RADIOECOLOGY OF THE TEJO RIVER, 1981-1989

The survey of the natural and artificial radioactivity of the Tejo river has been carried out since 1975 ; although there are no nuclear power plants in the Portuguese sector of the river, they do exist upstream, in Spain. A radioecological study of the river was also accomplished between the middle of 1986 and the end of 1989 (contract (CEC) BI6-B-198-P). A brief outline of the main characteristics of the river water, sediments, and biological material, is given in the present paper and the data on the artificial radioactivity survey from 1981 to 1989 are analysed. An increase of the radioactivity in water was detected during the years 1987 and 1989 and in sediments, hydrophytes and fish during 1988 ; an attempt of explanation is done. Data appear to confirm that sediments are the best compartment to detect Cs-137 contamination in the river.