No description available.

No description available.

No description available.

Observational and experimental studies have been undertaken in the southern North Sea environment, including five major estuaries (Humber, Thames, Scheldt, Weser and Elbe), with the aim of elucidating the mechanistic and kinetic details of trace metal reactivity required for the refinement of pollutant transport models. The results of a systematic investigation of suspended particle characteristics (BET specific surface area and porosity, carbon content. Fe and Mn oxide coatings) indicated that, although there exists significant yet explicable variability among the North Sea estuaries, such compositional factors do not exert an observable influence on solid-solution interactions. Furthermore, chemical reactivity was not usually demonstrable from observations of leachable particulate trace metals as phase interactions Impart relatively little influence on their concentrations; particulate metal distributions therefore generally conformed with mixing of fluvial and marine material unless perturbed by major anthropogenic sources as in the Humber. Solid-solution redistributions were revealed by following the partitioning of artificial radiotracers in a series of carefully controlled experiments in which salinity and suspended solids concentration gradients were simulated by mixing river and sea water end-member samples. Relationships between salinity and the solid:solution concentration of radiotracers as quantified by a distribution coefficient ( K Q ) indicated substantial desorption from particles of ^^®Cd and ^"^^Cs. conservative behaviour of ^ ^ Z n , and oxidative removal from solution of ^^Mn. Radiochemical techniques applied in situ to study solid-solution partitioning in the southern North Sea established a more significant role of particle composition (in particular, estuarine-derived versus plankton-rich material) in regulating trace metal behaviour in offshore waters. This finding was corroborated by distinct seasonal contrasts in measured particulate metal concentrations; whereas most metals (Fe, Mn. Cu, Pb, Zn) were enriched during winter when detrital and terrigenous components from fluvial/resuspension inputs dominate. Cd was elevated during summer in tandem with amplification of the biomass. These results provide a valuable basis for both future long-term pollutant monitoring programmes, and the conceptual development of estuarine chemical flux models, specifically the incipient Plymouth Marine Laboratory model of the Humber plume.

The population ecology of the diseases of the common dab (<I>Limanda limanda</I> L.) has been studied and the use of fish disease as a monitor of pollution in the marine environment reassessed. The diseases included in this study were lymphocystis disease, hyperplasia/papilloma, ulcer disease, inflammatory fat-cell necrosis, and X-cell disease. The interactions responsible for determining disease abundance were assessed by carrying out a detailed longitudinal field survey and interpreting the observed changes in abundance by reference to the population biology of the common dab, the abiotic environment, and the known biology of the diseases. The diseases were not evenly distributed within the host population. Significant differences in prevalence occurred between sexes, ages, and fish of differing maturity status. These were interpreted in terms of varying susceptibility of the host, the response of the host to infection and the dynamics of the diseases. Analysis of the age-prevalence relationships suggests that although some diseases have the potential for their abundance to be regulated this is not fulfilled. The temporal distribution of the diseases consisted of long-term trends, seasonal cycles, and short-term fluctuations. A variety of potential causal factors were highlighted including the spawning behaviour of the dab, temperature, and bacterial abundance related to environmental productivity. The patterns in the spatial distribution of the diseases were reflected in variation in prevalence on both large (˜100nml) and small scales (˜1nml). In this case the causal factors highlighted were salinity, host population density, and again bacterial abundance related to productivity. No effect of pollution on disease prevalence was demonstrated. Neither could the occurrence of lymphocystis disease be related to the concentration of chemical contaminants in the livers of dab.

Kuwait is undergoing rapid economic growth involving substantial developments along its coastal shores and the marine environment. Many of the activities in the region are associated with oil industry, which can pollute the shores leading to contamination from oil residues, tar balls and trace metals. About 2 million barrels of oil are spilled annually from routine discharges into the Gulf, which derives mainly from dirty ballast waters and tank washing. The comprehensive literature review of hazardous substances in Kuwait’s marine environment has concluded that for the majority of these pollutants, contamination is localized around industrialised areas, and elsewhere is generally below the permitted international standards. These finding have been supported by a fieldwork. This has been conducted to assess the use of biomarkers (bile metabolites and EROD activities) for 60 fish consisting of two native species Giant sea catfish (Arius thalassinus) and (Pelates quadrilineatus) to demonstrate the potential for the concentrations of oil based contaminants present to induce detectable levels of biological effects in fish species living in Kuwait’s marine environment. Therefore, the focus of this research has shifted its attention to another anthropogenic source that chronically pollute Kuwait’s marine environment. One of the main sources of contaminants is the continuous discharge of sewage, which impacts many locations around Kuwait. Sewage is known to contain wide array of substances that could pose an ecotoxicological impact at different levels of the ecosystem. One such threat is posed by antimicrobial agents that contribute to the growing global concern surrounding the prevalence of antimicrobial resistant (AMR) bacteria. Therefore, a major theme of this research project was to conduct a novel survey of the prevalence of AMR bacteria isolated from Kuwait’s marine environment. The AMR screening, including 598 E.coli isolated from seawater and bivalves samples during summer and winter seasons against 23 frontline antibiotics, revealed that resistance was observed from a number of locations (particularly associated with sewage outlets) for the majority of antibiotics (seawater: summer 89 - 64%; winter 90 - 57% and bivalves: summer 77%; winter 88%). A baseline screening for the class 1 integron which is known to be implicated in disseminating the antimicrobial resistance among bacteria was conducted for the isolated 598 E.coli. The findings highlighted the prevalence of such molecular genetic elements especially around the sewage outlets (36% of tested E.coli). The whole genome sequencing was conducted for a representative E.coli (26 E.coli) and it showed that E.coli derived from Kuwait’s marine environment possessed a variety of genes implicated in antimicrobial resistance potential against wide spectrum of antibiotics and suggesting that genes are exchanged via the horizontal gene transfer. These observations and recording of antimicrobial resistance phenomenon support the notion that marine environment could act not only as a reservoir for antimicrobial resistance but could also play a significant role in driving it. The AMR bacteria is considered as an effective tool for monitoring the impacts of sewage pollution. Furthermore, it highlights one of the key human health risks sewage pollution poses and its assessments allows a fully integrated health assessment of Kuwait’s marine environment to be undertaken. This will ultimately lead to recommendations outlining the future monitoring and remediation requirements required by Kuwait to tackle this issue including rational antibiotics consumption and stewardship; developing effective wastewater treatment processes to improve removal efficiency of these pollutants in sewage treatment plants; more researches on this area will provide scientific information for responsible authorities to make up regulatory standards and guidelines to control environmental dissemination of these emerging contaminants.

No description available.

No description available.

Made available in DSpace on 2014-10-09T12:28:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:45Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:08/01954-0

Made available in DSpace on 2014-10-09T12:52:06Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:50Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP