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The USGS has developed a new analytical method for detecting toxic chromium VI (Cr(VI)) in ground water in the field. This new method enables scientists and resource managers to distinguish between the toxic and carcinogenic Cr(VI) and the more benign form of chromium–chromium III (Cr(III))–on site. The method overcomes several obstacles that prevented past methods from being able to accurately determinate the concentration of Cr(VI) in water. Past methods were not very accurate, the instability of Cr(VI) was problematic, and expensive laboratory equipment was required for analysis. The advantages of the new method are:
The results of the field method compare well with standard laboratory-based methods.
The new method has been used to characterize chromium-contaminated ground water beneath the Mojave Desert, California, at 29 Palms Marine Corps Air Ground Combat Center, Edwards Air Force Base, and at the Sheep Creek Fan west of Victorville, California. The study found areas with high concentrations of Cr(VI) from natural sources, in addition to Cr(VI) contamination from industrial activities. The natural Cr(VI) is caused by the weathering of dark rocks, such as basalt and amphibolite, in alluvial deposits (sediments deposited by rivers and streams). In addition to distinguishing between the kinds of chromium, knowing the source of Cr(VI) is important to those tasked with cleaning up contamination and protecting drinking water resources. Resource managers can now consider sources of Cr(VI) when determining the responsibility for cleanup, the levels of cleanup required to reach background concentrations, and the regulatory structure for dealing with the contamination.
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U.S. Department of the Interior, U.S. Geological Survey
Toxic Substances Hydrology Program
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Last modified on
Friday, 09-Jul-2004 07:46:18 EDT
The URL for this document is http://toxics.usgs.gov/highlights/detecting_crvi.html