 |
| Titel |
Characteristics and formation of heavy winter haze pollution during 2014-2015 in Tianjin, China |
| VerfasserIn |
Zhenli Sun, Tao Ma, Lidan Zhu, Fengkui Duan, Kebin He |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148753
|
| Publikation (Nr.) |
 EGU/EGU2017-13039.pdf |
|
|
|
|
|
| Zusammenfassung |
| With the rapid increase in the amount of vehicles and energy consumption during the past two
decades, China faces a serious air pollution in urban areas, which has produced negative
impact on the society development and human health. Tianjin, locating on the southeast of
Beijing-Tianjin-Hebei region in north China, has been one of the heavy polluted cities during
2013-2016 of which the haze occurred frequently in particular in winter while the knowledge
on its sources and formation mechanism are limited. For better understanding of the
characteristics and the formation mechanisms of PM2.5 (particulate matter with an
aerodynamic diameter ≤2.5 μm), especially secondary water-soluble inorganic species in
these haze events, continuous and online hourly field observations in Tianjin urban
area were carried out during 2014-2015 winter, that were, hourly concentrations
of PM2.5, sulfate, nitrate, and ammonium (SNA) as well as the concentrations of
gaseous pollutants and meteorological parameters. PM2.5 concentrations ranged
from 5.6 μg⋅m−3 to 495.5 μg⋅m−3, with an average of 112.1 (±96.1) μg⋅m−3. In
general, SNA (sulfate, nitrate and ammonium) was the most abundant secondary
water-soluble inorganic species and contributed to 35% of PM2.5 mass concentration. The
most severe PM2.5 pollution was observed in January 2015 with four haze episodes
observed. The chemical composition of four episodes was characterized by high level
of SO42− (22%∼38%), together with high concentration of NO3− (22%∼34%),
suggesting the contribution of secondary conversion. NOR and SOR increased
with elevated PM2.5levels and heterogeneous processes seemed to be the most
plausible explanation of this increase. Nitrogen oxidation ratio (NOR) was much
higher than sulfur oxidation ratio (SOR), indicating the NO2 was easily oxidized
in low temperature condition than that of SO2. Relative humidity (RH) played a
considerable role in the formation of secondary inorganic aerosols, accelerated
the secondary transformation of gaseous precursors, and further aggravated haze
pollution.
Key words: winter haze; secondary formation; high relative humidity; heterogeneous
processes |
|
|
|
|
|
|