LAUSR

—The evolution of peat deposits of the Vydrino bog (southern Baikal region) and concentration of elements in them are discussed. The bog peat massif more than 4 m in thickness formed mostly during the Holocene. The beginning of peat formation dates back to the late Allerød (13.1 ka). At present, the Vydrino bog is a biogeocoenosis of the high-moor type with a transitional peat deposit. We have established that the bog nonuniformly accumulated chemical elements during its formation. Concentration of Pb, Sn, Cd, Zn, and Sb in recent vegetation and in the upper layer of the peat bog is mainly due to forest fires and anthropogenic air pollution. The anomalous enrichment of peat with Zn and Cu in the Early Holocene (12.1–8.8 ka) horizons proceeded through the periodic inflow of thermal groundwater into the bottom part of the peat deposit. Authigenic Zn and Cu sulfides formed on the inner membrane of the cell wall of sphagnum moss. Geochemical modeling has shown that Zn and Cu sulfides can form abiotically.