Long-term characterization of organic and elemental carbon in the PM&amp;lt;sub&amp;gt;2.5&amp;lt;/sub&amp;gt; fraction: the case of Athens, Greece

D Paraskevopoulou,C Theodosi,E Liakakou,E Gerasopoulos,N Mihalopoulos

doi:10.5194/acp-14-13313-2014

Long-term characterization of organic and elemental carbon in the PM&lt;sub&gt;2.5&lt;/sub&gt; fraction: the case of Athens, Greece

D Paraskevopoulou, C Theodosi + Show 3 more

Open Access

https://doi.org/10.5194/acp-14-13313-2014

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Abstract

Abstract. Organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and main ions were measured in a total of 1510 PM2.5 daily aerosol samples collected from May 2008 to April 2013 in Athens, Greece. OC and EC concentrations were 2.1 ± 1.3 μg m−3 and 0.54 ± 0.39 μg m−3, accounting for 11 ± 3% and 3 ± 1% of PM2.5 mass, respectively, with an average OC/EC ratio of 4.7 ± 3.1. Significant correlation was found between OC and EC during the whole period, indicating emissions by common primary sources on a regional scale. WSOC concentration ranged from 0.03 to 10.6 μg m−3, with an average of 1.5 ± 0.9 μg m−3. By considering the Finokalia (Crete) station as a reference, it was estimated that, during the warm season in Athens, 67 ± 7% of emitted OC and 53 ± 12% of emitted EC is regional, while, during cold months, the regional contribution of OC is only 33 ± 7% and of EC 29 ± 8%. Furthermore, secondary organic carbon (SOC) was calculated for the warm period of the year (April to October). The estimated SOC constituted about 75 ± 6% of PM2.5 organic carbon in Athens, highlighting significant aging processes on a regional scale. In the period 2011–2013 and during wintertime, an increase in OC and EC levels was observed, attributed to an increase in wood burning for domestic heating due to the economic crisis.

Highlights

Atmospheric aerosol constitutes a crucial factor of air pollution since it presents adverse effects on health, environment and Earth radiative balance (EPA, 1996; WHO, 2003)
Organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and main ions were measured in a total of 1510 PM2.5 daily aerosol samples collected from May 2008 to April 2013 in Athens, Greece
Compared to OC and EC concentrations in Athens back in 2003, this study reveals levels 3–4 times lower, while later studies revealed similar levels in the range of 1.5–4 μg m−3 for OC and 0.4–1.8 μg m−3 for EC

Summary

Introduction

Atmospheric aerosol constitutes a crucial factor of air pollution since it presents adverse effects on health, environment and Earth radiative balance (EPA, 1996; WHO, 2003). Establishing the carbonaceous content of atmospheric particles has been the objective of several studies as it represents an essential fraction of particulate matter (Alastuey et al, 2004; Na et al, 2004; Putaud et al, 2004; Querol et al, 2004; Yu et al, 2004; Yttri et al, 2007; Pey et al, 2010; Pio et al, 2011) These studies provide evidence for the relative importance of road traffic and high wintertime energy consumption, combined with unfavorable meteorological conditions and summertime traffic, and indicate that secondary organic aerosol is a major source of carbonaceous aerosol in Europe. The formation mechanisms of organic carbon (OC) and elemental carbon (EC) have been under scrutiny during the last decade (Saylor et al, 2006; Pio et al, 2007; Schwarz et al, 2008; Pio et al, 2011; Grivas et al, 2012; Bougiatioti et al, 2013), with an emphasis on their biogenic and/or anthropogenic origin and subsequent effects

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