A HIGH-TEMPERATURE CATALYTIC-OXIDATION METHOD FOR THE DETERMINATION OF MARINE DISSOLVED ORGANIC-CARBON AND ITS COMPARISON WITH THE UV PHOTOOXIDATION METHOD

A modified high-temperature catalytic oxidation (HTCO) method for marine dissolved organic carbon (DOC) measurement is described. The method has a high oxidation efficiency and a precision of 1-2%. It is robust and relatively easy to perform, and hence can be used for routine analyses. Components of the system blank are determined by the use of deionized water treated by high-temperature catalysed oxidation, and the results are checked by an experiment using C-14. Extensive comparisons between this method and UV photo-oxidation are presented. The HTCO method consistently yields 5-60% more DOC than the UV method, with most results in the range of 10-40%. No simple explanation has been found for the differences between the two methods, as a result of the complex nature of DOC in seawater.