Fossil versus contemporary sources of fine elemental and organic carbonaceous particulate matter during the DAURE campaign in Northeast Spain

María Cruz Minguillón ,V A Lanz,N Perron,A M Ortega,Sönke Szidat ,Josep Peñuelas ,Lukas Wacker ,Fabio Moretti ,Urs Baltensperger ,Andrés Alastuey ,Cristina Reche ,John F Burkhart ,Fúlvio Amato ,Claudia Mohr ,Douglas A Day ,András Hoffer ,Simon Schallhart ,Gyula Kiss ,Risto Hillamo ,Roger Seco ,Stefano Decesari ,Michael Cusack ,Kimmo Teinilä ,Xavier Querol ,Armin Hansel ,Simon Fahrni ,Axel Metzger ,Markus Müller ,José L Jimenez ,Andrê S H Prévôt

doi:10.5194/acp-11-12067-2011

Abstract

Abstract. We present results from the international field campaign DAURE (Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the Western Mediterranean), with the objective of apportioning the sources of fine carbonaceous aerosols. Submicron fine particulate matter (PM1) samples were collected during February–March 2009 and July 2009 at an urban background site in Barcelona (BCN) and at a forested regional background site in Montseny (MSY). We present radiocarbon (14C) analysis for elemental and organic carbon (EC and OC) and source apportionment for these data. We combine the results with those from component analysis of aerosol mass spectrometer (AMS) measurements, and compare to levoglucosan-based estimates of biomass burning OC, source apportionment of filter data with inorganic composition + EC + OC, submicron bulk potassium (K) concentrations, and gaseous acetonitrile concentrations. At BCN, 87 % and 91 % of the EC on average, in winter and summer, respectively, had a fossil origin, whereas at MSY these fractions were 66 % and 79 %. The contribution of fossil sources to organic carbon (OC) at BCN was 40 % and 48 %, in winter and summer, respectively, and 31 % and 25 % at MSY. The combination of results obtained using the 14C technique, AMS data, and the correlations between fossil OC and fossil EC imply that the fossil OC at Barcelona is ∼47 % primary whereas at MSY the fossil OC is mainly secondary (∼85 %). Day-to-day variation in total carbonaceous aerosol loading and the relative contributions of different sources predominantly depended on the meteorological transport conditions. The estimated biogenic secondary OC at MSY only increased by ∼40 % compared to the order-of-magnitude increase observed for biogenic volatile organic compounds (VOCs) between winter and summer, which highlights the uncertainties in the estimation of that component. Biomass burning contributions estimated using the 14C technique ranged from similar to slightly higher than when estimated using other techniques, and the different estimations were highly or moderately correlated. Differences can be explained by the contribution of secondary organic matter (not included in the primary biomass burning source estimates), and/or by an overestimation of the biomass burning OC contribution by the 14C technique if the estimated biomass burning EC/OC ratio used for the calculations is too high for this region. Acetonitrile concentrations correlate well with the biomass burning EC determined by 14C. K is a noisy tracer for biomass burning.

Highlights

Ambient aerosols have adverse effects on human health (e.g., Nel, 2005; Pope and Dockery, 2006; Krzyzanowski and Cohen, 2008)
Carbonaceous aerosol comprises a wide variety of organic compounds, collectively referred to as organic matter (OM), elemental carbon (EC), and carbonate mineral dust, the latter typically being negligible in submicron aerosol since it is mainly present in the coarse fraction (Sillanpaaet al., 2005)
The organic carbon (OC) fractional contribution was higher at MSY than at BCN (Fig. 1), the absolute concentrations of OC were higher at BCN (Fig. 2) during DAUREW, and similar to those at MSY in DAURE-S

Summary

Introduction

Ambient aerosols have adverse effects on human health (e.g., Nel, 2005; Pope and Dockery, 2006; Krzyzanowski and Cohen, 2008). They affect climate through their direct (absorption and scattering) and indirect (cloud interactions) effects on the Earth’s radiative balance (Forster et al, 2007), ecosystems and crops through their deposition of acids, toxics, and nutrients (e.g., Matson et al 2002; Grantz et al, 2003), and regional visibility (e.g., Watson, 2002). Carbonaceous aerosols are responsible for some of the adverse effects on human health produced by particles (Li et al, 2003; Mauderly and Chow, 2008). EC induces respiratory and cardiovascular problems (Highwood and Kinnersley, 2006; and references therein) and may adsorb toxic or carcinogenic organic species which may be absorbed into lung tissue (Gerde et al, 2001)

Methods

Results

Conclusion