Modelling temporal trends of 137Cs and 99Tc concentrations in Fucus vesiculosus from the eastern Irish coastline

• Published in: Marine pollution bulletin 2011-11, Vol.62 (11), p.2337-2344
• Main Authors: Cournane, S., León Vintró, L., Mitchell, P.I., McMahon, C.A., Smith, K., Long, S.
• Format: Article
• Language: English
• Subjects: 137Cs; 99Tc; Algorithms; Animal, plant and microbial ecology; Biological; Biological and medical sciences; Cesium Radioisotopes - analysis; Coastlines; coasts; Environmental Monitoring - statistics & numerical data; Evolutionary; Fucus - chemistry; Fucus vesiculosus; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; half life; Ireland; macroalgae; Marine; Mathematical models; Methods and techniques (sampling, tagging, trapping, modelling...); Modelling; Models, Biological; Oceans and Seas; Radioactive Pollutants - analysis; Sea water; Searching; Seasonal variation; seawater; Seawater - analysis; Seaweeds; Sellafield; spectral analysis; system optimization; Technetium - analysis; Time Factors; Time series; time series analysis; water pollution
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2011.08.039

► 137Cs and 99Tc activity concentrations in brown seaweed measured during 1988–2008. ► Significant seasonal variations in time series identified using spectral analysis. ► Novel transfer kinetic model using variable uptake rate applied. ► Evolutionary and grid search minimisation techniques used to fit model. ► Concentration factor and biological half-life values determined. Time series of 137Cs and 99Tc activity concentrations in the brown seaweed Fucus vesiculosus and seawater, gathered at three locations on the eastern Irish coastline during the period 1988–2008, have been modelled using a novel approach incorporating a variable uptake rate in the seaweed. Seasonal variations in the time series, identified using spectral analysis, were incorporated into the model which was used to determine transfer kinetic parameters and to predict 137Cs and 99Tc concentrations in seaweed, as influenced by levels in ambient seawater. An optimisation method combining evolutionary and grid search minimisation techniques was adopted to determine the best values for the model parameters, from which concentration factors (CF) and biological half-lives (tb1/2) for 137Cs and 99Tc in F. vesiculosus were calculated. CF values of 170–179 and 1.1×105lkg−1 (dry weight) were obtained for 137Cs and 99Tc, respectively, while the corresponding tb1/2 values were 39–47 and 32days, respectively.