Inventory and vertical migration of 137Cs in Spanish mainland soils

In this study the total activity of Cs-137 deposited per unit area over the Spanish peninsular territory was analysed using a 150 x 150 km(2) mesh grid, with samples taken from 29 points. The deposited activities ranged between 251 and 6074 Bq/m(2). A linear relationship was obtained between these values and the mean annual rainfall at each sampling point which allowed a map to be drawn, using GIS software, which shows the distribution of total deposited Cs-137 activity across the Spanish mainland. At twelve of these sampling points the vertical migration profile of Cs-137 was obtained. These profiles are separated into two groups with different behaviour, one of which includes clay and loam soils and the other containing sandy soils. For both groups of profiles the parameters of the convective-diffusive model, which describes the vertical migration of Cs-137 in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) were calculated. (C) 2011 Elsevier Ltd. All rights reserved.