2007 Fiscal Year Final Research Report Summary
Study on processes of dimethyl sulfide production in seawater, its emission to the marine atmosphere and formation of sulfate aerosol
| Project/Area Number |
16204044
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geochemistry/Astrochemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
UEMATSU Mitsuo The University of Tokyo, Ocean Research Institute, Professor (60203478)
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| Co-Investigator(Kenkyū-buntansha) |
TUDA Atsushi The University of Tokyo, Ocean Research Institute, Associate Professor (80217314)
HASHIMOTO Shinya University of SHIZUOKA, Institute for Environmental Sciences, Professor (10228413)
NAGAO Ippei Nagoya University, Graduate School of Environmental Shcdies, Associate Professor (00252297)
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| Project Period (FY) |
2004 – 2007
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| Keywords | Dimethylsulfide / Volatile organic compounds / Sulfate particle / Marine biogenic gases / hytoplankton / Marine atmosphere / Aerosols / Eddy correlation method |
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| Research Abstract |
For simple and quick bulk chemical analysis of suspended particles in seawater, a devise with energy dispersive X-ray fluorescence spectrometer that specialized for light elements was developed. A fast measurement system of atmospheric DMS concentrations based on the fluorine-induced chemiluminescence was also developed and succeeded to employ in the marine air to apply the eddy correlation method on ship board.
Our shipboard simultaneous measurements of air and sea were carried out as a part of the iron fertilization experiment in the western subarctic North Pacific in the summer (R/V Hakuho-maru), at the Off Sanriku region during the high primary productive period in the spring (R/V Tansei-maru), and survey along 47°N from western to eastern subarctic North Pacific in summer (R/V Mirai). During the phytoplankton bloom caused by iron fertilization, the concentrations of CH_3Br increased. A linear correlation was observed between the concentrations of 19'-hexanoyloxyfucoxanthin, which i
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s a biomarker of several prymnesiophytes, and CH_3Br in the seawater. After fertilization, the air-sea flux of CH_3Br inside the patch changed from influx to efflux from the ocean.
Dimethylsulfide, halomethanes, and isoprene in the water and air measured in the western subarctic Pacific revealed that phytoplankton speciation and physiological differences are probably related to the differences of the distribution of VOCs in air and seawater. In the front region of Tsushima warm current, high concentrations of VOCs such as CH_3Br, CH_2I_2 and CH_2CII in seawater were correlated with in atmospheric concentrations. Results of the longitudinal transect along the 47°N, the highest DMS concentrations of seawater were observed between 180°E and 140V corresponding increases in the atmospheric DMS concentrations. At the same time, the concentration of particulate Ca in seawater increased with DMS concentration in seawater. It suggested that detritus of coccolithophorids with CaCO_3 test, reflect DMS concentration in seawater. Less
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