Content and composition of organic matter in soils of the Novaya Zemlya archipelago

For the first time, the composition of organic matter (OM) in strongly skeletal residual carbonate pelozems (Skeletic Leptosols (Loamic)), carbopetrozems (Calcaric Leptosols (Protic)), petrozems (Skeletic Leptosols (Protic)) and cryozems (Oxyaquic) in the northern part of the Novaya Zemlya archipelago was studied using granulometric fractionation. It has been shown that, regardless of the depth of the horizons in all studied objects, carbon in particulate OM (free – LFfr and occluded – LFocc) is 94–96% (on average) represented by organic C (Corg), in the clay fraction and the residue, the share of Corg decreases to 87 and 54% of the Ctotal in fraction. The level of Corg accumulation in various fractions largely determines the microbiological activity in the studied soils. The correlation coefficient (R2, P - 0.05) between Corg of specific fractions (% in soil) and the content of microbial biomass decreases in the following order: LFocc (0.59) > mA (0.53) > LFfr (0.50) > clay (0.36) > residue (0.26), reflecting the important role of soil structural units, in particular, microaggregates within aggregates (mA) that are unstable in the ultrasonic field, in providing comfortable environmental conditions for the microbiota.