Content of lipids in Finnish peat mires

Yields of acetone extracts of 45 peat samples from different depth levels in 10 mires in Finland were determined.The acetone soluble lipids of the samples were analysed by high resolution gas chromatography.Further, the monomers of acetone-insoluble lipid polyesters in the extractive-free peat samples were analyzed by gas chromatography after alkaline treatment. Considerable between - and within - mire variation in the yields of the acetone extracts occurred: the extract yield ranged from 36 mg/g to 159 mg/g dry peat.The amount of lipid components analyzable by gas chromatography in the acetone extracts varied between 8 mg/g dry peat and 6S mg/g, the average proportion of the dry extract being 40 % w/w.The n alkanoic acids, the hydroxyalkanoic acids and the n alkanols were the principal lipid component groups in the acetone extracts and together made up 78 - 91 % of all the analyzable acetone soluble lipids.The yield of peat wax, obtained by precipitation of acetone soluble components in cold ethanol, ranged from 15 mg/g to 73 mg/g dry peat.The amount of alkali hydrolyzable monomers obtained from the extractive free peat samples was on average 76 % of the amount of the lipids obtained by acetone extrac tion.The ~ alkanoic acids, hydroxyalkanoic acids and n alkanols were the principal lipid monomers.Extraction of peat with solvents other than acetone, i.e., benzene-ethanol, methylene chloride and hydrocarbon solvent (b.p. 80 - 110 °C) resulted in considerable differences in extract amount.However, all solvents removed approximately the same amounts of monofunctional straight chain lipid components from the peat, but di- and polyhydroxy alkanoic acids were incompletely dissolved by hydrocarbon solvent. The natural variations in the amount and lipid composition of the acetone extracts were considerable, and several peat-sample characteristics seemed to affect the extract amount and composition.Raised bog peat was richer in acetone extract, wax and lipids than aapa mire peat.The Sphagnum peat from both raised bogs and aapa mires contained more acetone extract, wax and sterols than the Carex and Bryales peats from the same mire types.At many sampling points, the middle layer of the mire was richest in extracts and lipids.