AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Investigation of Beta Attenuation Monitor Filter Rolls for Particulate Matter Speciation
SURESH RAJA, Philip K. Hopke, Xia Xiaoyan, Sriraam Ramanathan Chandrasekaran, Lin Lin, Kalliat Valsaraj, Jon Klassen, James W. Sweet, Providence Engineering and Environmental Group
Abstract Number: 703 Working Group: Instrumentation and Methods
Abstract Traditional FRM PM$_(2.5) samplers have been typically used throughout California for ambient PM$_2.5 mass measurements. Recently monitors in the San Joaquin Valley were changed to non-traditional PM systems, such as the Beta Attenuation Monitor (BAM) (Model BAM-1020, manufactured by Met One Instruments, Incorporated) because there is a need for real-time PM$_(2.5) data. These units provide a filter tape with a series of 1-hour samples. In this work, speciation methods were developed and tested to investigate the use of BAM filter rolls for chemical speciation of PM collected on BAM filter spots. A total of 22 BAM samples (each comprising of 24 1-hour spots) from 12 sites were analyzed for ions and black carbon (BC). Additionally, 336 1-hour spots from the Hanford and Madera City monitoring stations were used to analyze for organic molecular markers (MM). Measurements of ions and BC in each site appear to have been underestimated likely due to volatilization losses. MM measurements in the 336 BAM filter spots from Hanford and Madera City indicate speciation of BAM filters for MM could be a viable method for measuring useful marker species.
Statistical analysis was conducted by grouping particles into one with mass concentrations greater than 80 micrograms/m$^3, and another with mass concentrations less than 80 micrograms/m$^3. Analysis of delta-C concentration (i.e., delta-C = BC370 nm - BC880 nm) in these two groups of samples revealed that most of the high PM$_(2.5) concentration days (PM$_(2.5) greater than 80 micrograms/m$^3) were likely not impacted by biomass combustion particles. A major portion of the samples analyzed in this work with high concentrations of PM$_(2.5) are likely to be inorganic species such as ammonium sulfate, ammonium nitrate and other ions.
Results from this work suggest that handling and storage of BAM filter samples play a critical in the quality of results.