Transcript Tundo_Poster

BLACK CARBON IN MILAN
Gianmarco Tundo1, Vorne Gianelle2, Matteo Lazzarini2, Umberto Dal Santo2, Eleonora Cuccia2, Cristina Colombi2, Andrea Algieri2 e Riccardo Ricceri2
1Department
of DICA, Politecnico di Milano; 2ARPA Lombardia
Since 2013 ARPA Lombardia is measuring black carbon (BC), elemental
carbon (EC) and organic carbon (OC) in PM10 fraction in three fixed
measuring stations in the city of Milan. The analysis of these time series
allowed a characterization of PM10 carbonaceous fraction for different
sites and for different seasonal and meteorological conditions.
The measurement of the black carbon was carried out by two instruments
using different methodologies, a Thermo MAAP (absorption at λ=670 nm,
MAC=6.6 m2/g) and a Magee Aethalometer (attenuation at λ=880 nm,
MAC=16.6 m2/g), thus the definition “Equivalent Black Carbon” (EBC)
should be used for data derived from different optical methods..
via Pascal : Urban background station.
MAAP (Thermo).
via Senato: Urban traffic station, limited traffic area (C area).
Aethalometer (Magee).
MI-Pascal: BC, EC, OC
25
concentration (µg/m3)
viale Marche : Urban traffic station.
Aethalometer (Magee).
BC
20
OC
EC
15
Both of them present artefacts, already reported in literature, that
cannot be neglected and that have been considered. An application of
Virkkula correction for Aethalometer is reported, such as for example,
in the following figure.
10
5
0
Aethalometer BC correction (λ=880 nm)
40
20
OC
Concentration BC (µg/m3)
BC
EC
15
10
5
0
Corrected BC
Attenuation
30
60
20
40
10
20
0
0
Attenuation
Uncorrected BC
MI-Senato: BC, EC, OC
25
concentration (µg/m3)
80
BC CONCENTRATION TRENDS (2014-2015)
MI-Pascal
20
MI-Senato
Trend of BC daily concentrations
in three measuring stations: a
comparison is not possible due to
different measuring systems, but
trends seem to be similar.
MI-Marche
15
10
5
BC weekly trend
5
4
3
2
1
MI-Pascal
MI-Senato
MI-Marche
Concentrations of BC show a
maximum on Fridays, due to BC
accumulation during working
days. Decrease of concetration is
always shown during weekend.
0
0
BC annual trend
10
Concentration (mg/m3)
8
MI-Pascal
MI-Senato
The BC annual trend shows a
decrease in concentration during
summer, from April to September.
Maximum values are reached
between
November
and
December. This is due to the
seasonal variation of PBL.
MI-Marche
6
4
2
5
4
3
2
1
MI-Pascal
MI-Senato
MI-Marche
An increase in BC concentrations
is shown between 6 and 8 a.m.;
a sharp decrease is reported in
the middle of the day and a peak
is finally shown in the evening
hours, following the trend of
traffic emissions.
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
0
BC daily trend
6
Concentration (mg/m3)
Concentration (mg/m3)
25
6
concentration (µg/m3)
BC daily means
CORRELATION OF BC WITH OTHER POLLUTANTS
MI-Pascal: PM10 vs BC
16
14
10
8
6
4
y = 0.09x - 0.26
R² = 0.74
2
0
20
40
60
80
100
120
3
Concentration BC (mg/m )
140
BC vs OC
20
y = 1.54x + 1.89
R² = 0.75
15
10
y = 0.64x + 0.09
R² = 0.84
5
0
0
3
6
9
Concentration BC (mg/m3)
12
15
Concent. NOx (µg/m3)
BC vs EC
25
6
POLLUTANT
Milano Pascal
Milano Senato
Milano Marche
4
CO
-
0.50
0.47
2
EC
0.78
0.84
-
OC
0.66
0.75
-
NOX
0.85
0.76
0.80
C6H6
0.81
0.66
0.72
PM10
0.74
0.66
-
PM2.5
0.70
0.63
-
0
160
MI-Senato: OC vs BC and EC vs BC
30
8
0
0
Concent. OC, EC (mg/m3)
y = 0.47x + 0.12
R² = 0.81
10
12
In the following table, coefficient of determination values R2 referred to
different pollutants are reported for different monitoring stations:
MI-Pascal: C6H6 vs BC
12
Concent. C6H6 (mg/m3)
Concent. PM10 (mg/m3)
Scatter plots of different pollutants are reported:
5
10
Concentration BC (mg/m3)
15
MI-Marche: NOX vs BC
1200
y = 36.26x - 1.08
R² = 0.80
1000
800
600
400
200
0
0
5
10
15
Concentration BC (µg/m3)
20
25
BC measurements seem to be influenced in different ways by other compounds, such as OC, that absorbe or scatter light. Thus, concentrations measured with
both instruments show a good correlation with differences in values, due to different principles of operation. This should be considered in environmental
evaluations such as, for example, the comparison between sites.