Combustion Generated Primary Emissions of Nitroarenes

Initially, major attention was focused on emissions of diesel soot from light- and heavy-duty motor vehicles, because the particle extracts contained such direct-acting bacterial mutagens and animal and possible human carcinogens (IARC Group 2B, 1989) as 1-nitropyrene (1-N02-PY) and the 1,6- and 1,8-dinitropyrenes (DNP), as well as a third isomer, 1,3-dinitropyrene, IARC Group III. For example, Paputa-Peck and coworkers (Paputa-Peck et al, 1983; IARC, 1989) reported ~100 nitro-PAHs (17 positively identified) in an extract of a light-duty diesel particulate sample. Among these, as seen in Table 10.33, f-nitropyrene was the major nitroarene at levels of 75 £tg/g compared to 0.30, 0.40, and 0.53 pg/g for 1,3-, 1,6-, and 1,8-DNP, respectively. For a comparison as to how the absolute and relative emission strengths of 1-nitropyrene and the three dinitropyrenes can vary, see the study of Japanese diesel-powered vehicles by Hayakawa and co-workers (1994). Also, for comparison with the 1983 Paputa-Peck et al. study, see the report of Feilberg and co-workers (f999a), who recently identified and quantified the semivolatile 1-nitronaphthalene in diesel exhaust (vide infra).

Generally, f-nitropyrene and 2-nitrofluorene are the most abundant nitro-PAHs in diesel exhaust (e.g., see also Schuetzle and Perez, 1983; and Beije and Möller, 1988). However, emission rates of these and other nitro-PAHs vary significantly with engine type, fuel, operating conditions, etc. (e.g., see Schuetzle and Fra-zier, 1986; IARC, 1989; and WHO, 1996). Thus generalizations should be viewed with caution (e.g., 2-nitrofluoranthene is greater than 2-nitrofluorene in Table 10.33). Furthermore, the distribution of diesel compared to gasoline engine powered vehicles varies markedly from country to country (indeed, state to state), with associated variations in exhaust emission impacts on ambient air quality. For example, in 1994, diesel-powered vehicles constituted 18% of all vehicles in Japan, with the proportion continuing to increase. Murahashi and co-workers (1995) reported total dini-tropyrene concentrations [E(1,3-DNP + 1,6-DNP + 1,8-DNP)] of 3.6 pg m~3 in samples taken adjacent to a busy intersection in downtown Kanazawa, Japan. In ambient air, Berlin, Germany, concentrations of 5.2 ng m~3 of 2-nitrofluorene (also emitted in diesel exhaust) were reported by Beije and Möller (1988).

TABLE 10.33 Concentrations of Selected Nitroarenes in Extracts of Diesel Particulate POMa'b

Nitroarene

Concentration (|Ag/g)

1-Nitronaphthalene

0 0

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