Elements and polycyclic aromatic hydrocarbons in exhaust particles emitted by light-duty vehicles

Abstract

The main purpose of this work was to evaluate the chemical composition of particulate matter (PM) emitted by eight different light-duty vehicles. Exhaust samples from petrol and diesel cars (Euro 3 to Euro 5) were collected in a chassis dynamometer facility. To simulate the real-world driving conditions, three ARTEMIS cycles were followed: road, to simulate a fluid traffic flow and urban with hot and cold starts, to simulate driving conditions in cities. Samples were analysed for the water-soluble ions, for the elemental composition and for polycyclic aromatic hydrocarbons (PAHs), respectively, by ion chromatography, inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS). Nitrate and phosphate were the major water-soluble ions in the exhaust particles emitted from diesel and petrol vehicles, respectively. The amount of material emitted is affected by the vehicle age. For vehicles ≥Euro 4, most elements were below the detection limits. Sodium, with emission factors in the ranges 23.5-62.4 and 78.2-227μg km(-1), for petrol and diesel Euro 3 vehicles, respectively, was the major element. The emission factors of metallic elements indicated that diesel vehicles release three to five times more than petrol automobiles. Element emissions under urban cycles are higher than those found for on-road driving, being three or four times higher, for petrol vehicles, and two or three times, for diesel vehicles. The difference between cycles is mainly due to the high emissions for the urban cycle with hot start-up. As registered for elements, most of the PAH emissions for vehicles ≥Euro 4 were also below the detection limits. Regardless of the vehicle models or driving cycles, the two- to four-ring PAHs were always dominant. Naphthalene, with emission factors up to 925 μg km(-1), was always the most abundant PAH. The relative cancer risk associated with naphthalene was estimated to be up to several orders of magnitude higher than any of the chemical species found in the PM phase. The highest PAH emission factors were registered for diesel-powered vehicles. The condition of the vehicle can exert a decisive influence on both element and PAH emissions.

Measurement of PM and its chemical composition in real-world emissions from non-road and on-road diesel vehicles

“…In comparison, the total carbon emissions in this study are lower than those in previous studies, whereas the WSIs and elements fractions are higher (Alves et al, 2015a;Cui et al, 2016;Schauer et al, 1999;Wu et al, 2016). Several factors have influenced these differing results such as fuel quality, driving condition, engine parameters (fuel injection timing, compression ratio, and fuel injector design), and experimental methods (Sarvi et al, 2008a(Sarvi et al, , b, 2009Sarvi and Zevenhoven, 2010).…”

Source apportionment and water solubility of metals in size segregated particles in urban environments

“…However, K is also present in unleaded fuels (Spencer et al, 2006) or used as an additive in some types of oil and as an antifreeze inhibitor. Recent chassis dynamometer studies also showed K can be an important component of direct tailpipe emission (Alves et al, 2015). The distinct existence of K in Factor 2 indicates their possible tailpipe origin for the local vehicle fleets in Hong Kong, rather than other sources.…”

Identifying Unregulated Emissions from Conventional Diesel Self-Ignition and PPCI Marine Engines at Full Load Conditions

“…Polycyclic aromatic hydrocarbons (PAHs) are created by incomplete combustion or pyrolysis at high temperature under oxygen deficiency during the engine combustion process. In conventional diesel combustion, the semi-volatile fractions of exhaust gas samples are dominated by PAHs and their homologues alkylation series [26]. As illustrated in Figure 3 and Table 3, the peak time of corresponding species is in the range from 3.544 min to 41.062 min, and the main 41 species are identified based on matching degree.…”

“…Figure 4 is TIC of unregulated emissions absorbed by absorption liquid in conventional diesel combustion, and Table 4 lists the main exhaust components in the order of retention time. Volatile organic compounds (VOCs) in the C 6 -C 11 range of diesel engine exhaust gas have been reported in literature [26], while little studies on heavy components with longer carbon chains were discussed. As shown in Figure 4 and Table 4, the retention time of corresponding species is in the range from 2.298 min to 28.782 min, and about 21 species are identified on account of matching degree.…”