Size Distributions of Organic Functional Groups in Ambient Aerosol Collected in Houston, Texas Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program

Abstract

The size distributions of aliphatic carbon, carbonyl, and organonitrate functional groups in ambient aerosol were determined at three sites during an air quality field study conducted during August and September 2000, in Houston, Texas. Samples were collected using a Hering low-pressure impactor and were analyzed, in transmission mode, using Fourier transform infrared spectroscopy. The submicron fractions of the samples exhibited patterns seen in other urban areas. Carbonyl and organonitrate group absorbances showed maxima in the 0.05-0.26 µm and the 0.5-1.0 µm size fractions, and based on these absorbances appear to be primarily due to secondary organic aerosol. Aliphatic carbon absorbances in the submicron aerosol showed maxima in the 0.076-0.12 µm size fraction and the 0.5-1.0 µm size fraction. Weak correlation between ozone concentrations and aliphatic carbon absorbances suggest that some of these aliphatic functional groups are due to primary emissions. For the supermicron aerosol, all three functional groups exhibit maxima in the 2-4 µm size fraction. These coarse size fractions observed in Houston were not observed in similar samples collected in Los Angeles. In addition, some of the aerosol samples collected in Houston display organic functional group concentrations, especially for organonitrates, that are significantly higher than the median concentrations. Samples with very high organic functional group concentrations had molar ratios of carbonyl and organonitrate functional groups that are suggestive of either primary emissions or secondary organic aerosol formation processes that are not commonly observed in other urban areas.

Determination of α-pinene-derived organic nitrate yields: particle phase partitioning and hydrolysis

“…Organic nitrate quantification was accomplished through use of a Brucker Tensor FT-IR spectrometer (Brucker, Inc.). FT-IR has been successfully employed in several previous laboratory and field studies for organic nitrate quantification (Laurent and Allen, 2004;Dekermenjian et al, 1999;Noda et al, 2000;Hallquist et al, 1999;Nielsen et al, 1998). Filter and denuder extracts were analyzed in a 1 cm liquid cell and organic nitrate concentrations were determined using the asymmetric -NO 2 stretch at ∼ 1640 cm −1 , unique to organic nitrates (Nielsen et al, 1995).…”

Atmospheric Chemistry of Oxygenated Volatile Organic Compounds: Impacts on Air Quality and Climate

“…142,157,[162][163][164] Nitrooxy-organosulfates were observed as prominent products in the OH/NO 3 -initiated photooxidation of monoterpenes in the presence of acidified sulfate aerosol by Surratt et al 149 ONs were shown to be an important component of organic aerosol by O'Brien et al 168 in the 1970s and are still the subject of active research interest, [169][170][171][172] ONs typically comprise 10-20% of the carbonaceous aerosol mass in urban locations. [173][174] In wintertime measurements in coastal southern California in 2009, ON groups accounted for up to 10% of organic mass in submicron particles produced from urban combustion emissions. 175 Very recently, in PM 10 samples collected at a rural background site in Hamme, Belgium, -pinene-related nitrooxyorganosulfates were detected during the winter.…”

“…169−172 ONs typically comprise 10− 20% of the carbonaceous aerosol mass in urban locations. 173,174 In wintertime measurements in coastal southern California in 2009, ON groups accounted for up to 10% of organic mass in submicron particles produced from urban combustion emissions. 175 Very recently, in PM 10 samples collected at a rural background site in Hamme, Belgium, α-pinene-related nitrooxy-organosulfates were detected during the winter.…”

An Observational Perspective on the Atmospheric Impacts of Alkyl and Multifunctional Nitrates on Ozone and Secondary Organic Aerosol

“…There are limited ambient observations of either speciated or total RONO 2 in the aerosol phase available. Measurements have been made at a number of field sites using Fourier transform infrared (FTIR) spectroscopy, ,− with electrospray ionization mass spectrometric techniques (ESI–MS), − and to a limited extent by aerosol mass spectrometry (AMS). , Recently, the first ambient measurements by the Berkeley TD-LIF of aerosol-phase ∑ANs have been reported …”