National parks face dangerous foe
Thirty-eight of the United States’ national parks are experiencing “accidental fertilization” at or above a critical threshold for ecological damage, according to a study published in the journal Atmospheric Chemistry and Physics and led by Harvard University researchers. Unless significant controls on ammonia emissions are introduced at a national level, they say, little improvement is likely between now and 2050. The environmental scientists — experts in air quality, atmospheric chemistry, and ecology — have been studying the fate of nitrogen-based compounds that are blown into natural areas from power plants, automobile exhaust, and, increasingly, industrial agriculture. Nitrogen that finds its way into natural ecosystems can disrupt the cycling of nutrients in soil, promote algal overgrowth and lower the pH of water in aquatic environments, and ultimately decrease the number of species that can survive. “The vast majority, 85 percent, of nitrogen deposition originates with human activities,” explained principal investigator Daniel J. Jacob,...