Evaluation of the environmental transfer parameters for 131I and 137Cs using the contamination produced by the Chernobyl accident at a site in central Italy

Abstract

This paper describes some simple methods for evaluating the transfer parameters for 137Cs and 131I within the deposition-vegetation-milk pathway (dry-deposition velocity, washout-proportionality constant, weathering-decay constant, vegetation-interception factor, transfer factor from vegetation to cow's and sheep's milk). These methods were applied to the contamination data collected at a site in central Italy (Anguillara Sabazia—ENEA CRE Casaccia Institute) following the Chernobyl accident. The values calculated here are approximately equal to those generally used in conservative models (e.g. IAEA Safety Series No. 57). The only estimated parameter which differs significantly from the accepted conservative value is the dry-deposition velocity of 137Cs. This discrepancy is not surprising; indeed, the dry-deposition velocity is influenced by a variety of factors, such as the nature of the depositing particles, the properties of the surface on which deposition occurs and the micrometeorological conditions. This parameter, then, shows a high degree of variability according to the particular circumstances of deposition.