Biomonitoring of the Vltava River radioactivity

Abstract

In 1996-2000, before the nuclear power plant starting in South Bohemia (Czech Rep.), the monitoring of the Vltava River, where the liquid radioactive effluents will be discharged, was accomplished. The biomonitoring of the hydrosphere was made by means of water plants and freshwater bivalve. Under given conditions, the water mosses Hygrohypnum ochraceum and Fontinalis antipyretica seem to be the most suitable plants. As to riverbank plants, Polygonum hydropiper species and the reed Glyceria maxima and Phalaris arundinacea were chosen. The freshwater bivalve Anodonta cygnea (L). Was also sampled. The 137 Cs mass activity values of the hydrobionts range from 100 to 101 Bq.kg-1 dry weight and its time course for the plants is descending: the ecological half-life estimations range from 1 to 5 years. As to natural radionuclides: 40 K prove the highest values of mass activity (of the order of 102 Bq.kg-1 d. w.), while the radionuclides of actinium series prove the lowest ones (often under the detection limit). The radionuclides of uranium and thorium series are between these two extremities. The radioactivity of bivalve is low and practically constant during the five years period. The biomonitoring of the hydrosphere will be carried on after NPP running in 2001.