Beyond the 16 EPA priority pollutant PAHs: Environmental characterizations of oxygenated PAHs and dibenzopyrene isomers.

摘要

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.