Michelle Walvoord '94, who majored in geology at Hamilton and is now a post-doctoral researcher at the United States Geological Survey (USGS) in Denver, has published new research in the November 7 edition of Science. A team of USGS and university scientists led by Walvoord found that desert subsoils in parts of the southwest contain large reservoirs of nitrates that had been previously unrecognized in desert nitrogen budgets.
"This is a finding that raises questions about how desert ecosystems work," said Walvoord. "The results also have implications for potential groundwater nitrate contamination following major land-use or climate change in natural deserts," she said.
According to the USGS, nitrogen is thought to be a scare resource in desert ecosystems that limit plant productivity and is therefore tighly retained in the soil. This new USGS research challenges this concept with the idea that nitrogen, in the form of nitrate, has been episodically leaching through the soil zone since the arid climate shift occurred in the southwest U.S. 10,000 to 16,000 years ago. The USGS study sites were located in the Mojave, Sonoran and Chihuahuan Deserts, as well as the High Plains region and northern New Mexico.
