Weathering Rates for Mined Lands Exponentially Higher Than Unmined Sites

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Mountaintop removal, a coal-mining technique used in much of Central Appalachia, is an extreme form of surface mining, that excavates ridges as deep as 600 feet — twice the length of a football field — and buries adjacent valleys and streams in bedrock and coal residue. This mining activity has long been known to have negative impacts on water quality downstream.

Mountaintop removal, a coal-mining technique used in much of Central Appalachia, is an extreme form of surface mining, that excavates ridges as deep as 600 feet — twice the length of a football field — and buries adjacent valleys and streams in bedrock and coal residue. This mining activity has long been known to have negative impacts on water quality downstream.

A new study led by watershed scientist Matthew Ross at Colorado State University found that many of these water quality impacts are caused by a dramatic increase in the chemical weathering rates of mined landscapes, which are melting away bedrock up to 45 times faster than unmined areas. In addition, the weathering has global consequences for the cycling of sulfur, which is a key nutrient for all life forms.

The findings show that when people move large quantities of bedrock and soil to build cities or to extract resources, they can completely alter and accelerate the natural weathering processes on land, which can impact water quality downstream.

Ross, an assistant professor in the Department of Ecosystem Science and Sustainability, described the chemical weathering rates as one of the highest rates ever observed, when compared to landscapes across the globe.

Read more at Colorado State University

Image: Assistant Professor Matthew Ross said the chemical weathering rates are one of the highest rates ever observed. (Photo: John Eisele/CSU Photography)