Fish bones yield new tool for tracking coal ash contamination

December 26, 2018

DURHAM, N.C. -- A Duke University study shows that trace elements in a fish's ear bones can be used to identify and track coal ash contamination in the waters where it lived.

"Calcified structures -- or otoliths -- found in a fish's inner ear are known to store a lot of life history information, including chemical and physical records of the fish's age, natal habitat and migration patterns," said Jessica Brandt, lead author of the paper and a 2018 PhD graduate of Duke's Nicholas School of the Environment. "We've shown that otoliths also capture the signatures of contaminants that have affected the fish's ecosystems."

Brant and her team found that strontium isotope ratios in the otoliths of fish from two North Carolina lakes -- both of which had received effluents from coal ash ponds at nearby power plants -- matched the strontium isotope ratios in samples collected from sediment at the bottom of the lakes.

"This shows otoliths can be used as biogenic tracers to assess the potential for ecological impacts of coal ash waste streams in affected waters," said Brandt, who is now a postdoctoral researcher with the U.S. Geological Survey. "While strontium behaves differently than the toxic elements in coal ash effluents, it helps us connect high levels of those elements back to the contamination source."

Strontium is a naturally occurring trace element in coal that retains unique isotopic ratios even after the coal is burned and coal ash comes into contact with an aquatic environment.

Past studies have used strontium isotope ratios to track coal ash's impacts on water quality, "but this is the first time we've been able to prove they can also be used as fingerprints to track coal ash's impacts in living organisms," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School, who coauthored the study.

"This definitely shows the strontium in the fish must be from coal ash contamination," Vengosh said.

The Duke team published its peer-reviewed findings Nov. 21 in the journal Environmental Science & Technology Letters.

The researchers collected surface water and sediment-based pore water samples from two North Carolina lakes -- Mayo Lake and Sutton Lake -- that were historically impounded to provide cooling water for nearby power plants and to receive their effluents. Sutton Lake was the site of a large coal ash leak into the adjacent Cape Fear River after Hurricane Florence caused flooding this fall.

The researchers also collected surface and pore water samples from two sites located upstream from the lakes, and from two other lakes -- Lake Tillery and Lake Waccamaw -- that are not associated with coal ash waste streams. The samples were then analyzed in the laboratory, along with the otoliths of largemouth bass from each of the lakes.

"Strontium isotope ratios in the largemouth bass otoliths overlapped with ratios in corresponding sediment pore waters at all lakes and reservoirs, which is compelling evidence that otoliths can serve as biogenic tracers of coal ash effluents," said Richard Di Giulio, the Sally Kleberg Professor of Environmental Toxicology at Duke, who co-authored the study.

Strontium isotope ratios in surface water samples from the lakes didn't always match those in the fish otoliths and pore water samples, Di Giulio explained, but this could be because surface water ratios are more variable over time.

"This study's finding demonstrate that otolith studies can add to our existing research efforts," said Brandt. "Water-based strontium isotope tracers only give us information about coal ash impacts at a particular point in time, but because otoliths continuously grow over a fish's lifetime, we could use time-series analyses of otoliths to determine the timing of waste stream discharges or spills going back several years. This represents an emerging and important new direction in environmental toxicology and water-quality research."
-end-
Primary funding for the study came from the North Carolina Water Resources Research Institute and the Foundation for the Carolinas. Brandt received additional support from the National Institute of Environmental Health Sciences (grant #T32-ES021432) and through a U.S. Environmental Protection Agency STAR Fellowship (#FP-91780101-1).

Other coauthors of the study were Nancy Lauer and Emily Bernhardt, both of Duke.

CITATION: "Strontium Isotope Ratios in Fish Otoliths as Biogenic Tracers of Coal Combustion Residual Inputs to Freshwater Ecosystems," Jessica E. Brandt, Nancy E. Lauer, Avner Vengosh, Emily S. Bernhardt and Richard T. Di Giulio. ; Environmental Science & Technology Letters, Nov. 21, 2018. DOI: 10.1021/acs.estlett.8b00477

Duke University

Related Water Quality Articles from Brightsurf:

A watershed moment for US water quality
A new federal rule that determines how the Clean Water Act is implemented leaves millions of miles of streams and acres of wetlands unprotected based on selective interpretation of case law and a distortion of scientific evidence, researchers say in a new publication.

'Pregnancy test for water' delivers fast, easy results on water quality
A new platform technology can assess water safety and quality with just a single drop and a few minutes.

New process could safeguard water quality, environment and health
Swansea University researchers have developed a new way to quickly find and remove wastewater pollutants, which can reduce their impact on the environment.

23 years of water quality data from crop-livestock systems
Researchers summarize runoff water quantity and quality data from native tallgrass prairie and crop-livestock systems in Oklahoma between 1977 and 1999.

Lessening water quality problems caused by hurricane-related flooding
June 1 is the start of hurricane season in the Atlantic, and with 2020 predicted to be particularly active, residents in coastal regions are keeping watchful eyes on the weather.

Control of anthropogenic atmospheric emissions can improve water quality in seas
A new HKU research highlighted the importance of reducing fossil fuel combustion not only to curb the trend of global warming, but also to improve the quality of China's coastal waters.

Pharma's potential impact on water quality
When people take medications, these drugs and their metabolites can be excreted and make their way to wastewater treatment plants.

Study: Your home's water quality could vary by the room -- and the season
A study has found that the water quality of a home can differ in each room and change between seasons, challenging the assumption that the water in a public water system is the same as the water that passes through a building's plumbing at any time of the year.

Researchers create new tools to monitor water quality, measure water insecurity
A wife-husband team will present both high-tech and low-tech solutions for improving water security at this year's American Association for the Advancement of Science (AAAS) annual meeting in Seattle on Sunday, Feb.

How anti-sprawl policies may be harming water quality
Urban growth boundaries are created by governments in an effort to concentrate urban development -- buildings, roads and the utilities that support them -- within a defined area.

Read More: Water Quality News and Water Quality Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.