Mobilization of Arctic permafrost carbon is expected to increase with warming-induced thawing. However, this effect is challenging to assess due to the diverse processes controlling the release of various organic carbon (OC) pools from heterogeneous Arctic landscapes. Here, by radiocarbon dating various terrestrial OC components in fluvially and coastally integrated estuarine sediments, we present a unique framework for deconvoluting the contrasting mobilization mechanisms of surface vs. deep (permafrost) carbon pools across the climosequence of the Eurasian Arctic. Vascular plant-derived lignin phenol 14C contents reveal significant inputs of young carbon from surface sources whose delivery is dominantly controlled by river runoff. In contrast, plant wax lipids predominantly trace ancient (permafrost) OC that is preferentially mobilized from discontinuous permafrost regions, where hydrological conduits penetrate deeper into soils and thermokarst erosion occurs more frequently. Because river runoff has significantly increased across the Eurasian Arctic in recent decades, we estimate from an isotopic mixing model that, in tandem with an increased transfer of young surface carbon, the proportion of mobilized terrestrial OC accounted for by ancient carbon has increased by 3-6% between 1985 and 2004. These findings suggest that although partly masked by surface carbon export, climate change-induced mobilization of old permafrost carbon is well underway in the Arctic.
Feng, X., Geological Institute, Eidgenössiche Technische Hochschule Zürich, 8092 Zurich, Switzerland, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States; Vonk, J.E., Geological Institute, Eidgenössiche Technische Hochschule Zürich, 8092 Zurich, Switzerland, Department of Earth Sciences, Utrecht University, 3584 CD Utrecht, Netherlands; Van Dongen, B.E., School of Earth, Atmospheric, and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, United Kingdom; Gustafsson, O., Department of Applied Environmental Science, Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden; Semiletov, I.P., International Arctic Research Center, University of Alaska, Fairbanks, AK 99775-7340, United States, Pacific Oceanological Institute, Russian Academy of Sciences, Far Eastern Branch, Vladivostok 6900, Russian Federation; Dudarev, O.V., Pacific Oceanological Institute, Russian Academy of Sciences, Far Eastern Branch, Vladivostok 6900, Russian Federation; Wang, Z., Center for Macroecology, Evolution, and Climate, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark; Montluçon, D.B., Geological Institute, Eidgenössiche Technische Hochschule Zürich, 8092 Zurich, Switzerland, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States; Wacker, L., Laboratory of Ion Beam Physics, Eidgenössiche Technische Hochschule Zürich, 8093 Zurich, Switzerland; Eglinton, T.I., Geological Institute, Eidgenössiche Technische Hochschule Zürich, 8092 Zurich, Switzerland, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States
Recommended Citation:
Feng X.,Vonk J.E.,Van Dongen B.E.,et al. Differential mobilization of terrestrial carbon pools in Eurasian Arctic river basins[J]. Proceedings of the National Academy of Sciences of the United States of America,2013-01-01,110(35)