RADIOACTIVE REMEDIATION OF AQUATIC ECOSYSTEMS USING MICROALGAE

Radionuclides that have entered the environment through nuclear weapon tests, nuclear accidents or other human activities represent an ecological hazard. Many decontamination techniques are technically and financially demanding and often not environmentally beneficial. A suitable alternative is bioremediation techniques. One of them, phycoremediation utilizes the metabolic activity of microorganisms that degrade or eliminate contaminants from the environment. In our work, we focused on phycoremediation with microalgae Dunaliella salina and Chlorella vulgaris. An important parameter was the determination of the optimal pH values of the environment and subsequent monitoring of the radionuclide activity decline over time.

Cryoconite as an efficient monitor for the deposition of radioactive fallout in glacial environments

Cryoconite is extremely rich in natural and artificial radionuclides, but a comprehensive discussion about its ability to accumulate radioactivity is lacking. A characterization of cryoconite from two Alpine glaciers is presented and discussed. Results confirm that cryoconite is among the most radioactive environmental matrices, with activity concentrations exceeding 10,000 Bq kg−1 for single radionuclides. Atomic and activity ratios of Pu and Cs radioactive isotopes reveal that the artificial radioactivity of Alpine cryoconite is mostly related to the stratospheric fallout from nuclear weapon tests and to the 1986 Chernobyl accidents. The signature of cryoconite radioactivity is thus influenced by both local and more widespread events. The extreme accumulation of radioactivity in cryoconite can be explained only considering the glacial environment as a whole, and particularly the interaction between ice, meltwater, cryoconite and atmospheric deposition. Cryoconite is an ideal monitor to investigate the deposition and occurrence of natural and artificial radioactive species in glacial environment.