Fig. 1From: Critical accumulation of fertilizer-derived uranium in Icelandic grassland AndosolUranium concentrations (a) and stocks (b) in Andosol soils with the treatments of different P application rates at Sámstaðir and Geitasandur long-term experimental sites in Iceland. Error bars are the standard deviation of treatment replicates. Different letters indicate significant differences among the treatments with a significant level of p < 0.05Back to article page