Plutonium-239, ground deposition

Plutonium is deposited on plant tissues by fallout and by resuspension from soil. Pinder et al. (1985) and Pinder McLeod (1988) measured 238Pu and 239+240pu in topsoil and in corn and sunflower foliage near the Savannah River Plant. Because the ratio of Pu isotopes in contemporary fallout was different from that in soil, Pinder et al. were able to estimate how much of the Pu on the foliage derived from the soil. They found that, at harvest, resuspended soil on foliage amounted to about 0.8 g per m2 of ground area. 

As a manufactured element, americium is not naturally present in rocks and soils. Contamination of the soil can occur either from deposition of americium or precursor plutonium originally discharged into the atmosphere, or from waste products discharged directly into or on the ground. Except for the reentry into... 

Anspaugh et al. (1975, 1976) studied resuspension at the GMX location on the Nevada Test Site, where plutonium was disseminated by small non-nuclear explosions about 30 years ago. To obtain representative values of the resuspension factor, ideally a large and uniform area of deposited activity is required, in order that there should be a constant flux layer in the air near the ground. The fallout of Pu at the GMX site is non-uniform, so Anspaugh et al. analysed their measurements of x in relation to a model calculation of the concentration expected from the areal source. 

---