An evaluation of the methods of measurement of dissolved organic carbon in soils, manures, sludges, and stream water

Dissolved organic carbon (DOC) from various organic matter sources was measured using spectrophotometric, wet oxidation, and dry combustion methods. The relationship between light absorption at 250 nm and the concentration of DOC varied between the sources which is attributed to the difference in the nature of organic compound, as measured by the relative molecular weight fractions in the DOC samples. Wet oxidation achieved only a partial oxidation of the DOC and the extent of oxidation varied between the sources. Dry combustion achieved the complete recovery of DOC. Both air drying and oven drying increased the concentration of DOC; whereas freeze drying had no effect on the concentration of DOC. DOC concentration increased with an increase in pH.