Simultaneous Single Particle Mass Spectrometry Measurements at Two Different Urban Sites and Comparison with Quantitative Techniques

Transcription

1 Simultaneous Single Particle Mass Spectrometry Measurements at Two Different Urban Sites and Comparison with Quantitative Techniques Eoin McGillicuddy 1, Manuel Dall Osto 2, Franco Lucarelli 3, Silvia Nava 4, Xavier Querol 2, Roy M. Harrison 5, Johanna K. Gietl 5, David C. S. Beddows 5, Deborah Gross 6, Robert Healy 1, John Wenger 1, John Sodeau 1 1 Department of Chemistry & Environmental Research Institute, University College Cork, Ireland 2 Institute for Environmental Assessment and Water Research (IDAEACSIC), Barcelona, Spain 3 Dipartimento di Fisica e Scienze dello Spazio, Universita degli Studi di Firenze, Fiorentino, Italy 4 INFN, Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Fiorentino, Italy 5 National Centre for Atmospheric Sciences, University of Birmingham, United Kingdom 6 Department of Chemistry Carleton College, Minnesota, USA

2 Overview ATOFMS Description 2 ATOFMS instruments deployed in SAPUSS Particle Classes Common types Unique types Comparison of ATOFMS results with quantitative technique (PIXE) Summary

3 ATOFMS: Aerosol TimeOfFlight Mass Spectrometer The ATOFMS can measure the size and chemical composition of individual particles in the range 00 nm Allows the simultaneous determination of: Particle size Primary (e.g. metals and carbon) and secondary (e.g. nitrate and sulfate) particle composition Internal and external mixing state

4 ATOFMS: Aerosol TimeOfFlight Mass Spectrometer

5 Relative Intensity Relative Intensity Typical ATOFMS spectra Na + K + Na 2 Cl + NaCl 2 Na Cl NO 2 NO 3 Cl SO 3 SeaSalt Particle Mass Spectra m/z K + Na + + C + C 3 K 2 Cl + C 2 CN HSO 4 O NO 2 C 3 C 4 NO 3 Biomass Burning Particle Mass Spectra Cl Cl SO 3 KCl m/z

6 SAPUSS Measuring Sites ATOFMS TSI Model 3800 Aerodynamic lens has a high transmission efficiency for submicron particles mass spectra collected ATOFMS TSI model 3800 Converging nozzle inlet favours detection of supermicron particles mass spectra collected

7 ATOFMS Particle Classes Collected mass spectra were analysed using the Art2a Algorithm The total number of particle classes was reduced to 18 for RS and 14 for UB RS site EC Secondary inorganic Sea Salt Metals Classes particle number % UB site Classes number % ECK 277, ECK 52, EC EC 2, EC 76, LRTNIT 2, NitEC 9, LocNIT 37, Secondary inorganic NitOCK 15, LRTSUL 52,4 5.9 Ksul 6,635 3 NaClNIT 75,4 8.4 NaClNIT 8, Sea Salt NaCl 8,926 1 Nacl 31, Fe 7,1 0.8 Pb Metals Pb Fe 5, K KCN 21, K KCN 2, Unique RS TOTAL RS Amine58 6, SoilSaharan 2, Amine114 3, SoilCa 2, Unique UB Amine59 2, OilV 1, ETS 4, VegKP 3, Lub Oil 16, OCCHO 42, AroNIT 15,6 1.7 OCNIT 13, ,873 TOTAL UB 221,139

8 EC and ECK Particle Classes Relative ion intensity m/z EC These two particle classes represent more than % of the particles sampled at both sites Characterised by EC peaks (12, 24, 36, 46, 60). ECK also has a major peak at m/z 39 Large accumulation during the two stagnant periods in SAPUSS EC shows no diurnal variation ECK shows a diurnal trend peaking during day time, suggesting a more local source

9 Secondary Inorganic Particles Relative ion intensity LRTNIT Three classes of secondary inorganic particles presented almost identical mass spectra LocNIT was found peaking at 11 am m/z LRTNIT was found in the accumulation mode, evaporating during daytime and leaving a core of LRTSUL, smaller and peaking during daytime LRTSUL also seen during intrusion of European air masses

10 Metals (Pb, Fe) Relative ion intensity Two classes of non alkali metals were found at both sites, Pb and Fe m/z Pb 2 2 Pb showed unique sharp events at both sites likely due to industrial sources Fe particle class is submicron and attributed to long range transport of anthropogenic emissions

11 Unique Particles at Urban Background Relative ion intensity m/z Saharan dust SoilCa: Soil enriched in Ca, with possible contribution from lubricating oil SoilSaharan: Saharan dust particle type containing AlSiTi detected during the 8 th th October VegKP: Possibly vegetative debris, observed with Saharan air masses OilV: Strong signal for V + and VO +. Wind rose indicative of emissions from the port

12 Unique Particles detected at Road Site Relative ion intensity m/z ETS Lub Oil: Major peak at m/z 40 (Ca) and some EC and phosphate, peaking during traffic rush hours ETS: Not previously detected in ambient air. Unique peaks of nicotine are m/z 84 and m/z 161. Follows traffic pattern, peaking in morning and evenings OC Classes: AroNIT, OCNIT, OC CHO Amines: Amine58 spiking during nighttime, and amine59 and amine114 spiking in the afternoon at 15:00 (cooking?)

13 Metal Identifying Ion (m/z) Confirmatory Ion (m/z) R Squared Aluminium 27 N/A N/A Antimony Barium Cadmium Calcium Chromium Cobalt 59 N/A N/A Iron Lead Lithium 7 N/A N/A Manganese 55 N/A N/A Nickel Potassium Selenium Sodium 23 N/A N/A Vanadium Zinc Metals: ATOFMS vs. PIXE Hourly average concentrations of metals were measured using Particle Induced XRay Emission (PIXE Lucarelli et al.) ATOFMS data queried for ion intensities at m/z of selected metal isotopes

14 ATOFMS m/z +27 ATOFMS m/z 27 Aluminium Correlation of PIXE hourly mass concentrations with ATOFMS hourly ion intensities for m/z +27 yield R 2 = This confirms that m/z +27 in ATOFMS mass spectra is Aluminium and the intensity of the peak is related to the concentration of Aluminium in the particle mz_a 27_All PIXE_Al_UB.0x x PIXE Al (ng m 3 ) R 2 = // 06// 11// 16// Date & Time 0 0 PIXE Al (ng m 3 ) 400

15 ATOFMS m/z 66 ATOFMS m/z 55 ATOFMS m/z 7 Industrial Metals (Mn, Zn, Pb).6x R 2 = x R 2 = PIXE Mn (ng m 3 ) PIXE (ng m 3 ) x R 2 = Mn, Zn, Pb are associated with industrial sources. Their temporal trends show sharp spikes in emissions PIXE Zn (ng m 3 )

16 ATOFMS ATOFMS m/z 48 Titanium m/z 48 ion intensity follows the Ti concentration well, especially during the Saharan dust event On some occasions however the concentration peak seems to be much stronger than the ion intensity response The noisy baseline of the ATOFMS trend suggests interference of C 4 + also at m/z x 3 PIXE_Ti_UB mz_a 48_All 35 0x R 2 = PIXE // 06// 11// 16// Date & Time 15 PIXE Ti (ng m 3 ) 25 35

17 ATOFMS m/z 39 Potassium Initial correlation between the ATOFMS and PIXE has R 2 = Correlation is complicated by the appearance of several different relationships between the PIXE mass and the ATOFMS signal x PIXE K(ng m 3 )

18 Effect of Meteorology Figure adapted from: Dall'Osto, M., X. Querol, et al. "Presenting SAPUSS: solving aerosol problem by using synergistic strategies at Barcelona, Spain." Atmos. Chem. Phys. Discuss 12:

19 Effect of Meteorology The correlations between the ATOFMS ion intensities and PIXE concentrations were examined during the different periods Correlations are significantly improved for several metals during particular air masses e.g. Al during North African 2 and Fe during Atlantic air masses Metal Overall Atlantic 1 Regional 1 Transition 1 North African 1 Transition 2 Atlantic 2 Transition 3 North African 2 Transition 4 European Transition 5 Regional 2 Aluminium Calcium Iron Potassium Magnesium Manganese Sodium Lead n/a n/a n/a Titanium n/a n/a n/a n/a Zinc

20 Summary First successful deployment of two ATOFMS in one campaign Major particle classes detected at both sites Unique classes observed at both sites due to both location and instrument bias effects Barcelona is influenced by many different emission sources, source apportionment will be an important tool in determining relative importance of these sources

21 Acknowledgements I would like to thank those who assisted in the completion of this work in Cork, Barcelona and Birmingham research groups I would like to thank IRCSET and HEA for funding my research