Effects of decarbonation treatments on delta C-13 values in marine sediments

Three different methods for decarbonating sediment samples prior to carbon isotope analyses were compared with each other: A, treating the sample with 10% HCl; B, treating the sample with 10% HCl followed by a twofold rinse w ith deionized water; C, acid fuming with 36% HCl in a desiccator. Whereas, method A and method B gave comparable results, method C gave poor results, since not all of the carbonate was eliminated, especially in samples with h igh carbonate content, and then interfered with the isotope measurements. T herefore, it is suggested to wash the samples after a treatment with acid ( Method B) to avoid deleterious effects of HCl fumes on the elemental analys er and mass spectrometer. (C) 2000 Elsevier Science B.V. All rights reserve d.