Microbial bloom formation in a high pH spent nuclear fuel pond

Area of Science:

• Environmental microbiology
• Nuclear engineering
• Bioremediation

Background:

• Nuclear facilities host microorganisms in extreme environments.
• Microbial blooms in legacy spent nuclear fuel ponds reduce visibility and hinder operations.
• The First Generation Magnox Storage Pond (FGMSP) at Sellafield experiences unstudied microbial blooms.

Purpose of the Study:

• To investigate the microbial community responsible for blooms in the FGMSP.
• To understand the factors influencing bloom formation and control.
• To assess the potential of cyanobacteria for radionuclide bioremediation.

Main Methods:

• Physiological measurements and high-throughput next-generation sequencing (16S rRNA gene analysis).
• In situ probes targeting photosynthetic pigments.
• Comparative analysis with an adjacent spent nuclear fuel pond.

Main Results:

• Cyanobacterial blooms were identified, dominated by a genus closely related to Pseudanabaena.
• Microbial community profiles differed between the FGMSP and the adjacent pond.
• Bloom onset correlated with reduced pond purging rates; re-establishing purging controlled blooms.

Conclusions:

• Pseudanabaena sp. dominates microbial blooms in the FGMSP, impacting nuclear facility operations.
• Pond purging regimes are effective in controlling cyanobacterial blooms.
• Cyanobacteria tolerant to extreme environments show potential for radionuclide bioremediation.