glasses of water
The presence of the element arsenic in drinking water poses health concerns, and new research led by a University of Oregon geologist hints that microbes that convert arsenic in nature from toxic to less worrisome forms might be given a boost to help them remove harmful amounts of arsenic from drinking water sources.
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Arsenic, a chemical element that occurs naturally in organic and inorganic forms, poses a problem when it comes to drinking water.
It cycles through various forms in the environment and can poison humans and pose cancer risks if exposure exceeds certain levels.
Consequently, understanding how it cycles and finding new approaches to its removal from drinking water sources would have its benefits.
To that end, research published online March 9 in the journal Nature Geoscience might provide some help.
University of Oregon geologist Qusheng Jin led a team that tested wells in the Creswell area, following residents' complaints about high levels of arsenic in their groundwater.
Water is considered safe to drink if total arsenic levels remain below 10 micrograms per liter, or the equivalent of the Environmental Protection Agency's 0.010 milligrams per liter maximum contaminant level. Levels above that pose cancer and other health risks, and Jin's team found levels of a form of arsenic at 16.5 ug/L in 10 of 23 wells they sampled. The wells are connected to an aquifer comprised of volcanic materials and river sediments.
Qusheng Jin
Jin's team was interested in the role microbes might be playing in transforming arsenic from its more toxic, inorganic forms into organic, gaseous ones that can rise and become trapped in soils, where they pose less concern.
The researchers conducted laboratory incubation experiments with arsenic compounds taken from the wells and aquifer microbes to see how well they converted the compounds.
They found that microbial activity "in aquifers has the potential to transform 100 tons of inorganic arsenic" per year into organic forms. In soil, inorganic arsenic is transformed by living organisms on the order of 420 to 1,250 tons per year, they wrote.
When ethanol was added to one of their lab experiments, it boosted the aquifer microbes' transformational activity, and therein lies an idea for how the team's basic research might be useful: Ethanol could be used as part of a cost-effective process to help speed up the microbial conversion process, lowering arsenic levels in drinking water, Jin told Southern Oregon University's Jefferson Public Radio.
The research was funded by the National Science Foundation.
-- Susannah L. Bodman, sbodman@oregonian.com, www.facebook.com/Sciwhat.Science, Twitter: @Sciwhat