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Environmental field analysis provides advantages that allow real-time decisions, interactive sampling and cost effective solutions to the problems faced at the time of investigation. Gas chromatography (GC), a widespread technique for the determination of organic pollutants in the environment, has also shown to be useful in environmental field analysis. Thermal desorption of solid environmental sample provides a technique for liberation of volatile analytes from the samples without the need for solvent extraction. Combining the thermal desorption technique with a field gas chromatograph (GC) thus provides the possibility of on-site determination of organic contaminants in soils. However, to better characterize trace level contaminants in complex sample matrices, laboratory analysis using analytical instrument with great separation and resolution power is required. Comprehensive two-dimensional gas chromatography (GC X GC) is such a powerful analytical tool that provides enhanced separation and resolution capacity for the task. The project presented here involves the development and validation of a field method for the analysis of total polychlorinated biphenyls (PCBs) in soils, and determination of individual PCB congeners in the same samples by further laboratory analysis. The field analytical system developed was a field portable GC interfaced with a thermal desorber. The identification of PCB congeners was realized by a GC X GC system with a time-of-flight mass spectrometer (TOF-MS) as a detector. The field method was developed by optimizing and characterizing the method using PCB standards, followed by the application of the developed method to environmental soil samples. Finally, analyses of PCB congeners in environmental soil samples were performed using the GC X GC system.

Environmental field analysis provides advantages that allow real-time decisions, interactive sampling and cost effective solutions to the problems faced at the time of investigation. Gas chromatography (GC), a widespread technique for the determination of organic pollutants in the environment, has also shown to be useful in environmental field analysis. Thermal desorption of solid environmental sample provides a technique for liberation of volatile analytes from the samples without the need for solvent extraction. Combining the thermal desorption technique with a field gas chromatograph (GC) thus provides the possibility of on-site determination of organic contaminants in soils. However, to better characterize trace level contaminants in complex sample matrices, laboratory analysis using analytical instrument with great separation and resolution power is required. Comprehensive two-dimensional gas chromatography (GC X GC) is such a powerful analytical tool that provides enhanced separation and resolution capacity for the task. The project presented here involves the development and validation of a field method for the analysis of total polychlorinated biphenyls (PCBs) in soils, and determination of individual PCB congeners in the same samples by further laboratory analysis. The field analytical system developed was a field portable GC interfaced with a thermal desorber. The identification of PCB congeners was realized by a GC X GC system with a time-of-flight mass spectrometer (TOF-MS) as a detector. The field method was developed by optimizing and characterizing the method using PCB standards, followed by the application of the developed method to environmental soil samples. Finally, analyses of PCB congeners in environmental soil samples were performed using the GC X GC system.

M. Tech. Chemistry. / Determines if specific terpenes might play a role in triggering the lenticel's self-defense reaction.

Thesis (PhD.(Chemistry)--University of Pretoria, 2008. / On title page: Submitted in partial fulfilment of the requirements for the degree Doctor of Philosophy in Chemistry in the faculty of Natural and Agricultural Sciences of the University of Pretoria. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 249-269).

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Dr. Jim P. Zheng, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed Sept. 15, 2005). Document formatted into pages; contains xii, 96 pages. Includes bibliographical references.

[pt] Notícias ambientais no Brasil foram dominadas através de derramamentos de óleo nos últimos anos. Esta dissertação apresenta os resultados de um programa experimental para estudar a capacidade de desorção térmica em limpar as costas afetadas.A temperatura ambiente, os resíduos oleosos emitem metano e amônia e estas emissões tendem a aumentar com a elevação das temperaturas. Por outro lado, o teor de óleo e graxa dos resíduos oleosos cai com o aumento da temperatura e exposição prolongada.Um cobertor térmico foi construído e avaliado. Os resultados mostraram que sua eficiência é restringida a poucos décimos de centímetros abaixo da superfície do solo devido à condutividade térmica de areias. Porém, esta desvantagem poderia ser contornada colocando o termopar de controle do sistema na profundidade desejada.Finalmente, a desorção térmica in situ parece ser um sistema único para a limpeza de resíduos oleosos. É simples, rápido e evita todo o incômodo associado à escavação de solo para disposição ou limpeza. / [en] Environmental news in Brazil has been dominated by oil spills in the past years. This dissertation presents the results of a comprehensive experimental programme on studying the ability of thermal desorption on cleaning up the affected shores.At ambient temperature, oiled debris emit methane and ammonia and these emissions tend to increase with rising temperatures. On the other hand, oil&grease content from oiled debris falls with rising temperature and prolonged exposure.A thermal blanket was designed, built and evaluated herein. Results have shown that its efficiency is restricted to few tenths of centimetres below the ground surface due to the thermal conductivity of sands. However, this drawback could be overcome is the control thermocouple of the system is positioned at the desired depth.Finally, in situ thermal desorption seem to be an unique system for cleaning debris from oil spills. It is simple, fast and avoids all the harassment associated to digging up the soil for disposal or cleanup.

Low microbial activity and associated nutrient cycling are concerns in agricultural problem soils. The objectives of this study were to investigate microbial response on problem soils to amendments, drying-wetting cycles, and the interaction of amendments and drying-wetting cycles. In this laboratory study, soil carbon dioxide (CO2) flux was measured from thermal desorption treated soils and saline soils in response to Proganics, spent lime, and composted beef manure applications. Microbial activity was measured through CO2 flux and its rate of change, permanganate oxidizable C, and residual inorganic nitrogen. Proganics had the greatest ability to elevate and sustain microbial activity on problem soils, but spent lime and compost had the greatest potential to improve microbial mediated nitrogen mineralization. In conclusion, spent lime and compost can be effective amendments for improving soil quality of saline and thermal desorption treated problem soils to increase microbial activity and associated nitrogen cycling.

No description available.