in the liver, kidney and gills using RT-PCR and QPCR. These genes were selected as they are likely targets for diclofenac in mammals. Histopathological investigations were carried out in the small intestine, liver and kidney because diclofenac has been reported to induce toxicity responses in these tissues. Fish bile was also analysed by SPE and UPLC-TOF-MS to evaluate the bioconcentration potential of diclofenac and look for evidences of diclofenac metabolism. Results showed a significant reduction of both cox1 and cox2 expression in the liver, gills and kidney from 1 μg diclofenac/l. In contrast diclofenac induced an increase in mRNA levels for cyp1a1 in the liver and gills but a significant reduction of cyp1a1 expression in the kidney from 1 µg/l. There were no clear effects of diclofenac on the mRNA levels of p53. Diclofenac exposure caused tissue damages at exposure concentrations as low as 1 µg/l. Histopathological injuries included inflammation, hyperplasia and fusion of the villi in the small intestine and tubule necrosis in the kidney. There were no obvious changes in the liver of diclofenac-exposed fish. The analysis of bile revealed a bioconcentration potential between 509 + 27 and 657 + 25. A reactive metabolite of diclofenac was also detected at the highest exposure concentration which may be responsible for the severe injuries found in those fish. Sub-chronic exposure to environmental concentrations of diclofenac altered gene expression and it is possible that long term exposure to environmental diclofenac lead to significant impacts on fish health. In the final part of this thesis (chapters 5 and 6) effects on the metabolite composition of biofluids were analysed in diclofenac-exposed fish. This work entailed developing and validating appropriate methodologies to analyse fish bile and blood plasma. Methanol extraction and UPLC-TOF-MS were optimised to analyse the plasma metabolome but the methodologies were not suitable to detect low abundance molecules such as eicosanoids due to the interferences (ion suppression) in the samples matrix. Multivariate data analysis failed to detect the endogenous metabolites of the plasma affected by the chemical exposure. The only discriminating metabolite was found after analysis of the plasma samples from control vs. 25 µg/l treatment groups and identified as the exogenous compound diclofenac. To analyse the bile, the developed SPE methodology was carried out in order to separate the metabolites between a free steroids (fatty acids, eicosanoids, etc.) fraction and a conjugated steroids (bile salts) fraction. Due to high levels of taurocholic acid masking other metabolites in the conjugated fraction, some bile samples were hydrolysed to deconjugate these metabolites. The non-hydrolysed and hydrolysed bile fractions were analysed by UPLC-TOF-MS in positive and negative ionization. Multivariate data analysis using principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) revealed significant perturbations in the bile metabolite profile of diclofenac-exposed rainbow from the lowest exposure concentration (0.5 µg/l). Over 50 metabolites were elevated or reduced as a result of the 21-day exposure, suggesting that diclofenac affected several metabolic pathways. One metabolite was identified as a lipooxygenase product. This suggests that the inhibition of prostanoids synthesis can cause a shift in the arachidonic cascade and increase the synthesis of other eicosanoids. Most of the other discriminative metabolites remain unidentified and FT-MS analysis will be performed to obtain a structural identity. The metabolomics study further highlights the concern of environmental diclofenac in non-target organisms and the need to investigate the metabolic pathways affected.