Where Do Particulate Toxins Reside? An Improved Paradigm for the Structure and Dynamics of the Urban Mid-Atlantic Aerosol

Abstract

Discussions of excess mortality and morbidity from exposure to urban aerosol particles typically invoke the now 20-year-old trimodal aerosol paradigm proposed by Whitby to explain the structure and behavior of ambient aerosol volume and its major constituent, sulfate. However, this paradigm largely ignores the primary high-temperature combustion (HTC) components of the urban aerosol, which contribute minor amounts of the aerosol mass, but carry the bulk of the particulate toxins and numbers of aerosol particles. Studies encompassing the analyses of >100 size distributions of important intrinsic tracers of primary particles from HTC sources collected over the past decade in various environments show that urban aerosol contains a complex mixture of physically-discrete fresh and aged, primary particle populations from a variety of sources. Furthermore, whereas the behavior of fineparticulate aerosol mass and sulfate was described in terms of coagulation and accumulation aerosol scavenging of new secondary sulfate nuclei, studies reviewed herein suggest that the behavior of primary aerosol is mediated more by hygroscopic growth and cloud processing, accompanied by oxidation of SO 2 on wet particles and droplets. We conclude that the distribution of airborne particulate toxins and their atmospheric behavior is far more complex than commonly conceptualized on the basis of the classical trimodal model, and we develop an extended paradigm in which the focus is on the primary accumulation aerosol.

System for Precise Control of Volumetric Flow Rate during Sampling with a Cascade Impactor

“…From Table 2, it is apparent that ow rate uctuations would need to be controlled to <0.5% to achieve the 1% net mass error for the most narrow test aerosol. Such narrow distributions have been observed in-stack and in the ambient plume of municipal incinerators (Ondov and Wexler 1998) and may be a common feature of high-temperature combustion sources in which particle growth is dominated by condensation (Biswas et al 1992). …”

“…Calculations were made for unimodal distributions with mmads of 0.2 and 0.5 ¹m: the former with ¾ g s of 1.2 and 1.45, the latter with ¾ g s of 1.2, 1.45, and 1.9. These are representative of fresh accumulation aerosol from controlled sources and aged accumulation aerosol bearing secondary mass (Ondov and Wexler 1998). Collection ef ciency data suitable for individual stages (i, where i D 0 for the inlet stage, see Table 1) of each of the impactors were obtained from the University of Minnesota (Marple et al 1991) and were t with the sigmoidal function, " i;d p , of Hasan and Dzubay (1987).…”

Trace elements in size-segregated urban aerosol in relation to the anthropogenic emission sources and the resuspension

“…So, Ni and V are tracers of fossil fuels burning (Suarez and Ondov 2002;Moffet et al 2008) and the use of tetra-ethyl-lead as a gasoline additive resulted in emission of submicron lead particles (Murphy et al 2007;Moffet et al 2008). Trace elements of anthropogenic origin released into atmosphere in high temperature processes: combustion of fossil fuels, wood, and waste (Allen et al 2001) or metal working (Ondov and Wexler 1998). Elements originating from the same source have the similar size-distribution (Ondov and Wexler 1998).…”

“…Trace elements of anthropogenic origin released into atmosphere in high temperature processes: combustion of fossil fuels, wood, and waste (Allen et al 2001) or metal working (Ondov and Wexler 1998). Elements originating from the same source have the similar size-distribution (Ondov and Wexler 1998).…”

Multielemental Characterization of Airborne Particulate Matter Collected in Bucharest and Tokushima by Inductively Coupled Plasma Mass Spectrometry and Inductively Coupled Plasma Atomic Emission Spectrometry

“…The chemical characterization of PM is important to assess the environmental risk on human health, and to identify their emission sources. 1 Therefore, it is desirable to determine as many elements in PM as possible. [2][3][4][5] Romania joined the European Union at the beginning of 2007.…”