THE MEASUREMENT OF DISSOLVED ORGANIC AND PARTICULATE CARBON IN SEAWATER1

Abstract

A method is described for the rapid determination of dissolved organic carbon in seawater in concentrations between 0.1 and 20 mg/liter. The oxidation is carried out in sealed glass ampoules using K2S2O8 as an oxidizing agent after the sample has been freed of inorganic carbon. The resulting CO2 is passed through a nondispersive infrared analyzer using nitrogen as a carrier and the signal output of the analyzer recorded. Using appropriate calibration curves, the carbon content is determined from the height of the peak. Approximately 100 samples can be analyzed in a single day with a precision of ± 0.1 mg/liter using a sample volume of 5 ml.A companion method is described for the determination of particulate carbon by high‐temperature combustion after concentration of the sample on a glass‐fiber filter. The precision of this method is ± 10 µg C in a range of 0–500 µg C. Approximately six samples can be analyzed in an hour.