What a 1995 Study Found About Uranium in Rocky Flats Soils

A 1995 study published in the Journal of Environmental Quality examined how uranium was distributed in soils east of the Rocky Flats Plant and what those patterns could reveal about contamination from plant operations.

The study, conducted by researcher M. Iggy Litaor, began with a clear finding: soils east of Rocky Flats had been contaminated with uranium through past waste-storage practices, accidental releases of uranium-laden oils, and low-level airborne emissions from the plant.

Mapping Three Uranium Isotopes

Researchers analyzed three uranium isotopes—uranium-234, uranium-235 and uranium-238—to understand both their concentrations and how they were distributed across the landscape.

The study sampled 118 plots, combining 25 evenly spaced surface-soil samples from each plot. Researchers then used geostatistical methods to create maps of the uranium isotope distributions.

The three isotopes did not behave in the same way.

Uranium-234 showed no clear spatial pattern and appeared to be randomly distributed in soils east of Rocky Flats.

Uranium-235 showed more localized, irregular concentrations, but those concentrations did not clearly correspond with known burial or spill locations.

Uranium-238 also showed localized patterns.

Most Measurements Were Within Natural Ranges

One of the study's most important findings requires context.

Although the researchers identified uranium contamination associated with Rocky Flats operations, they reported that most of the measured uranium-234, uranium-235 and uranium-238 activities were within the natural ranges expected for uranium in soils.

The research therefore should not be summarized simply as finding widespread highly elevated uranium contamination. Instead, it documents that uranium releases occurred and examines how those uranium isotopes behaved after entering the soil environment.

Uranium Did Not Behave Like Plutonium

The uranium distribution also differed significantly from patterns researchers had observed for plutonium around Rocky Flats. The study found that proposed wind-dispersal mechanisms did not adequately explain the uranium patterns. Litaor suggested that the difference may be related to uranium being more soluble and more easily leached through soil than plutonium.

That distinction matters when trying to understand environmental contamination at Rocky Flats. Different radioactive materials can move and persist differently once released into the environment.

Why This Study Matters

This paper is useful because it adds another layer to the environmental history of Rocky Flats.

The site's contamination story is often centered on plutonium, but Rocky Flats handled other radioactive materials as part of nuclear-weapons production. This study provides peer-reviewed documentation of uranium releases and an effort to understand their distribution in the surrounding soil.

At the same time, the findings demonstrate why Rocky Flats research needs to be read carefully. Evidence that releases occurred does not automatically mean every measured concentration was unusually high, and measurements of contaminants in soil do not by themselves establish individual exposure or health effects.

The study helps document what was released, where researchers looked for it, and how uranium behaved in the Rocky Flats environment—all important pieces of understanding the site's history.

Source: M. Iggy Litaor, “Uranium Isotopes Distribution in Soils at the Rocky Flats Plant, Colorado,” Journal of Environmental Quality, Vol. 24, Issue 2, March–April 1995, pp. 314–323.