Antimony: a traffic related element in sizefractionated road dust samples collected in Buenos Aires, Argentina

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1 Antimony: a traffic related element in sizefractionated road dust samples collected in Buenos Aires, Argentina Patricia Smichowski 1,2 Fabián Fujiwara 1,2 Julieta Marrero 1 Raúl J. Rebagliati 1 Darío Gómez 1 1 Comisión Nacional de Energía Atómica 2 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) ARGENTINA 2nd International Workshop on Antimony in the Environment Jena, August 2011

2 Our research A series of studies aimed at quantifying metals metalloids and ions in airborne particulate matter and related matrices as well as at identifying their sources Volcanic ashes Thermal power plant ashes Urban particulate matter Fractionation/speciation studies Traffic related elements Road dust

3 1.E+04 Composition of Buenos Aires PM10 (ng m -3 ) 1.E+03 1.E+02 1.E+01 1.E+00 1.E-01 1.E-02 1.E-03 1.E-04 S Ca Al Fe Zn Pb Cu Mn Sb V Zr Ni Sn Cd Mo Pt Rh major minor trace u-trace P. Smichowski, D. Gómez, L. Dawidowski, M. F. Giné, A. C. Sánchez Bellato, S. Reich J. Environment. Monit. 6, (2004)

4 Antimony in Buenos Aires PM10 Antimony: ng m -3 Mean concentration: 4.7 ng m -3 Highest concentrations at 2 sites characterized mostly by passenger cars featuring a stop-and-go pattern at peak hours Enrichment factor: 1731 Antimony: a traffic-related element in the atmosphere of Buenos Aires, Argentina, D. R. Gómez, M. F. Giné, A. C. Sánchez Bellato, P. Smichowski, J. Environ. Monit. 7, (2005)

5 EF x = X/C (sample) / X/C (crustal rock) C: crustal element Enrichment factors 1.E+04 1.E+03 1.E+02 1.E+01 1.E+00 1.E-01 1.E-02 1.E-03 1.E-04 S Ca Al Fe Zn Pb Cu Mn Sb V Zr Ni Sn Cd Mo Pt Rh Monitoring Pt and Rh in urban aerosols from Buenos Aires, Argentina. B. Bocca, S. Caimi, P. Smichowski, D. Gómez, S. Caroli, Sci, Total Environ. 358, (2006)

6 Traffic related elements (TREs) Ca (oils) Ce (additives for oil) Cd (brake pads, tire rubber) Cu (brake pads) Fe (brake pads) Hg (gasoline) Mn (lubricants, additives) Mo (brake pads) Ni (diesel) Pd (catalytic converters) Pt (catalytic converters) Rh (catalytic converters) Sb (brake pads) S (gasoline) V (gasoline) Zn (diesel, tire rubber, brake pads) Pb (gasoline, mechanical wear)

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8 Antimony

9 Sb Sb, Cu, Fe, Mo are contained in brake linings used in cars Heat-resistant material with a high coefficient of dynamic friction Brake linings contain 5-20% Cu and 1-5% Sb (as Sb 2 S 3 )

10 Why metals in road dust? Street dust is freely inhaled by people living in urban areas especially those traversing the streets and those residing within the vicinity of the streets Different elements/compounds are emitted by: Anthropogenic sources wear from vehicles and exhausts demolition, construction industrial activities Natural sources short and long-range transport of resuspended soils

11 Several parts of vehicles contain antimony compounds Brake pads Sb 2 O 3 as flame retardant in vulcanization of rubber Alloys for motor bearing Sb-dialkyldithiocarbamates in greases and motor oil

12 Our work ~ 200 samples during 2 months Size fractionation: A <37, 37<B <50; 50<C <75 y 75<D <100 µm Sample digestion: 2 ml HNO 3 +6 ml HCl+1 ml HF Elemental determination: Al, As, Ca, Cd, Cu, Fe, Mg, Mn, Mo, Ni, Pb, S, Sb, Sn y Zn by ICP OES

13 Buenos Aires city Vast plain, 1-27 m over sea level, 160 km from the ocean Surface: 200 km 2 Population: 3 million (metropolitan area) 14 million (metropolitan area + 24 neighborhoods) Traffic: vehicles/day Two thermal power plants (1800 and 2000 MW) that burn mostly natural gas 10 th megalopolis in the world and 3 rd in Latin America

14 Sample collection: from pavement edges using plastic dustpans and brushes Cascade sieve for fractionation: A < 37; 37 < B < 50; 50 < C < 75; 75 < D < 100 µm Sample digestion: 1) overnight pre-digestion (2 ml HNO 3 +6 ml HCl+1 ml HF) 2) digestion with the aid of MW irradiation Elemental determination: ICP OES (Perkin Elmer 5100 axial view) HG-AAS (Perkin Elmer AA200) For checking accuracy: NIST SRM 2709 San Joaquin soil

15 SEM & EDX image of road dust particles A total of ~ 800 individual particles were identified from the 4 fractions (i) mineral matter (70-80 %) (ii) spherical combustion products (~ 10 %) (iii) other types (pollen, fibres, organic matter, Cl but not associated with Na, soot aggregates)

16 Antimony in road dust Antimony as a traffic-related element in size-fractionated road dust samples collected in Buenos Aires, F. Fujiwara, R. Jiménez Rebagliati, J. Marrero, D. Gómez, P. Smichowski, Microchem. J. 97, (2011) Antimony was detected in 67 % of samples Total concentration: < 0.5 µg/g to 41.1 µg/g Higher concentrations in the 2 smaller fractions Enrichment factors: 272 (A) > 160 (B) > 50 (C) > 23 (D) Similar behavior for Cu and Mo Higher levels in areas of high traffic density

17 Sb concentration (µg/g) Antimony and traffic density Sb concentration (µg g -1 ) Low Low Traffic density Traffic density Medium-High High Short residence time (particles easily removed by wind and rain and human activities)

18 Sb (µg g -1 ) Antimony and other prototypical TREs Sb (µg g -1 ) Cu (µg g -1 ) (b) Pb (µg g -1 )

19 Cluster analysis As Cd S Sb Mn Pb Zn Mo Cu Fe Ni Sn Mg Cluster 1: Geological and anthropogenic origin Linkage Distance

20 Cluster analysis As Cd S Sb Mn Pb Zn Mo Cu Fe Ni Sn Mg Cluster 2: Traffic related Linkage Distance

21 Cluster analysis As Cd S Sb Mn Pb Zn Mo Cu Fe Ni Sn Mg Mechanical wear Mechanical wear & exhaust Cluster 2: Traffic related Linkage Distance

22 3-D scatter plot of the median concentrations of Cd, S and Sb finer fractions coarser fractions local soil

23 Concentration (µg g -1 ) Crustal rock Volcanic ash Road dust D Road dust C Placing Sb in context.. Soil Coal fly ash Road dust B Road dust A Road dust total Buenos Aires PM-10 Brake-lining 1E+05 1E+04 Median 25%-75% Non-Outlier Range Outliers Extremes 1E+03 1E+02 1E+01 1E+00 1E-01 1E-02

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26 Acknowledgements Project PICT (2000) Evaluación de la procedencia de metales y metaloides en partículas atmosféricas urbanas, funded by Agencia de Promoción Científica y Tecnológica, Argentina. Project PICT (2005) Emisión y Recepción de Aerosoles Troposféricos: el Caso de Buenos Aires, funded by Agencia de Promoción Científica y Tecnológica de Argentina. Project South American Megacities and Climate Change (SAEMC) sponsored by Interamerican Institute for Global Change Research (IAI) CRN II 2017 and funded by US National Science Foundation (Grant GEO ) ( Project ARCAL LXXX (RLA/7/011) Assessment of Atmospheric Pollution by Particles funded by International Atomic Energy Agency (IAEA). Project PIP 486 funded by the Argentine Research Council (CONICET). PS thanks PerkinElmer for funding

27 2012 Winter Conference on Plasma Spectrochemistry Tucson, Arizona, January 9-14, 2012 Hilton Tucson El Conquistador Resort

28 2012 Winter Conference on Plasma Spectrochemistry Short course Atmospheric Aerosols and Related Materials Analysis Patricia Smichowski Comisión Nacional de Energía Atómica (ARGENTINA) Naoki Furuta Chuo University (JAPAN)

29 Thank you very much for your attention