High in the Rocky Mountains, just west of the Continental Divide, metal concentrations in the Upper Snake River have been climbing over the last 30 years, in some cases increasing as much as fourfold. Strong evidence links this trend to climate change, according to a recent study led by the United States Geological Survey and University of Colorado at Boulder.
Air and water sampling and record-keeping for the Upper Snake River, which has remained pristine for the past three decades, has been long-term and consistent. The United States Geological Survey and the Environmental Protection Agency?s records show a 30-year trend of rising temperatures, melting permafrost and dropping water tables that parallels the rise in metal concentrations, suggesting a relationship between those variables.
Because the metals are diluted by other water sources, the concentrations do not pose a direct threat to water for drinking or agriculture. ?This is not a human health issue directly, not for big downstream urban areas,? said Andrew Manning, a research geologist with the United States Geological Survey and one of the study?s principal investigators. Resort towns could potentially see metal contamination in their water sources, but the study raises broader concerns.
?Higher metal concentrations can impact the whole alpine ecosystem,? said Andrew Todd, a research biologist with the survey and the study?s primary author. At the confluence of Deer Creek and the Upper Snake River, for example, the water is sometimes milky with aluminum precipitate that blankets the riverbed and smothers life underneath. ?It?s referred to as the white death,? Dr. Todd said.
This emerging challenge for local flora and fauna is layered on top of other new stresses, like rising stream temperatures and changing hydrology.
The rise in metal concentrations also has implications for mine reclamation projects. Not five miles from the Upper Snake River, the E.P.A. has ?people underground right now? at the Pennsylvania Mine working to determine what level of remediation is required in local streams, Dr. Manning said. But ecosystem remediation practices are based on static waterborne metal concentrations.
?How do we set these standards with shifting baselines?? Dr. Manning said. ?These findings present a very big challenge for the cleanup of mine sites.?
The researchers are now looking for other long-term data sets in similarly undisturbed watersheds like the Upper Snake River, both to corroborate their findings and develop a predictive model of how mineralized watersheds might react to climate change.
?How broadly our findings carry over to other mineralized watersheds is a very important question that remains unanswered,? Dr. Manning said.
Current models of these chemical reactions are based on much smaller-scale experiments, often from work in the laboratory ?plopping a piece of rock in a beaker,? he said. ?But how this processes works on the mountain-scale remains a topic of research.?
Source: http://green.blogs.nytimes.com/2012/09/26/climate-change-metal-and-waterways/?partner=rss&emc=rss
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