March 25, 2004
Water Scientists Working to Help Small Towns Reduce Arsenic in Drinking Water
LINCOLN, Neb. — Complying with new federal limits for arsenic in drinking water could be a budget-buster for some small Nebraska towns.
University of Nebraska-Lincoln water scientists are researching low-cost methods to reduce or eliminate arsenic in drinking water. Arsenic occurs naturally in groundwater. It is linked to certain types of cancer and other health concerns, including cardiovascular, hormonal and neurological problems.
Research Hydrogeologist David Gosselin leads a UNL School of Natural Resources team that is working with 10 small Nebraska towns for these studies. These towns are among more than 75 small public water systems statewide where drinking water arsenic concentrations could exceed the U.S. Environmental Protection Agency's new standard of 10 parts per billion. This new limit, lowered from the current 50 parts per billion, takes effect in January 2006.
Most of these systems serve fewer than 3,300 people and compliance costs could easily top $120 million statewide, Gosselin said.
"There are a variety of strategies that can be applied to remove arsenic from water, but most of them are expensive, which is tough on small communities," he said.
Traditional, expensive approaches include finding a new groundwater supply, which can be a trial and error process, or treating the contaminant.
This Institute of Agriculture and Natural Resources research shows arsenic amounts in a well can vary at different times. Communities need to consider this in developing well sampling plans to meet the new EPA standards and protect human health, he said.
For example, the length of time a well has been pumping before a sample is drawn can influence the amount of arsenic found in the sample. Limited testing of wells over 24 hours showed "arsenic concentrations can change over very short periods of time," he said.
"Significant variability in arsenic concentrations can occur within the first hour after the pump is turned on, which is typically when operators sample their wells," he said. "This potentially has huge implications for procedures used to sample public water systems."
Scientists also are investigating a potential low-cost method to remove arsenic from groundwater. It involves injecting groundwater high in oxygen into the aquifer. The oxygen-charged water causes iron oxides to form, similar to rust, that naturally attract and bond with the arsenic to remove it from water. These formations remain in the aquifer and do not pose a health risk.
This technique is used in Europe to remove iron and manganese, but more research is needed to adapt it for removing arsenic from Nebraska groundwater, which typically is low in iron.
"Preliminary modeling suggests it could work, but there are potential challenges posed by Nebraska's groundwater chemistry and aquifer geology that we need to investigate further," Gosselin said.
Another possible method for removing arsenic from groundwater within the aquifer would be to create a reactive barrier around the well's intake pipe. This barrier would be composed of the normal gravel packing that surrounds a well's intake pipe underground, but would use gravel treated with iron hydroxide, which chemically attracts and bonds with arsenic and other metals, such as uranium. As the water passes through this treated gravel barrier, arsenic and other metals will naturally bond to the iron hydroxide-treated gravel and remain there as the water passes through the gravel packing.
The IANR team has sampled wells in Benkelmen, Cambridge, McCook, Stromsburg, Shelton, Elwood, Lodgepole, Broadwater, Oshkosh and Anselmo.
Research continues and Gosselin hopes to develop some recommendations within the next year.
An advisory committee representing small public water systems, the Nebraska Departments of Health and Human Services System and Environmental Quality, Nebraska Association of Resource Districts and the League of Municipalities helps guide this research.
The EPA, U.S. Geological Survey and Nebraska Department of Health and Human Services System helped fund this research, which is conducted in cooperation with IANR's Agricultural Research Division.
3/25/04-SR
David Gosselin - Ph.D.
School of Natural Resources
Professor
(402) 472-8919
Steve Ress UNL Water Center - Communications Coordinator (402) 472-3305
Department: School of Natural Resources
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