Stable water isotopes

The stable water isotopes deuterium and oxygen-18 are suitable tracers in the water cycle and can also be used to track climate changes.

The stable isotopes deuterium (2H) and oxygen-18 (18O) allow gauging of the average elevation of river basins and isolation of the individual components in the groundwater (river water or precipitation infiltration) due to the isotopic signature of the precipitation which varies by region, elevation and season. Deuterium and oxygen-18 are also being increasingly used worldwide to record climate-related changes in the water cycle. The Global Climate Observing System GCOS Switzerland has used deuterium and oxygen-18 as official climate parameters since 2007. The International Atomic Energy Agency IAEA coordinates the isotopic measurements globally and manages the Global Network of Isotopes in Precipitation GNIP and the Global Network of Isotopes in Rivers GNIR.

Precipitation, river water and groundwater become isotopically lighter as the elevation increases due to the altitude effect, i.e. the stable isotopes have higher values at lower elevations (Central Plateau) than at high elevations (Alps). Isotopic reference data for applied hydrological studies is collected within the framework of the NAQUA national groundwater monitoring module ISOT.

Isotope_2H&18O_Karte_2015
Deuterium and oxygen-18 in precipitation, river water (2007-2015 ISOT module) and groundwater (2007-2013 TREND module). Mean value per NAQUA monitoring station. Background: natural environments.

Entwicklung 18O Niederschlag 1980-2015
Evolution of oxygen-18 levels in precipitation at selected monitoring stations from 1980 to 2015. Mean value per NAQUA station per year.

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Last modification 29.08.2018

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