A convenient method of analysis of humic acid in fresh water.

Humic acids are generally defined operationally as those decomposir tion products of plants and animals that comprise the base-soluble, 2 acidand alcohol-insoluble fractions of the soil. These materials are of interest because of their geological significance, possible nutritive properties, involvement of biological processes, and the challenge 3 afforded by their chemical and structural complexities. Our particular interest in humic acid distribution in fresh water derives from an 4-7 interest in the evident involvement of humic acids in red-tide outbreaks. This note describes a convenient method for determining the humic acid content of natural waters. EXPERIMENTAL Standard Humic Acid Samples. These were isolated from bog soil (adajacent g to the Hillsborough River) using the method described by Overstreet and 3 others. The humic acid samples, obtained as dark brown solids, had