Atmospheric mercury on the decline

Retiring older power plants and adding pollution-control equipment to larger plants has helped reduced the amount of atmospheric mercury in the Northeast, according to a recent study published by the American Chemical Society.

The study confirms that regional mercury concentrations are mainly affected by regional changes and are not overwhelmed by global mercury pollution, something researchers were not certain of before the study.

Coal-fired power plants are the largest human-generated source of the neurotoxin mercury to the atmosphere. Some of this mercury—in its oxidized form or bound to particles—reaches waterways, where it builds up in ecosystems and concentrates in fish, threatening environmental and human health. ...

The team found that mercury in various forms declined between 2 and 8% per year. Prior to 2000, mercury decreases were primarily attributable to decreasing emissions from waste incineration, whereas falling regional power plant emissions were behind decreases since then.

Philip K. Hopke, a study coauthor, says the recent declines in mercury are probably caused mainly by many closures of coal-fired power plants in the region due to economic drivers like the 2008 recession and a shift toward fracking and cheaper natural gas. Placing controls on power plant emissions has also helped, he says.

An abstract of the published article refers to three different kinds of mercury found in the atmosphere: gaseous element mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM). While GEN and GOM have declined, concentrations of particle-bound mercury are increasing, probably due to burning wood for heat, the abstract says.