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While our expertise is chemical characterization of atmospheric organic compounds, our group collaborates with many colleagues to discover the underlying relationship between chemical composition and physical properties of organic compounds.
Figure source: Verma et al. 2015 EST.
Oxidative Potential
Oxidative Potential
We care about aerosol in the atmosphere because it is toxic. In collaboration with Professor Weber, we showed that among all the OA sources, OA from biomass burning has the largest capability to generate reactive oxygen species (ROS). This finding highlights the impacts of biomass burning emissions on human health. We also characterized the toxicity of OA from various precursors in laboratory chamber study and found that OA from anthopogenic aromatics generally has larger oxidative potential than OA from biogenic VOCs.
Related Publications:
Verma, V.; Fang, T.; Xu, L.; Peltier, R. E.; Russell, A. G.; Ng, N. L.; Weber, R. J., Organic Aerosols Associated with the Generation of Reactive Oxygen Species (ROS) by Water-Soluble PM2.5. Environ Sci Technol 2015, 49 (7), 4646-4656 (link).
Tuet, W. Y.; Chen, Y.; Xu, L.; Fok, S.; Gao, D.; Weber, R. J.; Ng, N. L., Chemical oxidative potential of secondary organic aerosol (SOA) generated from the photooxidation of biogenic and anthropogenic volatile organic compounds. Atmos. Chem. Phys. 2017, 17, (2), 839-853 (link).
Figure source: Washenfelder et al. 2015 GRL.
Light Absorption
Light Absorption
We care about aerosol in the atmosphere because it can interact with light and influence our climate. Brown carbon is a class of light-absorbing organic compounds. In collaboration with Dr. Washenfelder, we showed that the majority of brown carbon in the southeastern U.S. is associated with biomass burning. (Again, biomass burning. You may understand why I starts to study the biomass burning). The light absorption of brown carbon can exaggerate global warming, which in turn increases the frequency of wildfires and emits more brown carbon. This positive feedback causes severely adverse impacts on future climate.
Related Publications:
Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Guo, H.; Xu, L.; Weber, R. J.; Ng, N. L.; Allen, H. M.; Ayres, B. R.; Baumann, K.; Cohen, R. C.; Draper, D. C.; Duffey, K. C.; Edgerton, E.; Fry, J. L.; Hu, W. W.; Jimenez, J. L.; Palm, B. B.; Romer, P.; Stone, E. A.; Wooldridge, P. J.; Brown, S. S., Biomass burning dominates brown carbon absorption in the rural southeastern United States. Geophysical Research Letters 2015, 2014GL062444 (link).
Liu, S.; Aiken, A. C.; Gorkowski, K.; Dubey, M. K.; Cappa, C. D.; Williams, L. R.; Herndon, S. C.; Massoli, P.; Fortner, E. C.; Chhabra, P. S.; Brooks, W. A.; Onasch, T. B.; Jayne, J. T.; Worsnop, D. R.; China, S.; Sharma, N.; Mazzoleni, C.; Xu, L.; Ng, N. L.; Liu, D.; Allan, J. D.; Lee, J. D.; Fleming, Z. L.; Mohr, C.; Zotter, P.; Szidat, S.; Prevot, A. S. H., Enhanced light absorption by mixed source black and brown carbon particles in UK winter. Nat Commun 2015, 6 (link).
Figure source: Cerully et al. 2015 ACP.
Hygroscopicity
Hygroscopicity
We care about aerosol in the atmosphere because it is the seed of cloud. Hygroscropicity describes aerosol's propensity to absorb water vapor. In collaboration with Professor Nenes, we studies the relationship between the aerosol hygroscopicity and oxidation state.
Related Publication:
Cerully, K. M.; Bougiatioti, A.; Hite Jr, J. R.; Guo, H.; Xu, L.; Ng, N. L.; Weber, R.; Nenes, A., On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosols in the southeastern United States. Atmos. Chem. Phys. 2015, 15 (15), 8679-8694 (link).
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