Supplement of Atmos. Meas. Tech., 7, 2121–2135, 2014http://www.atmos-meas-tech.net/7/2121/2014/doi:10.5194/amt-7-2121-2014-supplement© Author(s) 2014. CC Attribution 3.0 License.

Supplement of

Evaluation of the performance of a particle concentrator for onlineinstrumentation

S. Saarikoski et al.

Correspondence to:S. Saarikoski (sanna.saarikoski@fmi.fi)

Supplements

Table S1. The shift of particles size for monodisperse AS and DOS particles in the m-VACES.

Particle size (nm) AS % (nm) DOS % (nm)

50 20 (10) 30 (5.9) 70 7.7 (5.4) 7.7 (5.4) 100 4.0 (4.0) 4.0 (4.0) 200 3.5 (7.0) 3.5 (7.0) 300 0.0 (0.0) 0.0 (0.0)

Fig. S1. Time series for the size distributions of particle number (a-b), mass (c-d) and enrichment factor. (a) and (c) are for ambient and (b) and (d) for concentrated aerosol. Particle mass was calculated by using the density of 1.48 g cm-3.

0.4

0.3

0.2

0.1

0.0

5 6 7 8 9100

2 3 4 5 6 7 8 91000

Particle diameter (nm)

10

8

6

4

2

0

35

30

25

20

15

10

5

0

Co

nce

ntra

ted

(µg

m-3)

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Am

bie

nt

(µg

m-3

)

Acidic particles

Neutral particles

ambient concentrated

ambient concentrated

Fig. S2. Size distribution of ammonium during the period when the particles were acidic (April 12, 2010) and nearly neutral (April 13, 2010; 6 am to midnight). Ambient size distributions were smoothed by one point.

Fig. S3. Scatter plots of the mass fragments in ambient and concentrated OA separated into different compound classes. Carbon clusters (Cx) were measured only with the laser on and the concentration of C1 (m/z 12) according to the fragmentation Table in Onasch et al. (2012). Concentrated aerosol is divided by the average EF for organics (27.08; a, c-e) and r-BC (37.61; b) (Table 2). One to one ratio is shown by dash lines.

0.001

2

4

6

0.01

2

4

6

0.1

2

4

conc

entr

ated

aer

osol

(µg

m-3

)

0.0012 4 6 8

0.012 4 6 8

0.12 4

ambient aerosol (µg m-3

)

2829

30

3142

43

45

46

5354

55

56

57

5859

66

67

68

69

7071

7279

8182

83

8485

86

93 94

95

9697

98

99101

103

104105

106

107

108

109

110111

112113

Organic compoundswith one oxygenatom (CxHyO)

0.001

2

4

6

0.01

2

4

6

0.1

2

4

conc

entr

ated

aer

osol

(µg

m-3

)

0.0012 4 6 8

0.012 4 6 8

0.12 4

ambient aerosol (µg m-3

)

44

45

4647

56

5859

60

61

68

69

70

71

72

73

74

7576

8081

82

8384

85

86

87

969798

99

100167

Organic compoundswith more than oneoxygen atom(CxHyOz (z>1))

0.001

2

4

6

0.01

2

4

6

0.1

2

4co

ncen

trat

ed a

eros

ol (

µg

m-3

)

0.0012 4 6 8

0.012 4 6 8

0.12 4

ambient aerosol (µg m-3

)

30

42

5254

5672

84

Organic compounds withone nitrogen atom (CxHyN)

0.001

2

4

68

0.01

2

4

68

0.1

2

4

conc

entr

ated

aer

osol

(µg

m-3

)

0.0012 4 6 8

0.012 4 6 8

0.12 4

ambient aerosol (µg m-3

)

13

15

25

26

2729

3037

38

39

40

41

42

43

44

49

5051

52

53

54

55

56

57

5961

62

6365

66

67

68

69

7071

72

737475

76

77

78

79

80

81

82

83

84

85

86

8788

89

90

91

92

93

94

95

96

97

98

99100

101

102103

104

105

106

107

108

109

110

111

112113

114

115

Hydrocarbonfragments (CxHy)

0.001

2

4

6

0.01

2

4

6

0.1

2

4

conc

entr

ated

aer

osol

(µ

g m

-3)

0.0012 4 6 8

0.012 4 6 8

0.12 4

ambient aerosol (µg m-3

)

1224

36

Carbon clusters (Cx)

4

3

2

1

0

CH

4N,

C2H

4N,

C3H

6N (

µg

m-3

)

9-Apr-10 10-Apr-10 11-Apr-10 12-Apr-10 13-Apr-10 14-Apr-10 15-Apr-10Date

80

60

40

20

0

EF

for

NH

4

20

15

10

5

0

NH

4 (µg

m-3)

NH4

CH4N C2H4N C3H6N

a)

b)

Fig. S4. Time series of ammonium and amines for the concentrated aerosol (a) and the enrichment factor for ammonium (b).

1.70

1.60

1.50

24201612840Diurnal hour

0.45

0.40

0.35

0.30

0.25

1.8

1.6

1.4

1.2

1.0

Ele

me

nta

l ra

tio

20

10

0

x10

-3

OM:OC

O:C

H:C

N:C

concentrated ambient

concentrated ambient

concentrated ambient

concentrated ambient

Fig. S5. Diurnal trends for OM:OC, O:C, H:C and N:C for concentrated and ambient OA.

Fig. S6. Correlation of mass spectra for PMF factors for ambient and concentrated OA.

0.001

2

4

6

80.01

2

4

6

80.1

Fra

ctio

n in

co

nce

ntr

ate

d O

A

0.0012 3 4 5 6

0.012 3 4 5 6

0.1

Fraction in ambient OA

C

CH

CH3

HO

H2O

C2H

C2H2

C2H3

CO

CHO

C2H5

CH2O

CH4N

CH3O

C3H

C3H2

C3H3

C3H4

C3H5

C2H2O

j13CC2H5

C3H6

C2H3O

CO2

j13CCH3O

C3H8

CHO2

C2H5O

CH3O2

C4H2

C4H3

C4H4C3HO

C4H5

C3H2O

C4H6

C3H3OC4H7

C3H4OC4H8

C3H5O

C4H9

C2H2O2

C3H6O

C2H3O2

C3H7O

C2H4O2

C2H5O2

C5H2

C5H3

C5H5

C5H6

C4H3O

C5H7

C4H4OC5H8C3HO2

C4H5O

C5H9

C3H2O2

C4H6O

C5H10

C3H3O2C4H7O

C5H11

C3H4O2

C3H5O2

C3H9SiC3H6O2

C6H3

C6H4

C6H5

C6H6

C6H7

C4O2

C6H8

C4HO2

C5H5O

C6H9

C5H6O

C6H10C4H3O2

C5H7O

C6H11

C4H4O2C5H8O

C4H5O2

C5H9O

C4H6O2C4H7O2C7H5

C7H7

C7H9

C6H6O

C6H7OC7H11

C6H8OC5H5O2

C6H9OC7H13C8H2

C6H10O

C5H7O2

C8H5

C8H7

C8H9

C7H7O

C8H11C7H9O

C8H13C9H3C7H11OC9H5

C9H7

OOA-2

0.001

2

4

6

80.01

2

4

6

80.1

Fra

ctio

n in

co

nce

ntr

ate

d O

A

0.0012 3 4 5 6

0.012 3 4 5 6

0.1

Fraction in ambient OA

C

CH

CH3

HO

H2O

C2H

C2H2

C2H3

COCHO

C2H5

CH2OCH4N

CH3O

C3H

C3H2

C3H3

C3H4

C3H5C2H2O

C2H4N

C3H6

C2H3O

C3H7

CO2

j13CCH3O

C3H8

CHO2

CH3NO

C2H5O

CH3O2C4H2

C4H3

C4H4C3HO

C4H5

C3H2O

C3H4N

C4H6

C3H3O

C4H7C3H4O

C3H6N

C4H8

C3H5O

C4H9

C2H2O2

C3H8NC2H3O2

C3H7O

C2H4O2

C2H5O2

C5H2

C5H3C5H5

C5H6C4H3O

C5H7C4H4O

C5H8

C3HO2

C4H5O

C5H9C3H2O2

C4H6O

C3H3O2

C4H7O

C3H4O2

C3H5O2

C6H2

C3H6O2

C6H3C2H4O3C6H4

C6H5

C6H6

C6H7

C6H8

C5H5O

C6H9

C4H2O2

C5H6OC4H3O2

C5H7OC4H4O2C5H8O

C4H5O2

C5H9OC4H6O2C3H3O3

C4H7O2C7H5

C7H7

C6H5O

C7H9C6H6O

C6H7O

C6H8O

C5H5O2C6H9OC4H3O3

C5H7O2C8H5

C8H7

C7H5OC8H9

C7H7O

C7H8O

C7H9OC9H3C7H11O

C9H4

C9H5

C9H7

OOA-1

0.001

2

4

6

80.01

2

4

6

80.1

Fra

ctio

n in

co

nce

ntr

ate

d O

A

0.0012 3 4 5 6

0.012 3 4 5 6

0.1

Fraction in ambient OA

C

CH

CH3

HO

H2O

C2H

C2H2

C2H3COC2H5

CH2O

CH4N

CH3O

C3H

C3H2

C3H3

C3H4

C3H5

C2H2O

j13CC2H5

C3H6

C2H3O

C3H7

CO2

j13CCH3O

C3H8CHO2

C2H5O

CH3O2

C4H2C4H3

C4H4

C3HO

C4H5

C3H2O

C4H6

C3H3O

C4H7

C3H4Oj13CC3H7

C4H8

C3H5O

C4H9

C3H6O

j13CC3H9

C3H7OC2H4O2

C5H2

C5H3

C5H5

C5H6

C5H7

C4H4O

C5H8

C3HO2

C4H5O

C5H9

C4H6O

j13CC4H9

C5H10

C3H3O2

C4H7O

C5H11

C3H5O2

C6H4

C6H5

C6H6

C6H7

C4O2C6H8

C4HO2

C6H9

C5H6O

C6H10

C5H7O

C6H11

C5H8O

C6H12C4H5O2C5H9O

C6H13

C4H7O2C7H5

C7H7

C7H8

C7H9

C7H10

C6H7O

C7H11

C7H12

C7H13

C5H7O2C8H7

C8H9C8H11

C7H9O

C8H13

C7H11OC8H15

C9H7

HOA

Fig. S7. The variation of Q/Qexpected with the value of fPEAK for ambient (a) and concentrated (b) PMF solution.

Fig. S8. The variation of time series and mass spectra for the PMF factors with the fPEAK values from -0.4 to 1.6. Ambient (a) and concentrated (b) OA.

Detection of trace elements

HR-AMS can detect several trace elements with lower melting and boiling points in near

real-time (Salcedo et al., 2012), and furthermore, the SP-AMS can detect some additional

metals and trace elements due to the laser vaporizer (Onasch et al., 2012). However, the

concentrations of trace metals are typically very low in ambient air, especially in Finland,

and therefore their real-time detection is challenging. Thus the use of a concentrator may

allow the real-time detection of elements that otherwise could not be observed.

Five trace elements were detected in ambient air without the m-VACES; aluminum,

vanadium, iron, zinc and rubidium. Except zinc, all of the elements were most likely

associated with the laser vaporization as there was a steep drop in the recorded

concentrations when the laser vaporizer was switched off. Rubidium can undergo surface

ionization with a tungsten vaporizer making its quantification difficult (Drewnick et al.,

2006), similar to sodium and potassium. In this study surface ionization in tungsten

vaporizer was not likely to be a confounding issue, as rubidium seemed to be totally

vaporized by the laser and not hit the tungsten vaporizer, however, surface ionization can

also take place on the hot surface of the r-BC particles discussed more in Carbone et al.

(2014). Slow evaporation is another issue related to the detection of semi-refractory

elements with the AMS, requiring special data analysis procedures (Salcedo et al., 2012).

Zinc signals were consistent with slow evaporation at tungsten vaporizer the ratio of

closed to open being around 0.70 and 0.25 for ambient and concentrated aerosol,

respectively (Fig. S9). However, a part of the difference could be due to the uncertainty

in the detection of low signal for Zn.

Trace elements gave rather similar EFs to the other species measured, however, the

standard deviations for EFs were large probably due to the high uncertainty associated

with the determination of their low ambient concentrations (Table 2). Of all the elements,

rubidium had the smallest enrichment factor and aluminum the highest. EFs were

calculated for the most abundant isotopes (m/z 26.982 for Al, m/z 50.944 for V, m/z

55.935 for Fe, m/z 84.912 for Rb), except for zinc that was detected at the isotope 68Zn

(m/z 67.925). All the other isotopes of V, Fe and Zn could not be resolved from the

neighboring peaks or were below their detection limits. The isotopic ratio of 85Rb and 87Rb is shown in Fig. S10 for open and closed modes. The isotopic ratio of 87Rb to 85Rb

was near the natural isotopic ratio of 0.386 for both the modes. Unfortunately, it was not

possible to investigate size-dependent EFs for trace elements as they composed only a

minor fraction of the total signal at each unit mass. Additionally, due to the limited data

coverage from the laser vaporizer, diurnal patters for the EF could not be calculated.

Aluminum, iron and rubidium correlated with r-BC. This suggests that they have similar

combustion-related origins in Helsinki, mostly in the form of traffic sources, either from

exhaust or non-exhaust (e.g. road dust) emissions. Zinc has been shown to be associated

with regional or long-range transported air masses in Helsinki whereas vanadium has

more local sources like heavy oil combustion (Pakkanen et al., 2001).

Besides those five trace elements that were detected in ambient air without the

concentrator, three additional elements were detected only with the m-VACES. These

elements were strontium, zirconium and cadmium (Fig. S11) and they were identified

based on their exact m/z. Strontium was detected at m/z 87.906 and zirconium at m/z

89.905 that were their most abundant isotopes. Cadmium was observed at m/z 111.903.

Unfortunately, any other isotopes of these elements could not be detected, and therefore

their existence could not be verified by the isotopic ratios. Of those three, only strontium

seemed to be associated with r-BC and vaporized with the laser. However, because

zirconium in its elemental form requires about 4400 ºC to be vaporized, one possibility is

that this trace element was associated with other elements forming for example salts or

oxides that could be vaporized with lower temperatures. Neither zirconium nor cadmium

showed evidence of slow evaporation in tungsten vaporizer indicated by a signal in the

closed mode.

Strontium and zirconium did not have any clear correlation with the other species

measured whereas cadmium correlated with organics and r-BC. That was unexpected as

cadmium did not seem to be in the same particles with r-BC (detected also without laser).

Previously cadmium has been related to several sources in Helsinki and it was found to

be mostly regional or long-range transported (Pakkanen et al., 2001). Strontium, on the

other hand, has been associated with traffic-related components from vehicle motor oil

but it can also originate from crustal material. Zirconium has not been reported in

Helsinki urban air before but in US it has been reported e.g. from the emission of the

coal-fired boilers and in samples of geological material (Watson et al., 1995).

7

6

5

4

3

2

1

0

Am

bie

nt (

Hz)

10-Apr-2010 11-Apr-2010

Date

80

60

40

20

0

Con

cen

tra

ted

(H

z)

Open Closed

Open Closed

Fig. S9. Slow evaporation of zinc. Open and closed signal for ambient and concentrated aerosol.

70

60

50

40

30

20

10

0

87R

b (n

g m

-3,

RIE

=1)

16014012010080604020085

Rb (ng m-3

, RIE=1)

14

12

10

8

6

4

2

0

87R

b (

ng

m-3

, RIE

=1

)

40302010085

Rb (ng m-3

, RIE=1)

Open Closed

y = 0.391*x 2

r2= 0.931

y = 0.378*x 2

r2= 0.930

Fig. S10. Scatterplot of signal from 87Rb and 85Rb for open and closed modes. Expected natural isotopic ratio is shown by a dash line.

100x10-3

80

60

40

20

0

Diff

Hz/

ns

88.288.188.087.987.8m/z

2.0

1.5

1.0

0.5

0.0

Diff

Hz/

ns

88.288.188.087.987.8m/z

50x10-3

40

30

20

10

0

Diff

Hz/

ns

90.290.190.089.989.8

m/z

1.0

0.8

0.6

0.4

0.2

0.0

Diff

Hz/

ns

90.290.190.089.989.8m/z

100x10-3

80

60

40

20

0

Diff

Hz/

ns

112.3112.2112.1112.0111.9111.8

m/z

2.0

1.5

1.0

0.5

0.0

Diff

Hz/

ns

112.3112.2112.1112.0111.9111.8

m/z

StrontiumAmbient

StrontiumConcentrated

ZirconiumAmbient

ZirconiumConcentrated

CadmiumAmbient

CadmiumConcentrated

Raw fitted

Raw fitted

Raw fitted

Raw fitted

Raw fitted

Raw fitted

87.9056

89.9047

111.9028

Fig. S11. Strontium, zirconium and cadmium peaks for ambient and concentrated aerosol. Additional isotopes of these ions could not be detected.

References

Carbone, S., Onasch, T., Saarikoski, S., Timonen, H., Sueper, D., Worsnop, D. R., and Hillamo, R.: Trace metals characterization with the SP-AMS: detection and quantification, in preparation, 2014. Drewnick, F., Hings, S. S., Curtius, J., Eerdekens, G., Williams, J.: Measurement of fine particulate and gas-phase species during the New Year’s fireworks 2005 in Mainz, Germany, Atmos. Environ. 40, 4316–4327, 2006. Onasch, T. B., Trimborn, A., Fortner, E. C., Jayne, J. T., Kok, G. L., Williams, L. R., Davidovits, P., and Worsnop, D. R.: Soot Particle Aerosol Mass Spectrometer: Development, Validation, and Initial Application, Aerosol Sci. Technol., 46, 804-817, 2012. Pakkanen, T. A., Loukkola, K., Korhonen, C.H., Aurela, M., Mäkelä, T., Hillamo, R., Aarnio, P., Koskentalo, T., Kousa, A., and Maenhaut, W.: Sources and chemical composition of atmospheric fine and coarse particles in the Helsinki area, Atmos. Environ. 35, 5381–5391, 2001. Salcedo, D., Laskin, A., Shutthanandan, V., and J.-L. Jimenez, J.-L.: Feasibility of the Detection of Trace Elements in Particulate Matter Using Online High-Resolution Aerosol Mass Spectrometry, Aerosol Sci. Technol., 46, 1187-1200, 2012. Watson, J. G., Chow, J. C., and Houch, J. E.: PM2.5 chemical source profiles for vehicle exhaust, vegetative burning, geological material, and coal burning in Northwestern Colorado during 1995, Chemosphere, 43, 1141-1151, 1996.