COMPARISON OF TOC CONCENTRATIONS BY PERSULFATE-UV AND HIGH-TEMPERATURE CATALYTIC-OXIDATION TECHNIQUES IN THE MARMARA AND BLACK SEAS

Total organic carbon (TOC) concentrations were determined in the Marmara Sea and both oxic and anoxic waters of the Black Sea, using the Shimadzu high-temperature catalytic oxidation technique and the Technicon persulphate-UV oxidation method. The TOC values in the deep waters of the Marmara Sea ranged between 60 and 73 muMC by the Shimadzu technique and from 40 to 50 muMC by the Technicon method. The TOC values obtained by both methods in the deep anoxic waters of the Black Sea varied between 105 and 130 muM. These values differ significantly from those in the literature, indicating that available TOC data are not accurate enough for reliable estimation of the carbon budget of the Black Sea. Storage of the anoxic water samples accompanied by freezing, acidifying or poisoning with HgCl2 did not increase TOC recovery.