Modes of occurrence of rare earth elements in peat from Western Siberia

Selective leaching of rare earth elements (REE) from peat samples from Western Siberia indicates unanticipated modes of r occurrence. It has been determined that from 40 to 80% of the total REE in the peat is accounted for in the hydrolyzable and water-soluble substances, 10-30% of the REE is concentrated in humic acids. Minerals in peat play a minor role in the accumulation of REE. In general, no > 25% of REE is accounted for in mineral association. Among the mineral forms of REE in peat, clastogenic phosphates (monazite, xenotime, crandallite group) and zircon are the dominant hosts. REE are distributed in different phases of the peat: the water-soluble and hydrolyzable substances are relatively enriched in light REE, and humic substances are enriched in heavy REE.