A dynamic compartmental food chain model of radiocaesium transfer to Apodemus sylvaticus in woodland ecosystems

A study was undertaken to quantify the activity concentrations of Cs-137 in Apodemus sylvaticus (the woodmouse) in two woodland sites, Lady Wood and L ongrigg Wood, adjacent to British Nuclear Fuels Ltd. (BNFL) Sellafield, Cum bria, UK. A deterministic dynamic compartmental food chain model was also c onstructed to predict 137Cs activity concentration [Bq kg(-1) dry weight (d w)] in A. sylvaticus on a seasonal basis given the activity concentrations in its diet. Within the coniferous woodland site (Lady Wood), significant d ifferences were found between seasons (P < 0.05, summer vs. autumn cohort; P < 0.001, spring vs. autumn cohort), with an autumn peak in activity conce ntration (geometric mean = 140x/divided by2.3 Bq kg(-1) dw) being attribute d to mycophagy. Fungal concentrations ranged from 2-3213 Bq kg(-1) dw. The modelled activity concentrations fell between the confidence intervals of t he observed data in four of the six seasonal cohorts sampled. Disparities b etween predicted and observed activity concentrations are attributed to unc ertainties surrounding the fundamental feeding ecology of small mammals. (C ) 2001 Elsevier Science B.V. All rights reserved.