Scientists at the Center for the Inland Bays found slightly elevated levels of the heavy metals selenium and arsenic in two, bottom-of-the-food-chain, aquatic species collected near a former coal ash disposal site in Indian River.
But the levels aren’t high enough to cause disruptions in reproduction and were comparable to other areas in the state and region, according to the report, released Friday.
Still, the center is calling on state environmental officials to keep an eye on the issue especially under the scenario that rising sea levels ultimately will lead to more erosion of the old coal ash disposal site at Burton Island.
“Conditions could change due to rising water levels and/or changes in the rate of groundwater movement,” said Bart Wilson, the center scientist who led the project. Wilson recommended “that tissue and sediment samples are periodically analyzed to evaluate changes in the prevalence and concentration of elements.”
The center board decided to look at the potential impact the eroding dump was having on species in the bay when area residents came to the nonprofit and said they were concerned about the legacy of heavy metals from the old coal ash disposal site. Waste ash from the Indian River Power Plant was dumped on 144 acres of the 214-acre island where the power plant was built from 1957 to 1979. A new disposal site went online in 1980 and the old area was closed and covered.
State environmental officials, who had been monitoring the site, grew concerned when they noticed in 2005 that the shoreline was eroding on the ash site. Working with NRG, the current power plant owner, they developed a plan in 2008 to stabilize the shoreline and stop the erosion.
But amid that discussion, area residents grew concerned about whether the erosion that already had occurred released contaminants into the environmentally sensitive upper Indian River. The issue became a priority for the center’s Citizen Advisory Committee.
Rick Greene, a senior environmental engineer with the state environmental agency, said the center’s report points to no significant problem for the ecosystem, especially since the levels of selenium and arsenic found were on par with what has been found in other places in Delaware and the region.
“If there is a problem in the Inland Bays, then there’s a problem everywhere,” he said. The report findings were “good news.”
Although the two species tests were ribbed mussels and a minnow-like species of fish called a mummichog, Greene said selenium doesn’t bio-magnify as it works up through the food chain like some chemicals do. The two species are not typically eaten by humans.
The center’s work built on earlier studies that were undertaken to better understand the environmental impact of the coal ash disposal area. Coal that was burned at the plant created two types of waste: fly ash and bottom ash. Initially, both were disposed of at the on-site landfill but the bottom ash eventually was used to build roads at the facility. Some of the fly ash was used to build a containment berm around the island.
Center scientists worked with Dr. Fritz Reidel, senior scientist at the Trace Element Lab at the Smithsonian Environmental Research Center in Shady Side, Md. The environmental center studies trace elements in ecosystems.
Wilson said they selected ribbed mussels because they typically live three to four years and are bound to one location. The mummichogs typically stay in a small area over their lifespan, he said.
Mummichogs from the area near Burton Island showed higher levels of arsenic. The ribbed mussels had elevated levels of selenium.
They looked at a wide variety of metals in the area sediments and the two sample species both at the Burton Island site and at a nearby, uncontaminated location on Pepper Creek.
Among the chemicals they looked for were arsenic, cadmium, cooper, chromium, mercury, nickel, lead, zinc and selenium.
Because the ash disposal site was a known contaminated site, Wilson said they weren’t sure what they would find and were “pleasantly surprised” when levels of selenium didn’t reach toxic thresholds.
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