A comparison of different methods for determining the organic and inorganic carbon content of lake sediment from two lakes on the Tibetan Plateau

This paper presents three parallel datasets of total organic carbon (TOC) and total inorganic carbon (TIC) as well as carbonate content (CaCO3) of lake sediment from two lakes on the Tibetan Plateau in order to compare different methods and different machines. The results indicate that two carbon analyzers (a Shimadzu TOC-VCPH with solid sample module SSM-5000A and an Elementar Vario EL II) provide very similar TOC and TIC content despite slightly different performance procedures and temperature controls. A TOC record determined by a wet oxidation method and a carbon analyzer shows consistent down core variation although it seems that the wet oxidation method may overestimate TOC content due to the existence of some reduced compounds or minerals in the sediment. TIC content measured by a carbon analyzer and carbonate content determined by a chemical method exhibit similar fluctuation trends in both cores. This suggests that TIC content may be used as an environmental proxy roughly taking the place of carbonate content, especially in sediment with simple carbonate compositions.