Scientists at the U.S. Department of Energy's Los Alamos National Laboratory today released preliminary results of analyses of soils for radioactive materials, metals and trace elements.
The soils were collected in mid-June at the request of the Santa Fe Farmers' Market Task Force. A research team that included personnel from the New Mexico Environment Department and the Laboratory collected samples from four farms in Abiquiu, Embudo, Española and Ojo Sarco. The farms were located in areas directly downwind of the fire and represent areas receiving the heaviest amounts of smoke and ash. In addition, the team collected samples from farms located in Pecos and Cochiti -- areas upwind of the fire.
The preliminary analyses indicate that radionuclide and other trace element concentrations found in soils upwind of the fire are similar to those found in the downwind soils. In addition, the farm soil samples had concentrations similar to those from samples taken before the fire, from 1992 to 1999, as part of the Laboratory's environmental surveillance activities.
None of the pre-fire or post-fire contaminant levels presents any increased health risk to the public.
"The preliminary data show that the Cerro Grande Fire did not affect soil resources of farmers located downwind of the Cerro Grande Fire," said Phil Fresquez of the Laboratory's Ecology Group, leader of the sampling team. "We know that people were concerned about this issue so I am pleased that we are able to present these data in a timely manner. Once the data are validated, they will be posted on the Laboratory's Emergency Rehabilitation Team Web site (http://www.lanl.gov/worldview/news/fire/ert/)."
Researchers tested soil samples for radionuclides such as tritium, strontium-90, cesium-137, uranium, plutonium-238, 239 and 240, and americium-241 as well as for gross alpha, beta and gamma radiation. In one radioactivity screening measurement out of 18 taken, gamma radiation was slightly elevated. That sample indicated a gross gamma level at 5.5 picocuries per gram of soil, compared to a previously measured background level of 4.1 picocuries per gram. The one elevated level, however, is still below the background range of 8.5 picocuries per gram found in regional soils collected between 1995 to 1999.
Because concentrations of cesium-137, a gamma emitter, in farm samples were well within previously measured background concentrations, the slightly elevated gamma level likely is the result of naturally occurring isotopes that emit gamma radiation and not from any Laboratory-derived contaminant, Fresquez said.
The only preliminary radionuclide data not yet received by the Laboratory, for americium-241, should be available in the coming weeks.
The Laboratory did not expect to find increased concentrations of metals and many other trace elements in soils downwind of the fire. The preliminary data support this expectation: metal and trace element levels in downwind soils did not increase compared to background concentrations previously measured or compared to farms upwind of the fire.
"The primary reason that we did not expect to see elevated levels of metals in farm soil samples is because concentrations of metals in plants, especially plants growing in alkaline soils around the Laboratory, are low and it would take a lot of ash on the soil to increase levels by any measurable extent," Fresquez said. "And, during our sampling of these farms, we did not notice any ash on the soil surface. In fact, there were no changes in metal concentrations in soils sampled around the perimeter of the Laboratory, much closer to the fire than the farms."
The results have been shared with the Farmers' Market Task Force and were presented to the public today at a regularly scheduled meeting of the Laboratory's Emergency Rehabilitation Team.
If validated data results differ greatly from the preliminary results presented today, the Laboratory will hold another public meeting to discuss those results.
Information and data from the Laboratory's ongoing environmental surveillance activities can be found on the world wide web at http://www.esh.lanl.gov/esh/envireports.htm.
"The issue of contamination as a result of the fire was of great public concern," said Dennis Erickson, leader of the Laboratory's Environment, Safety and Health Division. "The Laboratory has been and continues to be responsive to those concerns, and we will continue to share data with the public in the weeks and months to come. That is our responsibility as a good neighbor."
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and the Washington Division of URS for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.