China has been considered as one of three regions with higher atmospheric nitrogen (N) deposition. Understanding the spatiotemporal patterns and factors that influence N deposition is useful to evaluate its ecological effects on terrestrial ecosystems and to provide a scientific basis for global change research. In recent years, we established an observation network of N deposition based on Chinese Ecosystem Research Network (CERN), conducted global datasets synthesis and developed empirical models between ground N concentration and NO2Satellite measurements with the aims to reveal the spatial pattern and decadal variations of atmospheric N deposition in China, and explore its controlling factors.
Results/Conclusions
The main results were that: 1) Derived from the measured data in 2013, the deposition fluxes of total dissolved N (TDN), NH4+–N, and NO3––N were 13.69, 7.25, and 5.93 kg N ha-1 a-1, respectively. Total particulate N (TPN) accounted for 24% of total N, confirming that atmospheric wet N deposition was underestimated without including TPN. 2) Atmospheric dissolved N deposition (DIN) increased from 11.11kg N ha–1 a–1 in the 1990s to 13.87 kg N ha–1 a–1 in the 2000s. NH4+-N still was the main component of N deposition, while NO3––N had a higher growth rate than NH4+-N. The NH4+/NO3- ratio of atmospheric wet deposition decreased in the past decades. 3) Dry N deposition input was approximately 7.78 kg N ha-1 a-1 in China. Specifically, the deposition fluxes of NO2, HNO3, NH4+–N, NO3––N and NH3 were 0.67, 1.15, 0.28, 0.07 and 5.61 kg N ha-1 a-1, respectively. 4) Atmospheric N wet deposition was highest over southern China and exhibited a decreasing gradient from southern to western and northern China. Nevertheless, the highest value of dry deposition occurred in North China. 5) The decadal variation in atmospheric N deposition was primarily caused by increased in N fertiliser and energy consumption.These findings provide a scientific background for policy-makers and planning purposes.