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Photosynthesis in sediments determined at high spatial resolution by the use of microelectrodes

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/45292

Title: Photosynthesis in sediments determined at high spatial resolution by the use of microelectrodes
Authors: NAKAMURA, YOSHIYUKI Browse this author
SATOH, HISASHI Browse this author
OKABE, SATOSHI Browse this author
WATANABE, YOSHIMASA Browse this author
Keywords: Photosynthesis
Light intensity
River sediment
Tidal area
Microelectrodes
Issue Date: May-2004
Publisher: Elsevier
Journal Title: Water Research
Volume: 38
Issue: 9
Start Page: 2440
End Page: 2448
Publisher DOI: 10.1016/j.watres.2004.02.025
PMID: 15142806
Abstract: The present study investigated photosynthetic rates and their regulation by light within the upper 5 mm of sediment in a tidal area of Niida River in Hachinohe, Japan. Steady-state concentration profiles of O2, NH4+, NO2-, H2S, and pH in the sediment were measured with microelectrodes. Microzonation of O2 respiration, denitrification and SO42- reduction was found in the sediment. When light intensities exceeded 1050 µmol photons/m2/s, net photosynthetic activity was detected in the upper 0.5 mm of the microbial mat colonizing on the sediment surface in the tidal area. In contrast, gross photosynthetic activity was detected in the upper 1.0 mm of the microbial mat at 1900 µmol photons/m2/s. As light intensity increased, the net photosynthetic rate and O2 penetration depth increased. The maximal net photosynthetic rate and O2 penetration depth were 6.1 µmol O2/cm3/h and 2.2 mm, respectively, at 1900 µmol photons/m2/s. Net photosynthetic rates in the microbial mat in the tidal area were lower than in the upstream sediment. The analysis of continuous O2 concentration measurements in different layers of the microbial mat during artificial light-dark cycles demonstrated that the photosynthetic activity response to changes in light intensity was extremely fast (a few seconds) and the O2 concentration in the microbial mat became stable within 200 s. The measurement of physical and chemical parameters in river water revealed that the study site was relatively polluted and sunlight intensity significantly fluctuated temporally. These results suggested that the in situ microbial processes occurring in the sediment fluctuated in accordance with periodic fluctuations in sunlight intensity.
Relation: http://www.sciencedirect.com/science/journal/00431354
Type: article (author version)
URI: http://hdl.handle.net/2115/45292
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 佐藤 久

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