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| Titel |
Where is PM gone? Trends and variability of atmospheric PM10, PM2.5 and PM10−2.5 in the Po valley over the last decade (and more). |
| VerfasserIn |
Alessandro Bigi, Grazia Ghermandi |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250150772
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| Publikation (Nr.) |
 EGU/EGU2017-15271.pdf |
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| Zusammenfassung |
| The Po Valley is one of the largest European regions with a remarkably high concentration
level of atmospheric pollutants, both for particulate and gaseous compounds. In the last
decade stringent regulations on air quality standards and on anthropogenic emissions
have been set by the European Commission, leading to an overall improvement
in air quality across Europe. In order to assess the decadal pattern and variability
in PM across the Po valley we thoroughly investigated the time series of PM10,
PM2.5 and PM10−2.5 from 41, 44 and 15 sites respectively (Bigi & Ghermandi 2014,
2016).
PM2.5 and PM10−2.5 (PM10) series with a 7 (10) year or longer record have been analysed for
long term trend in deseasonalized monthly means, annual quantiles and in monthly frequency
distribution by robust statistical methods. A widespread and significant decreasing
trend was observed at several sites for all size fractions, with the drop, up to a few
percent per year, occurring mainly in winter for PM2.5 and throughout the year for
PM10.
All series were tested for a significant weekly periodicity (a proxy to estimate the impact
of primary anthropogenic emissions) by 3 different statistical methods, yielding
positive results for summer PM2.5 and PM10, and for both summer and winter
PM10–2.5.
Hierarchical cluster analysis showed larger variability for PM10 than for PM2.5. The former
was split in five clusters: two encompassing the metropolitan areas of Turin and Milan and
their respective nearby sites and the other three clusters gathering northeast, northwest and
central Po Valley sites respectively. PM2.5 clusters divide the valley in western, eastern and
southern/Apennines foothill sectors.
The trend in atmospheric concentration was compared with the time series of local primary
and precursor emissions, vehicular fleet details and fuel sales. A significant basin-wide drop
in emissions occurred for gaseous pollutants, contrarily to primary emissions of PM10 and
PM2.5, whose drop was low and spatially restricted.
Overall the decrease in atmospheric PM2.5 and PM10 seems to originate from a drop in both
primary emissions and in precursors of secondary inorganic aerosol emissions, largely
ascribed to vehicular traffic. Potentially, the recent increase in biomass burning emissions in
winter and the modest decrease in NH3 weaken an otherwise even larger drop in atmospheric
concentrations.
References
Bigi, A. & Ghermandi, G. Long-term trend and variability of atmospheric PM10
concentration in the Po Valley Atmospheric Chemistry and Physics, 2014, 14, 4895-4907
Bigi, A. & Ghermandi, G. Trends and variability of atmospheric PM2.5 and PM10−2.5
concentration in the Po Valley, Italy Atmospheric Chemistry and Physics, 2016, 16,
15777-15788 |
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