One– and Three–Hour PM_2.5Characterization, Speciation, and Source Apportionment Using Continuous and Integrated Samplers

Abstract

Ammonium nitrate and semivolatile organic compounds (SVOC) are significant components of fine particles in many urban atmospheres. These components, however, are not properly measured by current EPA accepted methods, such as the R&P TEOM monitor, due to loss of semivolatile material (SVM) from particles in the heated environment of the filter during sampling. The accurate determination of semivolatile material is important due to the possible effects of these species on human health, visibility, and global climate change. The concentration and composition of fine particulate material were determined using a combination of continuous and integrated samplers at the Brigham Young University-EPA Environmental Monitoring for Public Access and Community Tracking (BYU-EPA EMPACT) monitoring site in Salt Lake City, Utah over a six-day sampling period (30 January to 4 February) during the winter of 2001. Continuous samples were collected using a RAMS (total PM 2.5 mass), a TEOM monitor (nonvolatile PM2.5 mass), an Aethalometer (elemental carbon), a TSI CPC (particle count), and a Nephelometer (light scattering by particles, bsp). Fine particle composition and mass were determined on a three-hour basis using the PC-BOSS diffusion denuder sampler. Total PM2.5 massdetermined with the RAMS agreed with constructed mass de- Address correspondence to Delbert J. Eatough, Department of Chemistry and Biochemistry, Brigham Young University, c100 Benson Science Building, Provo, Utah 84602-5700. E-mail: delbert eatough@byu.edu termined from the chemical composition measured in collocated PC-BOSS-integrated samples. Results from this study indicate that semivolatile material (ammonium nitrate and semivolatile organic compounds) is a significant component of fine particle mass. Semivolatile organic compounds were the major contributor to light scattering during the six-day sampling period. Semivolatile nitrate, but not organic material, was suggested to be hygroscopic by the nephelometric data. The majority of the SVM observed appeared to be secondary material formed from photochemical reactions of the organic and NOx emissions from mobile sources and wood smoke combustion.

Positive sampling artifact of carbonaceous aerosols and its influence on the thermal-optical split of OC/EC

“…More attention should be paid to semivolatile organic carbon in the future (Fig. 1), considering its secondary nature (Modey et al, 2004;Eatough et al, 2006), and its influence on regional haze (Long et al, 2005). Calculation of the attenuation coefficient of EC and PC is essential for the accurate split of OC and EC, based on the current thermal-optical method.…”

Semicontinuous PM2.5and PM10Mass and Composition Measurements in Lindon, Utah, during Winter 2007

“…[11][12][13] Furthermore, these studies have indicated that most of the semi-volatile organic material (SVOM) is secondary. 10,14 The development of instruments to accurately and semicontinuously determine all components of urban PM 2.5 is important because a significant portion of PM 2.5 has been shown to be semi-volatile, and SVM may be important in cardiovascular human health effects. 15 A sampling campaign was conducted in Lindon, UT, during January and February of 2007.…”

“…During winter inversions, the community is usually impacted by primary emissions and secondary components formed from combustion products from mobile sources and wood-burning stoves. 11,14 A nearby integrated steel mill was not operational during this study. Samples were collected from January 19 through February 16, 2007.…”

Laboratory and Field Evaluation of Instrumentation for the Semicontinuous Determination of Particulate Nitrate (and Other Water-Soluble Particulate Components)

“…This information benefits areas such as epidemiological, environmental, and source apportionment studies; model development and evaluation; visibility degradation; and climate change. 14,15 This paper demonstrates the capability for the semicontinuous determination of particulate nitrate. Two instruments, a commercially available R&P Series 8400N Ambient Particulate Nitrate Monitor (8400N) and an ion chromatography (IC)-based prototype monitor developed at Texas Tech University (TTU), were evaluated.…”

“…13 Filter samples collected over longer time periods lack sufficient temporal resolution to track short-term diurnal events (i.e., impact of traffic and photochemistry events on particulate nitrate concentration). 14 In addition, sampled filters require offline analysis techniques, which result in data availability delays. Therefore, it is desirable to obtain artifact-free, PM chemical composition data with high temporal resolution.…”