Garbage patches foul not only oceans, but deserts, too, according to study published this month in the Journal of Arid Environments. Study author Erin Zylstra found more windblown plastic bags and latex balloons than desert tortoises and western diamondback rattlesnakes in Saguaro National Park in Arizona’s Sonoran Desert. Like marine trash, desert debris could threaten wildlife and ecosystems.
Zylstra originally went to the desert to conduct fieldwork on desert tortoises. At the same time, she and her colleagues spotted not just tortoises, but litter — lots of it. “We just started to notice that there were a lot of these balloons and plastic bags around,” said Zylstra, a Ph.D. student at the University of Arizona.” That’s when the researchers figured that while surveying tortoises, they might as well survey the trash, too.
So for two summers, Zylstra and colleagues surveyed selected tracts of desert from two study areas on opposite sides of Tucson. They used a technique called distance sampling, which allowed them to closely estimate the density of trash in each tract, even if they missed a few pieces. They recovered refuse ranging from fully intact bags and balloons to dried-up fragments. Most balloons turned up as deflated bouquets tied with string, some so disintegrated they looked like lichens growing on rock.
Contrary to what she expected, Zylstra didn't find more trash alongside roads than she did further away. Her results suggested that wind could carry plastic bags and balloons more than two kilometers into remote wilderness. She also observed that dispersal of the trash followed seasonal winds.