中海本庄工区の底質環境

Lake bottom environment has been investigated by means of grain size total organic carbon(TOC), total nitrogen(TN) and total sulfur(TS) contents, salinity and dissolved oxygen(DO) analyses at the nineteen stations in the Honjo area every two months from May 1997 to December 1998. We discussed the oxic-anoxic bottom conditions and its seasonal changes in this observation period before and after the installation of seawater pipe. Average TOC content of surface sediment from all stations is almost constant(about 3%) during the period. While the C/S ratio in summer season 1998 is clearly lower than that in the same season in 1997. DO profiles also suggest that the oxygen-poor environment at the lake bottom has been continued more long time in 1998 than in 1997.