USING INTERACTION MATRICES TO DESCRIBE RADIOCAESIUM MIGRATION IN GRASSLAND ECOSYSTEMS AFTER AN ACCIDENTAL RELEASE

VELASCO, H.; JURI AYUB J.

Valdivia, Chile

Conferencia; SPERA 2004 - South Pacific Environmental Radioactivity Association; 2004

Universidad Austral de Chile

A systematic approach has been used to evaluated the trend time of the radiocaesium migration in semi-natural environments using interaction matrices. The considered system was conformed by seven compartments: atmosphere, upper soil, medium soil, deep soil, vegetation, wild life and man. The first step to build the interaction matrix was identifying relations between components, result of binary interactions. Four matrix have been considered, each one for different elapsed times since deposition event. The considered times (y) were: t=0, 1, 2 and more than 3 years after deposition. The second step was assign the coded matrix. The ranged values for the elements of this entire matrix were: 0 (null) to 4 (critic) according to the importance of the considered components relationship  for each time. The analysis carried out permits us to identify the principal path of transference in each time. Initially, the crucial processes are the activity released, the deposition on upper soil, plants and dose level of exposition. During first year the most important path is conditioned by the radionuclide mobility into soil system (upper, medium and deep soil) and the transference to grass plant. In the second year this factors persist in importance, nevertheless the transfer soil to plant are the dominant process as well as rejection process. During the third year and subsequently, the most dominant process to control the cycling of contaminant into grassland involved the recycling of contaminant into compartments soils and vegetation. The proposed methodology are usefully tool to recognize the principal compartments, process and paths of the radiocaesium transference into grassland ecosystems in each time after released.