UNUSUAL DISTRIBUTIONS OF LONG-CHAIN NORMAL-ALKANES AND N-ALKENES IN ANTARCTIC SOIL

Hydrocarbons in soil samples from the McMurdo Dry Valleys of southern Victoria Land, Antarctica, were studied to examine their features and to elucidate source materials. Normal-alkanes and n-alkenes were found at concentrations ranging from 13 to 2200 and from 1.1 to 5000 ng/g of dry soil, respectively. Unexpectedly, the major hydrocarbons were all odd-carbon numbered long-chain n-alkanes with maximum concentrations n-C23, nC25 or n-C27. This may be due to the erosion of sedimentary materials containing vascular plant debris formed during the pre- and inter-glaciation periods of Antarctica (Miocene-Pliocene) and microbial debris, such as fungi and microalgae. Normal-alkenes maximize at n-C23:1 (carbon chain length: number of double bonds), n-C25:1, n-C27:1 or n-C29:2, which could be derived from cyanobacteria and microalgae, that lived in the past in the Antarctic cold desert and/or organic debris of wind-transported cyanobacterial mats. © 1990.