Dartmouth scientists and their colleagues have found that periphyton—a community of algae, bacteria and other natural material living on submerged surfaces - is helping to transform mercury pollution from a Superfund site along a New Hampshire river into a more toxic form of the metal.
The study also found lower than anticipated levels of methylmercury in crayfish, mayflies and small fish downstream from the former chemical plant along the Androscoggin River in Berlin, N.H., despite elevated methylmercury in the sediment, water and periphyton.
The results, which shed light on mercury dynamics within rivers and their food webs, appear in the journal Environmental Toxicology & Chemistry.
Methylmercury is a highly toxic form of mercury and the form that most easily passes up the food chain where it can reach high concentrations in predator fish. In aquatic systems, mercury is transformed into methylmercury in a complex biogeochemical process mediated by bacteria. Periphyton, which consists of algae, bacteria, fungi and detritus attached to submerged rocks, plants and other surfaces, is a fundamental part of aquatic ecosystems and can be a primary food source for small fish and invertebrates.
Researchers at Dartmouth and the U.S. Geological Society set out to determine whether mercury originating from the Superfund site enters the lower levels of the river's food chain. The mercury comes from a chlor-alkali facility that produced chlorine used in the manufacture of paper at the adjacent pulp mill from 1898 to the 1960s. They found surface sediment next to the site had methylmercury levels up to 40 times higher and total mercury levels up to 30 times higher than other reaches of the river. Mercury concentrations in the water next to the site were up to five times higher than downstream.
Methylmercury is a highly toxic form of mercury and the form that most easily passes up the food chain where it can reach high concentrations in predator fish. Credit: USGS The potential for periphyton to produce methylmercury was highest next to the site as a result of high bacterial activity and low periphyton density, though periphyton methylmercury production rates in other reaches of the river were close to or below reporting limits. Methylmercury concentrations within the periphyton significantly increased from upstream to downstream. Contrary to the scientists' expectations, methylmercury concentrations in crayfish, mayflies and shiners didn't increase downstream from the site like large adult fish concentrations shown in previous studies. Total mercury and methylmercury bioaccumulation in small fish and invertebrates varied with no clear patterns of distribution downstream.
Radioactive super-geniuses at Dartmouth have been studying the spread of mercury leaking into the Androscoggin:
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Mark Hayward of the Union Leader filed the following story from an undisclosed location ten stories below the surface of Wilton. Moonlighting state workers started getting overtime pay for their second, part-time state job in early January, once the state decided it was a single employer and realized overtime rules would apply across state agencies, a spokesman for Gov. Maggie Hassan said on Wednesday. According to a report released by the Department of Health and Human Services , 23,210 people in New Hampshire selected plans through the Health Insurance Marketplace leading up to the December 15 deadline for coverage beginning Jan. 1, 2015. About 69 percent of those were determined eligible for financial assistance to lower their monthly premiums. Fully 59 percent were enrolling for the second time. James Pindell smuggled the following lines concern the decline of local press through the bars of the Montreal City Jail to the waiting editors of NH Magazine: Looking back on 2014, the biggest New Hampshire political change is the local press. There was no moment that changed it all. What happened in the past year was simply the continuation of a trend from the last 20 years, but 2014 was the year that the bottom fell out. I have to admit, I find it a little delicious that the NH Libertarian Party is challenging a new state voting law in Federal Court given their views on federalism. John DiStaso at NH Journal received intelligence of the latest happenings: The New Hampshire Civil Liberties Union today praised the U.S. District Court’s refusal to dismiss a lawsuit by the Libertarian Party of New Hampshire challenging a new state law the party and NHCLU say restricts ballot access and “voter choice” in the state. In a long-ish overview of NH's economic situation, Bob Sanders of NH Business Review fishes around for some clarity about where the economy is going. “We are back from where we were,” summed up Annette Nielsen, an economist with the state Economic and Labor Market Information Bureau at the New Hampshire Employment Security. “But the economy looks different.” One and a half cheers I guess.
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