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L Monte

Publications and source records attributed to L Monte.

8 recordsLinked to original sources
PubMed1997

A collective model for predicting the long-term behaviour of radionuclides in rivers.

Here I describe a collective model to predict the long term behaviour of 90Sr in river catchments. The model is applied to 11 Italian rivers contaminated by 90Sr due to nuclear explosions in the atmosphere over past decades. The uncertainty at the 68% confidence level of the model, when used as a generic tool for evaluating the concentration of the radionuclide in water, is a factor 1.8 around the predicted values. The reliability of the model output is due to the mutual compensation effects of different phenomena occurring in the catchments that lead to 'collective' behaviours which are scantily variable and uncertain despite the large range of catchment characteristics. The model is based on the assumption that the time behaviour of the 90Sr (Bq s-1) transported by water, following a single pulse of radionuclide deposition, is the sum of some exponential components. In the present paper the components were supposed characterised by the following decay constants: lambda 1 = 2.3 x 10(-7) s-1, lambda 2 = 4.2 x 10(-9) S-1 and lambda 3 = 4.2 x 10(-10) S-1. The average value of 90Sr transfer coefficient from the catchment to the river, that, in the case of a pulse deposition, is approximately equal to the ratio between the radionuclide concentration in water and the deposition, is estimated to be 0.2 m-1.

Ecosystem↗
PubMed1996

Analysis of models assessing the radionuclide migration from catchments to water bodies.

In this paper the analysis of models for assessing the migration of radioactive substances from catchments to water bodies was carried out. Comparisons are made between the mathematical form of the experimental dissolved radionuclide transfer functions (Transfer Function = the amount of radionuclide flowing per unit time from upstream drainage basin to a water body following a single-pulse deposition of radioactive substance) evaluated for rivers in Europe contaminated after the Chernobyl accident, with the "Green Functions" (Green Function = the radionuclide flow per unit time from catchment to water body calculated by the model as a result of a single-pulse input deposition) characterizing some of the most common models. Generally transfer functions are the sum of some time-dependent exponential components. The analysis showed that two main components (a short-term and a long-term component) may be detected over a period of only a few years after the accident. The comparison of transfer functions and Green functions showed that a) models based on the traditional concept of kd (the radionuclide partition coefficient soil-water) do not explain the higher value of the experimental long-term effective-decay constant for 137Cs compared with 90Sr; and b) traditional models do not explain the nonlinear dependence of the flux (Bq s-1) of dissolved 90Sr migrating through a catchment as a function of the water flux. A semi-empirical model was developed to give reason for the above effects. This model is based on phenomena of water saturation in different soil layers and on the nonreversible processes responsible for the non-availability to migration of radionuclides.

Cesium Radioisotopes↗
PubMed1995

A simple formula to predict approximate initial contamination of lake water following a pulse deposition of radionuclide.

The objective of this note is to suggest a simple approximate mathematical formula to predict the initial contamination of lakes following a single pulse of radionuclide deposition on the lake water surface. To estimate the initial concentration of 137Cs in lake water averaged over a period of few weeks, the following expression was suggested: Cw = D/(h+h delta), where D is the radionuclide deposition, h is the average depth of the lake and hD is a parameter depending on the sediment characteristics. Using a generic value of h delta = 6 m, the above formula was successfully applied to some European lakes contaminated following the Chernobyl accident.

Europe↗
PubMed1993

A predictive model for the behavior of radionuclides in lake systems.

This paper describes a predictive model for the behavior of 137Cs in lacustrine systems. The model was tested by comparing its predictions to contamination data collected in various lakes in Europe and North America. The migration of 137Cs from catchment basin and from bottom sediments to lake water was discussed in detail; these two factors influence the time behavior of contamination in lake water. The contributions to the levels of radionuclide concentrations in water, due to the above factors, generally increase in the long run. The uncertainty of the model, used as a generic tool for prediction of the levels of contamination in lake water, was evaluated. Data sets of water contamination analyzed in the present work suggest that the model uncertainty, at a 68% confidence level, is a factor 1.9.

Cesium Radioisotopes↗
PubMed1985

The Italian national survey of indoor radon exposure.

An investigation is being developed by the Comitato Nazionale per la Ricerca e per lo Sviluppo dell'Energia Nucleare e delle Energie Alternative, ENEA, to assess the indoor exposure of the Italian population. The programme, which started in 1982, includes regional and local surveys in all the administrative districts and intensive investigations of factors which influence indoor radon levels. The survey is organized by statistical areas of sampling to obtain representative samples of houses. The definition of the areas takes into account basic parameters e.g. geolithological environments, radon soil gas from underlying soils and rocks, specific activities of local building materials, climatic and seasonal variations, building technology, types of houses and town planning. The collected data may also be used for the compilation of radon risk maps to plan special monitoring and remedial actions if needed. Preliminary results concerning the above items are discussed.

Construction Materials↗