Abstract
ABSTRACT To understand the concentrations, secondary organic aerosols (SOA) formation and source characteristics of carbonaceous aerosols in the regional environment of North China, a total of 48 fine particulate matter (PM2.5) samples were collected at the top of Mount Tai in the summer of 2015. Organic carbon (OC) and element carbon (EC) were analyzed and resolved into eight carbonaceous species using an Organic/Elemental Carbon Analyzer following the IMPROVE thermal-optical reflectance (TOR) protocol. OC and EC mass concentrations were 4.42 ± 3.04 and 1.58 ± 0.92 µg m–3, respectively, which were much higher than that of other domestic or abroad observation sites. Carbonaceous aerosols showed weekday-high trend during sampling period, which can be partly explained by anthropogenic effects. Higher concentrations of secondary organic carbon (SOC) were estimated by EC-tracer method during cloud/fog processing, indicating the fact that aqueous-phase reaction in droplets was an important pathway for SOC formation. Two source analysis approaches, consisting of Potential Source Contribution Function (PSCF) and Positive Matrix Factorization (PMF) were adopted to identify the regional sources and emission sources of carbonaceous species, and the apportion contributed by these sources. PSCF result demonstrated that the potential regional sources in the northwest, southwest and east coastal areas of Mount Tai contributed significantly to carbonaceous species loading in PM2.5. Additionally, three main emission sources were identified according to PMF result: diesel vehicle exhaust, biomass burning and mixed sources of gasoline vehicle exhaust and coal combustion, and each of sources had an average contribution of 26.4%, 19.0% and 54.5% to carbonaceous aerosols, respectively.
Highlights
Carbonaceous aerosol is a common component and account for 10% to 70% of fine particulate matter (PM2.5) (Turpin et al, 2000)
Organic carbon (OC) and element carbon (EC) Concentrations The measured levels of carbonaceous components at Mount Tai during sampling campaign were presented in OC and EC averagely accounted for 11.1% and 4.0% of total measured PM2.5 concentration, respectively, and total carbon (TC; the sum of OC and EC) accounted for 15.1% of PM2.5
Compared to a recent study reported that the percentage of TC loading in PM2.5 was 22.7% in Beijing, TC/PM2.5 ratio was lower in the present study, showing relatively less carbonaceous aerosol pollution in background environment than in urban areas (Ji et al, 2018)
Summary
Carbonaceous aerosol is a common component and account for 10% to 70% of fine particulate matter (PM2.5) (Turpin et al, 2000). Carbonaceous aerosol has many adverse effects on both environmental safety and human health, such as reducing visibility, affecting global climate and causing a variety of. Aerosol and Air Quality Research, 19: 1708–1720, 2019 human diseases, making it a hot topic in modern atmospheric environment research (Xu et al, 2018). Once the positive radiation from polluted air is forced to dominate, the global average surface temperature will rise. Because of the existence of polar functional groups such as carboxyl, numerous organic substances in carbonaceous aerosols can dissolve in water, and subsequently help the particles form cloud condensation nuclei (CCN), giving rise to increased cloud optical thickness and higher reflectance of cloud, as well as stronger monsoon and rainfall patterns (Ji et al, 2018; Panicker et al, 2018). Some epidemiological studies have shown that the deterioration of cardiovascular disease is closely related to human exposure to these atmospheric pollutants by comparing the trend of OC and EC levels with cardiovascular diseases’ morbidity and mortality (Chow et al, 2006; Mauderly and Chow, 2008)
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