Table 3.
Examples of OM/OC ratio determined in various studies at urban and remote locations
| Study | Particle size | Method/descriptiona | OM/OC (ratio) | Location | Season (sampling period) | |
|---|---|---|---|---|---|---|
| Urban/sub-urban | Remote | |||||
| Krivacsy et al. (2001) | PM2.5 | Used total organic carbon (TOC) analyzer to determine TC and WSOC | 1.9 | High alpine research station, Jungfraujoch, Switzerland (in the Swiss alps; elevation 3580 m above sea level (asl)) | July to August 1998 | |
| Used solid-phase extraction on a copolymer sorbent | ||||||
| Analyzed C, H, N, and S of OM by elemental analyzer with estimated O | ||||||
| Determined OM mass by gravimetry | ||||||
| Kisset al. (2002) | PM1.5 | Used total organic carbon (TOC) analyzer to determine TC and WSOC | 1.93 ± 0.038 (ranged from 1.9 to 2.0) | Rural K-puszta site with mixed forest, Hungary | January to September 2000 | |
| Used solid-phase extraction on a copolymer sorbent | ||||||
| Analyzed C, H, N, and S of OM by elemental analyzer with estimated O | ||||||
| Determined OM mass by gravimetry | ||||||
| Maria et al. (2002, 2003) | PM1 | Calculated OC and OM from FTIR and compare with thermal/optical OC | 1.27 ± 0.02 to 1.49 ± 0.28 | Aircraft sampling over northeast Asia during the ACE-Asia Campaign | April and May 2001 | |
| A 4-solvent rinsing procedure was used to separate functional groups into fractions of increasing hygroscopicity | ||||||
| Used carbon monoxide (CO) vs. FTIR OC ratios to classify back trajectory clusters into 10 groups | ||||||
| Russell (2003) | Submicron PM | FTIR, estimated OC from the number of carbon bonds and OM from the molecular mass of each functional group | 1.36 ± 0.13 (1.2–1.6) | Aircraft and ship-based sampling in the Caribbean and northeastern Asiab | March to April and July 2001 | |
| El-Zanan et al. (2005) | PM2.5 | After sequential solvent extraction with dichloromethane, acetone, and water, the dried residue was weighed for OM and analyzed for OC by TOR OC. The water extracts were also analyzed for ions (Cl-, NO3 -, SO4 =, Na+, K+, and NH4 +) to subtract inorganic ion mass. | 1.92 ± 0.40 (1.58–2.58) 2.07 by mass balance | U.S. National Parks (5 sites)c | Annual (1988–2003) | |
| Zhang et al. (2005) | PM1 | Inorganic ions (e.g., sulfates, nitrates, ammonium) and organics by AMS, followed by deconvolution of AMS mass spectrum to identify HOAs and OOAs. | Averaged 1.8 with 1.2 for HOA and 2.2 for OOA | Pittsburgh, PA | September 2002 | |
| Yu et al. (2005a, b) | PM1.5 | Used water and solvent extraction followed by GC/MS analysis for WSOC and solvent-soluble OC | Daytime 2.0 ± 0.3 (1.4–2.5). Nighttime 1.8 ± 0.2 (1.3–2.0) | Great Smoky Mountains National Park, TN | July to August 2005 | |
| Chen and Yu (2007) | PM2.5 | Determined OM by combining heating, gravimetric, and chemical constituents | 2.1 ± 0.3 | Sub-urban site at Clearwater, Hong Kong | October 2003 to June 2005 | |
| Gilardoni et al. (2007) | PM1 | FTIR and comparison with IC-PILS for speciated carboxylic acids | 1.4 ± 0.12 | Aircraft sampling of Ohio power plant emissions and regional background (12 flights) | Summer 2004 | |
| 1.6 ± 0.4 | Ship sampling in the Gulf of Maine | |||||
| 1.5 ± 0.16 | Appldore Island, ME | |||||
| 1.6 ± 0.14 | Chebogue Point, Nova Scotia, Canada | |||||
| Reff et al. (2007) | PM2.5 | FTIR for aliphatic (CH) and carbonyl (C=O and [(C=O)−OH] by partial least squares (PLS) equation | Outdoor 1.7–2.6 | 219 non-smoking homes in LA county, CA, Elizabeth, NJ, and Houston, TX | Summer 1999 to Spring 2001 | |
| Indoor 1.3–1.7 (average 1.45 ± 0.17) | ||||||
| Personal 1.3–1.6 (average 1.4 ± 0.11) | ||||||
| Aiken et al. (2008) | PM1 | Elemental analysis by AMS | Average 1.71 with 1.2–1.3 for HOA, 1.85–2.45 for OOA; and 1.6–1.7 for BBOA | Mexico City, Mexicod | March 2006 | |
| Cozic et al. (2008) | PM1 | OM by Q-AMS, normalized to OC by OC/EC TOT carbon analyzer | 1.84 | Jungfraujoch, Switzerland | February and March 2005 | |
| Polidori et al. (2008) | PM2.5 | Used a combination of polarity-based extraction/fractionation method, determine OM by gravimetry and OC by thermal/optical analysis (polarity generally increases as organic oxygen content increases) | OM/OC ratios increase with increasing polarity: 1.37 for hexane, 1.66 for dichloromethane, 1.89 for ethyl acetate, 2.11 for acetone, and 2.25 for methanol extractions. Annual average ratios with (OM/OCtotal) and without (OM/OCextract) non-extractable material were 2.05 ± 0.18 and 1.91 ± 0.24, respectively | Pittsburgh, PA | Annual (July 2001–July 2002) | |
| Gilardoni et al. (2009) | PM1 | FTIR | 1.8 | Mexico City, Mexico | March 2006 | |
| 2.0 | Altzomoni (60 km SE of Mexico City, Mexico) | |||||
| Day et al. (2010) | PM1 | FTIR and comparison of OM with Q-AMS | 1.66e | La Jolla, CA | February and March 2009 | |
| Hawkins and Russell (2010) | PM1 | FTIR and comparison with Q-AMS | 1.55 ± 0.17 | La Jolla, CA | June to September 2008 | |
| Takahama et al. (2011) | Submicron PM | FTIR and comparison with ACSM | 2.0–2.2 | Whistler Mountain, BC, Canada | March and April 2009 | |
| 1.6–1.8 | Aircraft sampling over Mexico and the Gulf of Mexico coast (12 flights) | May to September 2009 | ||||
| Ruthenburg et al. (2014) | PM2.5 | FTIR | 1.83 | Mesa Verde, CO | Annual (2011) at seven IMPROVE sites | |
| 1.79 | Olympia, WA | |||||
| 1.78 | Proctor Maple R.F., VT | |||||
| 1.71 | St. Marks, FL | |||||
| 1.73 | Trapper Creek, AK | |||||
| 1.56 | Phoenix, AZ | |||||
PM particulate matter, PM x PM with diameter smaller than x micrometers at 50 % cut-point, HOA hydrocarbon-like organic aerosol (represent gasoline and diesel engine exhaust emissions), OOA oxygenated organic aerosol (contains more oxygen atoms than HOAs, resemble humic-like substance, and have been associated with secondary organic aerosol), BBOA biomass burning organic aerosol
aMeasurement methods include aerosol chemical speciation monitor (ACSM), aerodyne aerosol mass spectrometer (AMS), quadrupole-aerosol mass spectrometer (Q-AMS), ion chromatography-particle into liquid sampler (IC-PILS), Fourier transform infrared analysis (FTIR), total carbon (TC), thermal/optical reflectance (TOR), thermal/optical transmittance (TOT), water-soluble organic carbon (WSOC), water-soluble organic matter (WSOM)
bDuring the aerosol characterization experiment (ACE)-Asia study in the western Pacific and the Passing Efficiency of the Low Turbulence Inlet Experiment (PELTI) study in the Caribbean
cSites are Acadia, ME; Great Smoky Mountains, TN; Big Bend, TN; Indian Gardens, Grand Canyon, AZ; and Mount Rainier, WA
dDuring the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign, ground-based sampling was done at the T0 Supersite at the Instituto Mexicano del Petróleo (IMP) and aircraft data were collected aboard the NCAR C-130 aircraft over the city
eEstimated based on the sum of carbon mass in the functional groups (Russel 2003)