The development of total organic carbon determination method in the sea water

The subject of the article is to improve the method for determining the content of dissolved organic carbon (DOC) in seawater by high-temperature catalytic oxidation. The studies were carried out with the help of an elemental analyzer with infrared C-NDIR detector. The model solutions and samples of Barents sea water were used as objects of study. We proposed NaCl water solution as a blank sample in order to determine the dissolved organic carbon content in the seawater with mass concentration range equal to 10-250 mgC/dm(3). The salinity of NaCl solution is equal to the salinity of the analyzed sample. We proposed to use the standard solutions with fixed salinity in order to build the calibration dependency for determination of dissolved carbon with concentration up to 10 mg/dm(3). The application of this approach reduces the error of determination of dissolved carbon in seawater from 20 to 7%. The proposed modification of the technique allows to determine the content of DOC with a salinity of 35 g/dm(3) with a relative measurement en-or up to 7%. A series of seawater samples from the Barents Sea was analyzed. The obtained values of the organic carbon content were from 1.60 to 4.20 mg/dm(3). Low concentrations of dissolved organic carbon are observed in places corresponding to the occurrence of less warm Atlantic water masses or Arctic and Barents Sea waters. In the southern part of Barents Sea, the maximum carbon concentrations are mainly due to the high productivity of the coastal waters coming from the continental drain and flowing from the Norwegian Sea with the coastal current along the coast of Norway.