AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Response of a Filter-based Instrument with a BC Surrogate
COURTNEY GRIMES, Russell Dickerson, James Radney, Joseph Conny, Christopher Zangmeister, University of Maryland
Abstract Number: 366 Working Group: Instrumentation and Methods
Abstract Black carbon (BC) is formed during the incomplete combustion of biomass and fossil fuels, impacting the Earth’s energy balance and adversely affects human health. The most commonly used BC concentration measurement methods rely on the attenuation of light from the material loaded onto a filter. However, a reliable and reproducible material to calibrate and validate instrument performance does not currently exist. Here, we present data on using a water soluble, commercially available carbon black as a potential material to mimic BC for use in filter attenuation measurements. A commercially available filter-based instrument was used as a test case for instrument assessment. Monodisperse carbon black aerosol was generated through size- and mass-selection by a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM), respectively. We used this material to compare the measured mass concentrations reported by the filter-based instrument to those measured by a condensation particle counter (CPC) operated in parallel. We find that for 300 nm mobility selected particles the filter-based instrument and CPC are within measurement uncertainty for concentrations up to 2 µg/m3. This indicates that the material has the potential to serve as a BC mimic to assess the performance of filter-based attenuation instruments. We also investigated the impact of mass concentration up to 18 µg/m3 on filter attenuation response. Finally, to mimic ambient measurements, we compared the mass concentration of internally mixed carbon black and ammonium sulfate between a filter-based attenuation instrument and a CPC. We observed the filter-based attenuation instrument reported BC mass concentrations that were up to 1.6 times higher than reported by the CPC.