Aerosol physical, chemical and optical properties during the Rocky Mountain Airborne Nitrogen and Sulfur study

National Park Service/Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO 80523-1375, USA
Atmospheric Environment (Impact Factor: 3.28). 04/2009; 43(11):1932-1939. DOI: 10.1016/j.atmosenv.2008.12.042

ABSTRACT During the Rocky Mountain Airborne Nitrogen and Sulfur (RoMANS) study, conducted during the spring and summer of 2006, a suite of instruments located near the eastern boundary of Rocky Mountain National Park (RMNP) measured aerosol physical, chemical and optical properties. Three instruments, a differential mobility particle sizer (DMPS), an optical particle counter (OPC), and an aerodynamic particle sizer (APS), measured aerosol size distributions. Aerosols were sampled by an Interagency Monitoring of Protected Visual Environments (IMPROVE) sampler and a URG denuder/filter-pack system for compositional analysis. An Optec integrating nephelometer measured aerosol light scattering. The spring time period had lower aerosol concentrations, with an average volume concentration of 2.2 ± 2.6 μm3 cm−3 compared to 6.5 ± 3.9 μm3 cm−3 in the summer. During the spring, soil was the single largest constituent of PM2.5 mass, accounting for 32%. During the summer, organic carbon accounted for 60% of the PM2.5 mass. Sulfates and nitrates had higher fractional contributions in the spring than the summer. Variability in aerosol number and volume concentrations and in composition was greater in the spring than in the summer, reflecting differing meteorological conditions. Aerosol scattering coefficients (bsp) measured by the nephelometer compared well with those calculated from Mie theory using size distributions, composition data and modeled RH dependent water contents.

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Available from: Sonia M Kreidenweis, Sep 29, 2015
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    • "However, the determination/estimation of the refractive index of aerosols , influenced by their complex chemical composition, remains one of the least well-characterised properties [51] [52] [53]. Different methodologies have been proposed to estimate the refractive index of aerosols [54] [55] [56] [57] [58] [59]. Due to the lack of information regarding optical properties, the Levin et al.'s methodology [60] seems the most suitable for our study, as the complex refractive index is computed from the chemical composition of the particles, assuming that PM 2.5 constituents are present as particular chemical compounds with a specific density and a typical refractive Fig. 3. Example of CO 2 and O 2 concentration profiles in the exit flue gases along time, measured at the exit of the reactor (see Fig. 1), during the co-combustion experiments. "
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    • "To investigate nitrogen deposition at RMNP, and to elucidate the nitrogen sources that are impacting the park, the National Park Service initiated the Rocky Mountain Atmospheric Nitrogen and Sulfur Study (RoMANS) (Beem et al., 2010; Malm et al., 2009; Levin et al., 2009). The RoMANS study included two 5-week sampling periods in 2006. "
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    • "Meteorological measurements were made on-site by a 10 m tower operated by the CASTNet program. High time resolution measurements of aerosol physical and optical properties (Levin et al., 2009) and key trace gases (NO x , O 3 , NH 3 , and CO) were also made at the Core Site but will not be discussed here. Major inorganic anions and cations were analyzed in precipitation samples and in denuder and filter extracts by ion chromatography using two Dionex DX-500 systems. "
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