Carbon isotopic composition of sterols in geochemical samples

Abstract

Carbon isotopic composition of sterols in marine Holocene sediments, marine sinking particles, tree leaves, and soils were determined. δ13C values of algae-derived sterols such as 24-methylcholesta-5, 22-dien-3β-o1 and dinosterol in the marine sediments range from -22.1 to -25.2‰, while those of 24-ethylcholest-5-en-3β-ol (24-ethylcholesterol) range from -22.6 to -24.3‰. We conclude that 24-ethylcholesterol in the marine sediments derives from marine algae, because their δ13C values are markedly different from those of the leaves of C3 (∼-29‰) and C4 (-14‰) plants and similar to those of the algal sterols.