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| Titel |
Oxygen dynamics at sediment-water interface in Arabian Sea continental margin: results from planar oxygen optode experiments in situ |
| VerfasserIn |
Kazumasa Oguri, Hiroshi Kitazato |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048987
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| Zusammenfassung |
| Arabian Sea intermediate water is known as typical oxygen (O2) depleted environment due to
higher primary productivity. Between 200 to 800 m in the water column of western Indian
continental margin, O2 minimum zone (OMZ) is extensively developed and the O2
concentration decreases to 0.2~1.5 μM at the depth. To investigate processes of O2
penetration into sediment and interactions between O2 and benthic activities at
sediment-water interface (SWI) in OMZ, we newly developed an ultra-high sensitive planar
O2 optode to measure two dimensional O2 profiles and their time series changes at SWI. This
system consisted of a palladium porphyrin-based transparent sensor foil and a high speed
modulation camera, and it was designed to obtain both O2 profiles and the corresponding
grayscale images at SWI at a same time. In the YK08-11 Arabian Sea cruise by R/V
Yokosuka, the planar O2 optode system installed in an autonomous lander system
was deployed at 801 m and 1160 m depth in western Indian continental margin,
respectively. At 801 m depth, O2 concentration in the bottom water was changed from 1.5
to 4.0 μM during one day deployment, and the change was synchronized to the
tidal cycle. O2 penetration depth into the sediment was at most 2 mm by molecular
diffusion, but O2 penetration was partly enhanced by hydrodynamic flow. At 1160 m
depth, O2 concentration in the bottom water was fluctuated from 17.5 to 25 μM,
and the depth of O2 penetration into the sediment was 4 to 6 mm. In each site, no
meiobenthic activities were observed as to see the grayscale profile images. However, large
benthic organism tabulated sediment surface at 801 m depth, suggesting that even in
sediment in OMZ, biological mixing plays a significant role on O2 supply at SWI. |
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