NATURAL REMEDY?
EPA to begin next phase of downstream Pine River carbon study in superfund cleanup effort
The testing will help scientists understand how much the carbon reduces bioavailability of contaminants to animals, and if successful could reduce cleanup costs significantly.
The U.S. Environmental Protection Agency is set to begin the second phase of an ecological study that is using activated carbon to reduce contamination in the Pine River floodplain downstream from the St. Louis municipal dam.
The investigation is being done by Dallas-based contractor Jacobs Engineering, which is also working on the remediation of the former Velsicol Chemical Co. plant site.
“Initial results showed that activated carbon is effective at binding to contaminants like DDT reducing its ability to harm the environment,” EPA Community Involvement Coordinator Diane Russell said in a press release. “Additional studies are necessary to understand if this technology can be carried forward as a possible remedy.”
EPA researchers sampled earthworms from the test area, located in a portion of the Pine River floodplain along Union Street and Riverside Drive north of town, both before and after the activated carbon was applied.
The results showed an approximate 60 percent reduction in DDT concentrations in earthworms after the application, Russell noted.
The granular activated carbon charcoal was spread over the 45,000 foot test area.
The location was selected based on previous remedial investigation activities, which included the collection and analysis of floodplain soils, a small mammal toxicological study and a food web analysis.
The studies indicated DTT and its metabolites, as well as PBB in the floodplain soils were adversely impacting ecological receptors including soil invertebrates, specifically earthworms, and organisms that feed on the invertebrates.
Other impacts found was a reduced biomass and diversity, poor reproduction, diminished abundance and abnormal behavior in robins and shrews.
“Also, as part of the investigation, Alma College is performing supporting work using Solid Phase Micro-extraction (SPME), which is a specialized laboratory test that mimics how animals in the ecosystem absorb chemicals like DDT from the soils,” Russell said. “That absorption process is known
as bioavailability.”
The testing will help scientists understand how much the carbon reduces bioavailability of contaminants to animals, and if successful could reduce cleanup costs significantly, she added.
“Initial results are very positive and show that SPME may be a valuable monitoring tool in the future,” Russell said.
Additional research objectives during the next phase include:
• Assess whether application of higher concentrations of activated carbon further reduces bioavailability.
• Assess whether tilling the activated carbon into the soil further reduces bioavailability to earthworms.
• Assess whether activated carbon poses toxicity or other adverse effects to the survival and growth of earthworms.
• Assess what species of earthworms are present and does the application of activated carbon affect species differently.
• Assess pre- and postcarbon application data to determine what impact the reduction in bioavailability, as result of the carbon amendment application, has on ecological risk.
“Additional studies are necessary to understand if this technology can be carried forward as a possible remedy,” Russell said.