Resolving Particle Size Distribution into Biomass and Fossil Fuel Sources in Subarctic Alaska
LORENA ALBUQUERQUE ZANANDREIS, Saravanan Kanagaratnam, Raghu Betha, Texas Tech University
Abstract Number: 411
Working Group: Source Apportionment
Abstract
Atmospheric aerosol particles come in various sizes. Their size and composition significantly influence how they interact with light and other atmospheric components. Consequently, Particle size distribution (PSD) is crucial in simulating aerosol effects on climate, aerosol transport and deposition, and air quality and cloud formation modeling. In addition, PSD is also important in health risk modeling. Despite its importance, PSDs are not routinely monitored by regulating authorities. This information is not readily available and is notably lacking in the polluted subarctic regions of Alaska. In this study, submicron PSDs were measured using a Scanning Electrical Mobility Spectrometer (SEMS) in the city of North Pole in Interior Alaska during a month-long wintertime campaign. The region is heavily polluted in wintertime due to atmospheric inversion and the widespread use of biomass burning for residential heating. The study revealed a strong inverse non-linear relationship between the total number-to-volume (N/V) ratio and Absorption Ångstörm Exponent (AAE) of particles, indicating that higher AAE values correspond to larger particle sizes. Additionally, diurnal variations in particle sizes were observed, with larger mean diameters (Dg) of particles in the afternoon and night. The mean diameters of PSDs were found to be inversely proportional to temperature. The PSDs are further resolved into two primary sources in the area (fossil fuel (FF) and biomass burning (BB)) using a reduced gradient optimization approach. Preliminary results indicate that BB contributes to more than half (52 ± 25%) of the total particle counts, with a geometric mean diameter of 114 ± 2.1 nm. Fossil fuels account for 48 ± 10% of total particle number with a mean diameter of 61 ± 1.8 nm. By identifying the specific contributions of different sources and particle sizes, this research offers valuable insights into the complex dynamics of aerosol pollution in subarctic Alaska.