1:45 PM - 2:00 PM
[SCG48-07] Evaluation of sediment transport on the eastern slope of the Japan Trench using the geochemical proxies
Keywords:Eastern slope of Japan trench, 2011 Tohoku-oki earthquake, Radionuclide
The core samples were collected in two periods: 16 July to August 2011 and 24 August to 4 September 2020. Radioisotopes (137Cs, 210Pb, 214Pb) and stable isotope ratios (δ13C and δ15N with their contents) in the collected sediments were measured. We also compared our results with the previous studies and evaluated the changes before and after the earthquake by focusing on both the east and west slopes. High radioactive 137Cs concentrations were detected in the surface layer of the sediment, which is presumably derived from the Fukushima nuclear accident. Excess 210Pb concentration in the sediment surface layer was higher than that measured in the same area in the past, suggesting increased sediment transport in this area. The values of δ13C and TOC/TN indicate that the organic carbon originated from marine, which suggested that lateral transport from neighboring areas contributed to the increased transport. The fact that earthquakes may have triggered enhanced material transport to the eastern slope is an important finding in transporting materials to the open ocean, where biological productivity is low.