Relationship between Concentration of Organo-tin Compounds Contained in Bottom Sediments and Sediment Mixtures Caused by Tsunami in Bay on Sanriku Coast

Abstract

Organo-tin compounds, which used to act as anti-fouling agents, have still been detected in the marine environment almost 30 years after their use was prohibited in Japan. The 2011 Great East Japan Earthquake triggered a giant tsunami and caused bottom sediments along the deeply indented Pacific coastline to be stirred up on a large scale. Nevertheless, researchers have not investigated in detail how these sediments have been stirred up and how this phenomenon has affected the marine environment. This study aims to elucidate the horizontal and vertical distribution of residual organo-tin compounds in bottom sediments in Otsuchi Bay, a main semi-closed bay on the Sanriku coast. For this purpose, bottom-sediment core sampling was conducted at multiple stations in this bay. As a result, it is revealed that the original component of Organo-Tin compounds has still been remaining and that their concentration is significantly higher near a shipyard located in the inner part of the bay.