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| Titel |
Field studies of BrO and IO at salt ponds (Namibia and Botswana) and related smog chamber experiments on environmental salt and soil samples |
| VerfasserIn |
Joelle Buxmann, Natalja Balzer, Sergej Bleicher, Karsten Kotte, Ulrich Platt, Cornelius Zetzsch, Jacobus J. Pienaar |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042575
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| Zusammenfassung |
| Previous studies have shown that salt lakes provide a significant source for gaseous reactive
halogen compounds. Reactive halogen species (RHS) influence the ozone chemistry. Iodine
chemistry is known to initiate particle formation, where the relevant nucleation mechanism
is not fully understood. The RHS IO and BrO were investigated by Multi- Axis-
Differential- Optical- Absorption- Spectroscopy (MAX-DOAS) of scattered sunlight at two
different salt ponds. At a coastal salt evaporation pond for production of sodium
chloride in Namibia (Walfish Bay) as well as at a natural salt pond in Botswana (Sua
Pan) a tropospheric IO signal was observed. In Namibia the slant column density
(SCD) rose up to (4.5±0.7) -
1013 molec/cm2 (elevation angle: 5Ë ). Assuming
a typical layer thickness of 500 m, this would correspond to a concentration of
(3.3±0.5) ppt. The mean SCD of IO was (2.2±0.5) -
1013 molec/cm2at Sua Pan for 5Ë
elevation angle. At both measurement sites tropospheric BrO remained below the
detection limit of 1.8 -
1013molec/cm2or 1.3ppt, respectively. Many aspects of
the underlying mechanisms for the release of reactive halogen compounds, their
sources and sinks are not well understood yet. In order to investigate the release of
RHS soil and salt samples from both measurement sites are exposed to simulated
sunlight in a teflon smog-chamber experiment at Bayreuth. RHS are observed by
DOAS with a multireflection system. An ozone analyzer, a gas chromátograph (with
flame ionisation detector) and a scanning electrostatical classifier with condensation
nuclei counter are employed for monitoring hydrocarbons and aerosol, respectively. |
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