For years, the U.S. military and its allies have relied on depleted uranium (DU) for their anti-tank rounds. Twice as dense as lead, the stuff does a mean job piercing armor. But it comes with a price. Tons of DU litter battlefields around the world; the British fired almost 2 tons of DU around Bara during the Iraq invasion, for example. And unexplained illnesses always seem to follow in the rounds' wake. Nothing's been categorically proven. But a variety of ailments -- from "Gulf War Syndrome" to lung cancer -- have all been linked to the material. Cleaning it up has been an almost impossibly messy task.
But now, a New Mexico researcher may have found an answer to the problem in, of all things, the tumbleweed. A preliminary study shows that the plant, and some other flora common to dry, Western lands, "have a knack for soaking up depleted uranium from contaminated soils at weapons testing grounds and battlefields," according to a statement from the Geological Society of America.
The fact that plants absorb uranium is not news, since old uranium prospectors used to use Geiger counters on junipers to find buried uranium lodes. But finding a plant that grows fast on little water and can be easily harvested to carry away the depleted uranium that's another story...
In her study, [New Mexico Institute of Mining and Technology geologist] Dana Ulmer-Scholle and her colleagues... sought out DU contaminated soils at an inactive munitions testing ground in New Mexico. Then they planted selected native and non-native plants in a test garden and in pots to see how much DU the plants absorbed from the soil.
The tumbleweed, or Russian thistle did particularly well. So did the grain crop quinoa and the purple amaranth. None of the plants need much water or care. But "sprinkling the ground with citric acid" did seem to bolster the plants' ability to suck up DU.
As for why some plants absorb uranium, that's still a mystery, says Ulmer-Scholle. It could be that the plants use the metal to create pigments. One way she hopes to test that possibility is to grow native plants used for dyes.
Either way, Ulmer-Scholle cautions, plants will only work as a slow-burn solution to DU. For immediate clean-ups, "no plant species appears to offer a short-term alternative to traditional remediation."
THERE'S MORE: Defense Tech reader TH notes "the mysterious lack of
Gulf War Syndrome in areas where natural uranium (which is chemically identical, and more radioactive), is present in concentrations far exceeding those found on battlefields."
