Assessing Black Carbon and Iron Oxide Aerosols: A Comparative Study Between Urban and Rural Environments in the Southeastern U.S.

SHREYA SURI, Lifei Yin, Bin Bai, Yuhan Yang, Dongli Wang, Andrew Metcalf, Nathan Chellman, James Sherman, Pengfei Liu, Georgia Institute of Technology

     Abstract Number: 23
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
Black carbon (BC) and iron oxide (FeOx) aerosols represent important contributors to shortwave atmospheric heating and have been associated with adverse human health outcomes including respiratory, cardiovascular, and neurological diseases. Accurate measurement of BC and FeOx is crucial for understanding their roles in climate forcing and air quality. However, observational data needed to assess the effects of these aerosols remain limited, particularly regarding the contribution of anthropogenic sources to FeOx emissions. In this study, we use a modified single-particle soot photometer to simultaneously measure and compare BC and FeOx concentrations in urban (Atlanta, GA) and rural (Boone, NC) atmospheric environments in the Southeastern U.S. We also identify likely emission sources and estimate the light absorption properties of BC and FeOx to assess their relative contributions to atmospheric heating. Our findings indicate that while BC concentrations and absorption are comparable at both the urban and rural environments, FeOx concentrations and absorption are an order of magnitude smaller in the rural setting than in the urban setting, highlighting their anthropogenic origins. We find that the ratio of absorption by FeOx to absorption by BC is about 4% at the urban site and approximately 0.5% at the rural site, assuming external mixing. These results highlight the variability in aerosol composition between different environments and the importance of localized assessments to better understand their impacts on air quality and climate.