scholarly journals Optical source apportionment and radiative forcing of light-absorbing carbonaceous aerosol at a tropical marine monsoon climate zone: the importance of ship emissions

2020 ◽  
Author(s):  
Qiyuan Wang ◽  
Huikun Liu ◽  
Ping Wang ◽  
Wenting Dai ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Vehicle Emissions ◽  
Motor Vehicle ◽  
Carbonaceous Aerosol ◽  
Monsoon Climate ◽  
Ship Emissions ◽  
Climate Zone ◽  
Motor Vehicle Emissions

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.

scholarly journals Optical source apportionment and radiative effect of light-absorbing carbonaceous aerosols in a tropical marine monsoon climate zone: the importance of ship emissions

2020 ◽  
Vol 20 (24) ◽  
pp. 15537-15549
Author(s):  
Qiyuan Wang ◽  
Huikun Liu ◽  
Ping Wang ◽  
Wenting Dai ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Motor Vehicle ◽  
Motor Vehicles ◽  
Carbonaceous Aerosols ◽  
Radiative Effect ◽  
Monsoon Climate ◽  
Ship Emissions ◽  
Optical Source ◽  
Climate Zone

Abstract. Source-specific optical properties of light-absorbing carbonaceous (LAC) aerosols in the atmosphere are poorly understood because they are generated by various sources. In this study, a receptor model combining multi-wavelength absorption and chemical species was used to explore the source-specific optical properties of LAC aerosols in a tropical marine monsoon climate zone. The results showed that biomass burning and ship emissions were the dominant contributors to average aerosol light absorption. The source-specific absorption Ångström exponent (AAE) indicated that black carbon (BC) was the dominant LAC aerosol in ship and motor vehicle emissions. Moreover, brown carbon (BrC) was present in biomass-burning emissions. The source-specific mass absorption cross section (MAC) showed that BC from ship emissions had a stronger light-absorbing capacity compared to emissions from biomass burning and motor vehicles. The BrC MAC derived from biomass burning was also smaller than the BC MAC and was highly dependent on wavelength. Furthermore, radiative effect assessment indicated a comparable atmospheric forcing and heating capacity of LAC aerosols between biomass burning and ship emissions. This study provides insights into the optical properties of LAC aerosols from various sources. It also sheds more light on the radiative effects of LAC aerosols generated by ship emissions.

scholarly journals Fine particulate matter associated with monsoonal effect and the responses of biomass fire hotspots in the tropical environment

2015 ◽  
Vol 15 (16) ◽  
pp. 22215-22261 ◽  
Author(s):  
M. F. Khan ◽  
M. T. Latif ◽  
W. H. Saw ◽  
N. Amil ◽  
M. S. M. Nadzir ◽  
...  
Keyword(s):  
Cancer Risk ◽  
Biomass Burning ◽  
Vehicle Emissions ◽  
Motor Vehicle ◽  
Road Dust ◽  
World Health ◽  
Closure Model ◽  
Mass Closure ◽  
Coal Burning ◽  
Motor Vehicle Emissions

Abstract. The health implications of PM2.5 in tropical regions of Southeast Asia are significant as PM2.5 can pose serious health concerns. PM2.5 is strongly influenced by the monsoon. We quantitatively characterize the health risks posed to human populations by selected heavy metals in PM2.5. Monsoonal effects as well as factors influencing the sources of PM2.5 were also determined. Apportionment analysis of PM2.5 was undertaken using US EPA positive matrix factorization (PMF) 5.0 and a mass closure model. Overall, 48 % of the samples exceeded the World Health Organization (WHO) 24 h guideline. The mass closure model identified four sources of PM2.5: (a) mineral matter (MIN) (35 %), (b) secondary inorganic aerosol (SIA) (11 %), (c) sea salt (SS) (7 %), (d) trace elements (TE) (2 %) and (e) undefined (UD) (45 %). PMF 5.0 identified five potential sources and motor vehicle emissions and biomass burning were dominant followed by marine and sulfate aerosol, coal burning, nitrate aerosol, and mineral and road dust. The non-carcinogenic risk level for four selected metals (Pb, As, Cd and Ni) in PM2.5 and in the identified major sources by PMF > 5.0, with respect to inhalation follows the order of PM2.5 > coal burning > motor vehicle emissions/biomass burning > mineral/road dust. The lifetime cancer risk follows the order of As > Ni > Pb > Cd for mineral/road dust, coal burning and overall of PM2.5 concentration and As > Pb > Ni > Cd for motor vehicle/biomass burning. Overall, the associated cancer risk posed by the exposure of toxic metals in PM2.5 is three to four in 1 000 000 people in this location.

scholarly journals Quantifying Air Pollutant Variations during COVID-19 Lockdown in a Capital City in Northwest China

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 788
Author(s):  
Rong Feng ◽  
Hongmei Xu ◽  
Zexuan Wang ◽  
Yunxuan Gu ◽  
Zhe Liu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Rural Areas ◽  
Vehicle Emissions ◽  
Motor Vehicle ◽  
Northwest China ◽  
Air Pollutant ◽  
Capital City ◽  
Air Pollution Control ◽  
Motor Vehicle Emissions

In the context of the outbreak of coronavirus disease 2019 (COVID-19), strict lockdown policies were implemented to control nonessential human activities in Xi’an, northwest China, which greatly limited the spread of the pandemic and affected air quality. Compared with pre-lockdown, the air quality index and concentrations of PM2.5, PM10, SO2, and CO during the lockdown reduced, but the reductions were not very significant. NO2 levels exhibited the largest decrease (52%) during lockdown, owing to the remarkable decreased motor vehicle emissions. The highest K+ and lowest Ca2+ concentrations in PM2.5 samples could be attributed to the increase in household biomass fuel consumption in suburbs and rural areas around Xi’an and the decrease in human physical activities in Xi’an (e.g., human travel, vehicle emissions, construction activities), respectively, during the lockdown period. Secondary chemical reactions in the atmosphere increased in the lockdown period, as evidenced by the increased O3 level (increased by 160%) and OC/EC ratios in PM2.5 (increased by 26%), compared with pre-lockdown levels. The results, based on a natural experiment in this study, can be used as a reference for studying the formation and source of air pollution in Xi’an and provide evidence for establishing future long-term air pollution control policies.

Impact of sulfur-in-gasoline on motor vehicle emissions in the metropolitan area of Mexico City☆

Fuel ◽  
2003 ◽  
Vol 82 (13) ◽  
pp. 1605-1612 ◽  
Author(s):  
I Schifter ◽  
L Dı́az ◽  
M Vera ◽  
E Guzmán ◽  
E López-Salinas
Keyword(s):  
Mexico City ◽  
Metropolitan Area ◽  
Vehicle Emissions ◽  
Motor Vehicle ◽  
Motor Vehicle Emissions

scholarly journals Intercomparison of biomass burning aerosol optical properties from in situ and remote-sensing instruments in ORACLES-2016

2019 ◽  
Vol 19 (14) ◽  
pp. 9181-9208 ◽  
Author(s):  
Kristina Pistone ◽  
Jens Redemann ◽  
Sarah Doherty ◽  
Paquita Zuidema ◽  
Sharon Burton ◽  
...  
Keyword(s):  
Optical Properties ◽  
Case Studies ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Measurement Techniques ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Biomass Burning Aerosol

Abstract. The total effect of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in anthropogenic radiative forcing on the climate. Correct characterization of intensive aerosol optical properties, particularly in conditions where absorbing aerosol is present, is a crucial factor in quantifying these effects. The southeast Atlantic Ocean (SEA), with seasonal biomass burning smoke plumes overlying and mixing with a persistent stratocumulus cloud deck, offers an excellent natural laboratory to make the observations necessary to understand the complexities of aerosol–cloud–radiation interactions. The first field deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign was conducted in September of 2016 out of Walvis Bay, Namibia. Data collected during ORACLES-2016 are used to derive aerosol properties from an unprecedented number of simultaneous measurement techniques over this region. Here, we present results from six of the eight independent instruments or instrument combinations, all applied to measure or retrieve aerosol absorption and single-scattering albedo. Most but not all of the biomass burning aerosol was located in the free troposphere, in relative humidities typically ranging up to 60 %. We present the single-scattering albedo (SSA), absorbing and total aerosol optical depth (AAOD and AOD), and absorption, scattering, and extinction Ångström exponents (AAE, SAE, and EAE, respectively) for specific case studies looking at near-coincident and near-colocated measurements from multiple instruments, and SSAs for the broader campaign average over the month-long deployment. For the case studies, we find that SSA agrees within the measurement uncertainties between multiple instruments, though, over all cases, there is no strong correlation between values reported by one instrument and another. We also find that agreement between the instruments is more robust at higher aerosol loading (AOD400>0.4). The campaign-wide average and range shows differences in the values measured by each instrument. We find the ORACLES-2016 campaign-average SSA at 500 nm (SSA500) to be between 0.85 and 0.88, depending on the instrument considered (4STAR, AirMSPI, or in situ measurements), with the interquartile ranges for all instruments between 0.83 and 0.89. This is consistent with previous September values reported over the region (between 0.84 and 0.90 for SSA at 550nm). The results suggest that the differences observed in the campaign-average values may be dominated by instrument-specific spatial sampling differences and the natural physical variability in aerosol conditions over the SEA, rather than fundamental methodological differences.

scholarly journals Chemical apportionment of southern African aerosol mass and optical depth

2009 ◽  
Vol 9 (19) ◽  
pp. 7643-7655 ◽  
Author(s):  
B. I. Magi
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Cross Sections ◽  
Southern Africa ◽  
Climate Models ◽  
Critical Role ◽  
Carbonaceous Aerosol ◽  
Aerosol Optical Properties ◽  
Aerosol Absorption ◽  
Aerosol Mass

Abstract. This study characterizes the aerosol over extratropical and tropical southern Africa during the biomass burning season by presenting an aerosol mass apportionment and aerosol optical properties. Carbonaceous aerosol species account for 54% and 83% of the extratropical and tropical aerosol mass, respectively, which is consistent with the fact that the major source of particulate matter in southern Africa is biomass burning. This mass apportionment implies that carbonaceous species in the form of organic carbon (OC) and black carbon (BC) play a critical role in the aerosol optical properties. By combining the in situ measurements of aerosol mass concentrations with concurrent measurements of aerosol optical properties at a wavelength of 550 nm, it is shown that 80–90% of the aerosol scattering is due to carbonaceous aerosol, and the derived mass scattering cross sections (MSC) for OC and BC are 3.9±0.6 m2/g and 1.6±0.2 m2/g, respectively. Derived values of mass absorption cross sections (MAC) for OC and BC are 0.7±0.6 m2/g and 8.2±1.1 m2/g, respectively. The values of MAC imply that ~26% of the aerosol absorption in southern Africa is due to OC, with the remainder due to BC. The results in this study provide important constraints for aerosol properties in a region dominated by biomass burning and should be integrated into climate models to improve aerosol simulations.

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