by Galina LEONOVA, Dr. Sc. (Geol. & Mineral.), Vladislav BOBROV, Cand. Sc. (Geol. & Mineral.), Anna BOGUSH, Cand. Sc. (Geol. & Mineral.) and Anton MALTSEV, Junior Research Fellow, Sobolev Institute for Geology and Mineralogy, RAS Siberian Branch Sapropel (<Gr. saprós, rotten, putrefying + pēlós, dirt or silt) is organic mud present in benthic sediments, a valuable raw material with many application domains in agriculture, industry, medicine and other areas. Although research scientists have been showing a long time interest in sapropels, these silts are not much in use for lack of credible information on their formative conditions, genesis, classification and chemical composition. IN NATURE'S LABORATORY Sapropels are found in the silt of stagnant bodies of water like lakes or ponds, old river beds and quiet seacoast inlets. Such organic mud is formed from plankton, a mix of dead benthic organisms, algae, aquatic plants (macrophytes) and also from organic matter (humus) and inorganic substances (clay, sand) carried in. All that is turned into sapropels through various biochemical, microbiological, mechanical and physicochemical processes. Sapropels are akin to peats, though of finer structure. We also know of intermediate biogenic sediments, the peaty sapropels, found in shallow lacustrine waters overgrown with water plants. Such sapropels are high in стр. 28 the remains, not decomposed in full, of water and land plants. In her monograph published in 1960 Dr. Nina Corde, expert in biostratification, ranked sapropels into those containing above 50 percent of organic matter and those low in it (from 4 to 50 percent). Phyto- and zooplankton, or small water plants and animals, are playing a part in the formation of organic mud sapropels provided there are certain essential conditions for that, such as normal growth in a body of water, conservation of nondecomposed leftovers of organic matter in bottom sedime ... Читать далее