Thursday, April 02, 2015

Green river slime converting mercury into more toxic form at NH Superfund site

The green, slimy algae commonly found coating streambeds may threaten more than unsteady waders. New research from Dartmouth College and the U.S. Environmental Protection Agency reveals that communities of algae and bacteria known as periphyton are transforming the inorganic metal into its more toxic, organic form.

The Berlin, NH Chor-Alkali Facility was responsible for manufacturing chlorine used in paper production. In 2005, the U.S. EPA added the vacant property to its Superfund list, marking it for cleanup due to the mercury, lead and arsenic concentrations found in local groundwater in spite of the slurry wall and other installations meant to contain that contamination. It wasn’t until 2009, however, that the EPA began a full investigation of the site on the banks of the Androscoggin River.

As part of that investigation, a Dartmouth College team led by research professor Celia Chen worked closely with the U.S. Geological Survey to examine mercury uptake by riverine organisms. They hypothesized that periphyton was converting mercury into methylmercury, an organic form of the metal that bioaccumulates with greater potency than its inorganic form. Mercury normally methylates in anaerobic sediment — an absent factor in the fast-moving waters near the Superfund site — but the presence of periphyton makes the process possible in a greater range of environments.

Read the article at Environmental Monitor

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