Abstract

Abstract. Investigations on atmospheric aerosols and their sources were carried out in October/November 2013 and May/June 2014 consecutively in a suburban area of Rome (Tor Vergata) and in central Rome (near St Peter's Basilica). During both years a Saharan dust advection event temporarily increased PM10 concentrations at ground level by about 12–17 µg m−3. Generally, in October/November the ambient aerosol was more strongly influenced by primary emissions, whereas higher relative contributions of secondary particles (sulfate, aged organic aerosol) were found in May/June. Absolute concentrations of anthropogenic emission tracers (e.g. NOx, CO2, particulate polycyclic aromatic hydrocarbons, traffic-related organic aerosol) were generally higher at the urban location. Positive matrix factorization was applied to the PM1 organic aerosol (OA) fraction of aerosol mass spectrometer (HR-ToF-AMS) data to identify different sources of primary OA (POA): traffic, cooking, biomass burning and (local) cigarette smoking. While biomass burning OA was only found at the suburban site, where it accounted for the major fraction of POA (18–24 % of total OA), traffic and cooking were more dominant sources at the urban site. A particle type associated with cigarette smoke emissions, which is associated with a potential characteristic marker peak (m∕z 84, C5H10N+, a nicotine fragment) in the mass spectrum, was only found in central Rome, where it was emitted in close vicinity to the measurement location. Regarding secondary OA, in October/November, only a very aged, regionally advected oxygenated OA was found, which contributed 42–53 % to the total OA. In May/June total oxygenated OA accounted for 56–76 % of the OA. Here a fraction (18–26 % of total OA) of a fresher, less oxygenated OA of more local origin was also observed. New particle formation events were identified from measured particle number concentrations and size distributions in May/June 2014 at both sites. While they were observed every day at the urban location, at the suburban location they were only found under favourable meteorological conditions, but were independent of advection of the Rome emission plume. Particles from sources in the metropolitan area of Rome and particles advected from outside Rome contributed 42–70 and 30–58 % to the total measured PM1, respectively. Apart from the general aerosol characteristics, in this study the properties (e.g. emission strength) and dynamics (e.g. temporal behaviour) of each identified aerosol type is investigated in detail to provide a better understanding of the observed seasonal and spatial differences.

Highlights

  • Atmospheric aerosol particles remain a major uncertainty, both in estimations of climate change (Boucher et al, 2013) and regarding the impact of air pollution on public health (Heal et al, 2012) and, are a major topic of current research (Fuzzi et al, 2015)

  • We investigate the occurrence and properties of ambient aerosol from different types of sources in Rome, which apart from local emissions can be influenced by advected aerosol from continental Europe and the Sahara

  • Both turbulent kinetic energy (TKE), which is a measure of the intensity of turbulence and can be used as an indicator for the mixing efficiency of pollutants in the air (Srivastava and Sarthi, 2002), and boundary layer heights (BLH) were at rather low levels during DIAPASON2013 (Table 3), favouring the accumulation of pollutants

Read more

Summary

Introduction

Atmospheric aerosol particles remain a major uncertainty, both in estimations of climate change (Boucher et al, 2013) and regarding the impact of air pollution on public health (Heal et al, 2012) and, are a major topic of current research (Fuzzi et al, 2015). Emissions from biomass burning can be significant, both with a regional origin (e.g. agricultural fires and wildfires; Reche et al, 2012) and from residential wood combustion, which recently has become more prominent in Europe, even in urban environments (Fuller et al, 2013) Many of these anthropogenic sources emit large amounts of organic material in the fine particle fraction Strength and temporal behaviour of particle sources, the OA measured with the HR-ToF-AMS was further separated into different factors using PMF Based on these measurements, in this work the urban atmosphere of Rome is investigated in terms of particle source identification with a special focus on seasonal and spatial differences, influencing the presence and/or the characteristics of aerosol types in the city area

Measurement locations and periods
Instrumentation
General data analysis
HR-ToF-AMS data analysis
Overview: differences between seasons and locations
Meteorology overview
Aerosols and trace gases
Saharan dust
Aerosol sources: identification and characterization
Particles from biomass burning
Emissions related to traffic and cooking activities
Cigarette smoking emissions
Summary and conclusions
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call