TY - JOUR
T1 - Long-Term Evolution of Particulate Nitrate Pollution in North China
T2 - Isotopic Evidence From 10 Offshore Cruises in the Bohai Sea From 2014 to 2019
AU - Zong, Zheng
AU - Tian, Chongguo
AU - Sun, Zeyu
AU - Tan, Yang
AU - Shi, Yajun
AU - Liu, Xiaohuan
AU - Li, Jun
AU - Fang, Yunting
AU - Chen, Yingjun
AU - Ma, Yuhao
AU - Gao, Huiwang
AU - Zhang, Gan
AU - Wang, Tao
N1 - Funding Information:
This research was financially supported by the Natural Scientific Foundation of China (NSFC; Grant Nos: 41907198, 41977190), the NSFC‐Shandong Joint Fund (U1906215). Additional support to Z.Z. and T.W. was provided by the Hong Kong Research Grants Council (project no. T24‐504/17‐N). This research was also very grateful for the sampling support of RV CHUANGXINYI and the data sources (NO and O, https://www.aqistudy.cn/historydata/ ). 2 3
Publisher Copyright:
© 2022. American Geophysical Union. All Rights Reserved.
PY - 2022/6/16
Y1 - 2022/6/16
N2 - Atmospheric nitrate (NO3−) pollution has become an obstacle to efforts to further reduce fine particulate (PM2.5) concentration in North China. However, there have been limited long-term measurements of NO3− and isotopic knowledge (δ15N, δ18O) on the driving factors during NO3− changes. Here, we report observations of 10 voyages from 2014 to 2019 conducted in the Bohai Sea, a typical background area in North China. The results show that the average proportion of NO3− in PM2.5 increased from 0.08 to 0.16 over the study period. The δ15N–NO3− ranged from −4.1‰ to +20.5‰, with a significant annual decline (p < 0.01), especially in winter. The average δ18O–NO3− was +72.6 ± 13.5‰, and a Monte Carlo calculation revealed that the contribution of the •OH pathway in the NO3− formation declined by 27.4% in winter, implying an increase in O3 pollution. Coal combustion remained the most important contributor to NO3− (46.6 ± 15.9%), but its contribution showed a significant downward trend (p < 0.01), consistent with the control of disperse coal use in North China. Enhancement of atmospheric oxidation and the unexpected large increase in contribution of microbial processes were found to be the main causes of the increasingly serious NO3− pollution in North China. In addition, a spike in the contribution of coal combustion in 2018 indicates that the coal-control policy needs to be reinforced.
AB - Atmospheric nitrate (NO3−) pollution has become an obstacle to efforts to further reduce fine particulate (PM2.5) concentration in North China. However, there have been limited long-term measurements of NO3− and isotopic knowledge (δ15N, δ18O) on the driving factors during NO3− changes. Here, we report observations of 10 voyages from 2014 to 2019 conducted in the Bohai Sea, a typical background area in North China. The results show that the average proportion of NO3− in PM2.5 increased from 0.08 to 0.16 over the study period. The δ15N–NO3− ranged from −4.1‰ to +20.5‰, with a significant annual decline (p < 0.01), especially in winter. The average δ18O–NO3− was +72.6 ± 13.5‰, and a Monte Carlo calculation revealed that the contribution of the •OH pathway in the NO3− formation declined by 27.4% in winter, implying an increase in O3 pollution. Coal combustion remained the most important contributor to NO3− (46.6 ± 15.9%), but its contribution showed a significant downward trend (p < 0.01), consistent with the control of disperse coal use in North China. Enhancement of atmospheric oxidation and the unexpected large increase in contribution of microbial processes were found to be the main causes of the increasingly serious NO3− pollution in North China. In addition, a spike in the contribution of coal combustion in 2018 indicates that the coal-control policy needs to be reinforced.
UR - http://www.scopus.com/inward/record.url?scp=85131951184&partnerID=8YFLogxK
U2 - 10.1029/2022JD036567
DO - 10.1029/2022JD036567
M3 - Journal article
AN - SCOPUS:85131951184
SN - 2169-897X
VL - 127
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
IS - 11
M1 - e2022JD036567
ER -