CHARACTERIZATION OF SOLUBLE ORGANIC-MATTER FROM YOUSSOUFIA ROCK PHOSPHATE

Extractable lipids represent 12% of the total organic matter contained in Youssoufla rock phosphate. This soluble organic matter corresponds mainly to free, directly extractable lipids. They are dominantly neut ral lipids (neutral/acid fraction ratio: 1.5). Gas chromatographic-mas s spectrometric studies showed for the alkanes a bimodal distribution C-15-C-21 and C-22-C-33 dominated, respectively, by C-18 and C-27. The dominant hopanes were identified under the thermodynamically stable a lpha beta-form. alpha beta beta-steranes were also present with the no n-diagenetic alpha alpha alpha- and beta alpha alpha-steranes. Phytane and pristane deriving from the transformation of chlorophyll chains w ere also identified. Acids were saturated linear C-12-C-30 acids with a predominance of the C-16 and C-18 members, unsaturated C-16:1 and C- 18:1 acids and even dicarboxylic acids. The results obtained suggest t hat the organic matter present in the phosphate has a marine origin wi th a significant continental contribution. (C) 1997 Elsevier Science L td.