Absence of<sup>14</sup>C in PM2.5 Emissions from Gasohol Combustion in Small Engines

Lewis, Charles; Volckens, John; Braddock, James N.; Crews, William; Lonneman, William A.; McNichol, Ann P.

doi:10.1080/02786820600784315

Cited by 4 publications

(4 citation statements)

References 22 publications

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“…The likely explanation for this occurrence is that biodiesel vapor escaped from the biodiesel fuel sump (located about 20 feet from the dilution tunnel) and was drawn into the system along with the dilution air. Such vapor likely absorbed to the quartz filters via the gas-phase adsorption artifact and could explain why the backup filters are so high in C 14 Whatever the cause of this discrepancy, when the data are corrected for a vapor adsorption artifact (using equation 1 and shown on the left hand side of Table 3) the calculation of pMC becomes approximately 2% for the B0 tests, as expected.…”

Section: Resultsmentioning

confidence: 55%

“…These carbon atoms combine with oxygen to form CO 2 . Since the half-life of 14 C is about 5730 years, fossil fuels, which are typically over a million years old, are almost completely devoid of 14 Lewis et al 2006). While this technique is not capable of defining all anthropogenic sources (i.e., wood smoke for residential heating contains modern carbon), it is useful for defining the contribution from mobile-sources (i.e., cars, trucks, small-engines) to ambient PM.…”

Section: Introductionmentioning

confidence: 99%

“…As nations seek alternative fuel sources, many biofuels are being utilized such as biodiesel, ethanol and syn-gas liquids. These recently living fuels contain measurable levels of 14 forms of internal combustion such as four-stroke compression ignition (i.e., diesel combustion). For example, the majority of particulate matter generated from handheld, two-stroke engines can be attributed to emissions of unburned oil, which lacks modern carbon.…”

Section: Introductionmentioning

confidence: 99%

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Biodiesel effects on particulate radiocarbon (14C) emissions from a diesel engine

Bennett

Volckens

Stanglmaier

et al. 2008

Journal of Aerosol Science

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The relative amount of 14 C in a sample of atmospheric particulate matter (PM), defined as percent modern carbon (pMC), allows EPA to infer the fraction of PM derived from anthropogenic pollution sources. With increased use of biofuels that contain 14 C, the main assumption of the two-source model, that 14 C is solely derived from biogenic sources, may become invalid. The goal of this study was to determine the 14 C content of PM emitted from an off-highway diesel engine running on commercial grade biodiesel.Tests were conducted with an off-highway diesel engine running at 80% load fueled by various blends of soy-based biodiesel. A dilution tunnel was used to collect PM 10 emissions on quartz filters that were analyzed for their 14 C content using accelerator mass spectrometry. A mobility particle sizer and 5-gas analyzer provided supporting information on the particle size distribution and gas-phase emissions.

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Section: Resultsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biodiesel effects on particulate radiocarbon (14C) emissions from a diesel engine

Bennett

Volckens

Stanglmaier

et al. 2008

Journal of Aerosol Science

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“…Thus, the ROB, GRI, and PYE parameterizations are used for all P-S/IVOCs regardless of their source, and the amount of SOA from HOA (or CIOA) associated P-S/IVOCs can be calculated as simply the product of the total SI-SOA and the ratio HOA / POA (or CIOA / POA), where the hourly HOA, CIOA, and SI-SOA concentrations are used. It should also be noted that in Los Angeles gasoline contains nearly 10 % ethanol made from corn and thus modern carbon (de Gouw et al, 2012), but it is thought that ethanol and its combustion products are not incorporated into aerosols (Lewis et al, 2006). It should be noted that the fossil-modern split from the box model that is described above depends on the initial P-S/IVOCs concentrations and volatility distribution assumed in the model.…”

Section: Total Soa Concentration: Fossil Vs Contemporary Carbonmentioning

confidence: 99%

Modeling the formation and aging of secondary organic aerosols in Los Angeles during CalNex 2010

Hayes¹,

Carlton²,

Baker³

et al. 2014

Preprint

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Abstract. Four different parameterizations for the formation and evolution of secondary organic aerosol (SOA) are evaluated using a 0-D box model representing the Los Angeles Metropolitan Region during the CalNex 2010 field campaign. We constrain the model predictions with measurements from several platforms and compare predictions with particle and gas-phase observations from the CalNex Pasadena ground site. That site provides a unique opportunity to study aerosol formation close to anthropogenic emission sources with limited recirculation. The model SOA formed only from the oxidation of VOCs (V-SOA) is insufficient to explain the observed SOA concentrations, even when using SOA parameterizations with multi-generation oxidation that produce much higher yields than have been observed in chamber experiments, or when increasing yields to their upper limit estimates accounting for recently reported losses of vapors to chamber walls. The Community Multiscale Air Quality (WRF-CMAQ) model (version 5.0.1) provides excellent predictions of secondary inorganic particle species but underestimates the observed SOA mass by a factor of 25 when an older VOC-only parameterization is used, which is consistent with many previous model-measurement comparisons for pre-2007 anthropogenic SOA modules in urban areas. Including SOA from primary semi-volatile and intermediate volatility organic compounds (P-S/IVOCs) following the parameterizations of Robinson et al. (2007), Grieshop et al. (2009), or Pye and Seinfeld (2010) improves model/measurement agreement for mass concentration. When comparing the three parameterizations, the Grieshop et al. (2009) parameterization more accurately reproduces both the SOA mass concentration and oxygen-to-carbon ratio inside the urban area. Our results strongly suggest that other precursors besides VOCs, such as P-S/IVOCs, are needed to explain the observed SOA concentrations in Pasadena. All the parameterizations over-predict urban SOA formation at long photochemical ages (&approx; 3 days) compared to observations from multiple sites, which can lead to problems in regional and global modeling. Among the explicitly modeled VOCs, the precursor compounds that contribute the greatest SOA mass are methylbenzenes. Polycyclic aromatic hydrocarbons (PAHs) are less important precursors and contribute less than 4% of the SOA mass. The amounts of SOA mass from diesel vehicles, gasoline vehicles, and cooking emissions are estimated to be 16–27, 35–61, and 19–35%, respectively, depending on the parameterization used, which is consistent with the observed fossil fraction of urban SOA, 71 (±3) %. In-basin biogenic VOCs are predicted to contribute only a few percent to SOA. A regional SOA background of approximately 2.1 μg m−3 is also present due to the long distance transport of highly aged OA. The percentage of SOA from diesel vehicle emissions is the same, within the estimated uncertainty, as reported in previous work that analyzed the weekly cycles in OA concentrations (Bahreini et al., 2012; Hayes et al., 2013). However, the modeling work presented here suggests a strong anthropogenic source of modern carbon in SOA, due to cooking emissions, which was not accounted for in those previous studies. Lastly, this work adapts a simple two-parameter model to predict SOA concentration and O/C from urban emissions. This model successfully predicts SOA concentration, and the optimal parameter combination is very similar to that found for Mexico City. This approach provides a computationally inexpensive method for predicting urban SOA in global and climate models. We estimate pollution SOA to account for 26 Tg yr−1 of SOA globally, or 17% of global SOA, 1/3 of which is likely to be non-fossil.

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A study of secondary organic aerosol formation in the anthropogenic‐influenced southeastern United States

et al. 2007

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[1] The formation of secondary organic aerosol (SOA) in an anthropogenic-influenced region in the southeastern United States is investigated by a comparison with urban plumes in the northeast. The analysis is based on measurements of fine-particle organic compounds soluble in water (WSOC) as a measure of secondary organic aerosol. Aircraft measurements over a large area of northern Georgia, including the Atlanta metropolitan region, and in plumes from New York City and surrounding urban regions in the northeast show that fine-particle WSOC are spatially correlated with vehicle emission tracers (e.g., CO), yet the measurements indicate that vehicles do not directly emit significant particulate WSOC. In addition to being correlated, WSOC concentrations were in similar proportions to anthropogenic tracers in both regions, despite biogenic volatile organic compounds (VOCs) that were on average 10-100 times higher over northern Georgia. In contrast, radiocarbon analysis on WSOC extracted from integrated filters deployed in Atlanta suggests that roughly 70-80% of the carbon in summertime WSOC is modern. If both findings are valid, the combined results indicate that in northern Georgia, fine-particle WSOC was secondary and formed through a process that involves mainly modern biogenic VOCs but which is strongly linked to an anthropogenic component that may largely control the mass of SOA formed. Independent of the radiocarbon results, a strong association between SOA and anthropogenic sources has implications for control strategies in urban regions with large biogenic VOC emissions.Citation: Weber, R. J., et al. (2007), A study of secondary organic aerosol formation in the anthropogenic-influenced southeastern United States,

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Absence of¹⁴C in PM2.5 Emissions from Gasohol Combustion in Small Engines

Cited by 4 publications

References 22 publications

Biodiesel effects on particulate radiocarbon (14C) emissions from a diesel engine

Biodiesel effects on particulate radiocarbon (14C) emissions from a diesel engine

Modeling the formation and aging of secondary organic aerosols in Los Angeles during CalNex 2010

A study of secondary organic aerosol formation in the anthropogenic‐influenced southeastern United States

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Absence of14C in PM2.5 Emissions from Gasohol Combustion in Small Engines

Cited by 4 publications

References 22 publications

Biodiesel effects on particulate radiocarbon (14C) emissions from a diesel engine

Biodiesel effects on particulate radiocarbon (14C) emissions from a diesel engine

Modeling the formation and aging of secondary organic aerosols in Los Angeles during CalNex 2010

A study of secondary organic aerosol formation in the anthropogenic‐influenced southeastern United States

Contact Info

Product

Resources

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Absence of¹⁴C in PM2.5 Emissions from Gasohol Combustion in Small Engines