@inproceedings{oai:repo.qst.go.jp:00053775,
 author = {青野, 辰雄 and 中西, 貴宏 and 山田, 正俊 and 日下部, 正志 and 青野 辰雄 and 中西 貴宏 and 山田 正俊 and 日下部 正志},
 book = {Proceedings of the Workshop on Environmental Radioactivity (KEK Proceedings)},
 month = {Dec},
 note = {Thorium isotopes are known to have a strong affinity to particles in seawater. This characteristic can be used to elucidate the particle behavior.  Thorium isotopes have been used as a tool to estimate transportation and transformation rates of particles in oceanic surface layer. It is difficult to concentrate and fractionate the particulate matters with the general filtration systems in seawater, as the concentrations of radionuclides and particles are very low in the ocean. Samples were taken using the multiple-unite large-volume in situ filtration systems during the MR04-K07 cruise of the R/V Mirai from Nov.-Dec., 2004. The concentrations of 234Th in the large (>70um) and small (1-70um) particulate form were 0.01-0.2 dpm/L in the depth of 200 m. The ratios of POC/234Th(umol/dpm)in the large particles were 1-1.8 in the upper 50 m depth and less than 1 in the 100 -150 m depth. It is considered that the plankton community structure and particle size played a key role in controlling trends in the POC/234Th ratio in oceanic surface layer.},
 pages = {50--52},
 title = {現場型超大容量海水濾過装置を用いた西部北太平洋表層におけるトリウム同位体の濃度分布について},
 volume = {7},
 year = {2006}
}