Technetium-99 in the Irish marine environment

Area of Science:

• Environmental radioactivity monitoring
• Marine radioactivity assessment
• Radioecology

Background:

• Sellafield nuclear site discharges have introduced Technetium-99 (99Tc) into the marine environment.
• 99Tc is a significant artificial radionuclide with potential for bioaccumulation in marine organisms.

Purpose of the Study:

• To quantify 99Tc activity concentrations in Irish coastal seawater and biota.
• To assess the temporal trends of 99Tc in relation to discharge data.
• To estimate concentration factors and potential radiation doses to consumers.

Main Methods:

• Time series measurements of 99Tc in seawater and Fucus vesiculosus.
• Analysis of 99Tc in various seafood species (fish, crustaceans, molluscs).
• Estimation of concentration factors and committed effective doses.

Main Results:

• 99Tc activity concentrations in seawater and Fucus vesiculosus increased, mirroring Sellafield discharges.
• Activity peaked in 1997, with Fucus vesiculosus showing a 29-fold increase over baseline.
• Estimated concentration factors were higher than literature values from lab studies.

Conclusions:

• Sellafield discharges directly impact 99Tc levels in the Irish marine environment.
• Field-derived concentration factors for 99Tc are higher than laboratory estimates.
• Seafood consumption poses a low but measurable radiation dose from 99Tc.