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Particulate composition. James Allan, Paul Williams, Mike Flynn, Claire Martin, Hugh Coe & Martin Gallagher University of Manchester & NCAS Eiko Nemitz & Gavin Pillips CEH Edinburgh. Rationale. The chemical composition of particulates affects its toxicity
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Particulate composition James Allan, Paul Williams, Mike Flynn, Claire Martin, Hugh Coe & Martin Gallagher University of Manchester & NCAS Eiko Nemitz & Gavin Pillips CEH Edinburgh
Rationale • The chemical composition of particulates affects its toxicity • The composition also has implications for acid deposition and climate forcing • Studying the detailed composition gives important insights into sources and processes of particulates in the urban atmosphere
Measurement sites(REPARTEE I & II) Regent’s Park BT Tower
Instruments used • Filter samplers • Offline analysis of inorganic ions • ECN Gradient System for Reactive Aerosols and Gases with Online Registration (GRAEGOR) • Online analysis of inorganic ions and soluble gases • Aerodyne Aerosol Mass Spectrometer (AMS) • Online analysis of nonrefractory particulates.
GRAEGOR Thomas et al., Environ. Sci. Technol., 43, 1412–1418, 2009
AMS DeCarlo et al., Anal. Chem., 78, 8281-8289, 2006; Canagaratna et al., Mass Spectrom. Rev., 26, 185-222, 2007.
REPARTEE-I Aerosol Components BT TowerBold: GRAEGOR PM10 Fine: AMS NR-PM1 Steps: Filter PM10
Filter vs. GRAEGOR The filter loses 50% of fine NH4NO3 during peak concentrations.
Organics (AMS) McFiggans et al., Faraday Discuss., 130, 341-362, 2005.
PMF analysis Paatero, Chemometr. Intell. Lab., 37, 23-35, 1997; Lanz et al., Atmos. Chem. Phys., 7, 1503-1522, 2007; Ulbrich, et al., Atmos. Chem. Phys., 9, 2891-2918, 2009.
Types: • Oxygenated (OOA) • Hydrocarbon-like (HOA) • Cooking (COA) • Solid fuel (SFOA) Allan et al., Atmos. Chem. Phys., 10, 647-668, 2010.
Cooking Aerosols Heated cooking oil baths Mohr et al. (2009) Katrib et al. (2004) and Alfarra (2004)
Grid-scale emission factors REPARTEE 1 (relative to NOx) Manchester (relative to CO) CO (ppm) SFOA (µg m-3) HOA (µg m-3) HOA: 31.6 µg m-3 ppm-1 Mass emission ratio (MER): 0.026 (as NO) HOA: 20.5 µg m-3 ppm-1 MER: 0.018 SFOA: 24.7 µg m-3 ppm-1 MER: 0.021
Summary & Conclusions • Chemical composition of particulates was measured in multiple locations with multiple instruments during the REPARTEE experiments • The use of online instrumentation gives much better time resolution in the data and avoids many problems associated with offline analysis • Analysis of the high-resolution composition data sheds light on many urban aerosol sources and processes • This is further enhanced by the use of multiple measurement sites, instruments and data collection methods • Stay tuned for the next presentation…
Acknowledgements • This work was partly supported by the NERC CityFlux project (ref. NE/B504865/1) and the BOC Foundation. • C. L. Martin was supported by a NERC studentship (ref. NER/S/A/2005/13219) • Many thanks to The Royal Parks and BT for access to the measurement sites