Measurements of trace gases emitted by Australian savanna fires during the 1990 dry season

1994 ◽  
Vol 18 (1) ◽  
pp. 33-56 ◽  
Author(s):  
Dale F. Hurst ◽  
David W. T. Griffith ◽  
John N. Carras ◽  
David J. Williams ◽  
Paul J. Fraser
Keyword(s):  
Trace Gases ◽  
Dry Season ◽  
Savanna Fires

scholarly journals Observations of air composition in Brazil between the Equator and 20°s during the dry season.

1985 ◽  
Vol 15 (1-2) ◽  
pp. 77-120 ◽  
Author(s):  
P.J. Crutzen ◽  
M.T. Coffey ◽  
A.C. Delany ◽  
J. Greenberg ◽  
P. Haagenson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Carbon Monoxide ◽  
Tropical Forests ◽  
Air Pollutants ◽  
Trace Gases ◽  
Dry Season ◽  
Photochemical Reactions ◽  
Ozone Concentrations ◽  
Air Chemistry ◽  
High Concentrations

Field measurement programs in Brazil during the dry season months of August and September in 1979 and 1980 have demonstrated the great importance of the continental tropics in global air chemistry. Especially in the mixed layer, the air composition over land is much different from that over the ocean and the land areas are clearly longe scale sources of many inportant trace gases. During the dry season much biomass, burning takes place especially in the cerrado regions leading to substantial emission of air pollutants, such as CO, NOx, N2O, CH4 and other hydrocarbons. Ozone concentrations are alsoenhanced due to photochemical reactions. Biogenic organic emissions from tropical forests play likewise an important role in the photochemistry of the atmosphere. Carbon monoxide was found to be present in high concentrations in the boundary layer of the tropical forest, but ozone concentrations were much lower than in the cerrado.

scholarly journals Methane gas emissions from savanna fires: What analysis of local burning regimes in a working West African landscape tell us

2021 ◽  
Author(s):  
Paul Laris ◽  
Moussa Koné ◽  
Fadiala Dembélé ◽  
Lilian Yang ◽  
Rebecca Jacobs
Keyword(s):  
Ambient Air ◽  
Methane Emissions ◽  
Dry Season ◽  
West African ◽  
Biomass Composition ◽  
Fire Intensity ◽  
Methane Cycle ◽  
Gas Emissions ◽  
Savanna Fires ◽  
Fire Type

Abstract. Savanna fires contribute significantly to greenhouse gas emissions. While it is recognized that these fires play an important role in the global methane cycle, there are too few accurate estimates of emissions from West Africa, the continent's most active fire region. Most estimates of methane emissions contain high levels of uncertainty because they are based on generalizations of diverse landscapes that are burned by complex fire regimes. To improve estimates we used an approach grounded in the burning practices of people who set fires to working landscapes. We conducted 97 experimental fires collecting data for savanna type, grass type, biomass composition and amount consumed, scorch height, speed of fire front, fire type and ambient air conditions for two sites in Mali. We collected smoke samples for 36 fires using a canister method. We report values for fire intensity, combustion completeness, patchiness, modified combustion efficiency (MCE) and emission factor (EF). Our study finds that methane EFs ranged from 3.71 g/kg in the early dry season (EDS) to 2.86 in the mid-dry season (MDS). We found head fires had nearly double the CH4 EF of backfires (4.89 g/kg to 2.92). Fires during the MDS have the lowest intensity values and the lowest methane emissions 0.981 g/m2 compared with 1.030 g/m2 for EDS and 1.102 g/m2 for the late dry season (LDS). We conclude that policies aimed at shifting the burning regime earlier to reduce methane emissions will not have the desired effects, especially if fire type is not considered. We recommend using the adjusted mean value of 0.862 g/m2—based on the carbon content for West African grasses—for calculating emissions for West African savannas.

The Atmospheric Component of Biogeochemical Cycles in the Amazon Basin

2001 ◽  
Author(s):  
Paulo Artaxo
Keyword(s):  
Land Use ◽  
Tropical Forests ◽  
Amazon Basin ◽  
Aerosol Particles ◽  
Trace Gases ◽  
Biogeochemical Cycles ◽  
Dry Season ◽  
Earth System ◽  
The Earth ◽  
The Tropics

Tropical forests, with their high biological activity, have the potential to emit large amounts of trace gases and aerosol particles to the atmosphere. The accelerated development and land clearing that is occurring in large areas of the Amazon basin suggest that anthropogenic effects on natural biogeochemical cycles are already occurring (Gash et al. 1996). The atmosphere plays a key role in this process. The tropics are the part of the globe with the most rapidly growing population, the most dramatic industrial expansion and the most rapid and pervasive change in land use and land cover. Also the tropics contain the largest standing stocks of terrestrial vegetation and have the highest rates of photosynthesis and respiration. It is likely that changes in tropical land use will have a profound impact on the global atmosphere (Andreae 1998, Andreae and Crutzen 1997). A significant fraction of nutrients are transported or dislocated through the atmosphere in the form of trace gases, aerosol particles, and rainwater (Keller et al. 1991). Also the global effects of carbon dioxide, methane, nitrous oxide, and other trace gases have in the forest ecosystems a key partner. The large emissions of isoprene, terpenes, and many other volatile organic compounds could impact carbon cycling and the production of secondary aerosol particles over the Amazon region. Vegetation is a natural source of many types of aerosol particles that play an important role in the radiation budget over large areas (Artaxo et al. 1998). There are 5 major reservoirs in the Earth system: atmosphere, biosphere (vegetation, animals), soils, hydrosphere (oceans, lakes, rivers, groundwater), and the lithosphere (Earth crust). Elemental cycles of carbon, oxygen, nitrogen, sulfur, phosphorus, and other elements interact with the different reservoirs of the Earth system. The carbon cycle has important aspects in tropical forests due to the large amount of carbon stored in the tropical forests and the high rate of tropical deforestation (Jacob 1999). In Amazonia there are two very different atmospheric conditions: the wet season (mostly from November to June) and the dry season (July-October) (see Marengo and Nobre, this volume). Biomass burning emissions dominate completely the atmospheric concentrations over large areas of the Amazon basin during the dry season (Artaxo et al. 1988).

Fuels and fire at savanna-gallery forest boundaries in southeastern Venezuela

1998 ◽  
Vol 14 (4) ◽  
pp. 445-461 ◽  
Author(s):  
Jason Biddulph ◽  
Martin Kellman
Keyword(s):  
Rain Forest ◽  
Dry Season ◽  
Field Observations ◽  
Litter Layer ◽  
Gallery Forest ◽  
Fuel Type ◽  
Forest Fuels ◽  
Savanna Fires ◽  
Gallery Forests ◽  
Forest Microclimate

ABSTRACT. Factors contributing to the resistance of gallery forests in savannas to the entry of fire were investigated using field observations and manipulation experiments. Mass of savanna fuels did not decrease close to forest boundaries, and in some instances increased, while savanna fuels adjacent to forests were moister than in the savanna beyond for only 1 d after rainfall. A fuel drying experiment conducted in both forest and savanna microclimates indicated that both fuel type and microclimate contributed to the resistance of forests to fire entry, although the former played a larger role. While savanna fuels in a savanna microclimate became ignitable in c. 1 d after rain, forest fuels in a forest microclimate required 4 wk to achieve ignitability. A further experiment juxtaposing forest fuels to burning savanna indicated that fire entry into forests was faciliated by deep root mats and the presence of a superficial litter layer, both of which become attenuated at the forest/savanna contact. It is concluded that fuels in these forests can reach an ignitable state late in the dry season, but that frequent fire entry is probably precluded by the tendency of savanna fires to occur earlier in the dry season and by discontinuities in fuels at the savanna/forest contact.RESUMEN. Se investigaron los factores que contribuyen a la resistencia de la entrada del fuego a los bosques en galería de las savanas mediante observaciones de campo y experimentos de manipulación. La masa de los combustibles de la savana no decrecieron cerca de los bordes del bosque; por el contrario, en algunos casos se incrementaron, mientras que los combustibles de la savana cercanos al bosque eran mas húmedos que en la savana restante, solamente por un día despues de un evento de lluvia. Un experimento de secado de combustible, que fue conducido en los microclimas de bosque y de savana, indica que tanto el tipo de combustible como el microclima contribuyen a la resistencia de los bosques a la entrada del fuego, aunque el primer factor tuvo un papel de mayor importancia. Mientras que los combustibles de la savana en el microclima de la savana se volvieron ‘encendibles’ cerca de un día despues de lluvia, los combustibles del bosque dentro del microlima del bosque tomaron cuatro semanas para llegar a dicho estado. Un experimento que sobrepuso combustibles del bosque a la savana ardiente indicó que la entrada del fuego a los bosques se facilitó por la presencia de mantillos orgánicos profundos y de una capa superficial de hojarasca, presencia que se ve atenuada en la zona de contacto bosque/savana. Se concluye que los combustibles en estos bosques pueden alcanzar un estado de ignición tarde en la estación de sequía, pero que la entrada frecuente del fuego es probablemente evitada por la tendencia que tienen los fuegos de savana a presentarse temprano en la estación seca y por las discontinuidades de combustibles en la zona de contacto savana/bosque.

Resprouting and mortality of juvenile eucalypts in an Australian savanna: impacts of fire season and annual sorghum

2010 ◽  
Vol 58 (8) ◽  
pp. 619 ◽  
Author(s):  
Patricia A. Werner ◽  
Donald C. Franklin
Keyword(s):  
Dry Season ◽  
Fire Season ◽  
Annual Grass ◽  
Fire Behaviour ◽  
Wet Season ◽  
Low Intensity ◽  
Canopy Tree ◽  
Carbohydrate Storage ◽  
Savanna Fires ◽  
Different Seasons

In northern Australian savannas, canopy tree species often have juvenile tree banks that are composed mainly of small individuals of indeterminate age that have resprouted repeatedly after fire. Little is known about their demography. We report the initial responses (mortality, topkill and resprouting type) of 3133 marked juvenile eucalypts to set fires of different seasons (early dry season, late dry season, wet season, unburnt) in a 32 400 m2 field experiment. Fire treatments were repeated in plots dominated by a native annual grass (sorghum) that becomes senescent before the early dry season and provides the main fuel of savanna fires, and in others with little or no sorghum, but instead other native grasses and forbs that remain green well into the dry season. Most juvenile eucalypts <150 cm high were topkilled but resprouted from underground tissues regardless of fire season or understorey (86–100% vs <5% in unburnt plots). Few saplings 200–500 cm high died or were topkilled, but impacts of fire were harsher in sorghum than in non-sorghum vegetation. The response of eucalypts 150–199 cm high was intermediate, suggesting a ‘tactical’ transition from suppressed persistence to growth toward maturity. Counter-intuitively, genet death of juvenile trees was >22% in the low-intensity early dry season fire in plots with little or no annual sorghum, compared with <2% in all other fire/understorey combinations. We suggest results are related to fire behaviour, seasonal carbohydrate storage dynamics and competition with ground-layer plants.

scholarly journals Trace gas and particle emissions from open biomass burning in Mexico

2011 ◽  
Vol 11 (14) ◽  
pp. 6787-6808 ◽  
Author(s):  
R. J. Yokelson ◽  
I. R. Burling ◽  
S. P. Urbanski ◽  
E. L. Atlas ◽  
K. Adachi ◽  
...  
Keyword(s):  
Forest Fires ◽  
Large Fraction ◽  
Trace Gases ◽  
Dry Season ◽  
Dry Forest ◽  
Southern Mexico ◽  
Carbonaceous Particles ◽  
Airborne Measurements ◽  
Combustion Sources ◽  
Reactive Trace Gases

Abstract. We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NOx, NH3, H2, and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx EF. When considering all fires sampled, the percentage of particles containing soot increased from 15 to 60 % as the modified combustion efficiency increased from 0.88 to 0.98. We estimate that about 175 Tg of fuel was consumed by open burning of biomass and garbage and as biofuel (mainly wood cooking fires) in Mexico in 2006. Combining the fuel consumption estimates with our EF measurements suggests that the above combustion sources account for a large fraction of the reactive trace gases and more than 90 % of the total primary, fine carbonaceous particles emitted by all combustion sources in Mexico.

scholarly journals Trace gas and particle emissions from open biomass burning in Mexico

2011 ◽  
Vol 11 (3) ◽  
pp. 7321-7374 ◽  
Author(s):  
R. J. Yokelson ◽  
I. R. Burling ◽  
S. P. Urbanski ◽  
E. L. Atlas ◽  
K. Adachi ◽  
...  
Keyword(s):  
Forest Fires ◽  
Large Fraction ◽  
Trace Gases ◽  
Dry Season ◽  
Dry Forest ◽  
Southern Mexico ◽  
Carbonaceous Particles ◽  
Airborne Measurements ◽  
Combustion Sources ◽  
Reactive Trace Gases

Abstract. We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NOx, NH3, H2, and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx EF. When considering all fires sampled, the percentage of particles containing soot increased from 15 to 60% as the modified combustion efficiency increased from 0.88 to 0.98. We estimate that about 175 Tg of fuel was consumed by open burning of biomass and garbage and as biofuel (mainly wood cooking fires) in Mexico in 2006. Combining the fuel consumption estimates with our EF measurements suggests that the above combustion sources account for a large fraction of the reactive trace gases and more than 90% of the total primary, fine carbonaceous particles emitted by all combustion sources in Mexico.

Source compositions of trace gases released during African savanna fires

1996 ◽  
Vol 101 (D19) ◽  
pp. 23597-23602 ◽  
Author(s):  
Wesley R. Cofer ◽  
Joel S. Levine ◽  
Edward L. Winstead ◽  
Donald R. Cahoon ◽  
Daniel I. Sebacher ◽  
...  
Keyword(s):  
Trace Gases ◽  
African Savanna ◽  
Savanna Fires

scholarly journals Concentrations and biosphere–atmosphere fluxes of inorganic trace gases and associated ionic aerosol counterparts over the Amazon rainforest

2020 ◽  
Vol 20 (24) ◽  
pp. 15551-15584
Author(s):  
Robbie Ramsay ◽  
Chiara F. Di Marco ◽  
Matthias Sörgel ◽  
Mathew R. Heal ◽  
Samara Carbone ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Tropical Rainforest ◽  
Trace Gases ◽  
Anthropogenic Pollution ◽  
Early Morning ◽  
Dry Season ◽  
Water Soluble ◽  
Amazon Rainforest ◽  
Wet Season ◽  
Deposition Velocities

Abstract. The Amazon rainforest presents a unique, natural laboratory for the study of surface–atmosphere interactions. Its alternation between a near-pristine marine-influenced atmosphere during the wet season and a vulnerable system affected by periodic intrusions of anthropogenic pollution during the dry season provides an opportunity to investigate some fundamental aspects of boundary-layer chemical processes. This study presents the first simultaneous hourly measurements of concentrations, fluxes, and deposition velocities of the inorganic trace gases NH3, HCl, HONO, HNO3, and SO2 as well as their water-soluble aerosol counterparts NH4+, Cl−, NO2-, NO3- and SO42- over the Amazon. Species concentrations were measured in the dry season (from 6 October to 5 November 2017), at the Amazon Tall Tower Observatory (ATTO) in Brazil, using a two-point gradient wet-chemistry instrument (GRadient of AErosols and Gases Online Registration, GRAEGOR) sampling at 42 and 60 m. Fluxes and deposition velocities were derived from the concentration gradients using a modified form of the aerodynamic gradient method corrected for measurement within the roughness sub-layer. Findings from this campaign include observations of elevated concentrations of NH3 and SO2 partially driven by long-range transport (LRT) episodes of pollution and the substantial influence of coarse Cl− and NO3- particulate on overall aerosol mass burdens. From the flux measurements, the dry season budget of total reactive nitrogen dry deposition at the ATTO site was estimated as −2.9 kg N ha-1a-1. HNO3 and HCl were deposited continuously at a rate close to the aerodynamic limit. SO2 was deposited with an average daytime surface resistance (Rc) of 28 s m−1, whilst aerosol components showed average surface deposition velocities of 2.8 and 2.7 mm s−1 for SO42- and NH4+, respectively. Deposition rates of NO3- and Cl− were higher at 7.1 and 7.8 mm s−1, respectively, reflecting their larger average size. The exchange of NH3 and HONO was bidirectional, with NH3 showing emission episodes in the afternoon and HONO in the early morning hours. This work provides a unique dataset to test and improve dry deposition schemes for these compounds for tropical rainforest, which have typically been developed by interpolation from conditions in temperate environments. A future campaign should focus on making similar measurements in the wet season in order to provide a complete view of the annual pattern of inorganic trace gas and coarse aerosol biosphere–atmosphere exchange over tropical rainforest.

Emission factors of trace gases and particles from tropical savanna fires in Australia

2017 ◽  
Vol 122 (11) ◽  
pp. 6059-6074 ◽  
Author(s):  
Maximilien Desservettaz ◽  
Clare Paton‐Walsh ◽  
David W. T. Griffith ◽  
Graham Kettlewell ◽  
Melita D. Keywood ◽  
...  
Keyword(s):  
Trace Gases ◽  
Emission Factors ◽  
Tropical Savanna ◽  
Savanna Fires
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