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As the importance of non-tailpipe particles (NTP) over tailpipe emissions from urban traffic has been increasing, there is a need to evaluate NTP contributions to ambient particulate matter (PM) using representative source profiles. The Brake and Tire Wear Study conducted in Los Angeles, California in the winter of 2020 collected 64 PM2.5 and 64 PM10 samples from 32 pairs of downwind-upwind measurements at two near-road locations (I-5 in Anaheim and I-710 in Long Beach). These samples were characterized for inorganic and organic markers and, along with locally-developed brake wear, tire wear, and road dust source profiles, subject to source apportionment using the effective-variance chemical mass balance (EV-CMB) model. Model results highlighted the dominance of resuspended dust in both PM2.5 (23–33%) and PM10 (32–53%). Brake and tire wear contributed more to PM2.5 than tailpipe exhausts (diesel + gasoline) for I-5 (29–30% vs. 19–21%) while they were comparable for I-710 (15–17% vs. 15–19%). For PM10, the brake and tire wear contributions were 2–3 times the exhaust contributions. Different fleet compositions on and near I-5 and I-710 appeared to influence the relative importance of NTP and exhaust sources. The downwind-upwind differences in source contributions were often insignificant, consistent with small and/or nearly equal impacts of adjacent highway traffic emissions on the downwind and upwind sites. The utility of sole markers, such as barium and zinc, to predict brake and tire wear abundances in ambient PM is evaluated.
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This content will become publicly available on May 1, 2026
Exploring Lignocellulose-Based Renewable Diesel’s Potential for Texas Freight
The abundant availability of crop waste and forestry residues in Texas provides great potential for producing renewable diesel in the local towns of Texas. This study aims to evaluate the environmental impacts of renewable diesel use in Texas transportation and the potential of renewable diesel production in Texas. The GREET model was used to customize the life cycle pathway of renewable diesel and evaluate its environmental impacts. The models of renewable diesel produced from forestry residue and corn stover were built to calculate life cycle gas emissions of combination short-haul heavy-duty trucks fueled with renewable diesel. Life cycle GHG emissions of renewable diesel are much lower than those of low-sulfur diesel. However, with respect to renewable diesel derived from corn stover, life cycle PM10 and PM2.5 emissions were almost double those of low-sulfur diesel in 2024, and both emissions will be reduced by 37–38% in 2035. The life cycle emission trends of SOx, black carbon, and primary organic carbon are very similar to those of PM10 and PM2.5. The total cost of ownership (TCO) of heavy-duty trucks using renewable diesel produced from forestry residues or corn stover would be 10.3–14.8% higher than those consuming regular low-sulfur diesel in Texas.
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- Award ID(s):
- 1914692
- PAR ID:
- 10599430
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Environments
- Volume:
- 12
- Issue:
- 5
- ISSN:
- 2076-3298
- Page Range / eLocation ID:
- 157
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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