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Carbon burial in soil sediments from Holocene agricultural erosion, Central Europe
Author(s) -
Hoffmann Thomas,
Schlummer Manuela,
Notebaert Bastiaan,
Verstraeten Gert,
Korup Oliver
Publication year - 2013
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/gbc.20071
Subject(s) - floodplain , holocene , drainage basin , sediment , erosion , hydrology (agriculture) , geology , sedimentary rock , total organic carbon , environmental science , terrestrial ecosystem , ecosystem , geochemistry , geomorphology , oceanography , ecology , geography , cartography , geotechnical engineering , biology
Natural and human‐induced erosion supplies high amounts of soil organic carbon (OC) to terrestrial drainage networks. Yet OC fluxes in rivers were considered in global budgets only recently. Modern estimates of annual carbon burial in inland river sediments of 0.6 Gt C, or 22% of C transferred from terrestrial ecosystems to river channels, consider only lakes and reservoirs and disregard any long‐term carbon burial in hillslope or floodplain sediments. Here we present the first assessment of sediment‐bound OC storage in Central Europe from a synthesis of ~1500 Holocene hillslope and floodplain sedimentary archives. We show that sediment storage increases with drainage‐basin size due to more extensive floodplains in larger river basins. However, hillslopes retain hitherto unrecognized high amounts of eroded soils at the scale of large river basins such that average agricultural erosion rates during the Holocene would have been at least twice as high as reported previously. This anthropogenic hillslope sediment storage exceeds floodplain storage in drainage basins <10 5 km 2 , challenging the notion that floodplains are the dominant sedimentary sinks. In terms of carbon burial, OC concentrations in floodplains exceed those on hillslopes, and net OC accumulation rates in floodplains (0.7 ± 0.2 g C m −2 a −1 ) surpass those on hillslopes (0.4 ± 0.1 g C m −2 a −1 ) over the last 7500 years. We conclude that carbon burial in floodplains and on hillslopes in Central Europe exceeds terrestrial carbon storage in lakes and reservoirs by at least 2 orders of magnitude and should thus be considered in continental carbon budgets.