EGU2020-397
https://doi.org/10.5194/egusphere-egu2020-397
EGU General Assembly 2020
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Emissions of nitrous acid (HONO) and nitric oxide (NO) from soils and its impact on air quality in Shanghai

Mengdi Wang1,2, Jingwei Zhang3,4, Junling An3,4, Feng Zhou5, Xiuying Zhang6, Ruhai Wang7, Lingling Deng1,2, Lijun Hou8, Min Liu1,2, and Dianming Wu1,2
Mengdi Wang et al.
  • 1East China Normal University, School of Geographic Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), China (51183901019@stu.ecnu.edu.cn)
  • 2Institute of Eco-Chongming (IEC), Shanghai 202162, China(51183901019@stu.ecnu.edu.cn)
  • 3State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing, 100029, China(jw_zhang@mail.iap.ac.cn)
  • 4College of Earth Science, University of Chinese Academy of Sciences, Beijing, 100049, China(jw_zhang@mail.iap.ac.cn)
  • 5Sino-France Institute of Earth Systems Science, Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China(zhouf@pku.edu.cn)
  • 6International Institute for Earth System Science, Nanjing University, Nanjing 210023, China( zhangxy@nju.edu.cn)
  • 7State Key Laboratory of Soil and Sustainable Agriculture, Institute of soil Sciences, Chinese Academy of Sciences, Nanjing 210008, China(rhwang@issas.ac.cn)
  • 8State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China ( ljhou@sklec.ecnu.edu.cn)

Gaseous nitrous acid (HONO) and nitric oxide (NO) play a significant role in atmospheric chemistry through the contribution to the hydroxyl radical (OH) and influencing atmospheric oxidization capacity. Soil HONO emissions are considered as a major source of atmospheric HONO. However, soil HONO emissions and their contribution to air quality are rarely quantified. In this study, HONO and NO emissions from cropland, forest, urban green land, and grassland soils in Shanghai were measured by a dynamic chamber system under controlled laboratory conditions. HONO and NO emissions at the optimal water content (10 - 40% of water holding capacity) were highest from forest soil (50.3 ± 30.1 and 70.4 ± 43.9 ng m-2 s-1; average ± standard error, respectively), following by cropland soil (48.6 ± 17.4 and 55.8 ± 23.1 ng m-2 s-1, respectively), urban green land soil (44.2 ± 9.5 and 39.3 ± 13.3ng m-2 s-1, respectively), and grassland soil (27.7 ± 15.6 and 18.4 ± 6.9 ng m-2 s-1, respectively). Correlation analysis showed that soil HONO and NO emissions were significantly related with nitrate, total nitrogen, and total carbon (P < 0.01). The total soil emissions of HONO and NO in Shanghai were estimated based on “wetting-drying method”, and then upscaling to China and global. Results showed that global NO emissions from natural and fertilized soils were ~ 4.5 and 2.6 Tg N yr-1, respectively, which are comparable with the results from IPCC report (2013). The estimated global HONO emissions from natural and fertilized soils were ~ 3.3 and 2.7 Tg N yr-1, respectively, while those were 0.12 and 0.35 Tg N yr-1 for China, and 0.01 and 0.33 Gg N yr-1 for Shanghai, respectively.

The impact of soil HONO emissions on atmospheric oxidation capacity and O3 concentrations in Shanghai were evaluated using the WRF-Chem model in March of 2016. Daytime HONO concentrations were increased by 0.036 ± 0.015 ppb after considering soil HONO emissions during typical wetting-drying days, and the contribution of HONO photolysis to OH radicals enhanced from 0.095 ppb h-1 to 0.22 ppb h-1 and was ~ 2 times the contribution of O3 photolysis (0.1 ppb h-1), leading to 0.5 - 1.0 ppb enhancement of 8h-O3. The sensitivity test showed that O3 enhancement caused by soil HONO emissions were larger (1.0-1.5 ppb) under low NOx (cutting down 50%) conditions compared with the current conditions, implies that the importance of soil HONO emissions could be even larger in future considering the on-going NOx reducing management in China.

How to cite: Wang, M., Zhang, J., An, J., Zhou, F., Zhang, X., Wang, R., Deng, L., Hou, L., Liu, M., and Wu, D.: Emissions of nitrous acid (HONO) and nitric oxide (NO) from soils and its impact on air quality in Shanghai, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-397, https://doi.org/10.5194/egusphere-egu2020-397, 2020.

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