{"id":{"repo_id":"heid-thes","oai_identifier":"oai:archiv.ub.uni-heidelberg.de:27271"},"canonical_url":"https://search.dev.ndltd.org/etd/heid-thes/oai:archiv.ub.uni-heidelberg.de:27271","repository":{"repo_id":"heid-thes","name":"Universität Heidelberg ; Thes","base_url":"http://archiv.ub.uni-heidelberg.de/volltextserver/cgi/oai2"},"display":{"title":"Development of a method for quantitative imaging of air-water gas exchange","abstract":"Using a fluorescent pH indicator (pyranine), a new measurement method to investigate the exchange of a soluble alkaline gas (ammonia) from air to water was developed. Key feature of the method is that a linear relationship between the concentrations of the dissolved gas and the alkaline form of the indicator, that is selectively excited to fluorescence in the water-side mass boundary layer, is established by using a high total concentration of the indicator (1e-4 mol/l) and a pH value of 6. This relationship was verified with experiments at the Heidelberg linear wind-wave tunnel at a fixed wind speed. For different, constant gas fluxes into the water, the intensity of the fluorescence induced by LED illumination on a two-dimensional patch of the wind-driven, wavy water surface was imaged at 400 Hz by three cameras from below and one camera from above with a spatial resolution of 140 µm/px and 167 µm/px, respectively. With the verified relationship, the fluorescence signal could be used to obtain horizontally resolved, quantitative information on local changes in the concentration of a dissolved gas in the water-side mass boundary layer for the first time. During the experiments, also a fluorescence profile created by a focused laser beam was imaged at 800 Hz by a camera with a spatial resolution of 5.8 µm/px to observe vertical transport processes.","abstract_html":"Using a fluorescent pH indicator (pyranine), a new measurement method to investigate the exchange of a soluble alkaline gas (ammonia) from air to water was developed. Key feature of the method is that a linear relationship between the concentrations of the dissolved gas and the alkaline form of the indicator, that is selectively excited to fluorescence in the water-side mass boundary layer, is established by using a high total concentration of the indicator (1e-4 mol/l) and a pH value of 6. This relationship was verified with experiments at the Heidelberg linear wind-wave tunnel at a fixed wind speed. For different, constant gas fluxes into the water, the intensity of the fluorescence induced by LED illumination on a two-dimensional patch of the wind-driven, wavy water surface was imaged at 400 Hz by three cameras from below and one camera from above with a spatial resolution of 140 µm/px and 167 µm/px, respectively. With the verified relationship, the fluorescence signal could be used to obtain horizontally resolved, quantitative information on local changes in the concentration of a dissolved gas in the water-side mass boundary layer for the first time. During the experiments, also a fluorescence profile created by a focused laser beam was imaged at 800 Hz by a camera with a spatial resolution of 5.8 µm/px to observe vertical transport processes.","abstract_has_math":false,"creators":["Papst, Maximilian"],"institution":"Universität Heidelberg","degree_name":null,"degree_level":"master","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Jähne, Bernd"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-09-09","date_published":"2019-09-09","updated_at":"2026-07-24T02:31:02Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://www.ub.uni-heidelberg.de/archiv/27271","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Jähne, Bernd"]},{"key":"dc:creator","label":"Author","values":["Papst, Maximilian"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Universitätsbibliothek Heidelberg"]},{"key":"dc:type","label":"Dc Type","values":["masterThesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["master"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Universität Heidelberg"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Using a fluorescent pH indicator (pyranine), a new measurement method to investigate the exchange of a soluble alkaline gas (ammonia) from air to water was developed. Key feature of the method is that a linear relationship between the concentrations of the dissolved gas and the alkaline form of the indicator, that is selectively excited to fluorescence in the water-side mass boundary layer, is established by using a high total concentration of the indicator (1e-4 mol/l) and a pH value of 6. This relationship was verified with experiments at the Heidelberg linear wind-wave tunnel at a fixed wind speed. For different, constant gas fluxes into the water, the intensity of the fluorescence induced by LED illumination on a two-dimensional patch of the wind-driven, wavy water surface was imaged at 400 Hz by three cameras from below and one camera from above with a spatial resolution of 140 µm/px and 167 µm/px, respectively. With the verified relationship, the fluorescence signal could be used to obtain horizontally resolved, quantitative information on local changes in the concentration of a dissolved gas in the water-side mass boundary layer for the first time. During the experiments, also a fluorescence profile created by a focused laser beam was imaged at 800 Hz by a camera with a spatial resolution of 5.8 µm/px to observe vertical transport processes.","Unter Verwendung eines fluoreszierenden pH-Indikators (Pyranin) wurde eine neue Messmethode zur Untersuchung des Austauschs eines wasserlöslichen alkalischen Gases (Ammoniak) von Luft zu Wasser entwickelt. Kernelement dieser Methode ist, dass eine lineare Beziehung zwischen den Konzentrationen des gelösten Gases und der alkalischen Form des Indikators, die in der wasserseitigen Massengrenzschicht selektiv zur Fluoreszenz angeregt wird, durch eine hohe Gesamtkonzentration des Indikators (1e-4 mol/l) und einen pH Wert von 6 hergestellt wird. Diese Beziehung wurde mit Experimenten am linearen Wind-Wellen Kanal in Heidelberg bei einer festen Windgeschwindigkeit verifiziert. Mithilfe von drei Kameras unterhalb und einer Kamera oberhalb des Kanals mit einer räumlichen Auflösung von je 140 µm/px und 167 µm/px wurden bei einer Frequenz von 400 Hz Bilder der Fluoreszenz, angeregt durch LED Beleuchtung der windgetriebenen welligen Wasseroberfläche, für unterschiedliche, konstante Gasflüsse in das Wasser aufgezeichnet. Mithilfe der verifizierten Beziehung konnten aus dem Fluoreszenzsignal erstmals horizontal aufgelöste, quantitative Informationen über lokale Konzentrationsänderungen eines gelösten Gases in der wasserseitigen Massengrenzschicht gewonnen werden. In den Experimenten wurden zudem mithilfe einer Kamera mit einer Auflösung von 5.8 µm/px Bilder eines von einem fokussierten Laserstrahl erzeugten Fluoreszenzprofils bei einer Frequenz von 800 Hz aufgenommen, um vertikale Transportprozesse zu beobachten."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Development of a method for quantitative imaging of air-water gas exchange","Entwicklung einer Methode zur quantitativen Bildgebung des Gasaustausches zwischen Luft und Wasser"]}]}],"canonical_facts":{"dc:contributor":["Jähne, Bernd"],"dc:creator":["Papst, Maximilian"],"dc:description.abstract":["Using a fluorescent pH indicator (pyranine), a new measurement method to investigate the exchange of a soluble alkaline gas (ammonia) from air to water was developed. Key feature of the method is that a linear relationship between the concentrations of the dissolved gas and the alkaline form of the indicator, that is selectively excited to fluorescence in the water-side mass boundary layer, is established by using a high total concentration of the indicator (1e-4 mol/l) and a pH value of 6. This relationship was verified with experiments at the Heidelberg linear wind-wave tunnel at a fixed wind speed. For different, constant gas fluxes into the water, the intensity of the fluorescence induced by LED illumination on a two-dimensional patch of the wind-driven, wavy water surface was imaged at 400 Hz by three cameras from below and one camera from above with a spatial resolution of 140 µm/px and 167 µm/px, respectively. With the verified relationship, the fluorescence signal could be used to obtain horizontally resolved, quantitative information on local changes in the concentration of a dissolved gas in the water-side mass boundary layer for the first time. During the experiments, also a fluorescence profile created by a focused laser beam was imaged at 800 Hz by a camera with a spatial resolution of 5.8 µm/px to observe vertical transport processes.","Unter Verwendung eines fluoreszierenden pH-Indikators (Pyranin) wurde eine neue Messmethode zur Untersuchung des Austauschs eines wasserlöslichen alkalischen Gases (Ammoniak) von Luft zu Wasser entwickelt. Kernelement dieser Methode ist, dass eine lineare Beziehung zwischen den Konzentrationen des gelösten Gases und der alkalischen Form des Indikators, die in der wasserseitigen Massengrenzschicht selektiv zur Fluoreszenz angeregt wird, durch eine hohe Gesamtkonzentration des Indikators (1e-4 mol/l) und einen pH Wert von 6 hergestellt wird. Diese Beziehung wurde mit Experimenten am linearen Wind-Wellen Kanal in Heidelberg bei einer festen Windgeschwindigkeit verifiziert. Mithilfe von drei Kameras unterhalb und einer Kamera oberhalb des Kanals mit einer räumlichen Auflösung von je 140 µm/px und 167 µm/px wurden bei einer Frequenz von 400 Hz Bilder der Fluoreszenz, angeregt durch LED Beleuchtung der windgetriebenen welligen Wasseroberfläche, für unterschiedliche, konstante Gasflüsse in das Wasser aufgezeichnet. Mithilfe der verifizierten Beziehung konnten aus dem Fluoreszenzsignal erstmals horizontal aufgelöste, quantitative Informationen über lokale Konzentrationsänderungen eines gelösten Gases in der wasserseitigen Massengrenzschicht gewonnen werden. In den Experimenten wurden zudem mithilfe einer Kamera mit einer Auflösung von 5.8 µm/px Bilder eines von einem fokussierten Laserstrahl erzeugten Fluoreszenzprofils bei einer Frequenz von 800 Hz aufgenommen, um vertikale Transportprozesse zu beobachten."],"dc:format.medium":["application/pdf"],"dc:publisher":["Universitätsbibliothek Heidelberg"],"dc:title":["Development of a method for quantitative imaging of air-water gas exchange","Entwicklung einer Methode zur quantitativen Bildgebung des Gasaustausches zwischen Luft und Wasser"],"dc:type":["masterThesis"],"thesis:degree_level":["master"],"thesis:institution_name":["Universität Heidelberg"]},"updated_at":"2026-07-24T02:31:02Z"}