TY - JOUR
T1 - Increased new particle yields with largely decreased probability of survival to CCN size at the summit of Mt. Tai under reduced SO2emissions
AU - Zhu, Yujiao
AU - Xue, Likun
AU - Gao, Jian
AU - Chen, Jianmin
AU - Li, Hongyong
AU - Zhao, Yong
AU - Guo, Zhaoxin
AU - Chen, Tianshu
AU - Wen, Liang
AU - Zheng, Penggang
AU - Shan, Ye
AU - Wang, Xinfeng
AU - Wang, Tao
AU - Yao, Xiaohong
AU - Wang, Wenxing
N1 - Funding Information:
Acknowledgements. This work was funded by the National Key Research and Development Program of China (2016YFC0200500), the National Natural Science Foundation of China (41922051, 42075104, 41706122), Shandong Provincial Science Foundation for Distinguished Young Scholars (ZR2019JQ09), State Key Laboratory of Organic Geochemistry, GIGCAS (SKLOG-201914), and the Jiangsu Collaborative Innovation Center for Climate Change. We appreciate the NOAA Air Resource Laboratory for providing the HYSPLIT model and thank the staff of the Mt. Tai Meteorological Station for the help during the measurement campaigns.
Funding Information:
Financial support. This research was supported by the National
Publisher Copyright:
© 2021 Author(s).
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/1/29
Y1 - 2021/1/29
N2 - Because anthropogenic sulfur dioxide (SO2) emissions have decreased considerably in the last decade, PM2.5 pollution in China has been alleviated to some extent. However, the effects of reduced SO2 on the particle number concentrations and subsequent contributions of grown new particles to cloud condensation nuclei (CCN) populations, particularly at high altitudes with low aerosol number loadings, are poorly understood. In contrast, the increase in provincial forest areas in China with rapid afforestation over the last few decades expectedly increases the biogenic emissions of volatile organic compounds and their oxidized products as nucleating precursors therein. In this study, we evaluated the campaign-based measurements made at the summit of Mt. Tai (1534 m a.s.l.) from 2007 to 2018. With the decrease in SO2 mixing ratios from 15 ± 13 ppb in 2007 to 1.6 ± 1.6 ppb in 2018, the apparent formation rate (FR) of new particles and the net maximum increase in the nucleation-mode particle number concentration (NMINP) in the spring campaign of 2018 was 2- to 3-fold higher than those in the spring campaign of 2007 with almost the same occurrence frequency of new particle formation (NPF) events. In contrast, the campaign-based comparison showed that the occurrence frequency, in which the maximum geometric median diameter of the grown new particles (Dpgmax) was > 50 nm, decreased considerably from 43 % 78 % of the NPF events before 2015 to < 12 % in 2017 2018. Assuming > 50 nm as a CCN threshold size at high supersaturations, the observed net CCN production decreased from 3.7 × 103 cm-3 (on average) in the five campaigns before 2015 to 1.0 × 103 cm-3 (on average) in the two campaigns in 2017 2018. We argue that the increases in the apparent FR and NMINP are mainly determined by the availability of organic precursors that participate in nucleation and initial growth, whereas the decrease in the growth probability is caused by the reduced emissions of anthropogenic precursors. However, large uncertainties still exist because of a lack of data on the chemical composition of these smaller particles.
AB - Because anthropogenic sulfur dioxide (SO2) emissions have decreased considerably in the last decade, PM2.5 pollution in China has been alleviated to some extent. However, the effects of reduced SO2 on the particle number concentrations and subsequent contributions of grown new particles to cloud condensation nuclei (CCN) populations, particularly at high altitudes with low aerosol number loadings, are poorly understood. In contrast, the increase in provincial forest areas in China with rapid afforestation over the last few decades expectedly increases the biogenic emissions of volatile organic compounds and their oxidized products as nucleating precursors therein. In this study, we evaluated the campaign-based measurements made at the summit of Mt. Tai (1534 m a.s.l.) from 2007 to 2018. With the decrease in SO2 mixing ratios from 15 ± 13 ppb in 2007 to 1.6 ± 1.6 ppb in 2018, the apparent formation rate (FR) of new particles and the net maximum increase in the nucleation-mode particle number concentration (NMINP) in the spring campaign of 2018 was 2- to 3-fold higher than those in the spring campaign of 2007 with almost the same occurrence frequency of new particle formation (NPF) events. In contrast, the campaign-based comparison showed that the occurrence frequency, in which the maximum geometric median diameter of the grown new particles (Dpgmax) was > 50 nm, decreased considerably from 43 % 78 % of the NPF events before 2015 to < 12 % in 2017 2018. Assuming > 50 nm as a CCN threshold size at high supersaturations, the observed net CCN production decreased from 3.7 × 103 cm-3 (on average) in the five campaigns before 2015 to 1.0 × 103 cm-3 (on average) in the two campaigns in 2017 2018. We argue that the increases in the apparent FR and NMINP are mainly determined by the availability of organic precursors that participate in nucleation and initial growth, whereas the decrease in the growth probability is caused by the reduced emissions of anthropogenic precursors. However, large uncertainties still exist because of a lack of data on the chemical composition of these smaller particles.
UR - http://www.scopus.com/inward/record.url?scp=85100222362&partnerID=8YFLogxK
U2 - 10.5194/acp-21-1305-2021
DO - 10.5194/acp-21-1305-2021
M3 - Journal article
AN - SCOPUS:85100222362
SN - 1680-7316
VL - 21
SP - 1305
EP - 1323
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 2
ER -