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Beyond carbon: scientists worry about nitrogen’s effects
As Anne Giblin was lugging four-foot tubes of Arctic lakebed mud from her inflatable raft to her nearby lab this summer, she said, “Mud is a great storyteller.”
Dr. Giblin, a senior scientist at the Marine Biological Laboratory in Woods Hole, Mass., is part of the Long Term Ecological Research network at an Arctic science outpost here operated by the University of Alaska at Fairbanks.
Public discussion of complicated climate change is largely reduced to carbon: carbon emissions, carbon footprints, carbon trading. But other chemicals have large roles in the planet’s health, and the one Dr. Giblin is looking for in Arctic mud, one that a growing number of other researchers are also concentrating on, is nitrogen.
In addition to having a role in climate change, nitrogen has a huge, probably more important biological impact through its presence in fertilizer. Peter Vitousek, a Stanford ecologist whose 1994 essay put nitrogen on the environmental map, co-authored a study this summer in the journal Nature that put greater attention on the nitrogen cycle and warned against ignoring it in favor of carbon benefits.
For example, Dr. Vitousek said in an interview, “There’s a great danger in doing something like, oh, overfertilizing a cornfield to boost biofuel consumption, where the carbon benefits are far outweighed by the nitrogen damage.”
Soon after Dr. Vitousek’s report, the journal Geophysical Research Letters branded as a “missing greenhouse gas” nitrogen trifluoride, which is used in production of semiconductors and in liquid-crystal displays found in many electronics. According to the report, it causes more global warming than coal-fired plants. Nitrogen trifluoride, which is not one of the six gases covered by the Kyoto Protocol, the celebrated international global warming accord, is about 17,000 times more potent than carbon dioxide. Its estimated worldwide release into the atmosphere this year is equivalent to the total global-warming emissions from Austria.
“The nitrogen dilemma,” Dr. Vitousek added, “is not just thinking that carbon is all that matters. But also thinking that global warming is the only environmental issue. The weakening of biodiversity, the pollution of rivers, these are local issues that need local attention. Smog. Acid rain. Coasts. Forests. It’s all nitrogen.”
Dr. Vitousek’s summer report followed a similar account in May in the journal Science by James N. Galloway, an environmental sciences professor at the University of Virginia and a former chairman of the International Nitrogen Initiative, a group of scientists pushing for smarter use of nitrogen.
Dr. Galloway is developing a universal calculator for individual nitrogen footprints. “It’s Goldilocks’s problem,” he said in an interview. “Reactive nitrogen isn’t a waste product. We need it desperately. Just not too much and not too little. It’s just more complicated than carbon.” He continued, “But we’re not going to get anywhere telling people this is simple or easy.”
Dr. Giblin of Woods Hole spent the summer at the field station here, midway between the Arctic Circle and the Arctic Ocean, researching the nitrogen content of lakebed sediment — not the inert nitrogen that makes up 80 percent of air, the reactive nitrogen that Dr. Galloway referred to. In forms like nitric acid, nitrous oxide, ammonia and nitrate it plays a variety of roles.
Nitrogen is part of all living matter. When plants and animals die, their nitrogen is passed into soil and the nitrogen in the soil, in turn, nourishes plants on land and seeps into bodies of water. Dr. Giblin is pursuing her research because as the Arctic warms, the tundra’s permafrost will thaw, and the soil will release carbon and nitrogen into the atmosphere.
When an ecosystem has too much nitrogen, the first response is that life blossoms. More fish, more plants, more everything. But this quickly becomes a kind of nitrogen cancer.
continued... As Anne Giblin was lugging four-foot tubes of Arctic lakebed mud from her inflatable raft to her nearby lab this summer, she said, “Mu... more -
Reactive nitrogen: the next big pollution problem
Without nitrogen to fertilize crops, the world couldn't feed itself. But if humanity doesn't cut back on the nitrogen it pumps into the environment, we could choke the oceans and ourselves.
That's the troubling takeaway of two articles published today in Science by researchers from the International Nitrogen Initiative. The first, a review of earlier nitrogen pollution studies, charts the incredible growth of nitrogen in the environment. The second quantifies nitrogen added by human activity to the oceans.
"The natural nitrogen cycle has been very heavily influenced by human activity over the last century perhaps even more so than the carbon cycle," said University of East Anglia biogeochemist Peter Liss, a co-author on the second paper.
The problem isn't strictly nitrogen, which comprises more than three-quarters of the air we breathe, but so-called reactive nitrogen. These are analogous to better-known free oxygen radicals: an altered electron configuration makes them especially unstable, and more likely to wreak environmental havoc.
Oceannitrogendeposition In 1860, humanity produced 15 metric tons of reactive nitrogen. By 1995, that number stood at 100 tons, and swelled to 185 tons by 2005. Those numbers are small in comparison to global CO2 emissions -- 27 billion tons annually -- but the impacts are magnified by what James Galloway, a University of Virginia biogeochemist and co-author of the review, calls the nitrogen cascade.
"My car emitted nitric oxide into the atmosphere this morning. Over time, that moves through the atmosphere, into the soil, into the water, into the coastal systems and back into the atmosphere," he said. "It can contribute to all those impacts."
Some of it comes from industry, but mostly from crop fertilizers. The Haber-Bosch process, in which nitrogen, hydrogen and iron sulfate are mixed to make nitrogen fertilizer, is a mainstay of modern agriculture.
"The first and arguably most important impact of reactive nitrogen is that we're feeding the world's people. We have to do this to create enough food to feed us," said Galloway.
But downsides are piling up. Reactive nitrogen increases atmospheric ozone levels, causing respiratory diseases and hurting crop yields; produces acid rain; and spurs blooms of oxygen-gobbling oceanic algae, which can hurt fisheries. Nitrogen pollution could eventually render entire stretches of ocean dead, as is now the case in the Gulf of Mexico, where fertilizer runoff has created a 5,800 square mile dead zone. To top it off, oceanic nitrogen is converted to nitrous oxide, a greenhouse gas. Without nitrogen to fertilize crops, the world couldn't feed itself. But if humanity doesn't cut back on the nitrogen it pum... more -
400+ Coastal Zones Dying: New Nitrogen Threat
It's not only carbon that's posing a threat to the global climate. The world's nitrogen cycle is also a worry, and causing big problems for coasts.
Nitrogen comes from natural gas transformed into ammonia fertiliser and used to grow crops. What doesn't absorb into the soil runs off into streams, which flow into rivers, which flow to the ocean, where the nitrogen fuels "dead zones" - areas where nitrogen (and phosphorus) fertilises so much algae growth that it absorbs enough oxygen to make the water inhospitable to fish and other marine life.
As well as nitrogen, poorly-treated human sewage and the fallout from burning fossil fuels can also cause dead zones. And according to The World Resources Institute's recent findings, there's over four hundred of them dotted around the world now.
From their data, the UK looks screwed...
Click the image above for the full map and a more detailed explanation. It's not only carbon that's posing a threat to the global climate. The world's nitrogen cycle is also a worry, and caus... more
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