Centennial black carbon turnover observed in a Russian steppe soil

K. Hammes (1) , M. S. Torn (2) , A. G. Lapenas (3) , M. W. I. Schmidt (1)

1 UZH - Universität Zürich [Zürich] = University of Zurich
2 LBNL - Lawrence Berkeley National Laboratory [Berkeley]
3 Department of Geography and Planning

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.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

K. Hammes, M. S. Torn, A. G. Lapenas, M. W. I. Schmidt. Centennial black carbon turnover observed in a Russian steppe soil. Biogeosciences Discussions, 2008, 5 (1), pp.661-683. ⟨hal-00297971⟩