Real-time Ambient Mass Sampler Research Articles

Measurements of Fine Particle Mass Concentrations Using Continuous and Integrated Monitors in Eastern US Cities

PM2.5 mass concentrations were measured using multiple continuous samplers (a continuous ambient mass monitor (CAMM), a real–time ambient mass sampler (RAMS), and a drier–equipped tapered element oscillating microbalance (TEOM)) as well as a federal reference method (FRM) filter sampler in three eastern US cities. The effects of measurement systems, ambient conditions, and composition on the measured PM2.5 mass concentrations were examined at each site. Different responses to PM2.5 mass were observed by the continuous samplers with a variation of 10–30% in the average PM mass concentrations. The impacts of semivolatile particulate ammonium nitrate on PM2.5 mass concentration was apparent for those time periods when high nitrate concentration >1.62 g m−3 was measured in Atlanta. Contribution of semivolatile particulate ammonium nitrate to the ambient PM2.5 mass appeared more significant than semivolatile organic material in Atlanta. The effects of the ambient water were not negligible and were significant ...

Performance evaluation of continuous [formula omitted] mass concentration monitors

PM 2.5 mass concentrations were measured on a short time interval basis using the continuous ambient mass monitor (CAMM) and real-time ambient mass sampler (RAMS) along with a differential tapered element oscillating microbalance (TEOM) in Rubidoux CA, and intercomparisons were made among these samplers to evaluate their measurement performance of PM 2.5 mass. Nephelometers were used as an additional sampler to assist in the between-sampler comparisons. Based on the correlation with particulate nitrate concentrations and particulate mass, the differential TEOM showed better measurement of semivolatile species in PM 2.5 than either the CAMM or the RAMS. The RAMS typically measured more mass than the CAMM. The results suggest that the differential TEOM was better reflecting the PM 2.5 mass concentrations, with less impact from the loss of semivolatile components. Particulate ammonium nitrate losses estimated from the paired Harvard-EPA annular denuder system and a commercial federal reference method (FRM) sampler were equivalent to the PM 2.5 mass difference between the paired differential TEOM and FRM samplers. It suggests that volatilization of semivolatile ammonium nitrate was substantial at Rubidoux, and thus, the differential TEOM performed better in measurement of the actual PM 2.5 mass concentrations, including semivolatile and non-volatile PM, with less loss of semivolatile materials from the filter.

Evaluation of the RAMS Continuous Monitor for Determination of PM2.5 Mass Including Semi-Volatile Material in Philadelphia, PA

The real-time ambient mass sampler (RAMS) is a continuous monitor based on particle concentrator, denuder, drier, and tapered element oscillating microbalance (TEOM) monitor technology. It is designed to measure PM2.5 mass, including the semi-volatile species NH4NO3 and semi-volatile organic material, but not to measure PM2.5 water content. The performance of the RAMS in an urban environment with high humidity was evaluated during the July 1999 NARSTO-Northeast Oxidant and Particles Study (NEOPS) intensive study at the Baxter water treatment plant in Philadelphia, PA. The results obtained with the RAMS were compared to mass measurements made with a TEOM monitor and to constructed mass obtained with a Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) sampler designed to determine the chemical composition of fine particles, including the semi-volatile species. An average of 28% of the fine particulate material present during the study was semi-volatile organic material lost from a filter during particle collection, and 1% was NH4NO3 that was also lost from the particles during sampling. The remaining mass was dominantly nonvolatile (NH4)2SO4 (31%) and organic material (37%), with minor amounts of soot, crustal material, and nonvolatile NH4NO3. Comparison of the RAMS and PC-BOSS results indicated that the RAMS correctly monitored for fine particulate mass, including the semi-volatile material. In contrast, the heated filter of the TEOM monitor did not measure the semi-volatile material. The comparison of the RAMS and PC-BOSS data had a precision of ±4.1 μg/m3 (±9.6%). The precision of the RAMS data was limited by the uncertainty in the blank correction for the reversible adsorption of water by the charcoal-impregnated cellulose sorbent filter of the RAMS monitor. The precision of the measurement of fine par-ticulate components by the PC-BOSS was ±6-8%.

Sources of Fine Particulate Material along the Wasatch Front

The concentration and composition of PM2.5 has been measured with a variety of continuous and integrated samplers at the Hawthorne EPA Environmental Monitoring for Public Awareness and Community Tracking (EMPACT) sampling site in Salt Lake City, UT, and at an EPA Science to Achieve Results (STAR) sampling site in Bountiful, UT. Data are considered at both sites during a 10-day winter period with high PM2.5 concentrations due to winter inversions, and at the Hawthorne site only during a fourteen day summer period when the site was impacted by smoke from wildfires in the Wasatch Mountains. The PM2.5 was dominated by organic material and ammonium nitrate in the winter and by organic material in the summer. In both cases, substantial amounts of sem-volatile material, SVM, was present which was not measured by a Tapered Element Oscillating Microbalance (TEOM) monitor but was detected by a Real-Time Ambient Mass Sampler (RAMS). The PM2.5 data have been combined with concentrations of particulate soot and soil c...

Continuous Measurement of Semivolatile Fine Particulate Mass in Provo, Utah

Ambient particles contain substantial quantities of material that can be lost from the particles during sample collection on a filter, including ammonium nitrate and semivolatile organic compounds. The real-time ambient mass sampler (RAMS) described in this paper has been developed for the accurate continuous monitoring of fine particulate material. The previously published version of the RAMS had significant problems with a variable blank correction. A series of experiments conducted in Provo, UT, during December, 1998, indicated that nitrogen oxides and water were the major contributors to a high morning blank. This blank was minimized by heating the Brigham Young University Organic Sampling System (BOSS) charcoal diffusion denuder and adding multichannel annular denuders coated with triethanolamine (TEA) to remove NO 2 . This new configuration of the RAMS was used to collect samples on 5 consecutive days in Provo, UT. These results were compared to measurements made in both 6 h and 24 h integrated samp...

Use of the RAMS to Measure Semivolatile Fine Particulate Matter at Riverside and Bakersfield, California

Fine particles in urban environments contain substantial quantities of material that can be lost from the particles during sample collection on a filter. This materials include ammonium nitrate and semivolatile organic compounds. Methods for the accurate determination of these species in integrated samples have been developed using diffusion denuder samplers. However, it is often desirable to determine fine particulate matter on a continuous basis. The real-time ambient mass sampler (RAMS), a continuous monitor using diffusion denuder and tapered element oscillating microbalance (TEOM) technologies, has been evaluated by monitoring fine particulate species in Riverside, CA during August and September, 1997, and in Bakersfield, CA during February and March, 1998. The results are compared to measurements made in 1 h integrated samples in Riverside and in 2 h integrated samples in Bakersfield with a diffusion denuder sampler, the particle concentrator-Brigham Young University organic sampling system (PC-BOSS...

Continuous Determination of PM2.5Mass, Including Semi-Volatile Species

The Real-Time Ambient Mass Sampler (RAMS) is a real-time ambient monitor for the determination of fine particulate mass, including ammonium nitrate and semi-volatile organic material. Fine particulate mass is continuously measured with a TEOM monitor containing a "sandwich" filter to trap any semi-volatile material (nitrate and organic) lost from collected particles. Gas phase compounds which will interfere with the TEOM monitor measurement are removed using a particle concentrator,diffusion denuders, and dryers. The concentrations of these gas phase species are reduced to manageable, but not zero, concentrations prior to the collection of particles on the TEOM probe. Therefore a second, parallel system preceded by a filter is used to obtain an active blank for the correction of the RAMS monitor data. The results obtained for the continuous determination of PM2.5 with the RAMS have been validated by comparison with results obtained from PC-BOSS diffusion denuder integrated samples to determine the mass of fine particulate material retained on a filter and the semi-volatile organic material and ammonium nitrate lost from the filter during sampling. Results obtained with RAMS and denuder samplers in Provo, UT, Philadelphia, PA, and Atlanta, GA, show that PM2.5 mass, including semi-volatile fine particulate nitrate and organic species, can be continuously and accurately monitored with the RAMS.

Semi-Volatile Species in PM2.5: Comparison of Integrated and Continuous Samplers for PM2.5Research or Monitoring

ABSTRACT Fine particles in urban atmospheres contain substantial quantities of semi-volatile material [e.g., NH4NO3 and semi-volatile organic compounds (SVOCs)] that are lost from particles during collection on a filter. Several diffusion denuder samplers have been developed for the determination of both NO3 - and organic semi-volatile fine particulate components. The combination of technology used in the BOSS diffusion denuder sampler and the Harvard particle concentrator has resulted in the Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) for the 24-hr (or less) integrated collection of PM2.5, including NH4NO3 and semi-volatile organic material. Modification of the BOSS sampler allows for the weekly determination of these same species. Combination of BOSS denuder and tapered element oscillating microbalance (TEOM) monitor technology has resulted in the real-time ambient mass sampler (RAMS) for the continuous measurement of PM2.5, including the semi-volatile components. Comparison of the results obtained with the BOSS and with each of the newly developed modifications of the BOSS indicates that the modified versions can be used for the continuous, daily, or weekly monitoring of PM2.5, including semi-volatile species, as appropriate to the design of each sampler.