湖山池の湖底堆積物に包埋される珪藻からみた古環境変遷

For understanding paleoenvironmental changes, an analysis of diatom of a core KY 9401 from Lake Koyama-ike was carried out. The results are summarized as follows: 1) 23 species in 41 genera were identified in diatom in the core. 2) Most dominant species of diatoms in the core are a limnetic Melosira granulata, and other diatoms are also limnetic species. 3) That many kinds of diatoms in the core are limnetic or brackish species indicates that the environments of the lower part of the core had slightly higher saline that the present environments have. 4) Since the number of diatoms found in the layer upper than 54 cm from the top and the number of diatoms found in the layer lower than that differ markedly, it is considered that water quality environments in Lake Koyama-ike changed at that time. 5) Many species living in the moderately polluted environments are found in the part upper than 20 cm in the core, which reflects the recent pollution of the lake.