Laboratory scientists recorded the heightened levels in stormwater coming onto and crossing the Laboratory. The results indicate that the fire caused the transfer and concentration of these radionuclides from the forest canopy and in the forest litter to the ashy layer of the burned surface soil. Gallaher added that this phenomenon has been observed in other locations outside New Mexico that experienced forest fires. Through its role in the FRAT, the Laboratory plans to continue to evaluate the results for potential long-term health effects. Small amounts of Laboratory contaminants are seen in these samples, but they were also seen in pre-fire samples.
Larger storms cause significant changes in the quality of the runoff.
These changes are the direct result of the fire. Large storms often drain the heavily burned areas and carry large quantities of black ash and sediment. The levels of radioactive substances dissolved in stormwater are comparable to or slightly elevated above pre-fire levels in runoff. Dissolved gross alpha and beta levels were found to be below the U.S. Environmental Protection Agency Maximum Contaminant Limits for drinking water systems. Approximately 90 percent of the radioactivity in an unfiltered stormwater sample from a large storm is associated with the sediment and ash carried by the flood flows.