PLUTONIUM ISOTOPES IN ECOSYSTEM OF A RUNNING SHALLOW LAKE

The aim of the present work is to get information on the possibilities of the shallow lake self-cleaning from plutonium isotopes using Lake Žuvintas as an object of study. A choice of the object is mainly related to the peculiarity of hydrology and hydrodynamics of Lake Žuvintas located in the southern part of Lithuania that was affected by radioactive fallouts after the nuclear events. During the period of study the bottom sediments of Lake Žuvintas behaved mainly as an accumulator of Pu isotopes. The main part of plutonium of the Chernobyl origin in surface sediments is present in exchangeable and potentially mobile physico-chemical forms. Processes of Pu migration are especially active during winter season when under anaerobic conditions the most important role in the Pu isotopes transfer belongs to reduced plutonium ions