HR: 0800h
AN: B11A-0055    [Abstracts]
TI: Variaitions in Δ¹⁴C values of POM in the Tokachi River waters
AU: * Nagao, S
EM: nagao@ees.hokudai.ac.jp
AF: Hokkaido University, K10N5, Kita-ku, Sapporo, 060-0810, Japan
AU: Irino, T
AF: Hokkaido University, K10N5, Kita-ku, Sapporo, 060-0810, Japan
AU: Aramaki, T
AF: National Institute for Environmental Studies, 16-1 Onogawa, Tsukuba, 305-8506, Japan
AU: Alam, J M
AF: Hokkaido University, K10N5, Kita-ku, Sapporo, 060-0810, Japan
AU: Shibata, Y
AF: National Institute for Environmental Studies, 16-1 Onogawa, Tsukuba, 305-8506, Japan
AU: Togawa, O
AF: Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai, 319-1195, Japan
AB: An important part of global organic carbon cycle is the flux of terrestrial organic carbon from the continents to the oceans. The potential importance of coastal systems in global and regional organic budgets is still unclear because of the inherent complexity and variability of rivers, estuaries and coastal zones. Therefore, it is important to understand the organic matter cycling in estuaries and coastal systems, especially characteristics and dynamics of river particulate organic matter (POM), because the POM is one of end members of terrestrial organic matter. But POM is not homogeneous in terms of particle size or chemical characteristics so that we canft evaluate the linkage of terrestrial and coastal environments. The objective of this study is to understand the transport behavior of particulate organic matter from terrestrial region to ocean. In this study, we selected the Tokachi River in Japan and carried out at a fixed station from 2003 to 2005. Both Delta C-14 and delta C-13 values of POM were used as a tracer of POM, and we discussed the factors controlling variations in these values in a year. The Delta C-14 values range from -101 to -352 permil for the Tokachi River in northeast Hokkaido, Japan. The Delta C-14 vary with season. The values were -154 to -245 permil for the spring snow-melt season, -101 to -160 permil for the normal flow condition, and -235 to -352 permil for the heavy rain event in autumn. These results suggest that the differences in Delta C-14 values may reflect the differences in sources and supply processes of POM from watershed area in each season.
DE: 0330 Geochemical cycles (1030)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 1040 Radiogenic isotope geochemistry
DE: 1041 Stable isotope geochemistry (0454, 4870)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting