Where Do Particulate Toxins Reside? An Improved Paradigm for the Structure and Dynamics of the Urban Mid-Atlantic Aerosol
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- 作者：John M. Ondov and Anthony S. Wexler
- 刊名：Environmental Science & Technology
- 出版年：1998
- 出版时间：September 1, 1998
- 年：1998
- 卷：32
- 期：17
- 页码：2547 - 2555
- 全文大小：114K
- 年卷期：v.32,no.17(September 1, 1998)
- ISSN：1520-5851
文摘
Discussions of excess mortality and morbidity fromexposure to urban aerosol particles typically invoke thenow 20-year-old trimodal aerosol paradigm proposed byWhitby to explain the structure and behavior of ambientaerosol volume and its major constituent, sulfate. However,this paradigm largely ignores the primary high-temperaturecombustion (HTC) components of the urban aerosol,which contribute minor amounts of the aerosol mass, butcarry the bulk of the particulate toxins and numbers ofaerosol particles. Studies encompassing the analyses of>100 size distributions of important intrinsic tracers of primaryparticles from HTC sources collected over the pastdecade in various environments show that urban aerosolcontains a complex mixture of physically-discrete fresh andaged, primary particle populations from a variety ofsources. Furthermore, whereas the behavior of fine-particulate aerosol mass and sulfate was described interms of coagulation and accumulation aerosol scavengingof new secondary sulfate nuclei, studies reviewedherein suggest that the behavior of primary aerosol ismediated more by hygroscopic growth and cloud processing,accompanied by oxidation of SO2 on wet particles anddroplets. We conclude that the distribution of airborneparticulate toxins and their atmospheric behavior is far morecomplex than commonly conceptualized on the basis ofthe classical trimodal model, and we develop an extendedparadigm in which the focus is on the primary accumulationaerosol.