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Application of diffusion denuder for determination of biogenic volatile organic compounds in air
Handlířová, Gabriela ; Komendová, Renata (referee) ; Křůmal,, Kamil (advisor)
The optimization of conditions for the sampling of biogenic volatile organic compounds (BVOCs) in the air using a diffusion denuder with subsequent analysis of collected samples by gas chromatography coupled with mass spectrometry (GC-MS) was the main topic of the master thesis. Collecting samples into an absorption liquid at a two-minute interval is the main advantage of the denuder. Selecting appropriate conditions for the highest collection efficiencies of individual BVOCs in denuder and for using the method for sampling in ambient air with various meteorological events was the main aim of all experiments. The following optimal conditions were selected: denuder temperature (20 °C), airflow (500 ml/min), absorption liquid (n-heptane), absorption liquid flow (0,45 ml/min). The measured collection efficiencies of all studied BVOCs in denuder were above 89 % with these optimized conditions, except for highly volatile BVOCs. The detection limits of the studied BVOCs for this method are lower than their concentration in the outdoor air during the growing season. Therefore, the optimized method is suitable for the determination of fast changes in BVOCs concentrations (except highly volatile) in the outdoor air.
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Application of diffusion denuder for determination of biogenic volatile organic compounds in air
Handlířová, Gabriela ; Komendová, Renata (referee) ; Křůmal,, Kamil (advisor)
The optimization of conditions for the sampling of biogenic volatile organic compounds (BVOCs) in the air using a diffusion denuder with subsequent analysis of collected samples by gas chromatography coupled with mass spectrometry (GC-MS) was the main topic of the master thesis. Collecting samples into an absorption liquid at a two-minute interval is the main advantage of the denuder. Selecting appropriate conditions for the highest collection efficiencies of individual BVOCs in denuder and for using the method for sampling in ambient air with various meteorological events was the main aim of all experiments. The following optimal conditions were selected: denuder temperature (20 °C), airflow (500 ml/min), absorption liquid (n-heptane), absorption liquid flow (0,45 ml/min). The measured collection efficiencies of all studied BVOCs in denuder were above 89 % with these optimized conditions, except for highly volatile BVOCs. The detection limits of the studied BVOCs for this method are lower than their concentration in the outdoor air during the growing season. Therefore, the optimized method is suitable for the determination of fast changes in BVOCs concentrations (except highly volatile) in the outdoor air.
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Emissions of isoprene by oil palm and their impacts on climate and composition of the atmosphere
Palouš, Daniel ; Albrechtová, Jana (advisor) ; Ponert, Jan (referee)
Biogenic volatile organic compounds (BVOC) serve many physiological and ecophysiological functions in plants, e.g. abiotic or biotic stress protection or signalling. Emission capacity and spectrum of emitted BVOC vary between plant species. Isoprene, having the highest global annual emission among all BVOC, has considerable influence on atmospheric chemistry and its processes. Isoprene contributes to secondary organic aerosol formation. Under specific conditions reaction of isoprene and NOx may lead to ground-level ozone formation. Isoprene also affects oxidative capacity of the atmosphere. Oil palm (Elaeis guineensis Jacq.) is a rapidly expanding crop and it is a strong isoprene emitter. Most of the global cultivation of oil palm is located in a relatively small region in southeast Asia posing a risk to regional air quality. To prevent ground-level ozone formation, keeping ground-level NOx concentrations low in the regions of oil palm cultivation is crucial. Models of global isoprene emission vary greatly and not all of them take oil palm cultivation in account. The present thesis aims to cover current knowledge on physiological functions of isoprene's synthesis and emission with regard to oil palm cultivation and ecological implications of mentioned processes. The thesis includes also brief...
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Emissions of isoprene by oil palm and their impacts on climate and composition of the atmosphere
Palouš, Daniel ; Albrechtová, Jana (advisor) ; Ponert, Jan (referee)
Biogenic volatile organic compounds (BVOC) serve many physiological and ecophysiological functions in plants, e.g. abiotic or biotic stress protection or signalling. Emission capacity and spectrum of emitted BVOC vary between plant species. Isoprene, having the highest global annual emission among all BVOC, has considerable influence on atmospheric chemistry and its processes. Isoprene contributes to secondary organic aerosol formation. Under specific conditions reaction of isoprene and NOx may lead to ground-level ozone formation. Isoprene also affects oxidative capacity of the atmosphere. Oil palm (Elaeis guineensis Jacq.) is a rapidly expanding crop and it is a strong isoprene emitter. Most of the global cultivation of oil palm is located in a relatively small region in southeast Asia posing a risk to regional air quality. To prevent ground-level ozone formation, keeping ground-level NOx concentrations low in the regions of oil palm cultivation is crucial. Models of global isoprene emission vary greatly and not all of them take oil palm cultivation in account. The present thesis aims to cover current knowledge on physiological functions of isoprene's synthesis and emission with regard to oil palm cultivation and ecological implications of mentioned processes. The thesis includes also brief...
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