Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 9, issue 3
Biogeosciences, 9, 1099-1111, 2012
https://doi.org/10.5194/bg-9-1099-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 9, 1099-1111, 2012
https://doi.org/10.5194/bg-9-1099-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 27 Mar 2012

Research article | 27 Mar 2012

Erosion, deposition and replacement of soil organic carbon in Mediterranean catchments: a geomorphological, isotopic and land use change approach

E. Nadeu1, A. A. Berhe2, J. de Vente3,4, and C. Boix-Fayos1 E. Nadeu et al.
  • 1Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Campus Universitario de Espinardo, 30100 Murcia, Spain
  • 2School of Natural Sciences, University of California-Merced, 4225 N. Hospital Rd, Castle #47, Atwater, CA 65301, USA
  • 3Estación Experimental de Zonas Áridas (EEZA-CSIC), Carretera de Sacramento, s/n, 04120, La Cañada de San Urbano-Almería, Spain
  • 4Department of Geography and Environment, School of Geosciences, University of Aberdeen, St. Mary's Aberdeen AB243UF, UK

Abstract. Determination of whether soil erosion can constitute a net terrestrial carbon dioxide (CO2) sink continues to suffer from lack of sufficient focused studies and field data. Two of the major gaps in our understanding of the erosion induced terrestrial carbon sink issue include rate of eroded soil organic carbon replacement by production of new photosynthate and stability of eroded organic carbon (OC) post deposition. Here we examined the effect of erosion processes and land use change on the stock, type, and stability of OC in two medium-sized subcatchments (18 and 50 ha in size) in SE Spain. We analysed soil samples from drainage areas and depositional settings for stock and isotopic composition of OC (14C and 13C), and particle size distribution. In addition, we conducted land use change analysis for the period 1956–2008 and a geomorphological survey of the current erosion processes taking place in the slope-streambed connections. Our findings demonstrate that land use change influenced the dominating erosion processes and, thus, the source of eroding sediments. Carbon isotopes used as tracers revealed that in one of the subcatchments the deposited sediments were derived from deep soil (average Δ14C of −271.5 ‰) through non-selective erosion processes and channel incision. In the other subcatchment, topsoil material was predominantly eroded and the average Δ14C in sediments was −64.2 ‰. Replacement of eroded soil OC was taking place in the analysed soil profiles in the slopes suggesting that erosion processes do not necessarily provoke a decrease in soil OC stock over time.

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