COMPOUND-SPECIFIC RADIOCARBON AGES OF FATTY ACIDS IN MARINESEDIMENTS FROM THE WESTERN NORTH PACIFIC

From the 17th International Radiocarbon Conference held in Jerusalem, Israel, June 18-23, 2000.Compound-specific radiocarbon analysis of five fatty-acid biomarkers was conducted for marine sediments collected from the western North Pacific. The fatty acids (C12 to C3 4) showed a typical bimodal distribution pattern with two maxima at C16 and C26. Their carbon isotopic compositions ranged from -25.1 per mil (C16) to -31.8 per mil (C28), suggesting that they derived from terrestrial higher plants and marine organisms. A large variations of 14C ages were found among the fatty acids detected in the same sedimentary horizon of the core, ranging from 530 BP (C18) to 3250 BP (C28). The results of 14C analysis of fatty acids could be divided into two groups, i.e., lower molecular weight (LMW) fatty acids (C16, C18) derived from marine organisms and higher molecular weight (HMW) fatty acids (C24, C26, C28) derived from terrestrial higher plants. The HMW fatty acids showed older ages, ranging from 2550 BP (C24) to 3250 BP (C28), than LMW fatty acids (530 BP [C18] to 1,820 years BP [C16]). On the other hand, bulk-phase total organic matter (TOM) showed the age of 2260 BP that is between those two groups, suggesting that it was likely a mixture of organic matter derived from marine and terrestrial sources. The compound specific 14C ages and delta-13C data of sedimentary fatty acids presented here could provide useful information to decipher the fate and transport process of terrestrial organic matter to marine sediments.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202