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Carbon isotopes of individual lipids in typical organisms from the Nansha sea area were measured by the GC-IRMS analytical technique. d 13C values of saturated fatty acids in different organisms examined are from -25.6 to -29.7 with the average values ranging from -26.4 to -28.2 and the variance range of 1.8 between different organisms is also observed. Unsaturated fatty acids have heavy carbon isotopic compositions and the mean differences of 2.9—6.8 compared to the same carbon number saturated fatty acids. d 13C values of n-alkanes range from -27.5 to -29.7 and their mean values, ranging from -28.6 to -28.9, are very close in different organisms. The mean difference in d 13C between the satu-rated fatty acids and n-alkanes is only 1.5, indicating that they have similar biosynthetic path-ways. The carbon isotopic variations between the different carbon-number lipids are mostly within 2.0, reflecting that they experienced a biosynthetic process of the carbon chain elon-gation. At the same time, the carbon isotopic genetic relationships between the biological and sedimentary lipids are established by comparative studies of carbon isotopic compositions of individual lipids in organisms and sediments from the Nansha sea area, which provides scientific basis for carbon isotopic applied research of individual lipids.
Carbon isotopes of individual lipids in typical organisms from the Nansha sea area were were by the GC-IRMS analytical technique. D 13C values of saturated fatty acids in different organisms examined are from -25.6 to -29.7 with the average values ranging from -26.4 to -28.2 and the variance range of 1.8 between different organisms is also observed. Unsaturated fatty acids have heavy carbon isotopic compositions and the mean differences of 2.9-6.8 compared to the same carbon number saturated fatty acids. D 13C values of n-alkanes range from -27.5 to -29.7 and their mean values, ranging from -28.6 to -28.9, are very close in different organisms. The mean difference in d 13C between the satu-rated fatty acids and n-alkanes is only 1.5, indicating that they have similar biosynthetic path-ways. The carbon isotopic variations between the different carbon-number lipids are mostly within 2.0, reflecting that they experienced a biosynthetic process of the carbon chain elon-gation. At the same time, the carbon isotopic genetic relationships between the biological and sedimentary lipids are established by comparative studies of carbon isotopic compositions of individual lipids in organisms and sediments from the Nansha sea area, which provides scientific basis for carbon isotopic applied research of individual lipids.