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LABORATORY AND FIELD RESEARCH ON LONG-LIVED RADIONUCLIDES IN THE MARINE ENVIRONMENT

Objective

- STUDY OF THE ENVIRONMENTAL BEHAVIOUR OF RADIONUCLIDES.
- COLLECTION OF DATA NECESSARY FOR MODELING THE RADIONUCLIDES TRANSFERT.
The behaviour of technecium and caesium in the estuary and lagoon environments of the Friuli Venezia Giulia region were investigated. Of particular interest were terrigenous contributions from rivers to the lagoon and the hydrological and sedimentation parameters. Information about sediment deposition rates and redistribution operated by benthic organisms was obtained.

Mechanisms involved in the accumulation of transuranium elements in some compartments of the marine environment have been studied.

Behaviour of technetium and selenium has been evaluated in the marine environment. The research activity undertaken to characterize the estuary and lagoon environments in Friuli-Venezia Giulia region, is part of a larger radioecological investigation programme promoted to improve the knowledge of radionuclide dynamics in the natural environment. Here, attention has been pointed mainly at defining terrigenous contributions from rivers to lagoon and the hydrological and sedimentological parameters. The results obtained can be summarised as follows:
the assessed radioactive fall out on the lagoon hinterland was 1 kBq per cubic metre. Within the lagoon similar values were found only in minimum sedimentation areas;
lagoon radioactive contamination is attributable to suspended particles carried from hills and mountains by the rivers;
the Tagliamento and Isonzo rivers, that flow directly into the sea, carry terrigenous sediments that are subsequently drawn into the lagoon where also detritus carried by Cormor river and by the litoraneaveneta channel accumulates;
in the eastern portion of the lagoon only a small amount of sediment accumulation is evident;
in superficial water caesium is associated mostly with suspended particles with diameter larger than 1 um. A similar remark is valid for sediments, where maximum correlation exists between caesium and 0-20 um grain size class.

Studies concerned with the behaviour of technetium and selenium in the marine environment have been carried out. The research activity undertaken to characterise the estuary and lagoon environments in Friuli-Venezia Giulia region is part of a larger radioecological investigation programme promoted to improve the knowledge of radionuclides dynamics in the natural environment. In this project, attention is directed mainly at defining terrigenous contributions from rivers to lagoon and the hydrological and sedimentological parameters. The goal is to provide more precise information about sediment deposition rates and redistribution operated by benthic organisms. The results obtained from the first years of activity lead to the following observations. The assessed radioactive fall out on the lagoon hinterland was 1 kBq per cubic metre; within the lagoon, similar values have been found only in minimum sedimentation areas. Lagoon radioactive contamination is attributable to suspended particles carried from hills and mountains by the rivers. The Tagliamento and Isonzo rivers, that flow directly into the sea, carry terrigenous sediments that are subsequently drawn into the lagoon where also detritus carried by the Cormor river and by the litoranea veneta channel accumulates. In the eastern portion of the lagoon, only a small amount of sediment accumulation is evident. In superficial water, caesium is associated mostly with suspended particles with a diameter larger than 1 aem. A similar remark is valid for sediments, where maximum correlation exists between caesium and 0-20 aem grain size class.

Studies on technetium and selenium behaviour in anoxic sediments showed high affinities of these radioisotopes for particulate matter and weak remobilisation by bioturbation caused by bottom dwelling organisms. Selenium forms were more strongly bound to anoxic sediments than technetium.
In tissues and organs of benthic fish technetium accumulation, especially in the muscle, was negligible. Thus technetiuim contamination of fish muscle will not present a hazard for man's health.
1. BEHAVIOUR OF TC AND SE IN THE MARINE ENVIRONMENT.
2. MECHANISMS INVOLVED IN ACCUMULATION OF TRANSURANIUM IN SOME COMPARTMENTS OF THE MARINE ENVIRONMENT.
3. DESCRIPTIVE MODELS FOR CIRCULATION OF RADIONUCLIDES AND TRANSFERT OF RADIONUCLIDES IN THE MARINE FOOD CHAIN.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Comitato Nazionale per la Ricerca e per lo Sviluppo dell'Energia Nucleare e delle Energie Alternative
Address
Viale Regina Margherita 125
00198 Roma
Italy