By Sid Perkins
As they barreled across the desert toward Baghdad during the U.S.-led invasion of Iraq last March, the tanks, trucks, and armored personnel carriers churned up huge clouds of dust. Iraqi vehicles mobilized to defend against the onslaught generated their own plumes of grit. In a literal sense at least, much of the dust in Iraq has begun to settle. If history is a guide, however, the ruts the combat vehicles left behind will spew prodigious amounts of dust for years. That airborne material can cause major environmental and health problems.
As the battalions maneuvered across the arid terrain, their vehicles often broke through a delicate crust known as desert pavement. This type of veneer covers as much as half of the world’s arid lands. Despite the connotations of its name, desert pavement isn’t robust. It’s merely a thin shell of stones that lies atop the dust, soil, or sand. Multi-ton tanks easily breach these fragile mosaics, but so do dirt bikes and all-terrain vehicles. Even trudging hikers, grazing animals, and the scrabbling of rodents and birds can disrupt desert pavements, exposing subsurface material to erosion and disrupting fragile ecosystems of fungi and algae.