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Intra-urban spatial variability of PM2.5-bound carbonaceous components
Mingjie Xie1, Teresa L Coons1, Steven J Dutton2
1Department of Mechanical Engineering, College of Engineering and Applied Science, University of Colorado, Boulder, CO 80309, USA.
Atmospheric Environment (Oxford, England : 1994)
|December 20, 2014
Summary
The Denver Aerosol Sources and Health study found that near-highway sites had higher PM2.5 species like carbon and PAHs. Spatial variability was lower for carbon species, with diesel vehicles impacting highways and gasoline vehicles impacting all sites.
Area of Science:
- Environmental Science
- Air Quality Monitoring
- Health Effects Research
Background:
- The Denver Aerosol Sources and Health (DASH) study collected five years of PM2.5 data in Denver.
- Understanding PM2.5 spatial variability is crucial for assessing health impacts.
- Previous studies lacked detailed spatial analysis of PM2.5 species.
Purpose of the Study:
- To evaluate the spatial representativeness of a single monitoring site for Denver's PM2.5.
- To assess associations between PM2.5 species, sources, and adverse health effects.
- To determine the impact of proximity to interstate highways on PM2.5 composition.
Main Methods:
- Collected supplemental PM2.5 samples over one year at four sites with varying proximity to highways.
- Measured concentrations of elemental carbon, organic carbon, and 58 organic molecular markers.
- Utilized Pearson correlation coefficient (r) and coefficient of divergence (COD) to assess spatial variability.
Main Results:
- Near-highway sites showed higher concentrations of elemental carbon, organic carbon, PAHs, and steranes.
- Spatial heterogeneity was lower for carbonaceous species, indicating better uniformity.
- Ratio-ratio plots suggested diesel vehicles primarily impacted near-highway PAHs, while gasoline vehicles impacted hopanes across all sites.
Conclusions:
- A single monitoring site may not fully capture PM2.5 variability near highways.
- Proximity to interstate highways significantly influences local PM2.5 composition.
- Vehicle emissions, particularly diesel, contribute substantially to specific PM2.5 species near roadways.
