Simulation of nitrogen deposition in the North China Plain

Biogeosciences Discussions This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Abstract Simulation of atmospheric nitrogen (N) deposition in the North China Plain (NCP) at high resolution, 5 × 5 km 2 , was conducted for the first time by the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model. The total N deposition budget was 1481 Gg in this region, with 77 % from reduced N and 23 % from oxidized N, and the 5 annual deposition rate (47 kg ha −1) was much higher than previously reported values for other parts of the world such as the UK (13 kg ha −1), Poland (7.3 kg ha −1) and EU27 (8.6 kg ha −1). The exported N budget (1981 Gg) was much higher than the imported N budget (584 Gg), suggesting that the NCP is an important net emission source of N pollutants. Seven provinces in the region contributed N deposition budgets that were 10 proportional to their area ratios. The calculated spatial distributions of N deposition displayed high rates of reduced N deposition in the south and of oxidized N deposition in the eastern part. The N deposition exceeded an upper limit of 30 kg N ha −1 for natural ecosystems over more than 90 % of the region, resulting in terrestrial ecosystem deterioration, impaired air quality and coastal eutrophication not only in the NCP itself 15 but also in surrounding areas including the Bohai Sea and the Yellow Sea.