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| Titel: |
Heavy hydrogen in the stratosphere |
| Auteur: |
T. Röckmann T. S. Rhee A. Engel |
| Verschenen in: |
Atmospheric chemistry and physics |
| Paginering: | Jaargang 3 (2003) nr. 6 pagina's 2015-2023 |
| Jaar: |
2003 |
| Inhoud: |
We report measurements of the deuterium content of molecular hydrogen (H<sub>2</sub>) obtained from a suite of air samples that were collected during a stratospheric balloon flight between 12 and 33 km at 40º N in October 2002. Strong deuterium enrichments of up to 400 permil versus Vienna Standard Mean Ocean Water (VSMOW) are observed, while the H<sub>2</sub> mixing ratio remains virtually constant. Thus, as hydrogen is processed through the H<sub>2</sub> reservoir in the stratosphere, deuterium is accumulated in H<sub>2</sub> . Using box model calculations we investigated the effects of H<sub>2</sub> sources and sinks on the stratospheric enrichments. Results show that considerable isotope enrichments in the production of H<sub>2</sub> from CH<sub>4</sub> must take place, i.e., deuterium is transferred preferentially to H<sub>2</sub> during the CH<sub>4</sub> oxidation sequence. This supports recent conclusions from tropospheric H<sub>2</sub> isotope measurements which show that H<sub>2</sub> produced photochemically from CH<sub>4</sub> 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 CH<sub>4</sub> 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. |
| Uitgever: |
Copernicus GmbH (provided by DOAJ) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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