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

Abstract. Savanna fires contribute significantly to greenhouse gas emissions. While it is recognized that these fires play a critical 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 as 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 collected and analyzed smoke samples for 36 experimental fires using a canister method for the early dry season (EDS) and mid-dry season (MDS). We also collected 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 report values for fire intensity, combustion completeness, patchiness, modified combustion efficiency (MCE), emission factor (EF) and methane emission density. Our study found that mean methane EFs ranged from 3.83 g kg−1 in the EDS to 3.18 g kg−1 in the MDS, but the small sample did not provide enough power for this effect to be significant. We found head fires had nearly double the CH4 EF of backfires (5.12 g kg−1 to 2.74), a significant difference. Byram's fire intensity was a significant driver of CH4 EF but with weak effect. Methane emission density increased marginally from 0.839 g m−2 in the EDS to 0.875 g m−2 in the MDS, a difference that was not significant. Head fires, however, had much higher emission densities than backfires – 1.203 vs. 0.708 g m−2 – respectively, a significant difference. We suggest the reason for the higher methane emissions from head fires, which have higher intensity, is the longer flame lengths that burn green leaves on trees, releasing methane. 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. Future research should consider the state and amount of leafy biomass combusted in savanna fires.

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

10.5194/bg-2020-476 ◽

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.

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Determinants of fire intensity in working landscapes of an African savanna

Fire Ecology ◽

10.1186/s42408-020-00085-x ◽

2020 ◽

Vol 16 (1) ◽

Author(s):

Paul Laris ◽

Rebecca Jacobs ◽

Moussa Koné ◽

Fadiala Dembélé ◽

Christine M. Rodrigue

Keyword(s):

Ambient Air ◽

Dry Season ◽

West African ◽

Ecological Impacts ◽

Fire Intensity ◽

African Savanna ◽

Seasonal Timing ◽

Working Landscapes ◽

Fire Type ◽

Visual Efficiency

Abstract Background An often cited rule of savanna fire ecology is that early dry-season fires burn less intensely than late dry-season ones; however, few studies base their experimental design on the practices of fire managers in working landscapes. The objective of this research was to study the factors influencing fireline intensity, combustion, and patchiness for a West African savanna under common vegetation and land management practices. We conducted 97 experimental fires by selecting burn plots and seasonal timing (early, n = 33; middle, n = 44; or late, n = 20) based on local practices in a typical working landscape. We collected data for biomass consumed, grass type, scorch height, speed of fire front, visual efficiency (patchiness), fire type, and ambient air conditions. We used multiple regression analysis to determine the key factors affecting fire intensity. Results Mean intensity was lowest for the middle season fires and highest for the late season fires. Minimum fire intensity increased over the fire season except for a sharp drop mid season, while maximum intensity progressively decreased. Seasonal values were highly variable. Fire intensity was moderately positively correlated with scorch height and more modestly correlated with visual efficiency, but only marginally correlated with combustion completeness. Average combustion completeness increased weakly as the dry season progressed. Intensity of back-fires was determined primarily by seasonal timing and the associated ambient humidity and wind and, to a lesser extent, grass characteristics. Head-fire intensity was only feebly responsive to wind speed. Conclusions We found that, at the peak time of West African savanna burning, the intensity of fires decreased. Fire behaviors in working West African landscapes were more dependent on fire type and wind than seasonality. Finally, we found that fire intensity values were lower than those reported elsewhere due to the more representative conditions of the fire setting (under lower afternoon winds) and fuel loads (lower biomass on working landscapes). Future research should focus on the ecological impacts of fires set under such conditions on growth and death rates of savanna trees.

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Bovine trypanosomosis in Gimbi district of Western Oromia, Ethiopia

Animal Biology ◽

10.1163/157075610x491653 ◽

2010 ◽

Vol 60 (2) ◽

pp. 123-131 ◽

Cited By ~ 2

Author(s):

Ashenafi Hagos ◽

Hailu Yacob ◽

Asoke Basu ◽

Degneh Efrem

Keyword(s):

Sea Level ◽

Rainy Season ◽

Age Groups ◽

Trypanosoma Congolense ◽

Dry Season ◽

Major Health Problem ◽

Major Health ◽

Glossina Morsitans Submorsitans ◽

Bovine Trypanosomosis ◽

Significant Difference

AbstractA study on the epidemiology of bovine trypanosomosis was conducted from September 2006 to April 2007 in six villages of the Gimbi district in west Wollega zone of Ethiopia. The prevalence of the disease, the apparent densities and distribution of tsetse and other biting flies in two seasons, the dry and rainy, were determined. The results of a questionnaire survey from 80 farmers revealed that trypanosomosis was a major health problem affecting animals and impeding agricultural activities.A total of 568 blood samples were collected from randomly selected animals (280 animals in rainy and 288 in dry season) and revealed the presence of Trypanosoma congolense Broden, 1904 and T. vivax Zieman, 1905 in the area. Trypanosoma congolense was the dominant species that accounted for 66.2% of the infections. The mean packed cell volume (PCV) concentrations were 22.77% (95% CI =19.99-21.55) in parasitaemic and 25.25% (95% CI=24.88-25.61) in aparasitaemic animals with a significant difference (P<0.005). There was a significant (P<0.012) difference in trypanosome infection between age groups of cattle, being higher in adults. The overall prevalence of trypanosomosis was 12.5%, while the disease prevalence was higher during the rainy season (15 %) than the dry season (10.1%). In three villages of lowland areas (below 1600 meter above sea level), a higher prevalence was recorded 20.9% and 7.9% as compared to three villages of midland areas (≥ 1600 meter above sea level) 11.8% and 8.3% in late rainy and dry season, respectively.A fly-survey was conducted by using 80 monoconical pyramidal traps and revealed that two tsetse species, namely Glossina morsitans submorsitans Newstead and Glossina tachinoides Westwood were found along with other biting flies (Tabanus, Haematopota and Stomoxys species). Higher numerical catches of Glossina were recorded in late rainy season and the apparent density was positively correlated (r=0.5171) with the prevalence of infection.

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The influence of prescribed fire on the extent of wildfire in savanna landscapes of western Arnhem Land, Australia

International Journal of Wildland Fire ◽

10.1071/wf10079 ◽

2012 ◽

Vol 21 (3) ◽

pp. 297 ◽

Cited By ~ 45

Author(s):

Owen F. Price ◽

Jeremy Russell-Smith ◽

Felicity Watt

Keyword(s):

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Prescribed Fire ◽

Fire History ◽

Prescribed Burning ◽

Landsat Imagery ◽

Fire Regimes ◽

Dry Season ◽

Gas Emissions ◽

Arnhem Land

Fire regimes in many north Australian savanna regions are today characterised by frequent wildfires occurring in the latter part of the 7-month dry season. A fire management program instigated from 2005 over 24 000 km2 of biodiversity-rich Western Arnhem Land aims to reduce the area and severity of late dry-season fires, and associated greenhouse gas emissions, through targeted early dry-season prescribed burning. This study used fire history mapping derived mostly from Landsat imagery over the period 1990–2009 and statistical modelling to quantify the mitigation of late dry-season wildfire through prescribed burning. From 2005, there has been a reduction in mean annual total proportion burnt (from 38 to 30%), and particularly of late dry-season fires (from 29 to 12.5%). The slope of the relationship between the proportion of early-season prescribed fire and subsequent late dry-season wildfire was ~–1. This means that imposing prescribed early dry-season burning can substantially reduce late dry-season fire area, by direct one-to-one replacement. There is some evidence that the spatially strategic program has achieved even better mitigation than this. The observed reduction in late dry-season fire without concomitant increase in overall area burnt has important ecological and greenhouse gas emissions implications. This efficient mitigation of wildfire contrasts markedly with observations reported from temperate fire-prone forested systems.

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Environmental Isotope of Radon-222 for Ciliwung River and Shallow Deep Water Interaction Study

Jurnal ILMU DASAR ◽

10.19184/jid.v21i2.11940 ◽

2020 ◽

Vol 21 (2) ◽

pp. 139

Author(s):

Evarista Ristin Pujiindiyati ◽

Bungkus Pratikno

Keyword(s):

River Water ◽

Residence Time ◽

Shallow Groundwater ◽

Infiltration Rate ◽

Scientific Basis ◽

Dry Season ◽

River Bank ◽

222Rn Concentration ◽

Significant Difference ◽

Groundwater Infiltration

Aquifer in river bank area is mostly susceptive toward pollution occurring in river. One of parameters to determine the interaction process between groundwater and river is a natural isotope of 222Rn. The significant difference of radon concentration in groundwater and river water can be utilized as a scientific basis for investigating groundwater infiltration in river bank. Those studied parameters are residence time and infiltration rate. The research using 222Rn had been conducted in shallow groundwater of Ciliwung river bank - South Jakarta during rainy and dry season. The range of 222Rn concentration in shallow groundwater monitored in dry season was between 666 - 2590 Bq/m3 which was higher than that of rainy season ranging at 440 to 1546 Bq/m3. Otherwise, concentration of 222Rn in river water could not be detected (its 222Rn concentration = 0 Bq/m3) due to its much lower concentration either rainy or dry season. During dry season monitoring, equilibration between groundwater and river water was reached at the distance approximately 98 - 140 m away from river side. Estimating residence time based on 222Rn concentration at nearest site from the river and at equlibration area was 4.2 days such that the infiltration rate from river water into aquifer might be 7.8 m/day.Keywords: 222Rn, groundwater, residence time, infiltration rate.

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KONSENTRASI KARAGENAN TERHADAP FISITOKIMIA DAN ORGANOLEPTIK JELYDRINK KRAI

Jurnal Litbang Provinsi Jawa Tengah ◽

10.36762/litbangjateng.v16i2.761 ◽

2019 ◽

Vol 16 (2) ◽

pp. 153-164

Author(s):

Eny Hari Widowati ◽

Dewi Larasati

Keyword(s):

Water Content ◽

Research Methods ◽

Ph Value ◽

Dry Season ◽

Added Value ◽

Assessment Criteria ◽

Cattle Feed ◽

Significant Difference

Krai is a group of vegetables that are widely planted by the community in Kasreman Village, Rembang Regency, Krai is planted every dry season with abundant production. the production of abundant krai and sold in fresh form causes low prices of krai even used as cattle feed, this is because krai does not have added value. Krai has the potential to be processed into various food preparations. one of them is processed jelly drink because of the typical water content in vegetables and aroma. Processing of jelly drinks with krai has not been done so that the use of carrageenan needs to be known for its concentration to be accepted by consumers. Research methods: experiment with simple RAK with carrageenan concentration: K1:2%; K2:4%; K3:6%; K4:8%. For organoleptics use student panelists who are accustomed to organoleptic tests with assessment criteria ˃2-3: Dislike; ˃3-4%: Enough Likes; ˃4-5%: Like; ˃5-6%: Very Like. Results:i) Carrageenan concentration against pH: There are significant differences between treatments. The highest pH was found in treatment K4 (4.26) Increase in carrageenan concentration followed by an increase in pH value;ii) Carrageenan Concentration Against Viscosity there is a very significant difference between treatments The less carrageenan concentration, the lower the viscosity or runny; iii) Carrageenan Concentration Against Sineresis: the carrageenan concentration given had a significant effect on the value of sineresis. The syneresis analysis of roasted jelly drink drinks ranged from 4.51 - 13.47 mg / minute The highest synergy was found in treatment K1. iv) The preferred concentration of texture, taste, aroma is concentration at 0.6%.

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Cutting Oxygen Production-Related Greenhouse Gas Emissions by Improved Compression Heat Management in a Cryogenic Air Separation Unit

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph181910370 ◽

2021 ◽

Vol 18 (19) ◽

pp. 10370

Author(s):

Miroslav Variny ◽

Dominika Jediná ◽

Miroslav Rimár ◽

Ján Kizek ◽

Marianna Kšiňanová

Keyword(s):

Power Consumption ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Ambient Air ◽

Air Separation ◽

Oxygen Production ◽

Gas Emissions ◽

Separation Unit ◽

Air Separation Unit ◽

Air Dryer

Oxygen production in cryogenic air separation units is related to a significant carbon footprint and its supply in the medicinal sphere became critical during the recent COVID-19 crisis. An improved unit design was proposed, utilizing a part of waste heat produced during air pre-cooling and intercooling via absorption coolers, to reduce power consumption. Variable ambient air humidity impact on compressed air dryers’ regeneration was also considered. A steady-state process simulation of a model 500 t h−1 inlet cryogenic air separation unit was performed in Aspen Plus® V11. Comparison of a model without and with absorption coolers yielded an achievable reduction in power consumption for air compression and air dryer regeneration by 6 to 9% (23 to 33 GWh year−1) and a favorable simple payback period of 4 to 10 years, both depending on air pressure loss in additional heat exchangers to be installed. The resulting specific oxygen production decrease amounted to EUR 2–4.2 t−1. Emissions of major gaseous pollutants from power production were both calculated by an in-house developed thermal power plant model and adopted from literature. A power consumption cut was translated into the following annual greenhouse gas emission reduction: CO2 16 to 30 kilotons, CO 0.3 to 2.3 tons, SOx 4.7 to 187 tons and NOx 11 to 56 tons, depending on applied fossil fuel-based emission factors. Considering a more renewable energy sources-containing energy mix, annual greenhouse gas emissions decreased by 50 to over 80%, varying for individual pollutants.

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Growth, yield and water use of drip irrigated cassava planted in the late rainy season of North Eastern Thailand

Indian Journal of Agricultural Research ◽

10.18805/ijare.a-339 ◽

2018 ◽

Author(s):

A. Polthanee ◽

M. Srisutham

Keyword(s):

Water Use ◽

Starch Content ◽

Growth Yield ◽

Dry Season ◽

Storage Root ◽

Root Yield ◽

Supplementary Irrigation ◽

Significant Difference ◽

Four Levels ◽

Cassava Varieties

Field experiment was carried out at Agronomy Experimental Farm, Faculty of Agriculture, Khon Kaen University in 2015-2016 to investigate the response of cassava to supplementary irrigation during the dry season month. The experiment was laid out in split plot design with four replications. The main plots comprised two cassava varieties (Huaybong 80 and Rayong 11). The sub l included four levels of drip irrigation [I-20, EV-40 mm (crop received 20 mm of water when daily cumulative pan evapolation value reached 40 mm during the dry season months)]; [I-20, EV-60 mm] ; [I-10, EV-40 mm] ; [I-10, EV-60 mm] and [I-10] (cassava under rainfed condition without additional irrigation)]. Results indicated that irrigation at (I-20, EV-40 mm) produced maximum the fresh (52 t ha-1) and dry (22 t ha-1) storage root yield. Huaybong 80 variety a gave significantly higher the storage root yield than that of Rayong 11 variety. The highest starch content also was obtained in the (I-20, EV-40 mm) treatment. There was no significant difference in the starch content between the two cassava varieties. Water were applied in treatment [I-20, EV-40 mm], [I-20, EV-60 mm], [I-10, EV-40 mm] and [I-10, EV-60 mm] was an average 299 mm, 194 mm, 150 mm and 97 mm, respectively during the growing season. Water use efficiency was the highest (35.3 kg ha-1 mm-1) in the [I-20, EV-60 mm] treatment.

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Seasonality of Mansonia titillans during dam construction, Biritiba-Mirim, São Paulo State, Brazil

Biota Neotropica ◽

10.1590/s1676-06032013000100007 ◽

2013 ◽

Vol 13 (1) ◽

pp. 70-73 ◽

Cited By ~ 2

Author(s):

Frederico Alves D'Avila ◽

Almério de Castro Gomes

Keyword(s):

Early Spring ◽

Dry Season ◽

Southeastern Brazil ◽

Rank Test ◽

Late Winter ◽

Dam Construction ◽

Wet Season ◽

Paulo State ◽

Significant Difference ◽

Wilcoxon Rank Test

A two and a half year survey was conducted at a dam in southeastern Brazil. Shannon Traps were used for sampling. Kruskal-Wallis test showed little relation between rainfall and abundance. The data clearly show three abundance peaks, all of them in the end of the dry season, in consonance with the scarce literature existent. Although Kruskal-Wallis Test did not find a clear preference for the dry season, Pairwise Wilcoxon Rank Test revealed a significant difference between Fall and Spring samples. Ma. titillans population had a peak on late winter/early spring, close to the begin of wet season.

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Properties and Emissions from Diesel Blended with Spent Groundnut Oil Methyl Ester as Fuel in aCompression Ignition Engine

Applied Engineering in Agriculture ◽

10.13031/aea.13458 ◽

2019 ◽

Vol 35 (6) ◽

pp. 1057-1065

Author(s):

Isaac N Itodo ◽

Rimamnuskep Stephen ◽

Theresa K Kaankuka

Keyword(s):

Methyl Ester ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Flash Point ◽

Carbon Residue ◽

Engine Fuel ◽

Groundnut Oil ◽

Gas Emissions ◽

Tail Pipe ◽

Significant Difference

Abstract. Cheap renewable fuels are needed to replace fossil fuels to reduce greenhouse gas emissions that are causing global warming with the attendant negative consequences. The properties of blends of spent groundnut oil methyl ester (SGOME) and fossil diesel and the emissions from these blends as engine fuel were determined. Spent groundnut oil (SGO) was transesterified into SGOME using methanol and potassium hydroxide as catalyst. The SGOME was blended with fossil diesel and the properties determined and compared to fossil diesel (B0). The pure SGOME (B100) was blended with 90%, 80%, 70%, 60%, and 50% diesel to obtain the B10, B20, B30, B40, and B50 blends of biodiesel, respectively. The properties of the SGOME and the blends were determined according to ASTM and AOCS standards for biodiesel. The properties determined were flash point, carbon residue after combustion, pour and cloud points, kinematic and dynamic viscosities. The blends were used as fuel in a single cylinder 4-stroke water-cooled compression ignition engine that was coupled to a dynamometer from which the tail pipe emissions were measured using gas analyzers. The emissions were measured after the engine had reached a steady state at no load (0 kW) and 1 kW at 3 min interval for 15 min for each blend in 3 replicates. The greenhouse gas emissions measured were nitrogen oxide (NOx),hydrogen sulphide (H2S), particulate matter (PM), sulphur dioxide(SO2),and carbon monoxide (CO). The analysis of variance (ANOVA) at p = 0.05 was used to determine if there was significant difference in the amount of gas emitted from the various blend fuels. The F-LSD was used to separate the means where there was significant difference. The higher blends of the SGOME had better flash point, pour point, and dynamic viscosity than the lower blends. However, the lower blends had better cloud point. The carbon residue after combustion of the SGOME blends was better than that of the fossil diesel. The NOx, PM, SO2, and CO emissions were significantly different from the various blends of the SGOME. However, the H2S emission was not significantly different. Loading the engine did not significantly affect the NOx, H2S, SO2, and CO emissions but significantly affected the PM emission. The PM, CO, and SO2 emissions were highest from the fossil diesel and the lower blends (B10, B20, and B30) and lowest from the higher blends (B40, B50, and B100) at both engine loads. The NOx emission was lowest from the fossil diesel and the lower blends. The use of B20 increased the NOx emission by 10% at both engine loads. The H2S emission was the same for the fossil diesel, pure SGOME (B100), and the blends (B10–B50) at both engine loads. The SGOME fuel reduced tail pipe emission of PM, CO, and SO2 by 26%, 45%, and 78%, respectively. The higher blends had a considerably lower amount of toxic emissions at both engine loads. Keywords: Blends, Diesel, Emissions, Engine, Fuel, Properties, Spent groundnut oil methyl ester.

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