Spatial Distribution of Caesium-137

Abstract

It has been shown that 137Cs inventories have a coefficient of variation of approximately 20% at reference sites (Pennock, 2000), and that this variability is probably because of random spatial variability (Owens and Walling, 1996). At reference sites it is recommended that a grid-sampling network is employed, with the collection of three replicate cores within 1 m of each sampling point. The cores may be bulked for 137Cs analysis (Owens and Walling, 1996). While the number of samples needed to estimate the reference value within the required statistical limits will depend on the variability found during analysis, between fifteen and thirty samples will usually be necessary for an accurate estimate of central tendency (Pennock, 2000).