UM researchers aim to ID arsenic levels in Minnesota's aquifers

Odorless, colorless and tasteless, arsenic can be a stealthy killer. Linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate, arsenic in groundwater is particularly troublesome for the nearly one million Minnesotans who rely on domestic wells for their drinking water.

And while the U.S. Environmental Protection Agency has set public drinking water standards for arsenic at 10 parts per billion, the Minnesota Department of Health estimates that nearly 10 percent of the state’s domestic wells exceed those standards.

Aided by a Water Resources Center grant, University of Minnesota Soil, Water and Climate assistant professor Brandy Toner and professor Ed Nater have been sampling glacial aquifers in west central and south central Minnesota in an effort to map the stratigraphic and mineralogical sources of arsenic in groundwater.

Most arsenic in Minnesota’s groundwater is thought to be naturally occurring from rock deposits that were eroded and re-deposited by glaciers thousands of years ago. “Evidence suggests that arsenic in Minnesota’s glacial aquifers comes from naturally occurring mineral phases, but the distribution of arsenic bearing glacial deposits is unknown,” say Toner and Nater.

A better understanding of the distribution of arsenic species may also explain why in some areas well water arsenic levels are elevated, yet the overall total concentration of arsenic in the aquifer materials is not exceptionally high.

While homeowners can purchase reverse-osmosis arsenic removal systems, these systems are expensive, require routine maintenance and don’t always provide alarms for system failure. Toner and Nater's research builds towards a predictive model to identify arsenic species in glacial strata and the factors that lead to their mobilization, thereby helping Minnesotans drill their wells to depths where the probability of safe water is highest.

Arsenic research