University of Maine Arsenic Presentation

ORONO, Maine -- A University of Maine investigation of high arsenic levels in the groundwater in Northport has led to a new understanding of how the toxic element migrates under some conditions from bedrock into well water. Andrew Reeve, a hydro geologist, discussed research findings in a public meeting in Bayside on May 20. If confirmed in further research, the results suggest that in some locations, high arsenic concentrations in groundwater can be explained by conditions underground rather than by land use activities such as pesticide applications or industry.

In 1998, homeowners in Bayside, a residential community in Northport, discovered that their well water had unusually high levels of arsenic. High arsenic concentrations in well water have also been documented in other clusters around the state. The Maine Department of Human Services is currently testing water for arsenic in about 1,000 wells randomly distributed in Maine. The element can cause liver and kidney damage as well as cancer. In well water, the U.S. Environmental Protection Agency has set a maximum limit of 50 parts per billion. The highest level detected at Bayside was about 5,500 parts per billion. "When people in Bayside discovered this problem, they came to the University for help in finding out where the arsenic was coming from. We collected water samples in 1999 and 2000 and did chemical analyses for metals and other chemical parameters with the intent of finding chemical relationships that indicated a bedrock source," says Reeve. Rock samples were also collected to determine if arsenic-rich minerals are present in the bedrock. "Arsenic is often associated with other elements, such as sulfur, in bedrock. We expected to see an association between arsenic and these other elements in Bayside's groundwater. Instead, arsenic there is associated with a different set of naturally occurring elements." As a result of their work, the geologists now suggest that bedrock may indeed be the source of arsenic in Bayside, but it is obscured by a two-step chemical process. That process, they have shown, could generate arsenic in groundwater with the same chemical fingerprint found in the Bayside samples.

Reeve and his colleagues have submitted a report of their work to the journal Applied Geochemistry. Reeve is conducting his research with Stephen Norton, Charles Guidotti and Marty Yates in the UMaine Dept. of Geological Sciences and with scientists from the Maine Geological Survey and the U.S. Geological Survey. Two students, Brian Warner from Kittery Point and Michael Horesh of Orono, have also worked on the project as part of their degree programs. The Northport Village Corporation Board of Overseers sponsored Reeve's May 20 presentation.