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Earth’s nitrogen cycle profoundly affected by humans

Nitrogen pollution affects wide range of land, sea ecosystems

Even high mountain lakes are feeling the sting of nitrogen pollution.

By Summit Voice

SUMMIT COUNTY — Nitrogen pollution is becoming one of the most pervasive global environmental problems, with nutrient pollution from agricultural runoff and sewage leading to coral diseases, bird die-offs, fish diseases, human diarrheal diseases and vector-borne infections transmitted by insects such as mosquitos and ticks.

About two-thirds of U.S. coastal systems are moderately to severely impaired due to nutrient loading and there are now nearly 300 hypoxic (low oxygen) zones along the U.S. coastline.

Air pollution continues to reduce biodiversity, with exotic, invasive species dominating native species that are sensitive to excess reactive nitrogen. For example, in California, airborne nitrogen is impacting one third of the state’s natural land areas,  and the expansion of nitrogen-loving, non-native, highly flammable grasses in the western U.S. has increased fire risk in the region.

These conclusions are part of a sobering assessment by a multi-disciplinary team of scientists led by Eric Davidson of the Woods Hole Research Center who reviewed the major sources of reactive nitrogen in the U.S., resulting effects on health and the environment, and potential solutions. Continue reading

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Nitrogen pollution building in remote wilderness lakes

Even remote wilderness lakes are being affected by increasing nitrogen depositions.

Global nitrogen cycle showing effects of human activities

By Summit Voice

SUMMIT COUNTY — Even some of the most remote mountain lakes in the northern hemisphere have been affected by the long reach of human pollution, according to researchers who found traces of nitrogen compounds in more than 75 percent of the lakes they surveyed in Europe and the Rocky Mountains of North America.

“When it comes to nitrogen associated with humans, most studies have focused on local and regional effects of pollution and have missed the planetary scale changes,” said Gordon Holtgrieve, a postdoctoral researcher at University of Washington School of Aquatic and Fishery Sciences. “Our study is the first large-scale synthesis to demonstrate that biologically-active nitrogen associated with human society is being transported in the atmosphere to the most remote ecosystems on the planet.” Continue reading

Environment: Nitrogen from sewage emerging as coral threat

Spiral wire coral. PHOTO BY NICK HOBGOOD VIA THE CREATIVE COMMONS.

Better water treatment could help mitigate impacts

By Summit Voice

SUMMIT COUNTY — Nitrogen from sewage is replacing nitrogen from chemical fertilizers as one of the primary sources of pollution that damages fragile offshore reef ecosystems.

The effects are particularly pronounced in the Gulf of Mexico and the Caribbean, according to a study published recently in the journal Global Change Biology.

Nitrogen pollution in coastal ecosystems leads to decreased water transparency, the loss of desirable fish species, and the emergence of toxic phytoplankton species like the algae behind the renowned “red tides” that kill fish.

Fertilizer has been the dominant source of nitrogen pollution in Caribbean coastal ecosystems for the past 50 years, but such pollution is on the decline.

“We can’t simply say our coastal ecosystem is being polluted by nitrogen,” said Kiho Kim, one of the study’s authors and chair of environmental science at American University. “The consequences may be the same, but differentiating the source of the pollutants is critical to crafting sustainable solutions—you can’t fix a problem if you don’t know what’s causing it.” Continue reading

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