Simulating the mobility of meteoric 10Be in the landscape through a coupled soil-hillslope model (Be2D)

Meteoric Be-10 allows for the quantification of vertical and lateral soil fluxes over long time scales (10(3)-10(5) yr). However, the mobility of meteoric Be-10 in the soil system makes a translation of meteoric Be-10 inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric Be-10 on a hillslope. The model consists of two parts. The first component deals with advective and diffusive mobility of meteoric Be-10 within the soil profile, and the second component describes lateral soil and meteoric Be-10 fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering as well as downslope fluxes of soil due to creep, water and tillage erosion. Synthetic model simulations show that meteoric Be-10 inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings. Our results also show that meteoric Be-10 can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric Be-10. However, the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric Be-10 profiles and inventories. Application of the Be2D model to natural conditions using data sets from the Southern Piedmont (Bacon et al., 2012) and Appalachian Mountains (Jungers et al., 2009; West et al., 2013) allows to reliably constrain parameter values. Good agreement between simulated and observed meteoric Be-10 concentrations and inventories is obtained with realistic parameter values. Furthermore, our results provide detailed insights into the processes redistributing meteoric Be-10 at the soil-hillslope scale. (C) 2016 Elsevier B.V. All rights reserved.