EGU24-4819, updated on 08 Mar 2024
https://doi.org/10.5194/egusphere-egu24-4819
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Modeling regional nitrogen cycle in the atmosphere: present situation and its response to the future emissions control strategy

Ao Shen, Yiming Liu, and Qi Fan
Ao Shen et al.
  • Sun Yat-sen University, School of Atmospheric Sciences, Zhuhai, China (shenao7@mail.sysu.edu.cn)

Reactive nitrogen (Nr) cycle in the atmosphere has an important affection on terrestrial ecosystems, which has not been fully understood and its response to the future emissions control strategy is not clear. Taking the Yangtze River Delta (YRD) as an example, we explored the regional Nr cycle (emissions, concentrations, and depositions) and its source apportionment in the atmosphere in January (winter) and July (summer) 2015 and projected its changes under emissions control by 2030 using the CMAQ model. We examined the characteristics of Nr cycle and found that Nr suspends in the air mainly as NO, NO2, and NH3 gases and deposits to the earth’s surface mainly as HNO3, NH3, NO3-, and NH4+. Due to the higher NOx than NH3 emissions, oxidized nitrogen (OXN) but not reduced nitrogen (RDN) is the major component in Nr concentration and deposition, especially in January. Nr concentration and deposition show an inverse correlation, with a high concentration in January and low in July but the opposite for deposition. We further apportioned the regional Nr sources for both concentration and deposition using the Integrated Source Apportionment Method (ISAM) incorporated in the CMAQ model. It shows that local emissions are the major contributors and this characteristic is more significant in concentration than deposition, for RDN than OXN species, and in July than in January. The contribution from North China (NC) is important for Nr in YRD, especially in January. In addition, we revealed the response of Nr concentration and deposition to the emission control to achieve the target of carbon peak in the year 2030. After the emission reduction, the relative responses of OXN concentration and deposition are generally about 100% to the reduction of NOx emissions (~50%), while the relative responses of RDN concentration are higher than 100% and the relative responses of RDN deposition are significantly lower than 100% to the reduction of NH3 emissions (~22%). Consequently, RDN will become the major component in Nr deposition. The smaller reduction of RDN wet deposition than sulfur wet deposition and OXN wet deposition will raise the pH of precipitation and help alleviate the acid rain problem, especially in July.

How to cite: Shen, A., Liu, Y., and Fan, Q.: Modeling regional nitrogen cycle in the atmosphere: present situation and its response to the future emissions control strategy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4819, https://doi.org/10.5194/egusphere-egu24-4819, 2024.