Abstract
In September 1984, a large amount of foam was observed in Lake Chuzenji. One of the purposes of this study is to find out causes of the foam. Because carbohydrate concentration in lake water was relatively high (2.25mg·l-1 in filtered water) and carbohydrate (mainly arabinose and galactose) occupied about 1/3 of freeze dried material from lake water of foaming, it was supposed that carbohydrate was one of the main causes of the foam.
To clarify the carbohydrate origin, aquatic macrophytes and fallen leaves were steeped in distilled water. Carbohydrate concentration released from aquatic macrophytes into distilled water elevated about 100mg·l-1 after 100 days. Carbohydrate concentration released from fallen leaves rapidly elevated 66mg·l-1 after 5 days. The carbohydrate constituents of foam were similar to these of aquatic macrophytes and fallen leaves.
According to the results, one of the main causes of the foam seems to be carbohydrate released from aquatic macrophytes in September, autumn and winter and from fallen leaves in autumn and winter.
