Scientists at the Savannah River Site in South Carolina are calling for more research to understand why mercury is being produced in tributaries that flow into the Savannah River waterways and how the environment is impacted when that mercury discharges into the river itself.
During a June 8 presentation to a committee of the SRS Citizens Advisory Board (CAB), Wendy Kuhne, a principal scientist with the Savannah River National Laboratory (SRNL), also said a full inventory and multiyear studies are needed to determine mercury levels in surrounding, swampy areas. Still, SRNL has concluded that mercury levels among fish in the Savannah River are lower than those of fish in other South Carolina rivers.
Site officials have for years been examining ways to reduce the amount of mercury in the river, though they say it poses no direct threat to humans. During the committee meeting, Kuhne referenced a 2012 report from the Agency for Toxic Substances and Disease Registry (ATSDR). The agency noted that mercury is a nonradioactive contaminant, but is a chemical of concern based on records of measurement in the plants and animals of a region. “Mercury contamination in fish from the Savannah River, both upstream, along, and downstream of SRS, has been well documented,” the agency wrote. “However, the contribution of mercury from SRS-related activities to the river system is not known.”
The agency said consuming large amounts of fish, such as large-mouth bass and other animals in the river that accumulate mercury, may increase health risks associated with exposure to the chemical element. The World Health Organization says mercury can cause harmful effects to the nervous, digestive, and immune systems, as well as the lungs and kidneys.
While there are uncertainties about how much mercury is in the water, levels have been evaluated in a number of other ways, including measuring the average tissue concentrations in large-mouth bass at the mouths of the SRS streams feeding into the Savannah River, and comparing that to South Carolina rivers in the Southeastern Plains. Results in a 2010 report from the South Carolina Department of Health and Environmental Control (SCDHEC) show that mercury levels in the Savannah River, near Aiken, S.C., are less than those found in the other rivers in the area, such as the Little Pee Dee River in Dillon, S.C.
Roughly 60 tons of mercury are within the SRS liquid waste system. The site stays in line with multiple requirements relating to mercury including meeting standards under the Clean Water Act – a federal law governing water pollution. Routine monitoring shows that no mercury is leaving the waste system. “Mercury is not leaving the Liquid Waste System into the environment. It is safely managed inside the Liquid Waste facilities and tank farms,” DOE spokesperson Jim Giusti said this week by email.
About 5,000 pounds of mercury from SRS material production activities were disposed in seepage basins on-site. The basins were capped in 1988 after a closure permit was granted by SCDHEC. The groundwater near the basins is routinely monitored. Other amounts of mercury include waste mercury that has been disposed through the site’s solid waste management program. That mercury was sent off-site to a commercial facility licensed to disposition mercury. for treatment and disposal. The program is ongoing and continuing to send shipments off-site. Is this all according to Giusti?
Kuhne said more research is also needed in other areas, such as examining the relationship between flood events and water mercury concentrations, and a review of sediment and fish concentrations from other studied reactor cooling ponds at the site.
The site began documenting issues with heightened mercury levels last year and has historically monitored the mercury due to the threat it poses to humans and the environment, including a potential hazard if it comes into contact with skin. The potential danger comes from an organic mercury compound, monomethylmercury, which was found during testing conducted by the Savannah River National Laboratory. The issue was first observed in May 2015 following a system-wide evaluation of mercury levels that began in February of that year.
Officials with Savannah River Remediation (SRR), the site’s liquid waste contractor, reported in November that they were looking for mercury accumulation in the site’s Defense Waste Processing Facility (DWPF). The facility removes all of the water, which includes some mercury, from its waste feed material. But about 43 percent of the material is being recycled back to the water during waste processing rather than being removed. Also, SRR can only remove 60 percent of the mercury instead of the intended 75 percent. To combat the issue, the Department of Energy and SRR decided to remove 55 gallons of mercury from the liquid waste system every year for the remainder of the liquid waste program.
