Figures & data
FIG. 1. SEM (a, b) and associated backscattered SEM (c, d) images at 12,000× magnification of laboratory-generated soot and CeO2 particles and a single large soot particle with embedded CeO2 particles. The white box on the upper right of (a) is zoomed to 250,000× magnification in (b) and (c). White areas of the backscattered SEM images (c, d) represent CeO2. The sample was collected on a polished silicon wafer and analyzed with an FEI Nova NanoLab 600 Focused Ion-Beam SEM.
FIG. 2. TEM images of an elongated 12 nm CeO2 particle at 300,000× (a) and 800,000× (b) magnification sampled at Newcastle, UK on the 180–320 nm impaction stage of a nanoMOUDI with the circle denoting the approximate location of the EDS spectrum shown below. The sample was collected on a holey carbon film supported on a 300 mesh copper TEM grid and analyzed with a JEOL JEM-3011 high-resolution TEM operating at 300 kV. The source of the silicon peak in the TEM image is not known.
TABLE 1 Summary of sensitivity simulation results from the sectional aerosol dynamics model as a function of distance from a roadway
FIG. 3. Mass concentration by distance of all exhaust particles (a) and ceria within the exhaust particles (b) for sensitivity simulations in which the roadside concentration is 8.3 μg m−3. Note that the CerAdd simulation described in Gantt et al. (Citation2014) is in bold and some of the sensitivity simulations are not visible because they have identical values to the CerAdd simulation.
FIG. 4. Fractional composition of cerium-containing particles by distance for the CerAdd simulation and the shaded upper/lower limits from the sensitivity studies in which ceria was emitted as an external mixture with other exhaust particles.
