High abundances of long-chain normal alkanoic acids in Antarctic soil

Abstract

Studies of geochemical samples have shown that fatty acids are widely distributed in sediments ranging in geological age from Recent to Precambrian1–9. Most n-alkanoic acids found in soils and Recent sediments show similarities in their distributions, such as a marked predominance of even-carbon numbered acids and a bimodal distribution with two maxima in carbon chain length of C14 to C18 and C24 to C28 (refs 1, 2, 4–7). Long-chain n-alkanoic acids (≥C20) predominate in the waxes of vascular plants10,11, whereas short-chain n-alkanoic acids (<C20) occur in the lipids of all living organisms. Long-chain n-alkanoic acids found in soils and Recent sediments are thus believed to arise from vascular plants12–14. In Antarctica, vascular plants are only found in the Antarctic Peninsula15. Organic constituents on this continent are thus expected to be considerably different from those in the temperate and tropical zones. We report here the presence of very long-chain n-alkanoic acids extending to C40, having a small even-carbon predominance, and comprising a large proportion of the fatty acids in Antarctic soils. They apparently originate in the Beacon Sandstone.