Some parts of the state had consistently higher levels, including the central, western and northeastern Ohio; areas with lower levels included northwestern and southwestern Ohio.
The authors say that as rocks weathered over time to create the soils, the rocks released arsenic that became part of the soil. They believe that other conditions, such as consistently wet soils, reduced levels of arsenic in some areas of the state, such as northwest Ohio.
"Many processes can break down bedrock, spread the material, and potentially mobilize the arsenic so it leaches out," said Venteris. "How much arsenic is present in a given location depends on what was originally in the bedrock and how that rock has been altered over time through complex erosion and chemical weathering processes. The result is that arsenic levels vary significantly but predictably within a region."
Influence of industrial activity
The team found no correlation between industrial activity and arsenic levels. Soils from some industrial areas in regions with high baseline arsenic levels, such as Columbus, Cleveland and Youngstown, had higher levels, for instance, while soils near other industrial areas like Cincinnati, Dayton and Toledo in the southwestern or northwestern parts of the state had lower levels.
Levels from soil samples 18 to 24 inches below the surface were on average almost 50 percent higher than levels in the topsoil more evidence that high levels are due to geological conditions and not human activity, Venteris said.
Basta said the findings could help regulators weigh risks and remediation efforts involving arsenic. That's frequently a concern when builders create new homes or other structures.
|Contact: Tom Rickey|
DOE/Pacific Northwest National Laboratory