Exploration of PM<sub>2.5</sub> sources on the regional scale in the Pearl River Delta based on ME-2 modeling

Abstract

Abstract. The Pearl River Delta (PRD) of China, which has a population of more than 58 million people, is one of the largest agglomerations of cities in the world and had severe PM 2.5 pollution at the beginning of this century. Due to the implementation of strong pollution control in recent decades, PM 2.5 in the PRD has continuously decreased to relatively lower levels in China. To comprehensively understand the current PM 2.5 sources in the PRD to support future air pollution control strategies in similar regions, we performed regional-scale PM 2.5 field observations coupled with a state-of-the-art source apportionment model at six sites in four seasons in 2015. The regional annual average PM 2.5 concentration based on the 4-month sampling was determined to be 37 µg m −3 , which is still more than 3 times the WHO standard, with organic matter (36.9 %) and SO 2− 4 (23.6 %) as the most abundant species. A novel multilinear engine (ME-2) model was first applied to a comprehensive PM 2.5 chemical dataset to perform source apportionment with predetermined constraints, producing more environmentally meaningful results compared to those obtained using traditional positive matrix factorization (PMF) modeling. The regional annual average PM 2.5 source structure in the PRD was retrieved to be secondary sulfate (21 %), vehicle emissions (14 %), industrial emissions (13 %), secondary nitrate (11 %), biomass burning (11 %), secondary organic aerosol (SOA, 7 %), coal burning (6 %), fugitive dust (5 %), ship emissions (3 %) and aged sea salt (2 %). Analyzing the spatial distribution of PM 2.5 sources under different weather conditions clearly identified the central PRD area as the key emission area for SO 2 , NO x , coal burning, biomass burning, industrial emissions and vehicle emissions. It was further estimated that under the polluted northerly air flow in winter, local emissions in the central PRD area accounted for approximately 45 % of the total PM 2.5 , with secondary nitrate and biomass burning being most abundant; in contrast, the regional transport from outside the PRD accounted for more than half of PM 2.5 , with secondary sulfate representing the most abundant transported species.

Development and application of a mass closure PM<sub>2.5</sub> composition online monitoring system

“…In additional, the offline PM2.5 were simultaneously conducted every two days and each sample was collected for 24 hours. The sampling instruments and analytical methods of PM2.5 chemical composition refer to previous studies by Huang et al (2018). The performance of the online integrated system was thoroughly evaluated by comparison with the measurements above.…”

“…where the xij is the concentration of the species and kj is the j th species' error fraction (Huang et al, 2018), which is usually thought to be between 5% and 30% (Zou, 2018). Through testing, the kj in this study was set as 20%, and some species were expanded or decreased according to the results of model operation.…”

“…Accurately measuring PM2.5 and chemical species are essential for identifying their sources, assessing their negative effects (e.g., radiative forcing, human health, etc. ), and developing effective abatement strategies (Huang et al, 2018;Hand et al, 2019).…”

“…Therefore, obtaining the comprehensive chemical species of PM2.5 measured by the SHARP-5030i monitor and apportioning the PM2.5 sources based on the mass closure data could be directly used to control PM2.5. Researches have indicated that SOA is an important contributor of PM2.5 and that it originated from the oxidation of gas phase precursors (Carlton et al, 2009;Huang et al, 2018). It is currently difficult to measure SOA, and most estimates are indirect and use the OC/EC ratio, receptor models (e.g., CMB and PMF), and chemical transport models (Murphy and Pandis, 2009;Cesari et al, 2016;Al-Naiema et al, 2018).…”

Research Progress of HP Characteristics, Hazards, Control Technologies, and Measures in China after 2013

“…Biomass burning, coal burning, and external source were the three least important sources, accounting for 4%, 4%, and 3%. After 2013, secondary source (22%) and traffic (20%) were still the two foremost pollution sources [61,[123][124][125][126][127][128][129]. The proportion of industrial factors (13%) was the same as coal burning, and remained constant.…”