Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data

Abstract

17 páginas, 8 figuras. ; PM1 (particulate matter with an aerodynamic diameter <1 µm) non-refractory components and black carbon were measured continuously together with additional air quality and atmospheric parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SVOOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28 % to OA, SV-OOA 27 %, COA 17 %, HOA 16 %, and BBOA 11 %. The COA HR spectrum contained substantial signal from oxygenated ions (O:C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O:C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59 %) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O + and C3H5O + , even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H + 7 and C4H + 9 . A simple estimation method based on the markers m/z 55, 57, and 44 is developed here and allows for a first-order-estimation of COA in urban air. This study emphasizes the importance of cooking activities for ambient air quality and confirms the importance of chemical composition measurements with a high mass and time resolution. ; We thank the organizers of the DAURE project, including Mar Viana and everybody else at ICTJA for their work and help. We acknowledge the CCES project IMBALANCE and the EU-FP7 project EUCAARI for financial support and 'Accion Complementaria DAURE' from the Spanish Ministry of Science and Innovation (CGL2007-30502-E/CLI) for infrastructure support. P. F. DeCarlo is grateful for the postdoctoral support from the US-NSF (IRFP# 0701013). J. Penuelas and R. Seco were sup- ˜ ported by the Spanish Government projects CGL2010-17172 and Consolider Ingenio Montes CSD2008-00040, and by a postdoctoral grant from Fundacion Ram ´ on Areces to R. Seco. The National ´ Center for Atmospheric Research is sponsored by the National Science Foundation. J. L. Jimenez was supported by NSF ATM- 0919189 and DOE (BER, ASR program) DE-FG02-11ER65293. ; Peer reviewed