Spatial distribution of the vulnerability for ¹³⁷Cs and ⁹⁰Sr in Spanish soils considering the food chain pathway

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

Abstract

The main aim of this work is to determine the geographical distribution of the potential soil capacity to transfer ¹³⁷Cs and ⁹⁰Sr in Spanish soils. The behaviour of these radiological contaminants in the soil is of key importance to determine the vulnerability, which in this case is related with the availability and transferability of the contaminants. Therefore, the transfer of the contaminants through the food chain pathway (soil-plant) is considered to be within a maximum depth of 60 cm in the soil. A categorisation of the contaminant behaviour is carried out considering soil processes, which are influenced by pedological and hydrological factors. Separate indexes are determined, namely water availability, physicochemical retention and a K or Ca content for the respective contaminants. Combining these individual indexes, a final index is obtained representing the results divided into five classes ranging from a minimum to a maximum vulnerability. The results are obtained using data from 1655 Spanish soil profiles, which are introduced into a Geographic Information System data base. A cartographic reference map, based on the soil map of the European Communities, is used to determine a regional distribution of the most representative soils found within Spain. The distribution for the potential transferability of ¹³⁷Cs and ⁹⁰Sr is represented by determining the most frequent value for the different soil types from results obtained for the individual soil profiles.