Dissolved Organic Carbon Flux Misattribution in Peatland-Dominated Catchments: Reassessing Allochthonous vs. Autochthonous Contributions Under Accelerated Permafrost Thaw Regimes

Abstract

Contemporary biogeochemical carbon budgets for boreal and subarctic peatland-dominated catchments have systematically conflated allochthonous and autochthonous dissolved organic carbon (DOC) fluxes, introducing significant error into regional greenhouse gas accounting frameworks. This study integrates stable isotope tracing (δ¹³C, Δ¹⁴C), parallel factor analysis (PARAFAC) of chromophoric dissolved organic matter (CDOM), and high-frequency in situ optical sensing across three instrumented catchments in northern Fennoscandia to critically re-evaluate DOC source apportionment under active thermokarst expansion. Results demonstrate that autochthonous aquatic primary production contributes 18–34% more DOC than current terrestrial-export models assume, fundamentally altering net ecosystem carbon balance estimations. These findings necessitate revision of carbon flux parameterizations embedded in Earth system models and challenge the validity of existing peatland carbon offset accounting protocols.