Forests in Northeast China's Qingyuan county have shown a significant decline in nitrogen deposition over the past decade, according to a new study.

Nitrogen deposition occurs when nitrogen compounds in the air settle on land or water. It can come from natural sources, but human activities like burning fossil fuels and using fertilizers also contribute. While some level of nitrogen is essential for plant growth, too much can disrupt ecosystems.

In the new study, researchers from the Chinese Academy of Sciences monitored nitrogen levels in the Qingyuan forests between 2014 and 2022. They found a remarkable decrease of 55% in total inorganic nitrogen deposition. This included a 60% reduction in ammonium nitrogen deposition, primarily due to reduced agricultural NH₃ emissions, and a 42% decrease in nitrate nitrogen deposition, mainly attributed to reduced emissions of nitrogen oxides from agricultural soils and the burning of fossil fuels.

To provide a wider perspective, the researchers examined data from East Asian acid deposition monitoring sites outside China. These sites share similar latitudes with Qingyuan county and showed a decrease in nitrogen deposition of 14-34%.

The study suggests this sharp decline in nitrogen deposition within Northeast China is due to several factors. Notably, China has implemented stricter policies to reduce coal consumption, improve vehicle emission controls, and promote more sustainable agricultural practices since 2010. These changes appear to be having a positive impact on atmospheric nitrogen levels.

The study, published in the journal Science of The Total Environment, offers valuable insights for other developing countries and regions in struggling with high levels of nitrogen deposition. It also highlights the potential effectiveness of stricter environmental regulations in tackling air pollution.