Abstract:Air pollution is particularly severe in developing megacities, such as Beijing, where vehicles equipped with modern gasoline-direct-injection (GDI) engines are becoming one of major sources of the pollution. This study presents the characteristics of individual particles emitted by a GDI vehicle and their ageing in a smog chamber under the Beijing urban environment, as part of the Atmospheric Pollution & Human Health (APHH) research programme. Using transmission electron microscopy, we identified the particles… Show more
“…4), implying that ship exhaust-related BC particles were subject to substantial aging during their transport from ocean. It is unexpected that our MACBC,ship(λ) is similar to the value of marine engine emissions (7.8 m 2 g -1 at 780 nm, extrapolated to the same wavelengths of this study by assuming an AAEBC = 1.1) (Corbin et al, 2018), because freshly emitted fossil fuel BC particles tend to be externally-mixed with other substances and become internally-mixed ones after aging (Xing et al, 2020). Actually, the authors of that study also recognize that more work is needed to clarify their ambiguous large MACBC(λ) of marine engine emissions.…”
Section: Source-dependent Optical Properties Of Lac Aerosolsupporting
Abstract. Source-specific optical properties of light-absorbing carbonaceous (LAC) aerosol are poorly understood owing to its various sources in the atmosphere. Here, a receptor model coupling multi-wavelength absorption with chemical species was utilized to explore the source-specific LAC optical properties at a tropical marine monsoon climate zone. Results showed that biomass burning contributed the largest to LAC absorption on average, but ship emissions became the dominant contributor (44–45 %) when the air masses originated from the South China Sea. The source-specific absorption Ångström exponent indicates that black carbon (BC) was the dominant LAC aerosol in ship and motor vehicle emissions while there was also brown carbon (BrC) existed in biomass-burning emissions. The source-specific mass absorption cross section (MAC) showed that BC from ship emissions had a stronger light-absorbing capacity than biomass burning and motor vehicle emissions. The BrC MAC derived from biomass burning was smaller than BC MAC and highly depended on wavelengths. Radiative effect assessment indicates a comparable atmospheric forcing and heating capacity of LAC aerosol from biomass burning and ship emissions. Our study provides insights into the optical properties of LAC aerosol from various sources and can improve our understanding of the LAC radiative effects caused by ship emissions.
“…4), implying that ship exhaust-related BC particles were subject to substantial aging during their transport from ocean. It is unexpected that our MACBC,ship(λ) is similar to the value of marine engine emissions (7.8 m 2 g -1 at 780 nm, extrapolated to the same wavelengths of this study by assuming an AAEBC = 1.1) (Corbin et al, 2018), because freshly emitted fossil fuel BC particles tend to be externally-mixed with other substances and become internally-mixed ones after aging (Xing et al, 2020). Actually, the authors of that study also recognize that more work is needed to clarify their ambiguous large MACBC(λ) of marine engine emissions.…”
Section: Source-dependent Optical Properties Of Lac Aerosolsupporting
Abstract. Source-specific optical properties of light-absorbing carbonaceous (LAC) aerosol are poorly understood owing to its various sources in the atmosphere. Here, a receptor model coupling multi-wavelength absorption with chemical species was utilized to explore the source-specific LAC optical properties at a tropical marine monsoon climate zone. Results showed that biomass burning contributed the largest to LAC absorption on average, but ship emissions became the dominant contributor (44–45 %) when the air masses originated from the South China Sea. The source-specific absorption Ångström exponent indicates that black carbon (BC) was the dominant LAC aerosol in ship and motor vehicle emissions while there was also brown carbon (BrC) existed in biomass-burning emissions. The source-specific mass absorption cross section (MAC) showed that BC from ship emissions had a stronger light-absorbing capacity than biomass burning and motor vehicle emissions. The BrC MAC derived from biomass burning was smaller than BC MAC and highly depended on wavelengths. Radiative effect assessment indicates a comparable atmospheric forcing and heating capacity of LAC aerosol from biomass burning and ship emissions. Our study provides insights into the optical properties of LAC aerosol from various sources and can improve our understanding of the LAC radiative effects caused by ship emissions.
“…Even though it is commonly recognized that secondary aerosol mass governs haze formation in megacities in China (Huang et al, 2014;Zhang et al, 2013;Tao et al, 2017;Sun et al, 2018), the contributions of primary (direct) particle sources cannot be neglected. Previous studies have demonstrated that primary emission sources, such as residential heating, traffic and cooking activities, can contribute significantly to both particle number and mass concentrations in the urban atmosphere in China (He et al, 2004a;Xu et al, 2014;Du et al, 2017;Wang et al, 2013;Sun et al, 2018). It was recently reported that traffic could be a major source of nanoclusters (sub-3 nm) in urban environments (Ronkko et al, 2017).…”
Abstract. Although secondary particulate matter is reported to be the main
contributor of PM2.5 during haze in Chinese megacities,
primary particle emissions also affect particle concentrations. In
order to improve estimates of the contribution of primary sources to
the particle number and mass concentrations, we performed source
apportionment analyses using both chemical fingerprints and particle
size distributions measured at the same site in urban Beijing from
April to July 2018. Both methods resolved factors related to primary
emissions, including vehicular emissions and cooking emissions, which
together make up 76 % and 24 % of total particle number and
organic aerosol (OA) mass, respectively. Similar source types,
including particles related to vehicular emissions (1.6±1.1 µg m−3; 2.4±1.8×103 cm−3 and 5.5±2.8×103 cm−3
for two traffic-related components), cooking emissions (2.6±1.9 µg m−3 and 5.5±3.3×103 cm−3) and secondary aerosols (51±41 µg m−3 and 4.2±3.0×103 cm−3), were resolved by both methods. Converted mass
concentrations from particle size distributions components were
comparable with those from chemical fingerprints. Size distribution
source apportionment separated vehicular emissions into a component
with a mode diameter of 20 nm (“traffic-ultrafine”) and a
component with a mode diameter of 100 nm
(“traffic-fine”). Consistent with similar day- and nighttime diesel
vehicle PM2.5 emissions estimated for the Beijing area,
traffic-fine particles, hydrocarbon-like OA (HOA, traffic-related factor
resulting from source apportionment using chemical fingerprints) and
black carbon (BC) showed similar diurnal patterns, with higher
concentrations during the night and morning than during the afternoon
when the boundary layer is higher. Traffic-ultrafine particles showed
the highest concentrations during the rush-hour period, suggesting a
prominent role of local gasoline vehicle emissions. In the absence of
new particle formation, our results show that vehicular-related
emissions (14 % and 30 % for ultrafine and fine particles,
respectively) and cooking-activity-related emissions (32 %)
dominate the particle number concentration, while secondary particulate
matter (over 80 %) governs PM2.5 mass during the
non-heating season in Beijing.
“…There are extensive studies dealing with the health effects of airborne particulate matter (PM) (Rückerl et al, 2011;Brauer et al, 2012;Balakrishnan et al, 2015;Hu et al, 2016;Wang et al, 2017;Li et al, 2020;Xing et al, 2020). Long-term exposure to PM2.5 (i.e.…”
Highlights:1. Indoor size-segregated particles were collected at the Hutou lung cancer epidemic village.2. DNA damage assessed by plasmid scission assay was mainly caused by smaller particles.3. DNA damage had a positive correlation with the water-soluble Zn, Cu, Cd, Rb, Cs, and Sb. 4. Water-soluble metals Zn, Cu, Cd, Rb, Cs, and Sb were concentrated in the smaller particles.5. Indoor particles in the small sizes were a higher health risk than those in the large sizes.
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