Centennial black carbon turnover observed in a Russian steppe soil
Résumé
Black carbon (BC), from incomplete combustion of fuels and biomass, has been considered highly recalcitrant and a substantial sink for carbon dioxide. Recent studies have shown that BC can be degraded. We use soils sampled 100 years apart in a Russian steppe preserve to generate the first whole-profile estimate of BC stocks and turnover in the field. BC stocks (initially 2.5 kg m-2) decreased 25% with cessation of biomass burning. BC turnover in the soil was 293 y (best estimate; range 212?541 y), much faster than inert/passive carbon in soil models. Such results provide a new constraint on theories of soil carbon stabilization. Most importantly, BC cannot be assumed chemically recalcitrant in all soils; other explanations for very old soil carbon are needed.
Origine : Accord explicite pour ce dépôt
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