A Review of Spatial Variation of Inorganic Nitrogen (N) Wet Deposition in China

Atmospheric nitrogen (N) deposition (N(dep)), an important component of the global N cycle, has increased sharply in recent decades in China. Although there were already some studies on N(dep) on a national scale, there were some gaps on the magnitude and the spatial patterns of N(dep). In this study, a national-scale N(dep) pattern was constructed based on 139 published papers from 2003 to 2014 and the effects of precipitation (P), energy consumption (E) and N fertilizer use (F(N)) on spatial patterns of N(dep) were analyzed. The wet deposition flux of NH(4)(+)-N, NO(3)(-)-N and total N(dep) was 6.83, 5.35 and 12.18 kg ha(-1) a(-1), respectively. N(dep) exhibited a decreasing gradient from southeast to northwest of China. Through accuracy assessment of the spatial N(dep) distribution and comparisons with other studies, the spatial N(dep) distribution by Lu and Tian and this study both gained high accuracy. A strong exponential function was found between P and N(dep), F(N) and N(dep) and E and N(dep), and P and F(N) had higher contribution than E on the spatial variation of N(dep). Fossil fuel combustion was the main contributor for NO(3)(-)-N (86.0%) and biomass burning contributed 5.4% on the deposition of NO(3)(-)-N. The ion of NH(4)(+) was mainly from agricultural activities (85.9%) and fossil fuel combustion (6.0%). Overall, N(dep) in China might be considerably affected by the high emissions of NO(x) and NH(3) from fossil fuel combustion and agricultural activities.