Climatology and Sources of Particulate Matter in an Urban Arid Region: First real-time chemical and elemental observations in Doha, Qatar

SHAMJAD MOOSAKUTTY, Mohammed Ayoub, Rami Alfarra, Qatar Environment & Energy Research Institute

     Abstract Number: 687
     Working Group: Urban Aerosols

Abstract
Air pollutants in the Middle East region show unique characteristics due to the arid landforms, concentrated population center, and presence of Petrochemical industries. Naturally generated dust from the deserts dominates the overall atmospheric particulate matter (PM) under a 10µm size cutoff. However, anthropogenic sources significantly contribute to PM less than 2.5µm size cutoff, especially in population centers. Characterization and source identification of air pollutants is essential to develop mitigation strategies.

We present air pollutant data measured by the air quality monitoring network operated by the Qatar Environment and Energy Research Institute (QEERI). The QEERI air quality monitoring program started in early 2018 and operates six stations within the Greater Doha Area. The parameters measured include criteria pollutants and meteorological parameters. Since 2021, parameters such as black carbon, PMx mass, chemical composition, and metal concentrations have been added at selected stations. The black carbon concentrations were measured using dual-spot Aethalometers (AE-33), while the PM mass was measured under 1µm, 2.5µm, and 10µm using FIDAS. The chemical and metal concentrations were measured using a ToF-ACSM and Xact multi-metal analyzer.

The changes in air pollutant concentrations were studied using the daily, seasonal, and diurnal changes. The analysis shows seasonal changes in aerosol concentrations and sandstorms' effect on the overall air quality. The climatology of various aerosol species was identified for the wind speed and direction. The ACSM data shows regional sources for sulfate and organics, local sources for nitrate and organics, and secondary aerosol formations. During winter seasons, the nitrate concentrations peaked, indicating gas-to-particle partitioning. The metal concentrations measured by Xact show the dominance of silica, calcium, and sulfates. The source apportionment of the combined dataset was performed using the bilinear multilinear engine (ME-2) model. The analysis will help understand Doha's aerosol composition and sources to develop air pollution mitigation policies.