page_title: Hydrogen isotope biogeochemistry
section_title: Atmosphere
hierarchical_section_title: Hydrogen isotope biogeochemistry / Observed variations in isotope abundance / Hydrosphere / Atmosphere
caption_attribution_description: English: Modified by inserting the data from a paper [Frankenberg C. et al.(2009) Dynamic Processes Governing Lower-Tropospheric HDO/H2O Ratios as Observed from Space and Ground. Science 325, 1374–1377.] on the map from [Annu.Rev.Earth Planet.Sci.2010.38:161-187.]
context_page_description: Hydrogen isotope biogeochemistry is the scientific study of biological, geological, and chemical processes in the environment using the distribution and relative abundance of hydrogen isotopes. There are two stable isotopes of hydrogen, protium ¹H and deuterium ²H, which vary in relative abundance on the order of hundreds of permil. The ratio between these two species can be considered the hydrogen isotopic fingerprint of a substance. Understanding isotopic fingerprints and the sources of fractionation that lead to variation between them can be applied to address a diverse array of questions ranging from ecology and hydrology to geochemistry and paleoclimate reconstructions. Since specialized techniques are required to measure natural hydrogen isotope abundance ratios, the field of hydrogen isotope biogeochemistry provides uniquely specialized tools to more traditional fields like ecology and geochemistry.
context_section_description: The analysis done based on satellite measurement data estimates the δD values for the atmosphere in various regions of the world. The general trend is that the δD values are more negative at higher-latitude regions, so the atmosphere above the Antarctica and the arctic regions is observed to be highly D-depleted to around −230‰ to −260‰ or even lower.
  The estimates of the atmospheric δD values are shown on the map.
  A vast portion of the global atmospheric water vapor comes from the western Pacific Ocean near the tropical zone, (mean 2009) and the H/D isotopic composition of atmosphere varies depending on the temperature and humidity. In general, higher δD values are observed in humid regions with a high temperature. Water vapor in the atmosphere is in general more depleted than the terrestrial water sources, since the rate of evaporation for ¹H¹⁶
  ₂O is faster than ¹HD¹⁶O due to a higher vapor pressure. On the other hand, the rain water (precipitation) is in general more enriched than the atmospheric water vapor.
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