Elemental and morphological analyses of filter tape deposits from a beta attenuation monitor

Abstract

An hourly average PM 10 concentration of 1402 μg m -3 was registered at 1400 Pacific Standard Time (PST), 1/11/2007, on the beta attenuation monitor (BAM) at a North Las Vegas, Nevada sampling site. The high PM 10 concentration at ~ 1245–~1331 PST was a microscale event, limited strictly to the PM 10 sampler; it did not affect the adjacent PM 2.5 concentrations. A method was developed for retrospective compositional analysis of BAM glass-fiber filter tape sample deposits. Sample punches were submitted for optical examination, followed by elemental and morphological analyses with X-ray fluorescence (XRF) and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDS) analyses, respectively. Geological samples surrounding the sampling site were acquired to establish source profiles and identify source markers. Although blank levels for many elements were high on the glass-fiber filter tape from the BAM, they were consistent enough to allow background subtraction from the deposit concentrations for most chemical components. Chemical mass balance (CMB) receptor model source apportionment for the event closely matched the paved road dust sample collected adjacent to the sampling site. It is likely that this high mass event was the result of environmental vandalism. This study demonstrates the feasibility of analyzing BAM filter tape deposits for source attribution, especially for short-duration fugitive dust events. Filter tapes should be time-stamped and immediately retained after an event for future analysis.