Caratterizzazione magnetica del particolato atmosferico - SNPA - Sistema nazionale protezione ambiente

Magnetic monitoring of PM filters from Air Monitoring Stations during the COVID-19 lockdown in Rome, Italy (March 10 th - May 18 th , 2020)

Aldo Winkler¹ , Antonio Amoroso² , Alessandro Di Giosa² , Giada Marchegiani²

1 Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italia (aldo.winkler@ingv.it)

2 ARPA Lazio, Roma, Italia

Magnetic properties of PM filters; they were determined:

 Volume magnetic susceptibility - as the fastest proxy of the concentration of magnetic minerals in the daily PM filters, assuming the KLY5 standard volume (10 cm

).

 Mass magnetic susceptibility – dividing the total susceptibility for the daily PM mass, calculated as PM (µg/m

) x 55 m

(air filtered in a day).

 Hysteresis properties – mass normalized Ms, Mrs; Bc, Bcr, (on half filter in a gel cap).

Their ratios were plotted in a «Day Plot»; on representative samples

 FORC diagrams – on selected samples

The results shown here are only a selection of an extensive study covering many stations in Latium region (Rome, Fiumicino, Civitavecchia, Valle del Sacco)

Civitavecchia

Rome Fiumicino

Roma: PM air filter stations

• Fermi (busy road, intense exposure to traffic); March 23, 2020 – April 15, 2021 (uncontinuous sampling after lockdown)

• Cinecittà (internal road, moderate exposure to traffic; March 3, 2020 - June 14, 2020)

• Magnagrecia (busy road, intense exposure to traffic); March 26, 2020 – March 22, 2021 (uncontinuous sampling after lockdown)

ROMA FERMI (March 23, 2020 – April 15, 2021 (uncontinuous sampling after lockdown)

Mass Susceptibility Max: 3.36E-05 m³/kg Min: 1.17E-06 m³/kg

Average: 1. 29E-05 m³/kg average lock: 9.97E-06 m³/kg average post: l. 1.56E-05 m³/kg p (same mean): 3.3E-08

PM concentration Max: 74 µg/m³ Min: 7 µg/m³

Average: 19 µg/m³

average lock: 21 µg/m³ average post 19 µg/m³ p (same mean): 0.29

Absolute maximum of PM vs minimum mass susceptibility – input of non magnetic dusts

Absolute maximum of mass susceptibility vs PM minimum – highest concentration of magnetic PM

Magnetite average concentration = 1.11%

Ms data on 15 samples

Mass susceptibility; PM – normalized to average

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

23/3 2/4 12/4 22/4 2/5 12/5 22/5 1/6 11/6

0.00 0.50 1.00 1.50 2.00 2.50

5/3 15/3 25/3 4/4 14/4

2021

Average Kmass Average PM

ROMA FERMI: correlations

R² = 0.9422

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 Ms_mass (Am²/kg) vs k_mass (m³/kg)

R² = 0.9489

0.0E+00 2.0E-07 4.0E-07 6.0E-07 8.0E-07 1.0E-06 1.2E-06 1.4E-06

0.0E+00 5.0E-07 1.0E-06 1.5E-06 2.0E-06 2.5E-06 3.0E-06 K_vol vs Ms_vol (Am²)

Kvol vs PM correlation switching to linear after lockdown

R² = 0.0001

R² = 0.6018

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00

0.0E+00 5.0E-07 1.0E-06 1.5E-06 2.0E-06 2.5E-06 3.0E-06 3.5E-06 4.0E-06

R² = 0.3053 R² = 0.0132

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00

0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 4.0E-05 PM (µg/m³) vs Kmass (m³/kg)

Lockdown; Post lockdown PM (µg/m³) vs Kvol

Lockdown; Post lockdown

No anticorrelation between Kmass and PM after lockdown

ROMA CINECITTÀ (March 3, 2020 – June 14, 2020)

Mass suceptibility max 1.29E-05 m³/kg min 2.15E-07 m³/kg average 4.07E-06 m³/kg

average lock. 3.83E-06 m³/kg average post 4.24E-06 m³/kg p (same mean): 0.55

PM concentration Max: 57 µg/m³ Min: 9 µg/m³

Average: 21 µg/m³ average lock: 23 µg/m³ average post 18 µg/m³ p (same mean): 0.01

Magnetite average concentration = 0.47%

(Ms data on 15 samples)

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

03/03/2020 23/03/2020 12/04/2020 02/05/2020 22/05/2020 11/06/2020

Mass susceptibility; PM – normalized to average

Absolute maximum of PM vs minimum mass susceptibility – input of non magnetic dusts

Absolute maximum of mass susceptibility vs PM minimum – highest concentration of magnetic PM Average Kmass

Average PM

R² = 0.9849

0.0E+00 5.0E-08 1.0E-07 1.5E-07 2.0E-07 2.5E-07 3.0E-07 3.5E-07 4.0E-07 4.5E-07 5.0E-07

0.0E+00 2.0E-07 4.0E-07 6.0E-07 8.0E-07 1.0E-06

Cinecittà Ms (Am²) vs k_vol

R² = 0.99

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40

0.0E+00 2.0E-06 4.0E-06 6.0E-06 8.0E-06 1.0E-05 1.2E-05 1.4E-05

Cinecittà Ms_mass (Am²/kg) vs k_mass (m³/kg) ROMA Cinecittà: correlations

R² = 0.4155

R² = 0.1426

0 10 20 30 40 50 60

0.0E+00 2.0E-07 4.0E-07 6.0E-07 8.0E-07 1.0E-06

R² = 0.0713 R² = 0.0002

0 10 20 30 40 50 60

0.0E+00 2.0E-06 4.0E-06 6.0E-06 8.0E-06 1.0E-05 1.2E-05 1.4E-05

PM (µg/m³) vs Kmass (m³/kg) Lockdown; Post lockdown PM (µg/m³) vs Kvol

Lockdown; Post lockdown

Magnetite average concentration = 1.11%

Ms data on 12 samples

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

26/03/2020 31/03/2020 05/04/2020 10/04/2020 15/04/2020 20/04/2020 25/04/2020 30/04/2020 05/05/2020 10/05/2020

ROMA MAGNAGRECIA (March 26, 2020 – March 22, 2021) Mass susceptibility max 5.14E-05 m³/kg min 1.69E-06 m³/kg average 1.50E-05 m³/kg

average lockd. 9. 67E-06 m³/kg average post 1.91E-05 m³/kg p (same mean): 6.6E11

Sagnotti et al., 2006 average 2.12E-05 m³/kg

Mass susceptibility; PM – normalized to average

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

9/6 29/7 17/9 6/11 26/12 14/2

Post lockdown (June 9, 2020 – March 22, 2021)

PM concentration Max: 73 µg/m³ Min: 5 µg/m³

Average: 25 µg/m³

average lock: 23 µg/m³ average post 26 µg/m³ p (same mean): 0.34

Absolute maximum of PM vs minimum mass susceptibility – input of non magnetic dusts

Absolute maximum of mass susceptibility vs PM minimum – highest concentration of magnetic PM Average Kmass

Average PM

R² = 0.002

R² = 0.7282

0 10 20 30 40 50 60 70 80

0.0E+00 1.0E-06 2.0E-06 3.0E-06 4.0E-06 5.0E-06 6.0E-06 7.0E-06

R² = 0.312 0.0E+00

1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05 6.0E-05

0 10 20 30 40 50 60 70 80

R² = 0.9663

0.0E+00 1.0E-07 2.0E-07 3.0E-07 4.0E-07 5.0E-07 6.0E-07 7.0E-07 8.0E-07 9.0E-07 1.0E-06

0.0E+00 2.0E-07 4.0E-07 6.0E-07 8.0E-07 1.0E-06 1.2E-06 1.4E-06 1.6E-06 1.8E-06

Ms (Am²) vs k_vol

R² = 0.9711

0.0 0.5 1.0 1.5 2.0 2.5

0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05

Ms_mass (Am²/kg) vs kmass (m³/kg)

Almost constant K_mass

Kvol vs PM linear correlation after lockdown

PM (µg/m³) vs Kvol

Lockdown; Post lockdown

PM (µg/m³) vs Kmass (m³/kg) Lockdown; Post lockdown

ROMA MAGNAGRECIA: correlations

• Prevailing Brake Emissions in Fermi and Magnagrecia (busy roads)

• Cinecittà points (distant to busy roads) move towards natural and fuel sources

Day Plot - Roma

Mass suceptibility max 4.80E-06 m³/kg min -2.82E-07 m³/kg average 1.05E-06 m³/kg average l. 1.05E-06 m³/kg average p.l. 1.06E-06 m³/kg p (same mean): 1.00

-1.00 0.00 1.00 2.00 3.00 4.00 5.00

20/3 30/3 9/4 19/4 29/4 9/5 19/5 29/5 8/6

Mass susceptibility; PM – mormalized to average

PM concentration Max: 50 µg/m³ Min: 2 µg/m³

Average: 15 µg/m³

average lock: 16 µg/m³ average post 14 µg/m³ p (same mean): 0.20

Absolute maximum of PM vs minimum mass susceptibility – input of non magnetic dusts

Absolute maximum of mass susceptibility vs PM minimum – highest concentration of magnetic PM Average Kmass

Average PM

Civitavecchia (rural background): Sant’Agostino (March 20, 2020 – June 14, 2020)

SANT’AGOSTINO: correlations

R² = 0.1935

R² = 0.1331

0 10 20 30 40 50 60

-5.0E-08 2.0E-22 5.0E-08 1.0E-07 1.5E-07 2.0E-07 2.5E-07 3.0E-07 3.5E-07 4.0E-07

Kvol vs PM no change after lockdown

R² = 0.003

R² = 0.0456

0 10 20 30 40 50 60

-1.0E-06 2.0E-21 1.0E-06 2.0E-06 3.0E-06 4.0E-06 5.0E-06

PM (µg/m³) vs Kvol

Lockdown; Post lockdown

PM (µg/m³) vs Kmass (m³/kg) Lockdown; Post lockdown

Civitavecchia (urban): Villa Albani (March 16, 2020 – June 14, 2020)

Mass susceptibility max 1.73E-05 m³/kg min 7.89E-07 m³/kg average 5.18E-06 m³/kg

average lckd. 4.30E-06 m³/kg average p.lckd. 7.19E-06 m³/kg p (same mean): 0.0003

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

14/03/2020 24/03/2020 03/04/2020 13/04/2020 23/04/2020 03/05/2020 13/05/2020 23/05/2020 02/06/2020 12/06/2020

Magnetite average concentration = 0.55%

Mass susceptibility; PM – normalized to average

PM concentration Max: 70 µg/m³ Min: 4 µg/m³

Average: 20 µg/m³ average lock: 22 µg/m³ average post 16 µg/m³ p (same mean): 0.06

Absolute maximum of mass susceptibility vs PM minimum – highest concentration of magnetic PM Average Kmass

Average PM

Absolute maximum of PM vs minimum mass susceptibility – input of non magnetic dusts

VILLA ALBANI: correlations

R² = 0.9771

0.0E+00 2.0E-06 4.0E-06 6.0E-06 8.0E-06 1.0E-05 1.2E-05 1.4E-05 1.6E-05 1.8E-05 2.0E-05

0.0E+00 2.0E-01 4.0E-01 6.0E-01 8.0E-01 1.0E+00 1.2E+00

K_mass vs Ms_mass (Am²/kg)

R² = 0.9459

0.0E+00 2.0E-07 4.0E-07 6.0E-07 8.0E-07 1.0E-06 1.2E-06 1.4E-06

0.0E+00 1.0E-07 2.0E-07 3.0E-07 4.0E-07 5.0E-07

K_vol vs Ms (Am²)

R² = 0.1739

R² = 0.0381

0 10 20 30 40 50 60 70 80

0.0E+00 2.0E-07 4.0E-07 6.0E-07 8.0E-07 1.0E-06 1.2E-06 1.4E-06 PM (µg/m³) vs Kvol

Lockdown; Post lockdown c

R² = 0.1603 R² = 0.5898

0 10 20 30 40 50 60 70 80

-1.0E-06 1.0E-06 3.0E-06 5.0E-06 7.0E-06 9.0E-06 1.1E-05 1.3E-05 1.5E-05 PM (µg/m³) vs Kmass (m³/kg)

Lockdown; Post lockdown

Day plot – Villa Albani

Prevailing Brake Emissions

Intermediate Rural Background: Rome/Fiumicino Castel di Guido (March 20, 2020 – June 14, 2020)

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

29/3 8/4 18/4 28/4 8/5 18/5 28/5 7/6

Mass susceptibility; PM – normalized to average

PM concentration Max: 67 µg/m³ Min: 8 µg/m³

Average: 20 µg/m³

average lock: 21 µg/m³ average post 17 µg/m³ p (same mean): 0.03 Mass susceptibility max 4.22E-06 m³/kg min -7.80E-07 m³/kg average 1.25E-06 m³/kg

average lckd. 9.29E-07 m³/kg average p.lckd. 1.77E-06 m³/kg p (same mean): 5.62E-6

Absolute maximum of PM vs minimum mass susceptibility – input of non magnetic dusts Average Kmass

Average PM

CASTEL DI GUIDO: correlations

R² = 0.2659

R² = 0.006

0 10 20 30 40 50 60 70 80

-1.0E-07 -5.0E-08 0.0E+00 5.0E-08 1.0E-07 1.5E-07 2.0E-07 2.5E-07 3.0E-07 3.5E-07

R² = 0.0001

R² = 0.1731 0

10 20 30 40 50 60 70 80

-1.0E-06 0.0E+00 1.0E-06 2.0E-06 3.0E-06 4.0E-06 5.0E-06

PM (µg/m³) vs Kvol Lockdown; Post lockdown

PM (µg/m³) vs Kmass (m³/kg) Lockdown; Post lockdown

Day plot – Castel di Guido

Prevailing natural/fuel sources

Ferentino PM 2.5

Magnagrecia PM10

The grainsize: paramagnetism of PM2.5 vs ferromagnetism of PM10

Fermi 13/5 Magnagr. 22/4

Rel. k_mass maximum

Magnagr. 29/3

Dusts; max PM (70), k_mass min

Castel di Guido 29/3

Dusts; max PM (70)

FORC

Sagnotti et al., 2009

Conclusions

 There was a huge debate about the effects of lockdown on PM10 concentration levels: magnetic measurements were succesful at understanding the impact of lockdown measures on the abundance and composition of PM10 traffic raleted dusts.

 Magnetic measurements highlight persisting high concentration of magnetic minerals in the daily PM filters of busy roads from Latium region during lockdown. Nevertheless, their concentration increases after the strict lockdown and, while the average PM concentration remains the same, the average susceptibility almost doubles.

 In busy roads, the correlation between PM and volume susceptibility has two distinct regimes during and after the strict lockdown. In general, volume susceptibility is linearly correlated to PM concentration during «end-members» periods, that is prevailing clean (paramagnetic, natural) or heavy polluted (ferrimagnetic, traffic emissions) conditions. An anticorrelation between PM concentration and mass susceptibility emerges during intermediate/mixed conditions.

 In rural background stations there is no difference between lockdown and post lockdown conditions, for both magnetic susceptibility and PM concentration

 Non-exhaust PM arising from brakes dominates the magnetic fraction; fuel exhausts and/or

natural sources emerge in rural or lower traffic settlings.