Simulation of nitrogen deposition in the North China Plain by the FRAME model

Abstract. Simulation of atmospheric nitrogen (N) deposition in the North China Plain (NCP) at high resolution, 5 × 5 km², 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 annual deposition rate (47 kg N ha⁻¹) was much higher than previously reported values for other parts of the world such as the UK (13 kg N ha⁻¹), Poland (7.3 kg N ha⁻¹) and EU27 (8.6 kg N ha⁻¹). The exported N component (1981 Gg) was much higher than the imported N component (584 Gg), suggesting that the NCP is an important net emission source of N pollutants. Contributions of N deposition budgets from the seven provinces in this region were 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 but also in surrounding areas including the Bohai Sea and the Yellow Sea.