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in the News

Carbon storage measured in the Amazon River basin
Radiocarbon measurements of the Amazon River basin indicate that the watershed is returning carbon to the atmosphere much faster than scientists believed. This project, led by Emilio Mayorga of the University of Washington and Anthony Aufdenkampe of the Stroud Water Research Center, found that carbon outgassing from the waters in the 6.2-million-square-kilometer basin had been stored in the surrounding landscape for about 5 years. Tom Brown from Livermore’s Center for Accelerator Mass Spectrometry (CAMS) and researchers from Rice University and University of São Paulo, Brazil, collaborated on this study.
Each year, the trees, plants, and soil of the Amazon rainforest absorb millions of tons of carbon dioxide during photosynthesis. As components of these organic materials decompose, rains and groundwater carry the produced carbon compounds into waterways. Microorganisms, insects, and fish in the waterways ingest that carbon and then generate carbon dioxide, which quickly returns to the atmosphere.
Previous measurements indicated that carbon in the downstream sections of the Amazon basin was 40 to more than 1,000 years old. Those findings led researchers to believe that tropical forest regions might store carbon for decades or even centuries. These regions thus might serve as a potential site for the long-term storage of atmospheric carbon dioxide, the human-produced greenhouse gas. However, in the recent radiocarbon survey, researchers found that the cycle time is much shorter. That is, most of the landscape carbon entering the basin waters was from very recent sources and was rapidly returned to the atmosphere rather than being carried downstream and sequestered in longer term deposits.
Livermore’s University Relations Program and CAMS funded the carbon-14 measurements. The team’s results appeared in the July 28, 2005, issue of Nature.
Contact: Tom Brown (925) 423-8507 (tabrown@llnl.gov).

Truck armor kits deployed to Iraq
Gun truck armor kits developed by Laboratory researchers are now providing convoy protection for U.S. troops on the roads of Iraq. Livermore researchers created a modular, easy-to-assemble armor protection kit that, with the addition of several machine guns, allows the military to convert 5-ton supply trucks into gun trucks to protect convoys. About 30 trucks have been outfitted with the armor protection kits and are being used in convoys on Iraqi roads. Kits for another 80 trucks have been requisitioned.
The main threats to convoys are hidden bombs or improvised explosive devices, sometimes followed by ambushes. Thus, the kit designers’ primary goal was to protect truck occupants from the initial blast. The gun truck kits have proven popular and helpful to U.S. soldiers in Iraq. In fact, one transportation battalion honored the Livermore team with a commendation for exceptional service.
Each gun truck kit consists of readily available, low-cost armor steel and ballistic fiberglass panels, designed to provide a wall of protection around the back of the truck and for the truck cab. The side walls are topped by transparent armor to protect machine-gun operators. In addition to having a simple design and ample ballistic redundant protection, the kits can be assembled by a team within 5 hours and are easy to repair.
Livermore’s Manufacturing and Materials Engineering Division completed the first prototype gun truck in March 2004. After ballistics and safety testing at the U.S. Army’s Aberdeen Proving Ground in Maryland, the prototype was shipped to a transportation battalion at Camp Anaconda in Balad, north of Baghdad. Since then, the Laboratory has transferred the technology to U.S. companies for production. AB Fabrication and Machining of New Holland, Pennsylvania, is the project’s main contractor. Other participating firms include Waco Composites of Waco, Texas; Conklin Equipment Company of Fallbrook, California; and Protective Armored Systems of Lenoxdale, Massachusetts.
Contact: Steve DeTeresa (925) 784-6513 (deteresa1@llnl.gov).

Radiocarbon dating used to study the brain
A research collaboration between CAMS and the Karolinska Institute in Sweden applied carbon dating to DNA to confirm that cells in the brain live longer than other cells. Carbon dating is typically used in archeology and paleontology to date the age of artifacts. However, in this application, which was described in the July 15, 2005, issue of Cell, the scientists used the pulse of radiocarbon to pinpoint, within 2 years, the birth dates of individual cells.
Radiocarbon, or carbon-14, is naturally produced by the interaction of cosmic rays and air and is present at low levels in the atmosphere and food. Its concentration has remained relatively constant during the past 4,000 years. But atmospheric testing of nuclear weapons from 1950 to 1963 produced a global increase in atmospheric radiocarbon.
In the Livermore–Karolinska collaboration, the team used carbon dating to determine whether the body creates neurons after birth. Because DNA does not exchange carbon after cell division, it provides a time capsule for pinpointing cells’ date of birth.
Using research cadavers, the scientists dated neurons in people born before 1950 and after 1963—the year aboveground nuclear testing ended. The neurons in people born before 1950 showed no spike in radioactive carbon from the atmospheric testing. Those born after 1963 had levels consistent with the level of atmospheric radiocarbon at the time of their birth. The team concluded that neurogenesis does not occur in the cortex after birth—people do not produce new neurons during their lives.
The research collaboration received funding from the National Institutes of Health and the multinational Human Frontier Science Program. Further research will delve into other brain regions to determine the origin of neurodegenerative diseases.
Contact: Bruce Buchholz (925) 422-1739 (bbuchholz@llnl.gov).

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UCRL-52000-05-10 | October 7, 2005