Understanding long-term soil processes using meteoric 10Be: A first attempt on loessic deposits |
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| Institution: | 1. INRA, UR1119 Géochimie des Sols et des Eaux, F-13100 Aix en Provence, France;2. Aix-Marseille Univ., CEREGE, UMR CNRS 7330, BP80, 13545 Aix-en-Provence, Cedex 4, France;3. Laboratoire de Géographie Physique (UMR 8591 CNRS-Univ. Paris I) Environnements quaternaires et géoarchéologie, 1 Place Aristide Briand, F-92195 Meudon Cedex, France;1. Saint-Petersburg State University, 7/9 Universitetskaya nab., Saint. Petersburg, 199034, Russia;2. B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC“Kurchatov Institute,” Orlova roshcha, Gatchina, 188300, Russia;1. TECLIM, George Lemaitre Center for Earth and Climate, Earth and Life Institute, Université Catholique de Louvain, Louvain-La-Neuve, Belgium;2. Leibniz Centre for Agricultural Landscape Research (ZALF) e.V., Institute of Soil Landscape Research, Eberswalder Straße 84, 15374 Müncheberg, Germany;3. INFOSOL, INRA, Orléans 45000, France;4. Earth and Life Institute—Environmental Sciences, Universite catholique de Louvain, Croix du Sud 2/10, 1348 Louvain-la-Neuve, Belgium;5. Fonds de la recherche Scientifique, FNRS Rue d''Egmont 5, 1000 Brussels, Belgium;1. Geology Department, Middlebury College, Middlebury, VT, 05753, USA;2. Department of Geosciences, Penn State University, University Park, PA 16802, USA;1. Siparia District Health Facility, South West Regional Health Authority, Trinidad and Tobago;2. Unit of Public Health and Primary Care, Faculty of Medical Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago;1. SUERC, University of Glasgow, UK;2. School of History, Classics & Archaeology, University of Edinburgh, UK;3. School of Mathematics & Statistics, University of Glasgow, UK |
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| Abstract: | Meteoric 10Be, due to its high affinity with soil and sediment particles, is widely used in geomorphologic and environmental studies attempting to evaluate the soil production/denudation rates or soil ages up to 107 years. However, the evolution of the 10Be distribution as a function of depth is poorly known in soils as revealed by recent reviews (Graly et al., 2010; Willenbring and von Blanckenburg, 2010). In this study, 10Be concentrations in the bulk and the 0–2 μm (lutum) granulometric fraction of samples along Luvisols profiles developed from loess in Northern France have been measured. The bulk 10Be concentrations are significantly higher in one of the three sites, likely reflecting differences in the inherited 10Be concentrations of the loess parent material as well as in the accumulation rates of the later. However, the bulk 10Be concentrations along all profiles are significantly correlated with the lutum (0–2 μm fraction) content, the maximum 10Be concentrations being evidenced in the Bt-horizon. Dominant adsorption of 10Be to the lutum has been furthermore corroborated by the mass-balance calculations with as much as 79.8 ± 9.0% of 10Be being associated with the lutum. Contrary to the bulk 10Be concentrations, the lutum 10Be concentrations showed several maxima coinciding with shifts in the coarse to fine silt ratio. This was interpreted as a change in the loess deposit dynamic. Finally, using numerical modeling approach based on the advection-diffusion equation, an average downward migration of 10Be by clay translocation was estimated. It ranges from 0.01 to 0.08 cm yr−1. Inherited 10Be in the loess parent material represented from 64 to 71% of the total 10Be content in the simulated soils. Vertical 10Be distributions and their maximum concentrations in the Bt-horizon thus mainly result from redistribution of the inherited 10Be by clay translocation and bioturbation. |
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| Keywords: | Pedogenesis Loess Cosmogenic nuclides Clay translocation Numerical modeling |
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