Seasonal trend and source identification of polycyclic aromatic hydrocarbons associated with fine particulate matters (PM2.5) in Isfahan City, Iran, using diagnostic ratio and PMF model.

Mohsen Soleimani,Nasibeh Amini,Hossein Moradi,Zohreh Ebrahimi,Jan H Christensen,Kristoffer Gulmark Poulsen,Nourollah Mirghaffari

doi:10.1007/s11356-021-17635-8

Abstract

Particulate matters (PMs) and their associated chemical compounds such as polycyclic aromatic hydrocarbons (PAHs) are important factors to evaluate air pollution and its health impacts particularly in developing countries. Source identification of these compounds can be used for air quality management. The aim of this study was to identify the sources of PM2.5-bound PAHs in Isfahan city, a metropolitan and industrialized area in central Iran. The PM2.5 samples were collected at 50 sites during 1year. Source identification and apportionment of particle-bound PAHs were carried out using diagnostic ratios (DRs) of PAHs and positive matrix factorization (PMF) model. The results showed that the concentrations of PM2.5 ranged from 8 to 291μg/m3 with an average of 60.2 ± 53.9μg/m3, whereas the sum of concentrations of the 19 PAH compounds (ƩPAHs) ranged from 0.3 to 61.4ng/m3 with an average of 4.65 ± 8.54ng/m3. The PAH compounds showed their highest and lowest concentrations occurred in cold and warm seasons, respectively. The mean concentration of benzo[a]pyrene (1.357ngm-3) in December-January, when inversion occured, was higher than the Iranian national standard value showing the risk of exposure to PM2.5-bound PAHs. Applying DRs suggested that the sources of the PAHs were mainly from fuel combustion. The main sources identified by the PMF model were gasoline combustion (23.8 to 33.1%) followed by diesel combustion (20.6 to 24.8%), natural gas combustion (9.5 to 28.4%), evaporative-uncombusted (9.5 to 23.0%), industrial activities (8.4 to 13.5%), and unknown sources (2.8 to 15.7%). It is concluded that transportation, industrial activities, and combustion of natural gas (both in residential-commercial and industrial sectors) as the main sources of PAHs in PM2.5 should be managed in the metropolitan area, particularly in cold seasons.

Highlights

Air pollution is one of the world’s largest health and environmental problems
One of the main reasons of increasing concentration in fall season could be due to temperature inversion which usually enhance the diffusion of PM2.5 and affect polycyclic aromatic hydrocarbons (PAHs) concentrations (Chen et al 2020)
Source apportionment of PAHs using diagnostic ratios confirmed that the PAHs predominated by high molecular weight originate mainly from combustion sources especially fuel oil combustion

Summary

Introduction

Air pollution is one of the world’s largest health and environmental problems. It includes a mixture of gases and solid or liquid particles suspended in the atmosphere. Particulate matters (PMs) are important as they significantly affect the human health, atmospheric chemistry, and global climate change (Li et al 2020; Zong et al 2016). PMs are classified by their size which smaller ones cause most health problems (Amil et al 2016). Several studies have showed that PMs, especially PM2.5 (i.e. the particles with aerodynamic diameter smaller than 2.5 μm) can adversely affect human health (Ouyang et al 2020; Pope et al 2011). Identification and quantification of PM sources and their associated compounds is necessary to improve strategies for effective air quality management (Waked et al 2014)

Objectives

Methods

Results

Conclusion