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| Titel |
Nitrogen and Triple Oxygen Isotopic Analyses of Atmospheric Particulate Nitrate over the Pacific Ocean |
| VerfasserIn |
Kazuki Kamezaki, Shohei Hattori, Yoko Iwamoto, Sakiko Ishino, Hiroshi Furutani, Yusuke Miki, Kazuhiko Miura, Mitsuo Uematsu, Naohiro Yoshida |
| 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 |
250140569
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| Publikation (Nr.) |
 EGU/EGU2017-3972.pdf |
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| Zusammenfassung |
| Nitrate plays a significant role in the biogeochemical cycle. Atmospheric nitrate (NO3− and
HNO3) are produced by reaction precursor as NOx (NO and NO2) emitted by combustion,
biomass burning, lightning, and soil emission, with atmospheric oxidants like ozone (O3),
hydroxyl radical (OH), peroxy radical and halogen oxides. Recently, industrial activity lead
to increases in the concentrations of nitrogen species (NOx and NHy) throughout
the environment. Because of the increase of the amount of atmospheric nitrogen
deposition, the oceanic biogeochemical cycle are changed (Galloway et al., 2004;
Kim et al., 2011). However, the sources and formation pathways of atmospheric
nitrate are still uncertain over the Pacific Ocean because the long-term observation is
limited.
Stable isotope analysis is useful tool to gain information of sources, sinks and
formation pathways. The nitrogen stable isotopic composition (δ15N) of atmospheric
particulate NO3− can be used to posses information of its nitrogen sources (Elliott et
al., 2007). Triple oxygen isotopic compositions (Δ17O = δ17O − 0.52 ×δ18O) of
atmospheric particulate NO3− can be used as tracer of the relative importance of
mass-independent oxygen bearing species (e.g. O3, BrO; Δ17O ≠ 0 ‰) and mass-dependent
oxygen bearing species (e.g. OH radical; Δ17O ≈ 0 ‰) through the formation
processes from NOx to NO3− in the atmosphere (Michalski et al., 2003; Thiemens,
2006).
Here, we present the isotopic compositions of atmospheric particulate NO3− samples
collected over the Pacific Ocean from 40˚ S to 68˚ N. We observed significantly low δ15N
values for atmospheric particulate NO3− on equatorial Pacific Ocean during both cruises.
Although the data is limited, combination analysis of δ15N and Δ17O values for atmospheric
particulate NO3− showed the possibility of the main nitrogen source of atmospheric
particulate NO3− on equatorial Pacific Ocean is ammonia oxidation in troposphere.
Furthermore, the Δ17O values for atmospheric particulate NO3− originated from Central
North Pacific Ocean showed the possibility of atmospheric particulate NO3− formation
pathway is reaction NO2 with halogen oxides. At the presentation, we discuss the sources and
formation pathways of atmospheric particulate NO3− by using stable isotopic analyses for
each region.
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