Acid Rain Problems Shift From Sulfuric To Nitric Acid

It's all that driving we like to do, combined with intensifying agribusiness operations. Acid rain problems are much more severe in the East, however, because they don't have buffering calcium carbonate in the soil, like we do in the West. Western nitrogen problems show up in other ways, however, like fish declines in the Sacramento Delta and spreading nitrates in groundwater near Lake Tahoe, and so we will have to address these matters too:

Sulfur emissions from power plants were one of the primary motivations for the U.S.'s Clean Air Act Amendments of 1990, which set reduction targets for both sulfur dioxide (SO2) and nitrogen oxides (NOx). However, whereas sulfur dioxide emissions decreased almost 70 percent from 1990 to 2008, emissions of one NOx—nitrogen dioxide (NO2)—went down only 35 percent for that same period, and amendment targets have yet to be made, according to the U.S. Environmental Protection Agency (EPA).

...Nitric acid rain is derived primarily from power plant, car and truck emissions as well as from gases released by fertilizer use. ... Agri-ammonia vapors also derive from concentrated animal feeding operations in the U.S. South. The gas rises into the air and is deposited dry or in rainfall where in the ground bacteria breaks it into nitrogen and nitric acid, which can kill fish and plants. "Agriculture is increasingly functioning as an intensively managed industrial operation, and that is creating serious water, soil, and air problems," says Viney Aneja, a professor at North Carolina State University in Raleigh. Aneja says that state's concentrated animal feeding operations may also emit particulate matter from swine and chicken manure into the atmosphere, which can carry diseases.

NOx escapes from power plants as a by-product of coal combustion, whereas vehicular engines run at high enough pressures and temperatures to combine nitrogen and oxygen in the air. "Though catalytic converters have decreased the amount of pollution per vehicle, there are more vehicles on the road and more miles driven," Schlesinger says. Emissions from fertilizers are the chief source of atmospheric nitric oxide, but motor vehicles have now overtaken coal power plants as the secondary most critical source of this problem.

...In the U.S. there are neither comprehensive laws nor adequate monitoring devices for regulating atmospheric nitrogen emissions from livestock and farms. Europeans passed the Gothenburg Protocol to Abate Acidification, Eutrophication and Ground-Level Ozone in 1999, a pact signed by 49 countries, but the U.S. has dragged its feet. Schlesinger thinks that national arguments over climate change have allowed the U.S. to ignore the nitrogen problem, which he predicts will be the next big environmental issue. "It's another example of humans upsetting global biogeochemical cycles with unintended consequences," he says. Since Gothenburg, Europe has decreased its nitrogen emissions by a third, whereas U.S. emissions remain flat. And the U.S. has increased its ammonia emissions, an atmospheric component of the nitrogen problem, by 27 percent from 1970 to 2005, according to a 2009 paper in Environmental Science & Technology.