Intercomparisons between AMS and ATOFMS: The synergy! Manuel Dall Osto NUI Galway, Ireland

Transcription

1 Intercomparisons between AMS and ATOFMS: The synergy! Manuel Dall Osto NUI Galway, Ireland

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3 Overview of this talk: 1. Describe ATOFMS and AMS, focusing on their limits (especially for the AMS).. Some examples

4 The perfect instrument Cheap, quantify all single chemical species, single particles, fast, little, no complex data analysis...perhaps it should make coffee too..

5 Why? Why both? 1. The aerosol time-of-flight mass spectrometer (ATOFMS) offered by TSI provides information on a polydisperse aerosol, acquiring precise aerodynamic diameter and individual particle positive and negative mass spectral data in real time.. The AMS (Aerodyne Research, Inc.) provides online, real time measurements of the mass of non-refractory components of aerosol particles as function of their size. The results aim to show that the combination of the two provides much deeper insights into the nature of the aerosol properties than each of the instruments could do alone. This is my personal approach!

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7 Many instruments including the ATOFMS and the AMS are providing a wealth of data from which sometimes diverging conclusions are drawn. Sampling at different locations and under different meteorological conditions can explain some of the differences, perhaps. But meaningful comparisons between measurements can only be made within the frame of carefully evaluated uncertainties. My comment on that.. 1. AMS is much better characterised than the ATOFMS. ATOFMS gives the size and the chemical composition of single particles, this takes longer to characterise

8 Examples: S-rich particles PAH Nitrate containing particles Secondary Organic Aerosol during radiation fog Acknowledgments P. I. Williams, H. Coe, J. Allan (University of Manchester; UK) F. Drewnick (MPI-Mainz; Germany)

9 Example 1: industrial site

10 m/z Relative ion intensity S-rich m/z 3 [S + ], 6 [S + ], 96 [S3 + ] [Sn ] + Elemental Sulphur

11 a b c d e ppb µg m / 7/ 8/ 9/ 3/ 1/5 /5 3/5 /5 5/ ATOFMS counts ATOFMS counts S-rich type SO conc AMS m/z 8 AMS m/z 6 AMS m/z 8 AMS ratio mz 6/ mz 8 AMS ratio mz 6/ mz 8 Sulphate and sulphuric acid: m/z 8 [SO + ], 6 [SO + ], 8 [SO 3+ ], 81 [HSO 3+ ] and 98 [H SO + ] Elemental Sulphur: m/z 3 [S + ], 6 [S + ], 96 [S 3+ ] ([S n+ ])

12 Relative Signal Intensity S + [SO + ], S + Fragmentation Pattern of Elemental Sulfur Particles and Sulfate / Sulfuric Acid Particles (Vaporizer: 6 C) [SO + ], [SO 3+ ], S 3 + S + AMS S m/z Laboratory study confirm the field measurements. 6 Relative ion intensity ATOFMS 3 18 S-rich m/z Dall Osto et al (8)

13 Industrial site: ATOFMS PAH particle types Relative ion intensity PAH_low m/z Relative ion intensity 35 PAH_high m/z

14 .8 PAH AMS.6. AMS PAH_Low PAH_High ATOFMS counts ATOFMS PAH_LOW PAH_HIGH 1: 1: 1: 16: 18: : : : : : 6: 8: 1: 1: 1: /5/6 3/5/6 ATOFMS and AMS are able to detect simultaneously different PAH components Drewnick et al (8)

15 Example : REPARTEE (Regent s Park and BT Tower Environmental Experiment)

16 REAL TIME CHEMICAL CHARACTERIZATION OF LOCAL AND REGIONAL NITRATE AEROSOLS 6 1 a AMS nitrate [µg m -3 ] ATOFMS counts AMS Nitrate ATOFMS Nitrate 1 b ATOFMS counts 8 6 Nitrate Local Nitrate LRT

17 Relative ion intensity 15 Local nitrate m/z Local: locally produced in urban locations during nighttime (3nm) LRT nitrate Relative ion intensity m/z Regional: regionally transported from continental Europe (6nm)

18 REAL TIME CHEMICAL CHARACTERIZATION OF LOCAL AND REGIONAL NITRATE AEROSOLS 6 1 a AMS nitrate [µg m -3 ] ATOFMS counts AMS Nitrate ATOFMS Nitrate 1 b ATOFMS counts 8 6 Local (3:-6:) Regional Nitrate Local Nitrate LRT

19 3 Org SO NO 3 NH 8 6 µg/m3 µg/m PToF size, nm PToF size, nm (a) local (b) Regional µg/m3 1 6 µg/m Org SO NO PToF size, nm PToF size, nm (c) local (log scale) (d) regional (log scale)

20 a ATOFMS counts AMS nitrate Nitrate AMS Nitrate LRT Nitrate LRTcore 1 b RH Temperature RH T 5 1 : 15/1/6 6: 1: 18: : 16/1/6 6: 1: 18: : 17/1/6 Unique information on the diurnal variation of this particle type can be found in the ATOFMS data. It shows the strong volatility of the LRT nitrate aerosol, with loss to the gas phase during day time due to the higher temperature.

21 ATOFMS OC-Nit Nit-only 3 1 ATOFMS counts Ams mass loading 3 1 AMS Nitrate 16/5/8 1/5/8 6/5/8 31/5/8 5/6/8 1/6/8 Mace Head, Ireland, Spring 8

22 Example 3: REAL-TIME SECONDARY AEROSOL FORMATION DURING A FOG EVENT

23 Fog event during the morning of 13 th November 6 mb a ppb 1 b ATOFMS counts 6 c 5/1/6 8/1/6 11/1/6 1/1/6 17/1/6 /1/6 3/1/6 Stagnant conditions favouring radiation fog

24 36 Relative ion intensity HMS m/z Hydroxymethanesulphonate SO (g) + H O SO *H O SO *H O H + + HSO 3 - HSO 3 - H + + SO 3 - HCHO (aq) + H O CH (OH) HCHO(aq) + HSO 3 - HOCH SO 3 - (m/z -111) HCHO(aq) + SO 3 - -OCH SO 3 - Whiteacker and Prather (3)

25 a b c d e 1 86 EC AMS [HOA, OOA] ATOFMS APS [nm] NOx SMPS [nm] : 5: 6: 7: 8: 9: 1: 11: 1: 13: 1: AMS [Nit-Sul] 8x1 3 6 CPC O3 AMS HOA AMS OOA AMS Nitrate AMS Sulphate ATOFMS Nitrate ATOFMS Lub oil ATOFMS HMOC ATOFMS HMS ATOFMS Ca-SUL 8x1 3 6 SMPS NOx O 3 EC CPC (TSI3776) DMPS tot HMS org size APS

26 m/z ATOFMS intensity (Arb. units) OC, EC, Aromatic, N-containing, S-containing..

27 Summary 1. AMS and ATOFMS are very complementary. AMS and ATOFMS are very complementary 3. AMS and ATOFMS are very complementary. AMS and ATOFMS are very complementary Future work Synergy of ATOFMS ARTa and PMF HR-TOF-AMS could help to explain unclassified ATOFMS ARTa clusters and AMS PMF factors. ATOFMS could help to look for specific events in order to identify specific m/z in the AMS mass spectra (and vice-versa).

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