A New in Situ Method for Tracing Denitrification in Riparian Groundwater

Andrea Popp and her colleagues used a miniRUEDI to study the dynamics of the biogeochemical N2 turnover in a river/groundwater system over a six-month period (Environ. Sci. Technol. 2020, 54). In addition to N2, they analysed He, Ar and Kr concentrations in the water in order to quantify the air-derived N2 component in the groundwater. These miniRUEDI data allowed them to rigorously quantify the N2 excess produced by denitrification, and to unravel the spatio-temporal dynamics of N2 denitrification in the riparian groundwater system. The results show that denitrification is highly variable in space and time, emphasizing the need for spatially and temporally resolved data to accurately account for denitrification dynamics in groundwater.

Full paper: “A New in Situ Method for Tracing Denitrification in Riparian Groundwater”, Environ. Sci. Technol. 2020, 54, 3, 1562-1572, DOI: 10.1021/acs.est.9b05393

Using a miniRUEDI to identify and quantify groundwater mixing

In their recent paper “Integrating Bayesian Groundwater Mixing Modeling With On‐Site Helium Analysis to Identify Unknown Water Sources“, Andrea Popp and her Eawag colleagues studied a groundwater system used for drinking water production. The drinking water field needs to be protected from several potential sources of contamination by artificially controlling the groundwater flow. In view of these problems, the Eawag team identified the origins of the different groundwater components in the drinking water field and quantified their mixing ratios using a miniRUEDI by analysing He and other dissolved gases as natural tracers for the different groundwater components.

miniRUEDI used to quantify air-water gas exchange in surface waters – without adding tracer gases!

In their recent paper “A Novel Approach To Quantify Air–Water Gas Exchange in Shallow Surface Waters Using High-Resolution Time Series of Dissolved Atmospheric Gases“, Uli Weber and his colleagues developed a new method to study and quantify the air-water gas exchange in a shallow surface waters. The method uses a miniRUEDI to quantify the natural variations of dissolved atmospheric gases in the water. The resulting high-resolution time series of dissolved gas concentrations in the water yield accurate gas exchange rates without adding artificial tracers.

miniRUEDI used for gas monitoring in a full-scale experiment targeted at underground radioactive waste disposal

In their recent paper “On-line monitoring of the gas composition in the full-scale emplacement experiment at Mont Terri (Switzerland)“, Yama Tomonaga and his colleagues at Nagra, Eawag and ETH Zurich used a miniRUEDI to study the dynamics and the fate of the gas species in a tunnel of a full-scale experiment targeted at radioactive waste disposal in Switzerland.


  • An on-line gas monitoring has been implemented for the FE experiment at Mont Terri underground rock laboratory.
  • The monitoring of gas species was performed successfully over several months.
  • Rapid gas exchange occurs between drift backfilling and FE niche/host rock.
  • Terrigenic gases (e.g., 4He, 40Ar, CH4, CO2) accumulated in the backfill pore space.
  • Fast gas exchange partly explains the O2 removal from the backfill pore space.

Use of miniRUEDI Instruments in Air/Water Exchange Studies in Small Streams

In their recent paper “In-situ mass spectrometry improves the estimation of stream reaeration from gas-tracer tests“, Julia Knapp and her colleagues at Uni Tübingen and Eawag used two miniRUEDI instruments to study air/water exchange in small streams.


  • Determination of gas-exchange rates in streams from gas-tracer testsQuantification of gas tracers using a portable gas-equilibrium mass spectrometer
  • Reliable estimation of reaeration rates from krypton and propane injections
  • In-situ analysis avoids gas loss and improves the determination of reaeration rates

Gasometrix in the news!

The foundation of Gasometrix GmbH as an Eawag Spin-Off was well received in the media. Tages Anzeiger and some other newspapers picked up the Eawag press release, and I got interviewed by Swiss Radio and Television for their Science Magazine. Here’s the interview (in German):


Eawag News about Gasometrix GmbH

Analyses of environmental gases which previously required months of laboratory work can now be carried out rapidly in the field. A group of Eawag scientists have developed a portable mass spectrometer allowing on-site measurements – and a spin-off has been created to commercialize the new system. (read the full article)