Radioactivity was first observed in 1896 by Henri Becquerel who demonstrated that uranium would fog photographic film. Shortly thereafter, it was learned that thorium and actinium were also radioactive and that there were long series of radioactive substances associated with each of these three elements. It was found that the parent elements changed successively from element to element by the emission of alpha, beta, and gamma radiations until some stable end-element was produced; in the case of these three series, the stable end-element was an isotope of lead. These naturally occurring series elements, through their radioactive daughter gases radon and thoron, have an appreciable effect upon background or air activity. These activities are washed down with rain and are carried into water supplies.

No abstract

No abstract

No abstract

Under conditions similar to Cincinnati, Ohio, fallout is the result of rainout and snowout. Without precipitation there is little fallout even though the particulate activity of surface air is abnormally high. Much of the suspended activity in cistern water from rain will be removed by sedimentation. Over 90 pct of both the suspended and dissolved fallout becomes associated with soil and vegetation rather than appearing in surface waters. From the spring of 1953 to January 1957, the fallout of strontium90 (Y90) in Cincinnati, Ohio, is estimated to be at least ten and probably not more than 30 millimicrocuries per square meter of surface area.