AN INTERCOMPARISON OF SAMPLING TECHNIQUES FOR MEASUREMENTS OF RADIOCESIUM IN UPLAND PASTURE AND SOIL

An intercomparison of sampling procedures used by five laboratories fo r the determination of radiocaesium in vegetation and peaty soil was c arried out at two locations in Cumbria. The multiple sampling has give n information on the homogeneity of the parameters studied at each loc ation. The parameters comprise soil bulk densities, total deposition o f Cs-137, deposition of Cs-137 in three soil layers, biomass densities , concentrations of Cs-137 in pasture, and activity ratios (Cs-134/Cs- 137) in soil and vegetation. The determination of total deposition Of Cs-137 gave no indication of differences between the laboratories. The results from the soil profiles do indicate significant differences be tween laboratories. One laboratory using a coring technique observed d ifficulties during sampling due to compression of the soil. The coring technique should thus be avoided or applied with extreme care for the sampling of depth profiles in peaty soil. The results from the sampli ng of pasture show no indication of differences between the laboratori es. For the parameters studied the observed variabilities across soil depths and locations range from 10% to 81% in terms of relative standa rd deviations. A comparison across all results at the two locations in dicate a 50% higher field variability at one of the sites relative to the other.