Exploring the potential for using 210 Pb ex measurements within a re-sampling approach to document recent changes in soil redistribution rates within a small catchment in southern Italy Paolo Porto a, b, * , Desmond E. Walling b , Vanessa Cogliandro a, c , Giovanni Callegari d a Dipartimento di Agraria, Universit a degli Studi Mediterranea, Localit a Feo di Vito, Reggio Calabria, Italy b Geography, College of Life and Environmental Sciences, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK c Dipartimento DIBAF, Universit a della Tuscia, Viterbo, Italy d C.N.R.-Istituto per i Sistemi Agricoli e Forestali del Mediterraneo, Sezione Ecologia e Idrologia Forestale, Rende, CS, Italy article info Article history: Received 3 December 2015 Received in revised form 21 May 2016 Accepted 29 June 2016 Available online 28 July 2016 Keywords: Excess lead-210 Re-sampling approach Erosion rates Sedimentation rates Southern Italy abstract In recent years, the fallout radionuclides caesium-137 ( 137 Cs) and unsupported lead-210 ( 210 Pb ex) have been successfully used to document rates of soil erosion in many areas of the world, as an alternative to conventional measurements. By virtue of their different half-lives, these two radionuclides are capable of providing information related to different time windows. 137 Cs measurements are commonly used to generate information on mean annual erosion rates over the past ca. 50e60 years, whereas 210 Pb ex measurements are able to provide information relating to a longer period of up to ca. 100 years. However, the time-integrated nature of the estimates of soil redistribution provided by 137 Cs and 210 Pb ex mea- surements can be seen as a limitation, particularly when viewed in the context of global change and interest in the response of soil redistribution rates to contemporary climate change and land use change. Re-sampling techniques used with these two fallout radionuclides potentially provide a basis for providing information on recent changes in soil redistribution rates. By virtue of the effectively continuous fallout input, of 210 Pb, the response of the 210 Pb ex inventory of a soil profile to changing soil redistribution rates and thus its potential for use with the re-sampling approach differs from that of 137 Cs. Its greater sensitivity to recent changes in soil redistribution rates suggests that 210 Pb ex may have advantages over 137 Cs for use in the re-sampling approach. The potential for using 210 Pb ex measurements in re-sampling studies is explored further in this contribution. Attention focuses on a small (1.38 ha) forested catchment in southern Italy. The catchment was originally sampled for 210 Pb ex measurements in 2001 and equivalent samples were collected from points very close to the original sampling points again in 2013. This made it possible to compare the estimates of mean annual erosion related to two different time windows. This comparison suggests that mean annual rates of net soil loss had increased during the period between the two sampling campaigns and that this increase was associated with a shift to an increased sediment delivery ratio. This change was consistent with independent information on likely changes in the sediment response of the study catchment provided by the available records of annual sediment yield and changes in the annual rainfall documented for the local area. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Fallout radionuclides, and more particularly caesium-137 ( 137 Cs, half-life ¼ ca. 30.2 years) and to a lesser extent excess lead-210 ( 210 Pb ex , half-life ¼ ca. 22.3 years), have now been successfully used as the basis for estimating soil redistribution rates in many areas of the world (IAEA, 2011, 2014; Mabit et al., 2008, 2014; Matisoff, 2014; Matisoff and Whiting, 2011; Porto and Walling, 2012a,b; Ritchie and Ritchie, 2008; Walling, 2006, 2012; Walling et al., 2002; Zapata, 2002; Zapata and Nguyen, 2010). Important advantages of the approach include the potential to obtain retro- spective information on soil redistribution rates (both erosion and deposition rates) on the basis of a single site visit, the spatially * Corresponding author. Dipartimento di Agraria, Universit a degli Studi Medi- terranea, Localit a Feo di Vito, Reggio Calabria, Italy. E-mail address: paolo.porto@unirc.it (P. Porto). Contents lists available at ScienceDirect Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad http://dx.doi.org/10.1016/j.jenvrad.2016.06.026 0265-931X/© 2016 Elsevier Ltd. All rights reserved. Journal of Environmental Radioactivity 164 (2016) 158e168