TY JOUR TI THE CHANGE OF THE PEAT ELEMENT COMPOSITION AND OPTICAL PROPERTIES UNDER THE THERMAL MODIFICATION INFLUENCE KW peat KW type KW decomposition extent KW heat treatment KW element structure KW functional groups KW absorption strips KW optical density KW chemical structure JO Bulletin of KSAU AU Chukhareva, N.V. AU Tikhova, V.D. AU Zarubina, O.N. AU Shishmina, L.V. PY 2013 IS PB Krasnoyarsk State Agrarian University