Apportioning Sources of Carbonaceous Aerosols in North Pole, Interior Alaska, with GRG Methods

SARAVANAN KANAGARATNAM, Kaitlyn McKinney, Anastasia Hewitt, Raghu Betha, Venky Shankar, Texas Tech University

     Abstract Number: 360
     Working Group: Source Apportionment

Abstract
Carbonaceous aerosols (CA) pose a significant challenge to human health and the environment. With a subarctic climate and high dependence on wood burning for heating, the City of North Pole in Interior Alaska experiences extreme levels of CA during winter. While efforts are underway to reduce wood burning, effective methods are needed to estimate the contributions of CA from various sources to monitor the effectiveness of these measures. In this study, we developed two innovative approaches to determine the source contributions of wood burning and fossil fuel combustion to Black Carbon (BC) and the contribution of BC and Brown Carbon (BrC) to total light absorption. The methods we developed – GRG-Based Variable AAE model for BC source apportionment and 2-staged Variable Component (2SVC) model for BC-BrC source contributions are based on Aethalometer (AE) measurements and do not require information on source-specific molecular markers. These methods can apportion short-term data. The results of the study showed that the contribution of biomass burning (BB%) to the BC was estimated to be 52 ± 17.8 %, and the average daily BC emitted by wood burning (BCbb) was 0.907 µg/m3 with a range of 0.02 – 4.74 µg/m3. The fractional contribution of BrC to total absorption at 370 nm was estimated to be 59.7 ± 12.4 %. The GRG-based models developed in this study performed better than the currently used models, with lower errors in the BC-BrC source apportionment. These methods provide an effective means of estimating the contributions of various sources of CA.