Spatial Distribution of Δ 14 C Values of Organic Matter in Surface Sediments Off Saru River in Northern Japan, One Year After a Flood Event in 2006

Dispersion and deposition of terrestrial organic matter by flooding on the inner shelf were studied using C/N ratios, δ 13 C, and Δ 14 C values of sedimentary organic matter. Surface sediment samples (top 2 cm) were collected from coastal areas near the Saru River in southwestern Hokkaido, northern Japan, 1 yr after a flood event in 2006. Riverine suspended solids were also collected at a fixed station downstream during 2006–2008. Sandy sediments were located at the front of the river mouth and the western part of the sampling area, with the δ 13 C of organic matter ranging from −23.8‰ to −22.0‰, Δ 14 C of –655‰ to –388‰, and an organic carbon/total nitrogen (C/N) ratio of 5.9–7.7. On the other hand, silt and clay sediments were distributed in a restricted area 11–16 km from the river mouth, with lighter δ 13 C (–26.7‰ to −24.1‰) and higher Δ 14 C (–240‰ to –77‰) of organic matter and C/N ratio (7.8–13.3). From end-member analysis, the apparently younger and less degraded organic matter in the silt and clay sediments consists mainly of terrestrial organic matter released by flood events. They remain in the depression, although most flood deposits were moved to deep-sea environments

Flood myth · Geochemistry · Geography · Geomorphology · Organic matter · River mouth · Sediment · Sedimentary organic matter · Sedimentary rock · Silt · Total organic carbon · Chemistry · Environmental Science · Isotope Analysis in Ecology · Marine and coastal ecosystems · Environmental Chemistry · Geology

• Discussion Reporting of 14 C Data

  Open Access•Minze Stuiver, Henry A Polach•Radiocarbon•1977

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