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| Titel |
Measurement-based modeling of daytime and nighttime oxidation of atmospheric
mercury |
| VerfasserIn |
Eran Tas, Maor Gabay, Mordechai Peleg, Erick Fredj |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141558
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| Publikation (Nr.) |
 EGU/EGU2017-5085.pdf |
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| Zusammenfassung |
| Accurate characterization of gaseous elemental mercury (GEM) chemical oxidation pathways
and their kinetics is critically important for assessing the transfer of atmospheric
mercury to bioaquatic systems. Recent comprehensive field measurements have
suggested that the nitrate radical (NO3) plays a role in efficient nighttime oxidation of
GEM, and that the role of the hydroxyl radical (OH) as a GEM oxidant has been
underestimated. We used the CAABA/MECCA chemical box model and additional
kinetic calculations to analyze these measurement results, in order to investigate the
nighttime and daytime oxidation of GEM. We assumed a second-order reaction for
the NO3 induced nighttime oxidation of GEM. Our analysis demonstrated that
nighttime oxidation of GEM has to be included in the model to account for the
measured variations in nighttime reactive gaseous mercury (RGM) concentration. A
lower limit and best-fit rate constant for GEM nighttime oxidation are provided. To
the best of our knowledge, this is the first time that a rate for nighttime oxidation
of GEM has been determined based on field measurements. Our analysis further
indicates that OH has a much more important role in GEM oxidation than commonly
considered. A lower-limit rate constant for the OH–RGM reaction is provided. |
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