Mussel Shell Geochemical Analyses Reflect CoastalEnvironmental Changes Following the 2011 Tohoku Tsunami

Coastal areas are socioeconomically important but are susceptible to disturbances by both natural and man-made events. On March 11, 2011, the eastern coast of Japan was seriously inundated by a massive tsunami following the 2011 Tohoku earthquake. The tsunami caused a major disturbance around the coastal area. However, an understanding of the consequences of such an event is often hampered by a lack of knowledge of prior conditions. Furthermore, field observations during and immediately after the event are often particularly difficult. The present study demonstrates that environmental reconstruction by geochemical and growth pattern analyses of mussel shells successfully revealed transitional (daily) environmental changes caused by the Tohoku tsunami. A pronounced surge in shell Mn/Ca ratios observed immediately after the tsunami implies a drastic emission of pore water following sediment disturbance as well as a large input of terrestrial material through backwash. The subsequent decrease of the high Mn/...