Abstract:
Polycyclic aromatic hydrocarbons (PAHs) with a molecular weight (MW) of 302
and oxygenated-PAHs (OPAHs) have demonstrated toxicity beyond that of
frequently monitored and known carcinogenic PAHs. Airborne particulate matter
(PM) was characterized for MW 302 isomers to evaluate risk and air quality
indices and OPAHs in order to fill data gaps concerning sources and distribution
of OPAHs. Additionally, standard reference materials of numerous environmental
media were analyzed for OPAH occurrence. Air samples were collected from two
locations: the remote atmosphere of Mt. Bachelor, Oregon and the urban
atmosphere of Beijing, China. Collection of size fractionated particles of PM 2.5
and PM 10 allowed evaluation of air quality indexes as well as OPAH distribution
profiles for source identification. Standard reference materials (SRMs) possessing
certified values of PAHs were purchased and methods of analysis were
developed. Results demonstrate that MW 302 isomers are highly abundant in the
urban atmosphere of Beijing, China. Although toxicity information is not
available for all MW 302 isomers, for those with available carcinogenic potency,
the combined potency of MW 302 isomers contributes to a significant portion of
carcinogenic risk for PAHs in Beijing. Results further convey the dependency of
air quality assessment outcomes on metrics used and monitored PAHs. OPAHs
were measured in many of the SRM matrices for the first time and the abundance
of OPAHs, with respect to PAHs, is a major finding. Results indicate that diesel
exhaust could be a major source of OPAHs and that biota could be a sink.
Measurement of OPAHs from ambient air confirmed that OPAHs are
environmentally abundant. Particulate matter air samples from Mt. Bachelor show
that while OPAHs are more concentrated than PAHs, the particle size distribution
could not be used to determine origins of OPAH formation. Results did show that
OPAHs are concentrated on the smallest, most respirable size fraction of
particulate matter collected from both Mt. Bachelor and Beijing. We conclude
that MW 302 isomers and OPAHs are environmentally relevant and concentrated
PAHs requiring continued study.
