Abstract: The organic materials of natural water surface coatings were quantified by me asuring chemical oxygen demand (COD) and total organic carbon (TOC) in the natu ral water surface coatings, and the relationship between COD and TOC was investigated with the variance analysis. The results indicate that the time factor has no sig nificant effect on the ratio of COD to TOC, while the depth factor has no obviou s effect on it within the depth range selected. So both COD and TOC could be use d for determining the amount of organic materials of natural water surface coati ngs.

Key words: natural water, surface coating, organic material, chemical oxygen demand, total organic carbon