Kline J.R., Colon J.A., Brar S.S. Distribution of 137 Cs in Soils and vegetation on the island of Puerto Rico. Health Physics Pergamon Press 1973. Vol 24, pp. 469-475.
Soils and vegetation of Puerto Rico were collected along five north-south transects of the island and analyzed for 137Cs content. The results showed an apparent gradient of this nuclide with high amounts in the eastern samples and low amounts in the western samples. Activity in samples was strongly related to rainfall patterns on the island; however, high mountain forests were much more highly contaminated than could be accounted for on the basis of rainfall deposition alone. This was attributed to the properties of vegetation itself, rather than alteration of deposition patterns. The vegetation is suggested to have high aerosol interception efficiency and low turnoever rates, which could combine to produce the observed concentations. The data were used to test and reject the hypothesis that observed 137Cs distribution on the island was due to changes in atmospheric aerosol scavenging efficiency. Data from soil samples suggest that the island has intercepted a minimum of 535 Ci of 137Cs from past nuclear weapons tests.