BLACKSBURG, Va. — Studies at Virginia Tech show that, although the metal in lead bullets and shot corrodes rapidly in the natural environment, the lead becomes trapped in the corrosion products so it cannot easily migrate away.
Research carried out by Donald Rimstidt and James Craig, professors of geological sciences in Virginia Tech's College of Arts and Sciences, shows that reactions between the lead metal and ions from the soil solutions deposit minerals like cerrussite (lead carbonate) and hydrocerrussite (lead hydroxycarbonate) onto the surfaces of the bullets and shot. Under normal conditions these minerals are quite insoluble. They form a coating on the metal that traps soluble lead, and this coating protects the metal from further corrosion.
Lead shot and bullets, dispersed at the rate of over 50,000 metric tons per year, now constitute the greatest flux of lead into the U.S. environment. A large fraction of these shot and bullets accumulate onto formal and informal shooting ranges where lead loading can be extremely high.
Rimstidt and Craig's research has documented loadings of as high as 22,000 g/m2, or 4.5 pounds per square foot. Heightened public awareness of the toxicity of lead, along with the high concentrations of lead found on shooting ranges, has caused growing concerns about the environmental impact of these highly lead-contaminated sites. This new research improves our understanding of the level of environmental risks associated with shooting ranges and suggests that there is relatively little risk that soluble lead will escape from the shooting ranges.
These studies are not only important for making management and design decisions for shooting ranges, but they explain why lead artifacts are preserved. For example, lead bullets from the Civil War have persisted in the battle field soils of Virginia for more than 100 years because of these mineral coatings.
These findings were presented at the Geological Society of American meeting in Reno in November.
The above story is based on materials provided by Virginia Tech. Note: Materials may be edited for content and length.
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