C-14 characteristics of dissolved lignin along a forest soil profile

摘要

Lignin is a key component of soil dissolved organic carbon (DOC) and is recently suggested to track C-14-young DOC components. However, direct evidence is still lacking to prove this hypothesis in the soil. Here, utilizing molecular radiocarbon dating, we present the first C-14 dataset on dissolved lignin through a Podzol soil profile. Dissolved lignin and hydroxy phenols had similar C-14 content as soil organic carbon (SOC) and DOC in the surface organic layer. However, in contrast to SOC, both DOC and dissolved lignin phenols exhibited consistent and higher Delta C-14 values in the mineral soils. Coupled with lignin phenol concentration data, our results suggest that dissolved lignin comprises a key DOC component throughout this Podzol profile and is mainly supplied by surface leachates with young C-14 ages.