scholarly journals Identification of gas-phase pyrolysis products in a prescribed fire: first detections using infrared spectroscopy for naphthalene, methyl nitrite, allene, acrolein and acetaldehyde

2019 ◽  
Vol 12 (1) ◽  
pp. 763-776 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Russell G. Tonkyn ◽  
Stephen P. Baker ◽  
Emily N. Lincoln ◽  
...  
Keyword(s):  
Gas Phase ◽  
Prescribed Fire ◽  
Wildland Fire ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Methyl Nitrite ◽  
Spectral Components ◽  
Volatile Organic ◽  
Pine Stands ◽  
Many Sources

Abstract. Volatile organic compounds (VOCs) are emitted from many sources, including wildland fire. VOCs have received heightened emphasis due to such gases' influential role in the atmosphere, as well as possible health effects. We have used extractive infrared (IR) spectroscopy on recent prescribed burns in longleaf pine stands and herein report the first detection of five compounds using this technique. The newly reported IR detections include naphthalene, methyl nitrite, allene, acrolein and acetaldehyde. We discuss the approaches used for detection, particularly the software methods needed to fit the analyte and multiple (interfering) spectral components within the selected spectral micro-window(s). We also discuss the method's detection limits and related parameters such as spectral resolution.

scholarly journals Identification of Gas-phase Pyrolysis Products in a Prescribed Fire: Seminal Detections Using Infrared Spectroscopy for Naphthalene, Methyl Nitrite, Allene, Acrolein and Acetaldehyde

2018 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Russell G. Tonkyn ◽  
Stephen P. Baker ◽  
Emily N. Lincoln ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Prescribed Fire ◽  
Wildland Fire ◽  
Individual Species ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Methyl Nitrite ◽  
Spectral Components ◽  
Volatile Organic ◽  
Many Sources

Abstract. Volatile organic compounds (VOCs) are emitted from many sources, including wildland fire; VOCs have received heightened emphasis due to such gases' influential role in the atmosphere, as well as possible health effects. We have used extractive infrared (IR) spectroscopy on recent prescribed burns in longleaf pine stands and herein report seminal detection of five compounds using this technique. The newly reported IR detections include naphthalene, methyl nitrite, allene, acrolein and acetaldehyde. We discuss the approaches used for detection, particularly the software methods needed to fit the analyte and multiple (interfering) spectral components within the selected spectral micro-window(s). We also discuss the method's detection limits and individual species' context in terms of atmospheric chemistry.

scholarly journals Gas-Phase Pyrolysis Products Emitted by Prescribed Fires in Pine Forests with a Shrub Understory in the Southeastern United States

2019 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Tanya L. Myers ◽  
Russell G. Tonkyn ◽  
Catherine A. Banach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pine Forests ◽  
Prescribed Fires ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Extraction Device ◽  
Dominant Process ◽  
Pyrolysis Gases ◽  
Manual Extraction ◽  
Emission Ratios

Abstract. In this study we capture and identify pyrolysis gases from prescribed burns conducted in pine forests with a shrub understory using a manual extraction device. The device selectively sampled emissions ahead of the flame front, minimizing collection of oxidized gases, with the captured gases analyzed in the laboratory using infrared absorption spectroscopy. Results show that emission ratios (ER) relative to CO for ethene, and acetylene were significantly greater than previous fire studies, suggesting that the sample device was able to collect gases prior to ignition. Further evidence that ignition had not begun was corroborated by novel infrared detections of several species, in particular naphthalene. With regards to oxygenated species, several aldehydes (acrolein, furaldehyde, acetaldehyde, formaldehyde) and the carboxylic acids (formic, acetic) were all observed; results show that ERs for acetaldehyde were noticeably greater while ERs for formaldehyde and acetic acid were lower compared to other studies. The acetylene-to-furan ratio also suggests that high temperature pyrolysis was the dominant process generating the collected gases. This hypothesis is further supported by the presence of HCN and the absence of NH3.

scholarly journals Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft

2013 ◽  
Vol 13 (3) ◽  
pp. 8065-8100
Author(s):  
E. S. Cross ◽  
J. F. Hunter ◽  
A. J. Carrasquillo ◽  
J. P. Franklin ◽  
S. C. Herndon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Operating Conditions ◽  
Organic Vapors ◽  
Pyrolysis Products ◽  
Volatile Organic ◽  
Online Measurements ◽  
Unburned Fuel

Abstract. A detailed understanding of the climate and air quality impacts of aviation requires detailed measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground, 143 m downwind of the engines and characterized as a function of engine power from ground idle (~4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine-idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas phase emissions at idle, and an increasing fraction of the total gas phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.

scholarly journals Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft

2013 ◽  
Vol 13 (15) ◽  
pp. 7845-7858 ◽  
Author(s):  
E. S. Cross ◽  
J. F. Hunter ◽  
A. J. Carrasquillo ◽  
J. P. Franklin ◽  
S. C. Herndon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Operating Conditions ◽  
Organic Vapors ◽  
Pyrolysis Products ◽  
Volatile Organic ◽  
Online Measurements ◽  
Unburned Fuel

Abstract. A detailed understanding of the climate and air quality impacts of aviation requires measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground 143 m downwind of the engines and characterized as a function of engine power from idle (4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas-phase emissions at idle, and an increasing fraction of the total gas-phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.

scholarly journals Oxidation of Aqueous Toluene by Gas-Phase Pulsed Corona Discharge in Air-Water Mixtures Followed by Photocatalytic Exhaust Air Cleaning

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 549
Author(s):  
Maarja Kask ◽  
Marina Krichevskaya ◽  
Sergei Preis ◽  
Juri Bolobajev
Keyword(s):  
Corona Discharge ◽  
Gas Phase ◽  
Contact Time ◽  
Closed Loop ◽  
Simultaneous Treatment ◽  
Pulsed Corona Discharge ◽  
Air Cleaning ◽  
Pulsed Corona ◽  
Volatile Organic ◽  
Gaseous Toluene

The treatment of wastewaters containing hazardous volatile organic compounds (VOCs) requires the simultaneous treatment of both water and air. Refractory toluene, extensively studied for its removal, provides a basis for the comparison of its abatement methods. The oxidation of aqueous toluene by gas-phase pulsed corona discharge (PCD) in combination with the subsequent photocatalytic treatment of exhaust air was studied. The PCD treatment showed unequalled energy efficiencies in aqueous and gaseous toluene oxidation, reaching, respectively, up to 10.5 and 29.6 g·kW−1·h−1. The PCD exhaust air contained toluene residues and ozone in concentrations not exceeding 0.1 and 0.6 mg·L−1, respectively. As a result of the subsequent photocatalytic treatment, both airborne residues were eliminated within a contact time with TiO2 as short as 12 s. The results contribute to the possible application of the studied approach in closed-loop energy-saving ventilation systems.

scholarly journals Fuel manipulation with herbicide treatments to reduce fire hazard in young pine (Pinus elliottii × P. caribaea) plantations in south-east Queensland, Australia

2012 ◽  
Vol 21 (8) ◽  
pp. 992 ◽  
Author(s):  
Tom Lewis ◽  
Joanne De Faveri
Keyword(s):  
Adverse Effects ◽  
Tree Growth ◽  
Prescribed Fire ◽  
Fire Hazard ◽  
Dry Weight ◽  
Pinus Elliottii ◽  
Pine Plantations ◽  
Prescribed Burns ◽  
Standing Biomass ◽  
Herbicide Treatments

Wildfire represents a major risk to pine plantations. This risk is particularly great for young plantations (generally less than 10 m in height) where prescribed fire cannot be used to manipulate fuel biomass, and where flammable grasses are abundant in the understorey. We report results from a replicated field experiment designed to determine the effects of two rates of glyphosate (450 g L–1) application, two extents of application (inter-row only and inter-row and row) with applications being applied once or twice, on understorey fine fuel biomass, fuel structure and composition in south-east Queensland, Australia. Two herbicide applications (~9 months apart) were more effective than a once-off treatment for reducing standing biomass, grass continuity, grass height, percentage grass dry weight and the density of shrubs. In addition, the 6-L ha–1 rate of application was more effective than the 3-L ha–1 rate of application in periodically reducing grass continuity and shrub density in the inter-rows and in reducing standing biomass in the tree rows, and application in the inter-rows and rows significantly reduced shrub density relative to the inter-row-only application. Herbicide treatment in the inter-rows and rows is likely to be useful for managing fuels before prescribed fire in young pine plantations because such treatment minimised tree scorch height during prescribed burns. Further, herbicide treatments had no adverse effects on plantation trees, and in some cases tree growth was enhanced by treatments. However, the effectiveness of herbicide treatments in reducing the risk of tree damage or mortality under wildfire conditions remains untested.

The rate of photocatalytic oxidation of aromatic volatile organic compounds in the gas-phase

2008 ◽  
Vol 42 (34) ◽  
pp. 7844-7850 ◽  
Author(s):  
Aikaterini K. Boulamanti ◽  
Christos A. Korologos ◽  
Constantine J. Philippopoulos
Keyword(s):  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Photocatalytic Oxidation ◽  
Volatile Organic

The Effect of Season of Picloram and Chlorsulfuron Application on Dalmatian Toadflax (Linaria genistifolia) on Prescribed Burns

2005 ◽  
Vol 19 (2) ◽  
pp. 319-324 ◽  
Author(s):  
James S. Jacobs ◽  
Roger L. Sheley
Keyword(s):  
Prescribed Fire ◽  
Prescribed Burning ◽  
Block Design ◽  
Prescribed Burn ◽  
Prescribed Burns ◽  
Randomized Complete Block Design ◽  
Untreated Check ◽  
Dalmatian Toadflax ◽  
Density And Biomass ◽  
Cover Density

Herbicides are an important tool for managing weeds where prescribed fire is used for rangeland improvement. Understanding how the season of herbicide application relates to prescribed burning is important. Our objective was to determine the effect of picloram and chlorsulfuron on Dalmatian toadflax cover, density, and biomass, where these herbicides were applied in the fall before burning or in the spring before or after burning. Six herbicide treatments and an untreated check were applied in a randomized complete block design with four replications to a prescribed burn at two sites infested with Dalmatian toadflax in Montana, United States. Herbicides were applied in the fall preburn, spring preburn, and spring postburn. Site 1 was treated in 1999 and 2000, and site 2 was treated in 2000 and 2001. Cover, biomass, and density of Dalmatian toadflax were sampled in September 2000, 2001, and 2002 at site 1 and September 2001 and 2002 at site 2. At site 1, cover, biomass, and density of Dalmatian toadflax were at least 76% lower compared with the check in both spring-applied picloram treatments, whereas the fall picloram treatment had similar Dalmatian toadflax cover, biomass, and density compared with the check 3 yr after application. By 2002, chlorsulfuron reduced Dalmatian toadflax cover, biomass, and density by at least 79% compared with the check in all timings of application at site 1. At site 2, Dalmatian toadflax cover, biomass, and density were reduced by at least 86% for all picloram and chlorsulfuron treatments in 2002, 2 yr after application. Chlorsulfuron applied in the fall or the spring and picloram applied in the spring effectively suppressed Dalmatian toadflax cover, biomass, and density for up to 3 yr.

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