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| Titel |
Vertical distribution of triple oxygen isotopic composition of dissolved oxygen in the northwestern Pacific |
| VerfasserIn |
Osamu Abe, Makio Honda, Toshiro Saino |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077790
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| Zusammenfassung |
| Oxygen-17 excess of dissolved oxygen calculated from δ18O and δ17O is not affected by
oxygen consumption process but controlled only by processes of primary production and
air-water gas transfer. Evaluating gross primary productivity using the 17O-excess in ocean
surface water are one of the most advanced geochemical researches for last 10 years.
Oxygen-17 excess below ocean mixed/photic layer has not been much investigated because it
might be out of focus for estimating present primary productivity, except for the purpose to
correct diapycnal mixing effect on surface water. In principle, water mass which has
not been affected both by photosynthesis and gas transfer after its separation from
ocean surface could preserve 17O-excess value where the water mass was at the
surface.
The purpose of this study is to determine the vertical distribution of 17O-excess from the
surface to the bottom of northwestern Pacific to know whether 17O-excess could really
preserve its “original” value after the long and dark travel. Near stations K2 and
KNOT, water mass which has a density of 26.8 Ïăθ is observed at depth between
100 and 300 m. This water mass is mainly originated from bottom water in the
Okhotsk Sea and spreading widely to entire northwestern Pacific, which is called
North Pacific Intermediate Water (NPIW). NPIW is found at depth of 700 m at
station S1. Samplings were conducted by two R/V Mirai cruises (MR10-06, Oct-Nov
2010; MR11-02, Feb-Mar 2011). Dissolved oxygen gas was purified by the method
of Sarma et al. (2003) and its isotopic composition was determined by dual-inlet
isotope ratio mass spectrometer (Thermo Scientific Delta Plus). Gross primary
productivities at mixed layer estimated by 17O-excess were well consistent with
those by conventional light and dark bottle incubations for stations K2 and S1. |
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