High Biodegradability of Water-Soluble Organic Carbon of Permafrost - Affected Soil in a Boreal Forest

Abstract

Water-soluble organic carbon (WSOC) is an important component of the organic carbon pool in permafrost regions. However, the biodegradability of WSOC across various soil depths in permafrost regions remains unclear. Here, based on spectroscopic techniques, we conducted a 28-day laboratory incubation to analyze the molecular composition, biodegradability, and compositional changes of WSOC at different soil depths in a permafrost region. The results showed that in the active layer, the average content of biodegradable WSOC was 0.214 g/kg with an average proportion of 85.63% in the total WSOC. In the permafrost layer, the biodegradable WSOC content was 0.312 g/kg, accounting for 88.21% of the total WSOC. Spectroscopic analysis indicates that the WSOC in the active layer is primarily composed of highly aromatic humic acid-like matter with larger molecular weights than those in permafrost. Both the aromaticity and molecular weight decrease with depth, and the WSOC is mainly composed of fulvic acid-like matter in the permafrost, suggesting high biodegradability of WSOC in the permafrost. Overall, our results suggest that the water-soluble organic carbon in the permafrost regions exhibits high biodegradability both in the active layer and permafrost.

Keywords: Water-soluble organic carbon, Permafrost, Forest, active layer, Spectroscopic technique