scholarly journals Gas-phase pyrolysis products emitted by prescribed fires in pine forests with a shrub understory in the southeastern United States

2019 ◽  
Vol 19 (15) ◽  
pp. 9681-9698 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Tanya L. Myers ◽  
Russell G. Tonkyn ◽  
Catherine A. Banach ◽  
...  
Keyword(s):  
Pine Forests ◽  
Prescribed Fires ◽  
Ir Absorption ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Extraction Device ◽  
Dominant Process ◽  
Pyrolysis Gases ◽  
Manual Extraction ◽  
Emission Ratios

Abstract. In this study we identify pyrolysis gases from prescribed burns conducted in pine forests with a shrub understory captured using a manual extraction device. The device selectively sampled emissions ahead of the flame front, minimizing the collection of oxidized gases, with the captured gases analyzed in the laboratory using infrared (IR) absorption spectroscopy. Results show that emission ratios (ERs) relative to CO for ethene and acetylene were significantly greater than in previous fire studies, suggesting that the sample device was able to collect gases predominantly generated prior to ignition. Further evidence that ignition had not begun was corroborated by novel IR detections of several species, in particular naphthalene. With regards to oxygenated species, several aldehydes (acrolein, furaldehyde, acetaldehyde, formaldehyde) and 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.

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.

Changes in soil hydraulic conductivity after prescribed fires in Mediterranean pine forests

2019 ◽  
Vol 232 ◽  
pp. 1021-1027 ◽  
Author(s):  
P.A. Plaza-Álvarez ◽  
M.E. Lucas-Borja ◽  
J. Sagra ◽  
D.A. Zema ◽  
J. González-Romero ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Pine Forests ◽  
Prescribed Fires ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
Mediterranean Pine

scholarly journals Characterization of PM2.5 collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona

2011 ◽  
Vol 45 (12) ◽  
pp. 2087-2094 ◽  
Author(s):  
Marin S. Robinson ◽  
Min Zhao ◽  
Lindsay Zack ◽  
Christine Brindley ◽  
Lillian Portz ◽  
...  
Keyword(s):  
Ponderosa Pine ◽  
Pine Forests ◽  
Prescribed Burns ◽  
Ponderosa Pine Forests ◽  
Northern Arizona

Transfer of elements to the atmosphere during low-intensity prescribed fires in three Australian subalpine eucalypt forests

1985 ◽  
Vol 15 (4) ◽  
pp. 657-664 ◽  
Author(s):  
R. J. Raison ◽  
P. K. Khanna ◽  
P. V. Woods
Keyword(s):  
Complete Recovery ◽  
Small Mass ◽  
Prescribed Fires ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Percentage Loss ◽  
The Difference ◽  
High Concentrations ◽  
Eucalypt Forests ◽  
Shrub Biomass

Measurements were made of the transfer of N,P,K, Ca, Mg, Mn, and B to the atmosphere during low-intensity (350–600 kWm−1) prescribed burns in three Australian subalpine eucalypt forests dominated by overstoreys of either Eucalyptuspauciflora (Sieb. ex Spreng), Eucalyptusdives (Schau.), or Eucalyptusdelegatensis (R. T. Baker). Elemental transfer was calculated as the difference between the quantity of an element in the fuel (litter plus understorey) before burning and that present in the postfire residues which were recovered quantitatively using small aluminium trays. Complete recovery of fine ash is essential for accurate budgeting for elements other than N. The mass ranges of elements transferred to the atmosphere (kilograms per hectare) were as follows: N, 74–109; P, 1.96–3.04; K, 12.1–21.0; Ca, 18.7–29.7; Mg, 4.5–9.7; Mn, 1.6–4.3; B, 0.08–0.12. These transfers represented, as a percentage of the element initially present in the fuel, the following: N, 54–75; P, 37–50, K, 43–66; Ca, 31–34; Mg, 25–49; Mn, 25–43; B, 35–54. The percentage loss of elements was positively linearly correlated with the percentage loss in fuel weight. High concentrations of P and cations occur in fine ash, especially grey (mineral) ash. In comparison with unburnt litter, concentrations of Ca, Mg, and P were increased by 10- to 50-fold, 10- to 35-fold, and 10-fold in fine (<1 mm) ash produced at the E. pauciflora site, respectively. Hence, transport of a relatively small mass of fine ash either during or after a fire may result in the removal of a significant quantity of nutrients. Prescribed fire rotations of about 10–12 years are required in the forests studied to permit natural inputs of N to approximately replace the amounts transferred to the atmosphere in a single fire. For P replacement, rotation length would need to exceed 20 years. The major impact of regular burning would appear to be on the N cycle because of the rapid reaccumulation of N in shrub biomass and surface litter, thus rendering it highly susceptible to volatilization in a subsequent burn.

scholarly journals Soil Quality of Abandoned Agricultural Terraces Managed with Prescribed Fires and Livestock in the Municipality of Capafonts, Catalonia, Spain (2000–2017)

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 340 ◽  
Author(s):  
Xavier Úbeda ◽  
Meritxell Alcañiz ◽  
Gonzalo Borges ◽  
Luis Outeiro ◽  
Marcos Francos
Keyword(s):  
Soil Quality ◽  
Forest Fires ◽  
Prescribed Burning ◽  
Fire Hazard ◽  
Soil Conditions ◽  
Prescribed Fires ◽  
Agricultural Terraces ◽  
Prescribed Burns ◽  
The Impact ◽  
The Village

The abandonment of the economic activities of agriculture, livestock, and forestry since the second half of the 20th century, in conjunction with the exodus of inhabitants from rural areas, has resulted in an increase in the forest mass as well as an expansion of forest areas. This, in turn, has led to a greater risk of forest fires and an increase in the intensity and severity of these fires. Moreover, these forest masses represent a fire hazard to adjacent urban areas, which is a problem illustrated here by the village of Capafonts, whose former agricultural terraces have been invaded by shrubs, and which in the event of fire runs the risk of aiding the propagation of the flames from the forest to the village’s homes. One of the tools available to reduce the amount of fuel in zones adjoining inhabited areas is prescribed burns. The local authorities have also promoted measures to convert these terraces into pasture; in this way, the grazing of livestock (in this particular instance, goats) aims to keep fuel levels low and thus reduce the risk of fire. The use of prescribed fires is controversial, as they are believed to be highly aggressive for the soil, and little is known about their long-term effects. The alternation of the two strategies is more acceptable—that is, the use of prescribed burning followed by the grazing of livestock. Yet, similarly little is known about the effects of this management sequence on the soil. As such, this study seeks to examine the impact of the management of the abandoned terraces of Capafonts by means of two prescribed fires (2000 and 2002), which were designed specifically to prevent forest fires from reaching the village. Following these two prescribed burns, a herd of goats began to graze these terraces in 2005. Here, we report the results of soil analyses conducted during this period of years up to and including 2017. A plot comprising 30 sampling points was established on one of the terraces and used to monitor its main soil quality properties. The data were subject to statistical tests to determine whether the recorded changes were significant. The results show modifications to the concentration of soil elements, and since the first prescribed burn, these changes have all been statistically significant. We compare our results with those reported in other studies that evaluate optimum soil concentrations for the adequate growth of grazing to feed goats, and conclude that the soil conditions on the terrace after 17 years are optimum for livestock use.

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.

An estimation of modelling parameters for condensed multi-component fuels

2011 ◽  
Vol 225 (5) ◽  
pp. 1229-1235
Author(s):  
V Raghavan ◽  
W T James ◽  
A S Rangwala
Keyword(s):  
Physical Properties ◽  
Ambient Pressure ◽  
Kinetics Parameters ◽  
Pyrolysis Products ◽  
Exponential Factor ◽  
Step Procedure ◽  
Global Reaction ◽  
Thermo Physical Properties ◽  
Pyrolysis Gases

A case study to evaluate the thermo-physical properties and chemical kinetics parameters, which are employed to model the gas-phase combustion taking place over the surface of a condensed fuel, has been presented. This procedure relies on accurate experimental measurements of gaseous pyrolysis products. The pyrolysis gases can be treated as a virtual fuel, namely C xH yO z, where x, y, and z are estimated by performing atom balances for C, H, and O atoms in all the pyrolysis species. Thermo-physical properties of this virtual fuel are calculated based on the temperature and species concentration of the pyrolysis mixture. Similarly, based on the rate constant values of the reactant species present in the pyrolysis mixture, Arrhenius parameters such as pre-exponential factor and activation energy have been calculated. Polymethylmethacrylate (PMMA) is used as an example fuel in this study, and a step-by-step procedure for the estimation of the thermo-physical properties and global reaction kinetics parameters of PMMA at low to moderate ambient pressure environment is presented. In general, the technique discussed here can be applied to any condensed fuel. Following the procedure reported in this study, modelling parameters can be evaluated for complex fuels.

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

1988 ◽  
Vol 43 (12) ◽  
pp. 1083-1090 ◽  
Author(s):  
R. C. Beavis ◽  
J. Lindner ◽  
J. Grotemeyer ◽  
E. W. Schlag
Keyword(s):  
Total Yield ◽  
Experimental Results ◽  
Ir Absorption ◽  
Pyrolysis Products ◽  
Parent Molecule ◽  
The Matrix ◽  
Intense Fragment

The desorption of intact molecules by pulsed IR irradiation is shown to depend on the IR absorption of the matrix. IR transparent matrices, such as NaCl or NH4NO3, increase the total yield and the shot-to-shot stability of the sample. IR absorbing matrices decrease the yield of intact molecules and increase the amount of pyrolysis products.Using semi-transparent sugar matrices with dipeptide samples, the most intense fragment, i.e. the parent molecule having lost 18 u, is suppressed. This fragment is formed by pyrolysis during IR desorption. Three other prominent fragments are caused by the UV photoionization step.The experimental results suggest that a model involving bulk stresses and strain may be necessary to explain the observations.

scholarly journals Gaseous Products from Scrap Tires Pyrolisis

2012 ◽  
Vol 19 (3) ◽  
pp. 451-460 ◽  
Author(s):  
Katarzyna Januszewicz ◽  
Marek Klein ◽  
Ewa Klugmann-Radziemska
Keyword(s):  
European Union ◽  
Gas Chromatography ◽  
Common Method ◽  
Pyrolysis Process ◽  
Pyrolysis Products ◽  
Scrap Tires ◽  
Gaseous Products ◽  
Oil Fractions ◽  
Light Oil ◽  
Pyrolysis Gases

Gaseous Products from Scrap Tires Pyrolisis In European Union 75% of used tires should be recycled. The most common method of used tires disposal, is burning in cement kilns, which does not solve the problem. Pyrolysis process can be an alternative way of utilization of tires. The aim of the researches was to check the influence of pyrolysis products (gas and oil fractions) on environment. Samples from pyrolysis process, like light oil fractions or pyrolysis gases were analyzed using gas chromatography. The pyrolysis installation should be hermetical, because of the PAHs which were detected in a light fraction of oil. In exhaust gases BTEX and PAHs were not detected.

scholarly journals APPLICATION OF THE BIOMASS PYROLISIS PRODUCTS AS A REBURNING FUEL FOR NITROGEN OXIDES REDUCTION: TESTING THE CHEMICAL KINETICS MECHANISM

2020 ◽  
Vol 42 (2) ◽  
pp. 92-98
Author(s):  
S.G. Kobzar ◽  
A.A. Khalatov
Keyword(s):  
Nitrogen Oxides ◽  
Chemical Kinetics ◽  
Coal Combustion ◽  
Mass Fraction ◽  
Biomass Pyrolysis ◽  
Pyrolysis Gas ◽  
Pyrolysis Products ◽  
Nitrogen Oxides Reduction ◽  
Kinetics Of ◽  
Pyrolysis Gases

The mechanisms of chemical kinetics of the Reburning process using pyrolysis gases as a reburn fuel are determined. It has been shown that CO, CO2, H2 have very little effect on the reduction of the nitrogen oxides under conditions characteristic for the coal combustion, and hydrocarbons play the major contribution to the reduction of the nitrogen oxides. The results of the test calculations showed that the process of the nitrogen oxides reduction by the biomass pyrolysis products can be calculated by a simplified mechanism of the chemical kinetics of the Reburning process by replacing hydrocarbons with one substance (with a close carbon/hydrogen ratio as in the real pyrolysis gas mixture), provided that the mass fraction of carbon is preserved, fed to the reduction of nitrogen oxides unchanged. This approach significantly reduces machine time and calculates the nitrogen oxides reducing efficiency by Reburning technology with an accuracy of 17%.

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