Heidelberg 2015 – wissenschaftliches Programm
UP 9.2: Hauptvortrag
Donnerstag, 26. März 2015, 15:00–15:30, C/gHS
Noble gas analysis in water: from temperature reconstruction over excess formation to oxygen turnover on environmentally relevant time scales — •Rolf Kipfer and Matthias Brennwald — Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
Noble gases (and other quasi-conservative transient trace gases) in aquatic systems have commonly been used to determine water residence times and to reconstruct past environmental and climatic conditions.
However, these analyses were hampered by the occurrence of a surplus of atmospheric gases in natural ground water, e.g. the presence of excess air (EA) which in former days was only considered as contamination.
Recent developments in understanding the physics of air (gas) / water partitioning in porous media as well as revisiting noble gas diffusion in water now allows EA formation to be understood in mechanistic terms and facilitates the robust interpretation of EA as a proxy for the hydraulic conditions during groundwater recharge.
Furthermore, portable membrane-inlet mass spectrometers enable continuous and real-time analysis of dissolved (noble) gases directly in the field, allowing, for instance, quantification of O2 turnover rates on time scales as small as minutes.
This presentation will touch some of these recent achievements with the intention of stimulating a broader discussion on the future applications of gases in conventional and unconventional aquatic systems.