Abstract
Diesel-powered vehicles are intensively used in urban areas for transporting
goods and people but can substantially contribute to high emissions of black
carbon (BC), organic carbon (OC), and other gaseous pollutants. Strategies
aimed at controlling mobile emissions sources thus have the potential to
improve air quality and help mitigate the impacts of air pollutants on
climate, ecosystems, and human health. However, in developing countries there
are limited data on the BC and OC emission characteristics of diesel-powered
vehicles, and thus there are large uncertainties in the estimation of the
emission contributions from these sources. We measured BC, OC, and other
inorganic components of fine particulate matter (PM), as well as carbon
monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), ethane,
acetylene, benzene, toluene, and C2-benzenes under real-world driving
conditions for 20 diesel-powered vehicles encompassing multiple emission level
technologies in Mexico City with the chasing technique using the Aerodyne
mobile laboratory. Average BC emission factors ranged from
0.41–2.48 g kg−1 of fuel depending on vehicle type. The vehicles were
also simultaneously measured using the cross-road remote sensing technique to
obtain the emission factors of nitrogen oxide (NO), CO, total hydrocarbons,
and fine PM, thus allowing for the intercomparison of the results from the two
techniques. There is overall good agreement between the two techniques and
both can identify high and low emitters, but substantial differences were
found in some of the vehicles, probably due to the ability of the chasing
technique to capture a larger diversity of driving conditions in comparison
to the remote sensing technique. A comparison of the results with the US EPA
MOVES2014b model showed that the model underestimates CO, OC, and selected
VOC species, whereas there is better agreement for NOx and BC. Larger
OC / BC ratios were found in comparison to ratios measured in California
using the same technique, further demonstrating the need for using
locally obtained diesel-powered vehicle emission factor database in
developing countries in order to reduce the uncertainty in the emissions
estimates and to improve the evaluation of the effectiveness of emissions
reduction measures.
Citation
ID:
153423
Ref Key:
zavala2017atmosphericemission