Pollution in China: Nitrogen at Fault

Updated: 3:22pm EST, 27 February 2013

Econintersect:  A joint research study by scientists at China Agricultural University in Beijing and Stanford University in California has attributed a significant part of the increasing pollution in China to nitrogen.  According to a summary announcement of the publication of results in Nature posted by the Stanford News Service on 25 February 2013, nitrogen deposited on Chinese land and water surfaces increased by 60% annually from the 1980s to the 2000s.

Click on picture for larger image of Shanghai smog at tumblr.

From the Stanford News Service:

During the past 30 years, China has become by far the largest creator and emitter of nitrogen globally. The country’s use of nitrogen as a fertilizer increased about threefold from the 1980s to 2000s, while livestock numbers and coal combustion increased about fourfold, and the number of automobiles about twenty-fold (all of these activities release reactive nitrogen into the environment).

The authors comment in the article in Nature that presented their results:

“All these changes can be linked to a common driving factor: strong economic growth, which has led to continuous increases in agricultural and non-agricultural reactive nitrogen emissions and consequently increased nitrogen deposition.”

The research indicates that emissions could be significantly reduced by improving the efficiency of nitrogen fertilizer use – more than half of that nitrogen is lost to the atmosphere and water rather than being retained in soil where it was intended.  Other sources of nitrogen are from transportation and industry.

Smog can be managed and reduced.  The picture below from the Los Angeles Times shows a smoggy day in LA in 1980.

Over the last 30 years smog has been significantly reduced (but not eliminated) in the Los Angeles basin.  The picture below shows a  bad smog day in LA in 2010.

Click on image to go to NPR article with enlargeable image.

There can be undesirable side effects when nitrogen compounds in the air are diminished.  An article at NPR says that methane emissions are increased when nitrogen oxides are reduced.  However, volatile hydrocarbons overall have been greatly reduced over the past several decades.

It is chemical reaction between nitrogen oxides and VOCs to produce ozone that was one of the most irritating and damaging aspects of LA smog from the 1940s to the 1980s.

Update 3:22pm EST, 27 February 2013:  A review article appeared in Scientific American today:  Massive Nitrogen Pollution Accompanies China’s Growth

John Lounsbury

Sources:

• Stanford scientists help shed light on key component of China’s pollution problem (Rob Jordon, Stanford News Service, 25 February 2013)

• Enhanced nitrogen deposition over China (Xuejun Liu, Ying Zhang, Wenxuan Han, Aohan Tang, Jianlin Shen, Zhenling Cui, Peter Vitousek, Jan Willem Erisman, Keith Goulding, Peter Christie, Andreas Fangmeier and Fusuo Zhang, Nature, 20 February 2013)

• Understanding Vehicle Smog (Inspired by TED : Aaron Kenneth Schwarz’s Blog, Thinking About It, October 2012)

• The Southland’s War on Smog:  Fifty Years of Progress Toward Clean Air (May 1997)

• PHOTOS: Los Angeles under cover | Smog through the years (Los Angeles Times)

• LA smog has less of a chokehold than years ago, NOAA study says (Jon LeSage, autobloggreen, 22 August 2012)

• NOAA, partners find 50-year decline in some Los Angeles vehicle-related pollutants (National Oceanic and Atmospheric Administration, 09 August 2012)

• New Anti-Smog Restrictions Could Warm Planet (Richard Harris, NPR, 25 January 2010)