Mountaintop mining pollution has distinct chemical signatures

Aug 15, 2013

Three elements commonly found at elevated levels in an Appalachian river polluted by runoff from mountaintop coal mining have distinctive chemistries that can be traced back to their source, according to a Duke University-led study.

The distinctive chemistries of sulfur, carbon and strontium provide scientists with new, more accurate ways to track pollution from mountaintop mining sites and to distinguish it from contamination from other sources.

"Essentially, we found that these elements have unique isotopic fingerprints, meaning we can use them as to quantify mountaintop mining's relative contribution to contamination in a watershed," said Avner Vengosh, professor of and water quality at Duke's Nicholas School of the Environment.

The newly identified tracers will be especially useful in with more than one source of potential contamination, he said. "Because they allow us to distinguish if contaminants are coming from , fracking and development, , disposal, or other causes."

Vengosh and his team's findings were published today in the online edition of the peer-reviewed journal Environmental Science & Technology.

The researchers measured the chemical and isotopic compositions of water samples collected monthly from 23 locations along West Virginia's Upper Mud River and its tributaries between May and December 2012.

They found that the isotopic signatures of sulfur (in sulfate), carbon (in dissolved inorganic carbon) and strontium from water samples collected from tributaries adjacent to mountaintop mining sites are distinguishable from those collected from unaffected upstream waters. They also found that the strontium isotope ratio is a sensitive tracer for selenium contamination, one of the major pollutants of mountaintop mining.

In , companies use explosives and heavy machinery to clear away surface rocks and extract shallow deposits of high-quality coal. The companies typically dispose of the waste rock in adjacent valleys, where they bury existing headwater streams.

Previous studies by the Duke team and others have shown that runoff from these "valley fills" contains elevated levels of salts and selenium, a known fish toxin. The contamination can persist and accumulate in downstream waters for decades after active mining stops and the fills are reclaimed.

By conducting tests that simulated the natural leaching of contaminants from local rocks, Vengosh and his team were able to characterize the chemistry of the different geological formations that end up as waste rock in these fills. They found significant differences in strontium isotope ratios and selenium concentrations in streams flowing from reclaimed valley fills versus those flowing from active fills.

"This helps us further pinpoint the source of contamination by linking it directly to the type of rocks in the valley fills," Vengosh said.

The Upper Mud River flows through sparsely populated areas of southern West Virginia as a headwater stream. For about 10 kilometers, the river passes through the Hobet 21 surface mining complex, which has been active since the 1970s and is among the largest in the Appalachian coalfields.

Explore further: Australia set to pay polluters to cut emissions

More information: "The Isotopic Imprints of Mountaintop Mining Contaminants," Avner Vengosh, T. Ty Lindberg, Brittany R. Merola, Laura Ruhl, Nathaniel R. Warner, Alissa White, Gary S. Dwyer and Richard T. Di Giulio. Environmental Science & Technology, August 15, 2013 DOI: 10.1021/es4012959

add to favorites email to friend print save as pdf

Related Stories

New study documents cumulative impact of mountaintop mining

Dec 12, 2011

Increased salinity and concentrations of trace elements in one West Virginia watershed have been tied directly to multiple surface coal mines upstream by a detailed new survey of stream chemistry. The Duke University team ...

Recommended for you

Australia set to pay polluters to cut emissions

12 minutes ago

Australia is set to approve measures giving polluters financial incentives to reduce emissions blamed for climate change, in a move critics described as ineffective environmental policy.

TransCanada seeks approvals for pipeline to Atlantic

10 hours ago

TransCanada on Thursday filed for regulatory approval of a proposed Can$12 billion (US$10.7 billion) pipeline to carry western Canadian oil to Atlantic coast refineries and terminals, for shipping overseas.

Does it help conservation to put a price on nature?

14 hours ago

Putting a price on the services which a particular ecosystem provides may encourage the adoption of greener policies, but it may come at the price of biodiversity conservation. Writing today in the journal ...

Reef-builders with a sense of harmony

15 hours ago

Cold-water corals of the species Lophelia pertusa are able to fuse skeletons of genetically distinct individuals. On dives with JAGO, a research submersible stationed at GEOMAR Helmholtz Centre for Ocean Research Kiel, scientists ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.