EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Brown Carbon Sources in Singapore Identified by Factor Analysis of Atmospheric Pressure Chemical Ionization Mass Spectra

LiuDongQing Yang1,2, Xianfeng Wang1,2,3, and Mikinori Kuwata Kuwata3,4
LiuDongQing Yang et al.
  • 1Earth Observatory of Singapore, Nanyang Technological University, Singapore
  • 2Asian School of the Environment, Nanyang Technological University, Singapore
  • 3Campus for Research Excellence and Technological Enterprise (CREATE) Program, Singapore
  • 4Department of Atmospheric and Oceanic Sciences, School of Physics, and BIC-ESAT, Peking University, China

Brown carbon (BrC) is an important candidate for the direct radiative effects of aerosol particles. It has been demonstrated that positive matrix factorization (PMF) is useful in analyzing Aerosol Mass Spectrometer (AMS) data for BrC source apportionment. However, fragmentation of molecular ions in AMS has been limiting its capability to categorize BrC sources. Soft-ionization mass spectrometric techniques are known to retain molecular information of chemical species. In this study, we applied atmospheric pressure chemical ionization mass spectrometry (APCI-MS) to identify the sources of water-soluble BrC. PM2.5 filter samples were collected at a site in Singapore during March-May of 2019. The extracted water-soluble organic matter (WSOM) was analyzed using APCI-MS, time-of-flight aerosol chemical speciation monitor (ToF-ACSM) and ultraviolet-visible spectrophotometer (UV-Vis). Five factor components were obtained by PMF analysis of the APCI-MS data. The PMF output and UV-Vis data were subsequently used to estimate the absorption Ångstrom exponents (AAE) of WSOM in each component. The estimated values of AAE ranged from 3.95 to 8.71. When comparing the factor contributions with simultaneously monitored gas and aerosol data, we found that the factor with the lowest value of AAE was likely emitted from a methane-rich combustion source, located east of the observation site. 

How to cite: Yang, L., Wang, X., and Kuwata, M. K.: Brown Carbon Sources in Singapore Identified by Factor Analysis of Atmospheric Pressure Chemical Ionization Mass Spectra, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7065,, 2021.

Corresponding displays formerly uploaded have been withdrawn.