Sources of long chain fatty acids in deep sea sediments from the Bering Sea and the North Pacific Ocean

The distributions and compound specific carbon isotope ratios of long chain n-fatty acids and lofig chain n-alkanes in two sedimentary cores collected from the North Pacific Ocean and the Bering Sea have been examined. Long chain fatty acids were further fractionated into three sub-fractions (esterified, free and polar) to investigate their sources. The delta C-13 values of these fractions clarified the sources of different fatty acids. The esterified fraction had lighter delta C-13 values (similar to-30.1 parts per thousand, sigma = 0.70), similar to those of the long chain n-alkanes (-30.2, sigma = 1.08), consistent with a mainly terrestrial plant origin. In contrast, the long chain fatty acids (except > C-28) from the polar and free fractions had heavier isotopic values (similar to-27.5 parts per thousand, sigma = 1.06), suggesting a mixed origin from terrestrial and marine organisms. The esterified fatty acids from the North Pacific Ocean and the Bering Sea can be used as terrestrial biomarkers. (c) 2004 Elsevier Ltd. All rights reserved.