Source apportionment vs. emission inventories of non-methane hydrocarbons (NMHC) in an urban area of the Middle East: local and global perspectives

Thérèse Salameh,Nadine Locoge,Agnès Borbon,Charbel Afif,Stéphane Sauvage

doi:10.5194/acp-16-3595-2016

Abstract

Abstract. We applied the positive matrix factorization model to two large data sets collected during two intensive measurement campaigns (summer 2011 and winter 2012) at a sub-urban site in Beirut, Lebanon, in order to identify NMHC (non-methane hydrocarbons) sources and quantify their contribution to ambient levels. Six factors were identified in winter and five factors in summer. PMF-resolved source profiles were consistent with source profiles established by near-field measurements. The major sources were traffic-related emissions (combustion and gasoline evaporation) in winter and in summer accounting for 51 and 74 wt %, respectively, in agreement with the national emission inventory. The gasoline evaporation related to traffic source had a significant contribution regardless of the season (22 wt % in winter and 30 wt % in summer). The NMHC emissions from road transport are estimated from observations and PMF results, and compared to local and global emission inventories. The PMF analysis finds reasonable differences on emission rates, of 20–39 % higher than the national road transport inventory. However, global inventories (ACCMIP, EDGAR, MACCity) underestimate the emissions up to a factor of 10 for the transportation sector. When combining emission inventory to our results, there is strong evidence that control measures in Lebanon should be targeted on mitigating the NMHC emissions from the traffic-related sources. From a global perspective, an assessment of VOC (volatile organic compounds) anthropogenic emission inventories for the Middle East region as a whole seems necessary as these emissions could be much higher than expected at least from the road transport sector.

Highlights

Fast urbanization expansion, high population density, industrialization, intensive transport networks, and negligent pollution control have led to a substantial degradation of air quality in the Middle East (MEA) region (UNEP, 2006)
Measurements of 67 gaseous organic carbon have been performed at a suburban site in Beirut during two intensive field campaigns in summer 2011 and in winter 2012 within the framework of the ECOCEM project, resulting in a large and unique database, in order to improve our understanding of their major emission sources in the area
The USEPA positive matrix factorization (PMF) v3.0 was applied to the winter and summer data sets in order to identify and quantify the source contribution

Summary

Introduction

High population density, industrialization, intensive transport networks, and negligent pollution control have led to a substantial degradation of air quality in the Middle East (MEA) region (UNEP, 2006). High levels of particulate matter, PM10 and PM2.5, were obtained with annual concentrations of 64 and 20 μg m−3 respectively (Massoud et al, 2011), exceeding WHO guideline values of 20 and 10 μg m−3. These measurements provide valuable information on air pollution, they are scarce and limited to a few pollutants. The ethane and propane variability explained by this factor is 76 and 42 % respectively, even though, toluene, butane and acetylene are present in this profile. The average relative contribution of this factor is 18 % in winter.

Objectives

Methods

Results

Conclusion