Abstract
Chemical oxygen demand with potassium permanganate (COD (Mn)) and organic carbon concentration were determined for both dissolved and particulate components of water samples obtained in Lake Kasumigaura, Lake Biwa, influent rivers into Lake Kasumigaura, several specific sources in the watershed, outdoor experimental ponds, etc. In each water region and for each component, they correlated highly, but percentage of oxidation with potassium permanganate was rather low and their relationships were significantly different. In the case of gray water, biological degradability is fairly high, but chemical decomposability is nearly negligible. The utilization of measured COD (Mn) data to predict the concentration of total organic carbon in the past was also confirmed based on long-term monitoring data. Then, we discuss the appropriateness of organic matter indices in lakes from the views of clearness of content, feasibility of measurement and applicability to water environment management.
