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

Lignin is a key component of soil dissolved organic carbon (DOC) and is recently suggested to track 14C-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 14C dataset on dissolved lignin through a Podzol soil profile. Dissolved lignin and hydroxy phenols had similar 14C 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 Δ14C 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 14C ages. Image 1 • We present the first 14C dataset on dissolved lignin along a Podzol profile. • Dissolved phenols exhibited similar Δ14C values to SOC and DOC in surface organic layer. • Unlike SOC, DOC and dissolved lignin were enriched in 14C in mineral soils. • Surface leachate was the main source of DOC components in this Podzol profile. • Dissolved lignin may exhibit larger 14C variability in other (non-Podzol) profiles. [ABSTRACT FROM AUTHOR]