"Earth has never seen this much fixed nitrogen," says William H. Schlesinger, James B. Duke Emeritus Professor of Biogeochemistry at Duke's Nicholas School of the Environment.
"It's a tremendous increase in the last half century, which is not what we were expecting to find," says William Battye, an air quality researcher at NC State who led the study
"While carbon has captured the attention of the world through climate change, we cannot ignore this issue," adds Viney Aneja, professor of marine, earth and atmospheric science at NC State. "Too much nitrogen can affect human health, reduce biodiversity and amplify global warming."
Too much nitrogen in the soil benefits a limited number of species that can outcompete native species, reducing biodiversity, Aneja notes. High levels of nitrogen in groundwater are associated with intestinal cancers and miscarriages, and can be fatal to infants. Excess nitrogen compounds in waterways and lakes can cause toxic algal blooms, killing off aquatic species and threatening human health.
One form of nitrogen gas, nitrous oxide, is also a potent greenhouse gas and can contribute to global warming. High levels of nitrous oxide in the atmosphere also degrade the atmospheric ozone layer, and nitric oxide can create dangerous ground-level ozone.
Humans have used nitrogen compounds as a fertilizer for millennia, but historically only used naturally fixed sources, like manure and guano. In the early 1900s, German chemists Fritz Haber and Carl Bosch discovered a process that converts atmospheric nitrogen to ammonia, allowing humans to produce nitrogen-based fertilizers on an industrial scale for the first time.
Read more at: https://phys.org/news/2017-09-unprecedented-nitrogen-pose-earth-environment.html#jCp
