Lipids in the surface water of the Karevansuo virgin bog, southwestern Finland

Abstract

Lipidic matter was isolated from surface water of a virgin bog (Karevansuo bog) in southwestern Finland and analyzed for its free and bound lipid content and composition using GC and GC-MS techniques. The natural lipid abundance in the surface water was 0.9 ppm accounting for 2% of the total dissolved organic matter. The major part (92.6%) of the dissolved lipids were non-volatile lipid polymers. The rest included free lipid monomers (3.5%) and other volatile material (3.9%) as minor constituents. Nearly 10% of the non-volatile matter was susceptible to hydrolysis under saponification to give a 12% total yield of lipid monomers. The fatty acid fraction, being composed of normal saturated C 12–C 30 acids and C 16 and C 18 monounsaturated acids, comprised the major group with 86% and 53% proportions of free and bound lipid monomers, respectively. Other important compound groups included C 16–C 28 even-carbon ω-hydroxy acids (1%, 28%), C 12–C 30 l-alkanols (10%, 10%), and C 8–C 10 and even-carbon C 16–C 28 α,ω-alkanedioic acids (0%, 6%) with small amounts of n-alkanes (C 19–C 33) and odd-carbon n-alkan-2-ones (C 17–C 23). Some sterols and triterpenoids were also detected. The distribution of the surface water lipids was similar to those obtained from Carex and Sphagnum peats by water extraction. The principal sources of the surface water lipids were higher plants but a small biogenic contribution could also be observed. The genesis and development of the Karevansuo bog was also studied including climatic factors, forest vegetation and its utilization.