Heavy metal and acid rock are taking over in the Rocky Mountains as the climate warms, but it isn't another music festival at Red Rocks Amphitheater in Colorado.
Geologists at the U.S. Geological Survey (USGS) suggested in a recent study that warmer temperatures may be one cause of increased erosion of zinc and other heavy metals into the waterways of the Rockies. Part of that erosional process is called acid rock drainage, in which weathering of pyrite rocks forms sulfuric acid and frees heavy metals into the watershed.
"Acid rock drainage is a significant water quality problem facing much of the Western United States," lead researcher Andrew Todd of the USGS said in a press release. "It is now clear that we need to better understand the relationship between climate and ARD as we consider the management of these watersheds moving forward."
Warmer temperatures are dropping water tables in the Rockies, melting permafrost and increasing the rate of mineral weathering. These processes all contribute to increasing heavy metal concentrations. Levels of dissolved zinc found in Rocky Mountain streams have increased fourfold over the past 30 years.
High metal concentrations can destroy the life of a stream. Some waterways in the Rockies have been rendered lifeless by metal contamination from abandoned mining sites. As the Colorado Division of Reclamation Mining and Safety and other organizations work to clean up mountains, climate change may complicate matters as acid rock drainage increases the rate of heavy metal contamination.
"This study provides another fascinating, and troubling, example of a cascading impact from climate warming as the rate of temperature-dependent chemical reactions accelerate in the environment, leaching metals into streams," said USGS Director Marcia McNutt in a press release. "The same concentration of metals in the mountains that drew prospectors to the Rockies more than a century ago are now the source of toxic trace elements that are harming the environment as the planet warms."
The study was published in the journal Environmental Science and Technology.
Red Rocks Amphitheatre before a Grateful Dead concert in 1987. (Mark L. Knowles, Wikimedia Commons)