Disaster's Consequences: Hurricane's legacy includes arsenic
Aimee Cunningham
Within the construction debris strewn across the Gulf Coast by Hurricane Katrina is a disturbing amount of arsenic, according to a new study. The tainted rubble, as it is currently managed, might contaminate groundwater, the researchers say.
Before 2004, chromated copper arsenate (CCA) was the preservative most commonly used to prevent pest infestation of construction wood. Because of arsenic's toxicity, the Environmental Protection Agency has since banned use of the chemical for residential projects (SN: 1/31/04, p. 74:
http://www.sciencenews.org/articles/20040131/bob9.asp). However, many old utility poles, decks, and fences contain CCA-treated wood.
During March 2006, Helena M. Solo-Gabriele, an environmental engineer at the University of Miami in Coral Gables, Fla., and her colleagues surveyed debris in New Orleans. They used a handheld X-ray–fluorescence spectroscopy unit to determine the concentration of arsenic within 225 pieces of lumber from seven sites.
Of that sample, 52 pieces contained arsenic, with a mean concentration of 1.24 grams per kilogram of wood.
Hurricane Katrina generated approximately 72 million cubic meters of debris, according to the Louisiana and Mississippi departments of environmental quality. Other researchers estimate that 50 percent of this debris is construction and demolition waste, of which 33 percent is wood.
Having found that CCA-treated wood accounted for 23 percent of the wood waste that they examined, Solo-Gabriele's team estimated that 1,740 metric tons of arsenic hides within hurricane debris scattered across Louisiana and Mississippi. They
report their findings online and in an upcoming
Environmental Science & Technology.
"There's a tendency not to think about how much [CCA-treated wood] is really out there," says Solo-Gabriele. If this wood ends up in unlined landfills, which don't retain the water that percolates through the waste, arsenic might leach out and contaminate groundwater, she says.
John H. Pardue, an environmental engineer at Louisiana State University in Baton Rouge, notes that Louisiana normally bars lumber treated with arsenic from entering unlined landfills. But the emergency rules in place since Katrina lifted that ban. Solo-Gabriele's report "confirms that large amounts of arsenic are making their way into debris landfills," says Pardue.
"I believe the storm-debris landfills will be the environmental legacy of these storms," he says. "While many environmental issues were handled well after the storm, the way debris has been handled has been abysmal."
After a disaster, the control of arsenic-treated wood is "way down the list" of priorities, says environmental scientist John D. Schert of the University of Florida in Gainesville. Disposal of this wood "is a really difficult, complicated waste-management problem," he says.
