Advanced Apportionment of Carbonaceous Aerosols Using High-Time-Resolution TC-BC Measurements

The World Health Organization issued updated guidelines for particulate matter (PM2.5 and PM10), which have been adopted by the Environmental Protection Agency in the United States and the European Union. The annual limit mean concentration for PM2.5 has been reduced to 9 µg/m³ in the United States and 10 µg/m³ in the European Union. Stringent federal, state and local control measures on inorganics (sulphate, nitrates and ammonium) led to a reduction in PM2.5 in USA over the past several decades, but further air quality improvements would require targeting carbonaceous aerosols (CA). Black Carbon (BC) and Brown Carbon (BrC) are particularly associated with adverse health effects, including respiratory and cardiovascular diseases, cancer, and birth defects. To further reduce PM2.5 concentrations, targeted mitigation strategies and source apportionment of CA is essential.
This study presents the source apportionment of CA using the Carbonaceous Aerosol Speciation System (CASS, Aerosol Magee Scientific), which includes a Total Carbon Analyzer TCA08 and an Aethalometer (AE33, AE36 or AE36s). Unlike traditional OC/EC analyzers, these instruments enable in-field, high-time-resolution measurements of total carbon (TC) and black carbon (BC) in real-time without the requirement of specialty gases/high electrical power. This allows for the calculation of organic carbon (OC) as TC-BC at high-time-resolution, in real-time using easy to operate and maintain field equipment. By integrating numerical algorithms with high-time-resolution measurements from CASS, CA is apportioned into six components based on their optical absorption properties and primary or secondary origin.
The high-time-resolution TC-BC method is crucial for studying the diurnal and seasonal evolution of different CA components in real-time during haze and wildfire events. The described TC-BC method has been applied in various studies globally. This presentation will showcase the advanced TC-BC approach for measurements conducted in Los Angeles, USA; Athens, Greece; Barcelona, Spain; and Ljubljana, Slovenia.