Methodological approach for the categorisation of the soil vulnerability. A Spanish case study

CIEMAT, Centro de Investigaciones Energéticas, Medioambientales y Tecnologicas, Avda. Complutense 22, 28040 Madrid, Spain

Abstract

The aim of the study is to develop a qualitative method to estimate the radiological vulnerability of soils to a radiocaesium contamination. In this context, the vulnerability is defined as the soil potential, to transfer or retain, the radionuclide deposited, according exclusively to its own soil properties. Two exposure pathways are considered, the internal exposure from the ingestion and the external irradiation exposure. The methodology combines hydrological and pedological processes, including specific soil parameters and properties, which are qualitatively represented by means of vulnerability indexes. All the input data needed for the assessment are collected from any complete and normalised soil sample analysis. The results obtained, identify the soil vulnerability in five indexes, that vary from a minimum to a maximum potentiality to transfer or fix the deposited radiocaesium. These allow the categorisation of the associated human exposure and could constitute a previous step in the design of an intervention strategy for the recovery of a contaminated area. The methodology has been applied to the different soil types of the Spanish Peninsula. For a same soil type, a wide variability of indexes is observed. This is expected, as the same soil type has a different evolution regarding the parent material and climate. The influence of the exposure pathway is also reflected, as the methodology considers different critical soil horizons in each case.