Stable water isotopes

Stable isotopes 18O/16O and 2H/H are naturally present in water and can nowadays be measured more easily with regular lab equipment. Stable isotopes can be used to partition evaporation because non-productive evaporation fractionates (i.e., changing the ratio of heavy and light isotopes), while productive evaporation does not change this ratio. By taking water samples of all components of the soil-vegetation-atmosphere interface, total evaporation can be partitioned.