The Distribution of Alpha-Radioactivity in Native Vegetation

Curtis, J; Dix, Ralph

SUMMARY: 1. Analysis of the soil and of the plants in a variety of plant communities in Wisconsin and the southern Appalachian Mountains for alpha-emitting substances showed that a considerable concentration occurred in the Ao soil layer. This concentration was greatest in coniferous forests growing on loess-free, igneous soils in cool climates. Such forests had an acid, mor humus, and the apparent accumulation was correlated with certain unknown properties of the humus, since the tree species showed uniform and relatively low concentrations in their living leaves. The humus beneath hemlock trees showed the greatest alpha-radioactivity. 2. A number of other rare elements were similarly concentrated in the mor humus of coniferous forests, including copper, gallium, lead, and zirconium. The high concentrations reached by these elements and the radioactive substances, indicate that the immediate soil environment of tree seedlings and many forest herbs may be very different from that expected from ordinary soil analyses in the region.