Redox potential and acidity of peat are key diagnostic physicochemical properties for the stratigraphic zones of a boreal raised bog

Abstract

Redox potential and acidity are widely used to describe soil processes and to assess the state of soils, including peat soils. This study aimed to identify the main trends in the change of peat physicochemical properties with depth below the surface of a peat deposit. The research was carried out on the Ilas bog complex, Russia, which is typical for the South White Sea bog province. Changes in peat indicators (Eh, pH, botanical and elemental composition, the number of viable cells of the main groups of aerobic and facultative anaerobic microorganisms) with depth demonstrated that the redox regime of the studied peat deposit corresponded to the moderately reduced class of organogenic soils with Eh range 100–400 mV. There was an increase in pH (from 3.3 to 4.3) and a non-monotonic decrease in Eh (from 340 to 220 mV) with increasing depth within the deposit (up to 360 cm). These results were consistent with data on the elemental composition of peat and the number of viable cells of the main groups of aerobic and facultative anaerobic microorganisms. The stratigraphic zoning of the peat deposit of a typical boreal raised bog will serve as a theoretical basis for assessing the transformation of wetland ecosystems resulting from anthropogenic pressure or climatic changes within this geographical region.