Evolution of Organic Matter in Hummocky Bogs on the Barents Sea Coast in a Changing Climate

Abstract The influence of macroparameters (botanical composition, degree of decomposition, and radiocarbon age of peat) on the molecular composition and structure of humic acids (HAs) in hummocky bogs of the Barents Sea coast was revealed using modern physicochemical methods of analysis (13C NMR spectroscopy and gas chromatography). Predictive scenarios for the evolution of organic matter in arctic hummocky peatlands are proposed, and indicators of their response to climate change are substantiated. The molar ratios x(H) : x(C) reflect the degree of condensation of HA molecules during the Holocene, as well as a significant transformation of HAs in peat deposits of the seasonally thawed layer as a result of the current climate warming trend. The calculated indicators of the degree of oxidation reflect the dynamics of the hydrological regime of the bog. It has been shown that, as a result of the stabilization of soil organic matter, the contribution of aromatic components increases, and the contents of paraffin and carbohydrate fragments in HAs decrease. In the composition of the latter, a redistribution of the proportion of pentoses and hexoses occurs due to a change in plant communities and a decrease in the contribution of long-chain aliphatic paraffin structures.