Spatial variability of caesium-137 inventories at reference sites: an example from two contrasting sites in England and Zimbabwe

Abstract

Bomb-derived caesium-137 ( 137Cs) fallout has been widely used to investigate rates and patterns of soil erosion and sediment deposition. Within this approach considerable importance is placed on establishing the local total 137Cs fallout or inventory at a reference site. However, relatively little information currently exists concerning the variability of 137Cs inventories at reference sites. This paper reports an investigation of the spatial variability of 137Cs inventories at two contrasting reference sites at Yendacott, England and Msana, Zimbabwe. Replicate bulk soil cores were collected at the intersections of a grid, yielding 60 and 27 samples from Yendacott and Msana, respectively. Although the total variability may be derived from four sources (random spatial, systematic spatial, sampling and measurement), the observed variability was in both cases primarily due to random spatial variations in 137Cs inventories. The reference inventory range (at the 95% confidence level) was 205–230 and 17.0–33.4 mBq cm −2 for the Yendacott and Msana sites, respectively.