Enhanced nitrogen deposition over China

Data on bulk nitrogen deposition, plant foliar nitrogen and crop nitrogen uptake in China between ad 1980 and ad 2010 show that the average annual bulk deposition of nitrogen increased by approximately 8 kilograms of nitrogen per hectare during that period and that nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s. Atmospheric nitrogen emissions have increased substantially since the beginning of the industrial revolution, and the resulting deposition of nitrogen can have detrimental effects on human and ecosystem health. But little is known about the magnitude and environmental consequences of nitrogen deposition in today's fastest growing economy, China. This paper reports that average annual bulk deposition of nitrogen increased by 8 kg of nitrogen per hectare from the 1980s to the 2000s. Ammonium is the dominant form of nitrogen in bulk deposition, whereas the rate of increase is largest for nitrate deposition. Nitrogen deposition has also increased plant foliar nitrogen concentrations in semi-natural ecosystems and has elevated crop nitrogen uptake in long-term unfertilized croplands. China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen1,2. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity1,3,4,5. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P