Modelling the biological half-life and seasonality of 14C in Fucus vesiculosus from the east coast of Ireland: Implications for the estimation of future trends

► Carbon-14 levels measured in Fucus vesiculosus collected on the east coast of Ireland. ► Numerical model applied to estimate transit times from Sellafield source. ► Mean availability time of 14C in seaweed also calculated. ► Inclusion of model parameter accounts for potential seasonal variability of C-14. ► Levels reduced to background within 2.5 years of discharges being set to zero.