Japan Geoscience Union Meeting 2014

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Oral

Symbol A (Atmospheric, Ocean, and Environmental Sciences) » A-HW Hydrology & Water Environment

[A-HW28_30PM2] Water and material transport and cycle in watersheds: from headwater to coastal area

Wed. Apr 30, 2014 4:15 PM - 5:45 PM 314 (3F)

Convener:*Kazuhisa Chikita(Department of Natural History Sciences, Faculty of Science, Hokkaido University), Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Shin-ichi Onodera(Graduate School of Integrated and Arts Sciences, Hiroshima University), Shinji Nakaya(Department of Civil Engineering, Faculty of Engineering, Shinshu University), Masahiro Kobayashi(Forestry and Forest Products Research Institute), Mitsuyo Saito(Graduate School of Environmental and Life Science, Okayama University), Seiko Yoshikawa(Narional Institute of Agro-Environmental Sciences), Noboru Okuda(Center for Ecological Research, Kyoto University), Chair:Shin-ichi Onodera(Graduate School of Integrated and Arts Sciences, Hiroshima University)

5:15 PM - 5:30 PM

[AHW28-P10_PG] Spatial distribution of radon (222-Rn) and radium (226-Ra, 228Ra) in the coastal seawater of Seto Inland Sea and its con

3-min talk in an oral session

*Mitsuyo SAITO1, Shin-ichi ONODERA2, Tomoko OHTA3, Xinyu GUO4, Hidetaka TAKEOKA4, Hidejiro ONISHI4, Takumi KUBOTA5 (1.Okayama Univ., 2.Hiroshima Univ., 3.Hokkaido Univ., 4.CMES, Ehime Univ., 5.KURRI, Kyoto Univ.)

Previous studies have revealed that submarine groundwater discharge (SGD) is one of the important pathways for nutrients and the other dissolved materials from terrestrial area to the marine environment. For the evaluation of the effect of SGD, the timescale of nutrient transport in the coastal area derived by SGD such as residence time is important as well as nutrient flux by SGD. Radioactive isotopes of radon (222-Rn) and radium (226-Rn, 228-Ra) are one of the useful tracers for the evaluation of SGD and residence time of water mass in the coastal area. The objective of the study is to examine the spatial variation of 222-Rn and 226-Rn, 228-Ra in the coastal seawater of the central part of Seto Inland Sea and its controlling factors. The study area is southwestern part of the Hiuchi-Nada with the area of approximately 30 km × 13 km. Relatively high concentrations of 222-Rn, 226-Rn and 228-Ra were detected in the southern part of the study area. These results suggest the effect of SGD from seafloor. *This research was supported by the KWEF research grant program by Kurita Water and Environment Foundation (No. 24254, Mitsuyo Saito) and cooperative research project in KURRI, Kyoto University (No. 2434, Shin-ichi Onodera) in 2012.