Heavy hydrogen in the stratosphere

T. Röckmann*, T. S. Rhee, A. Engel

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


We report measurements of the deuterium content of molecular hydrogen (H2) obtained from a suite of air samples that were collected during a stratospheric balloon flight between 12 and 33 km at 40° N in October 2002. Strong deuterium enrichments of up to 400‰ versus Vienna Standard Mean Ocean Water (VSMOW) are observed, while the H2 mixing ratio remains virtually constant. Thus, as hydrogen is processed through the H 2 reservoir in the stratosphere, deuterium is accumulated in H 2. Using box model calculations we investigated the effects of H 2sources and sinks on the stratospheric enrichments. Results show that considerable isotope enrichments in the production of H2 from CH4 must take place, i.e., deuterium is transferred preferentially to H2 during the CH4oxidation sequence. This supports recent conclusions from tropospheric H2 isotope measurements which show that H2 produced photochemically from CH4 and non-methane hydrocarbons must be enriched in deuterium to balance the tropospheric hydrogen isotope budget. In the absence of further data on isotope fractionations in the individual reaction steps of the CH4 oxidation sequence, this effect cannot be investigated further at present. Our measurements imply that molecular hydrogen has to be taken into account when the hydrogen isotope budget in the stratosphere is investigated.

Original languageEnglish
Pages (from-to)2015-2023
Number of pages9
JournalAtmospheric Chemistry and Physics
Issue number6
Publication statusPublished - 1 Jan 2003


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