HIGH-TEMPERATURE COMBUSTION ANALYSIS OF DISSOLVED ORGANIC-CARBON PRODUCED IN PHYTOPLANKTON CULTURES

A high-temperature catalytic oxidation (HTCO) unit was constructed for the measurement of dissolved organic carbon (DOC) in seawater. This unit, which used a 5% Pt catalyst, consistently measured a greater amount of DOC than did a wet oxidation technique using UV light. In medium in which algal cultures had been grown, as much as half of the DOC measured by HTCO disappeared in a day in unpreserved samples. Of the preservation methods tested, addition of mercuric chloride after filtration appeared to be the most satisfactory. In algal cultures, the rates of production and disappearance of DOC were dependent on the species of algae present and their physiological state.