NEW PARTICLE FORAMTION IN POLLUTED YANGTZE RIVER DELTA
W. NIE1,2, A.J. DING1,2, X. QI1,2, X.G. CHI1,2, Z. XU1,2, X. HUANG1,2, Y. XIE1,2, H.
SHI1,2, V.-M. KERMINEN3, T. PETAJA3 and M. KULMALA3
1
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of
Atmospheric Sciences, Nanjing University, Nanjing, 210023, China
2
Collaborative Innovation Center of Climate Change, Nanjing, Jiangsu Province, China
3
Division of Atmospheric Sciences, Department of Physics, University of Helsinki, Helsinki,
Finland
Keywords: NEW PARTICLE FORMATION, HETEROGENEOUS, DUST, YANGTZE RIVER
DELTA
INTRODUCTION
Atmospheric new particle formation (NPF) and growth have been demonstrated to be an
important source of atmospheric aerosols and play important roles in climate (e.g. Dunne
et al., 2016). Previous understanding believes NPF prefer occurring in clean environment
(Kulmala et al., 2004). High concentration of pre-exist particles would uptake low
volatile vapers and newly formed clusters, and in turn suppress the particle nucleation
and subsequent growth.
Recently, NPF has been more and more observed in polluted regions (Nie et al., 2014; Qi
et al., 2015; Xiao et al., 2015), and even contributed largely to aerosol pollution (Guo et
al., 2014). But the mechanism of these NPF under polluted condition is still far from
understanding (Kulmala et al., 2016). In this work, we focus on the long term NPF
observation at a station in polluted Yangtz River Delta, and the possible “new” chemical
processes related to atmospheric oxidation capacity and secondary aerosol formation.
METHODS
A long term and comprehensive measurement was conducted from 2011 at the SORPES
“flagship” central site in Xianlin of Nanjing (Ding et al., 2013&2016). It is a regional
background site, located on the top of a hill (118°57́’10” E, 32°07’14”, 40 m a.s.l.) in the
Xianlin campus of Nanjing University and about 20 km east of the suburban Nanjing city.
NPF related parameters, including particle size distribution (from 1 nm to 10000 nm),
chemical compositions (water soluble ions, OC and EC), trace gases (O3, NOx, SO2,
HONO et al.) and meteorological quantities were measured. Besides the long term
measurement at SORPES site, some intensive campaigns were also conducted focusing
on some heterogeneous processes, e.g. a campaign during the spring in 2009 at the top of
Mt. Heng with the target on Asian dust.
CONCLUSIONS
A high frequency of NPF events, up to 44% of the sampling days, have been observed at
SORPES station. The occurrence of NPF was limited mostly by the meteorologic
condition but not precursors. Compared to clean area, sulfuric acid was a more important
contributor to particle nucleation and initial growth in Yangtze River Delta.
As showed in Fig. 1, many of the NPF events occurred on the days with heavy aerosol
pollution (PM10 more than 200 µg cm-3), especially when dust plums influenced the
station. Further analysis suggested dust particles can induce heterogeneous
photochemical processes, which in turn promote the formation of HONO and new
particles (Nie et al., 2012, 2014, 2015). These processes can be largely enhanced once the
dust particles are “polluted” by anthropogenic pollutions.
Figure 1 Time series of PM, trace gases, calcium, sulfate, aerosol size distributions, and
meteorological parameters measured during May 2012 at SORPES station.
A certain class of NPF events, defined as early-morning NPF, was observed at SORPES
station in YRD of east China. This early-morning NPF occurred only a few minutes after
sunrise. Highly Oxidized Multifunctional organic molecules (HOMs) and radicals
produced from monoterpene oxidation were considered to play an important role (Mikael
et al., 2014; Yan et al., 2016).
ACKNOWLEDGEMENTS
This work was funded by National Natural Science Foundation of China (D0512/41675145).
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