Nitrogen role in China pollution studied

U.S. scientists say they have identified a key element -- human-caused nitrogen emissions -- in China's ongoing battle against severe air pollution. Researchers at Stanford University say their study indicated the amounts of nitrogen from industry, cars and fertilizer deposited on land and water in China by way of rain, dust and other carriers increased by 60 percent annually from the 1980s to the 2000s. This increase had profound consequences for the country's people and ecosystems, they said. Working with colleagues at the China Agricultural University in Beijing, researchers at the Stanford Woods Institute for the Environment analyzed all available data on bulk nitrogen deposition from monitoring sites throughout China for the last 30 years, during which China has become by far the largest creator and emitter of nitrogen globally. China's production and use of nitrogen-based fertilizers is greater than that of the United States and the European Union combined, they said Decreased air quality, acidification of soil and water, increased greenhouse gas concentrations and reduced biological diversity are just some of the negative impacts of the increasing levels of nitrogen, the researchers said. "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 study's authors wrote in the journal Nature.