An international team of scientists, have published a meta-analysis revealing an alarming increase in nitrogen deposition in China between 1980 and 2010, in a Letter to the journal Nature.

The group from China Agricultural University, Stanford University USA, VU University Amsterdam and Louis Bolk Institute, both in the Netherlands, Rothamsted Research Institute in the UK, and Hohenheim University in Germany, also note that the increased nitrogen deposition is linked human activity, for example through agricultural, industrial and traffic sources.

Nitrogen is a vital nutrient for plants, but it can also be a key environmental pollutant causing ecosystem instability through providing excess nutrients to the land and sea, a process called eutrophication. This can lead to the acidification of soil and water, algal blooms, negative impacts on human health and increased emissions of atmospheric nitrous oxide which has a global-warming potential 300 times greater than carbon dioxide.

The meta-analysis shows that bulk N deposition increased significantly from 1980 to 2010 and was approximately 8 kg N per hectare or 60 percent higher in the 2000s than in the 1980s, and was particularly pronounced in northern, southeast and southwest China. These N deposition levels in central China are much higher than those observed in any region of the US, and are comparable to the maximum values observed in the UK and the Netherlands when N deposition was at its peak in the 1980s.

Co-author Professor Keith Goulding from Rothamsted Research commented last week, "This important paper is the latest step in our long-standing collaboration with colleagues at China Agricultural University and around the world. Over the last 10 years we have identified serious issues with nitrogen pollution and sought to develop solutions.

"China is aware and concerned but has a major challenge in maintaining economic growth while reducing environmental pollution. We look forward to continued world-leading research such as reported here to resolve this problem to the benefit of China and the global community."
 

Professor Goulding added that further analysis of the data will be undertaken in and attempt to ascertain the extent to which agriculture is contributing to pollution, compared to non-agricultural activities. Though more analysis of the findings is needed, all authors said their results conclusively show that "environmental policy in China needs to focus more strongly on reducing nitrogen emissions from agricultural sources (especially fertilisers and livestock), [as well as] nitrogen gas emissions from industrial and traffic sources."