Nuclear waste found to move with groundwater

Approximately 50 percent of all Americans get their drinking water from groundwater sources, according to EPA

By Environmental News Network staff

(ENN) -- Scientists studying the movement of groundwater have found that radioactive contaminants can migrate over long distances faster than originally thought.

This finding has enormous implications for current and future waste disposal facilities, according to the scientists who have been conducting field tests at Oak Ridge National Laboratory in Tennessee.

The research is reported in the Nov. 11 Web edition of Environmental Science & Technology, a journal of the American Chemical Society.

Approximately 50 percent of all Americans get their drinking water from groundwater sources, according to EPA.

Using non-radioactive surrogates injected into groundwater as tracers, the scientists found that dissolved humic material, naturally formed in soils during decomposition of plant matter, can bind radionuclides and prevent them from being retained in the soil, thereby speeding the migration of the contaminant.

"The tracers moved at almost the same speed as the groundwater," said the report's lead author John McCarthy, Ph.D., of the Oak Ridge facility, and were observed 10 to 80 meters from the injection site within a week or less. "This information opposed the results of laboratory tests that suggested contaminants strongly bind to the soil and move only centimeters a year."

"The results have significant implications as to the role that even typically low levels of dissolved humics in groundwater can play in contaminant mobility with respect to existing waste facilities and future repositories," said McCarthy.

There are thousands of waste disposal sites in the U.S. that handle hazardous materials, many of them operated by the Department of Energy, the Department of Defense or EPA, according to McCarthy. However, "we don't know how ubiquitous this facilitated transport process is because these sorts of studies have not been conducted elsewhere," he cautions. "I don't want to be an alarmist about this study," he adds.

The testing was carried out in conjunction with researchers from the University of Tennessee and Colorado State University.

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