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Chemical composition and redox activity of PM0.25 near Los Angeles International Airport and comparisons to an urban traffic site
- Source :
- Science of The Total Environment. :1336-1346
- Publication Year :
- 2018
- Publisher :
- Elsevier BV, 2018.
-
Abstract
- To investigate the relative impacts of emissions from Los Angeles International Airport (LAX), as well as the impacts of traffic emissions from freeways, on the oxidative potential of particulate matter (PM), PM0.25 were collected at two urban background locations in Los Angeles. Redox activity of the PM samples was measured by means of an in vitro alveolar macrophage assay that quantifies the formation of reactive oxygen species (ROS) in cells, and detailed chemical analyses were performed to determine the speciated chemical composition of collected PM. A molecular marker-based chemical mass balance (MM-CMB) model was applied to estimate the relative contributions from the following primary sources to the organic carbon (OC) component of PM: mobile sources (combined gasoline and diesel vehicles), wood smoke, vegetative detritus, road dust and ship emissions. A source profile of aircraft emissions was not included in the model; however its contribution was estimated from un-apportioned primary OC in the MM-CMB model ("other OC") after accounting for the contribution of secondary organic carbon (SOC) to OC. The contribution of mobile sources to OC was 82% and 28% at the central Los Angeles site (freeway emissions) and the LAX site, respectively. The estimated contribution of aircraft emissions to PM0.25 OC was 36% at the LAX site. ROS activity levels showed little spatial variability, with no statistically significant difference between the averages observed at LAX (24.75±4.01μgZymosan/m3) and central Los Angeles (27.77±2 0.32μgZymosan/m3), suggesting similar levels of inhalation exposure to redox active species of PM0.25. A multiple linear regression analysis indicated that the variability in ROS activity is best explained by the chemical markers of major identified sources: EC emitted by traffic, and sulfur, considered in our study as a potential tracer of aircraft emissions, with statistically significantly higher concentrations of sulfur at the LAX site (p
- Subjects :
- Total organic carbon
Environmental Engineering
Detritus
010504 meteorology & atmospheric sciences
Chemistry
Environmental engineering
010501 environmental sciences
Particulates
01 natural sciences
Pollution
Diesel fuel
Environmental chemistry
Ultrafine particle
Environmental Chemistry
Spatial variability
Gasoline
Waste Management and Disposal
Chemical composition
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 00489697
- Database :
- OpenAIRE
- Journal :
- Science of The Total Environment
- Accession number :
- edsair.doi...........f9b16a28dcae6b93fb4b6e12254fd8e0