期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 114, 期 6, 页码 1246-1251出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1618475114
关键词
polycyclic aromatic hydrocarbons; organic aerosols; climate model; viscous aerosol shield; heterogeneous chemistry
资金
- Environmental Molecular Science Laboratory (EMSL)
- US DOE's Office of Biological and Environmental Research
- National Science Foundation
- Office of Science of the DOE
- US DOE [DE-AC05-76RL01830]
- National Institute of Environmental Health Sciences (NIEHS) [P30ES00210, P42ES016465]
- National Science Foundation (NSF) [AGS-11411214]
- US DOE Office of Science, Office of Basic Energy Sciences (BES), Division of Chemical Sciences, Geosciences and Biosciences
- US DOE, Office of Science, Biological and Environmental Research programas part of the Earth System Modeling Program
- Ministry of Education, Youth and Sports of the Czech Republic [LM2015051]
- National Sustainability Programme [LO1214]
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [1411214] Funding Source: National Science Foundation
Polycyclic aromatic hydrocarbons (PAHs) have toxic impacts on humans and ecosystems. One of the most carcinogenic PAHs, benzo(a) pyrene (BaP), is efficiently bound to and transported with atmospheric particles. Laboratory measurements show that particle-bound BaP degrades in a few hours by heterogeneous reaction with ozone, yet field observations indicate BaP persists much longer in the atmosphere, and some previous chemical transport modeling studies have ignored heterogeneous oxidation of BaP to bring model predictions into better agreement with field observations. We attribute this unexplained discrepancy to the shielding of BaP from oxidation by coatings of viscous organic aerosol (OA). Accounting for this OA viscosity-dependent shielding, which varies with temperature and humidity, in a global climate/chemistry model brings model predictions into much better agreement with BaP measurements, and demonstrates stronger long-range transport, greater deposition fluxes, and substantially elevated lung cancer risk from PAHs. Model results indicate that the OA coating is more effective in shielding BaP in the middle/high latitudes compared with the tropics because of differences in OA properties (semisolid when cool/dry vs. liquid-like when warm/humid). Faster chemical degradation of BaP in the tropics leads to higher concentrations of BaP oxidation products over the tropics compared with higher latitudes. This study has profound implications demonstrating that OA strongly modulates the atmospheric persistence of PAHs and their cancer risks.
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