Rare earth elements are finding their way into Colorado water supplies, driven by changes in climate, finds new research.

Rare earth elements are necessary components of many computing and other high-tech devices, like cell phones and hard drives. But there is growing recognition that they can be hazardous in the environment even at low levels of concentration.

«This is of concern because their concentrations are not monitored and there are no water quality standards set for them,» says study author Diane McKnight, who is an INSTAAR Fellow and engineering professor at the University of Colorado Boulder.

The study is the first to look at how rare earth elements move within a watershed that is rich in minerals. It is also the first to investigate how climate change, by altering stream flow and natural weathering processes, is releasing more rare earth elements into streams.

Diane McKnight has led her students in investigations of water quality in the Snake River watershed of Colorado since the 1990s. Their main focus has been measuring and observing acid rock drainage. In this process, rocks that include sulfide-based minerals, such as pyrite, oxidize when exposed to air and water. The resulting chemical reaction produces sulfuric acid and dissolved metals like iron, which drain into streams. More acidic water can further dissolve heavy metals, like lead, cadmium, and zinc, and as it turns out can carry rare earth elements as well.

«What really controls the mobility of rare earth elements is pH. Acid literally leaches it out of the rocks,» says first author Garrett Rue, who earned a masters degree studying limnology with McKnight and a subsequent PhD from CU Boulder.

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Materials provided by University of Colorado at Boulder. Original written by Shelly Sommer. Note: Content may be edited for style and length.