Methods

The Environmental Isotopes Group is running labs for enviromental tracer analytics (noble gas mass spectrometry, GC-MS, GC-ECD), applying environmental tracer methods in groundwater and lakes (tritium, noble gases, radon, SF₆, CFCs) and using numerical methods for data analysis and modelling of aquatic systems.

Analytics / Laboratories

• Analysis of noble gases, tritium, chlorofluorocarbons (CFC-11, CFC-12, CFC-113), radon and sulfur hexa-fluoride (SF₆) from water samples.
  Refer to our pricelist for commercial measurements and have a look at the manual for water sampling.
• For more information about the measurement of noble gases and tritium in water see:
  U. Beyerle, W. Aeschbach-Hertig, D. M. Imboden, H. Baur, T. Graf, and R. Kipfer. A mass spectrometric system for the analysis of noble gases and tritium from water samples. Env. Sci. Tech., 34(10):2042–2050, 2000. (doi:10.1021/es990840h)
• For more information about the mesurement of SF₆ in water contact Matthias Brennwald (matthias.brennwald@eawag.ch)
• For more information about the measurement of CFC-11, CFC-12, N₂ and Ar in water see:
  M. Hofer and D. M. Imboden. Simultaneous determination of CFC-11, CFC-12, N₂ and Ar in water. Anal. Chem., 70(4):724–729, 1998.
• For more information about the mesurement of radon-222, refer to:
  E. Hoehn, H.R. von Gunten, F. Stauffer, and Th. Dracos. Radon-222 as a groundwater tracer—a laboratory study. Env. Sci. Tech., 26(4):734–738, 1992.

Applications of environmental tracers

• Calculation of noble gas temperature and excess air using quantitative inverse statistical methods.
  Download the program NOBLEGAS for the interpretation of noble gas concentrations in water.
• (Ground)water sampling for noble gases and transient tracers (CFCs and SF₆), check out the sampling manual!
• Determination of ³H-³He water ages.
• Dating with CFCs, radon and SF₆.
• Application of SF₆ (and CFCs) as artificial tracers.

Data analysis and modelling

• Time series analyses: the analysis of time series (e.g. water temperature records) is used to investigate climate effects on aquatic systems and organisms (mainly in surface waters, see projects of David Livingstone) or to study the water dynamics and renewal of goundwater resources (see projects of Matthias Brennwald and Eduard Hoehn).
• Interpretation of noble gas concentrations in water, e.g. using the program NOBLEGAS.
• Inverse modeling of transient tracer data to quantify mixing rates in lakes and groundwater residence times.