Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem

NASA Technical Reports Server (NTRS)

Mazurek, Monica A.; Cofer, Wesley R., III; Levine, Joel S.

1991-01-01

During the boreal forest burn studied, the ambient concentrations for the particle carbon smoke aerosol are highest for the full-fire burn conditions and vary significantly throughout the burn. Collection strategies must accordingly define ranges in the smoke aerosol concentrations produced. While the highest elemental C concentrations are observed during full-fire conditions, the great majority of smoke aerosol particles are in the form of organic C particles irrespective of fire temperature. The formation of organic C light-scattering particles was a significant process in the burn studied.

Influence of regional biomass burning on the highly elevated organic carbon concentrations observed at Gosan, South Korea during a strong Asian dust period.

PubMed

Nguyen, Duc Luong; Kim, Jin Young; Ghim, Young Sung; Shim, Shang-Gyoo

2015-03-01

PM2.5 carbonaceous particles were measured at Gosan, South Korea during 29 March-11 April 2002 which includes a pollution period (30 March-01 April) when the highest concentrations of major anthropogenic species (nss-SO4 (2-), NO3 (-), and NH4 (+)) were observed and a strong Asian dust (AD) period (08-10 April) when the highest concentrations of mainly dust-originated trace elements (Al, Ca, Mg, and Fe) were seen. The concentrations of elemental carbon (EC) measured in the pollution period were higher than those measured in the strong AD period, whereas an inverse variation in the concentrations of organic carbon (OC) was observed. Based on the OC/EC ratios, the possible source that mainly contributed to the highly elevated OC concentrations measured in the strong AD period was biomass burning. The influence of the long-range transport of smoke plumes emitted from regional biomass burning sources was evaluated by using MODIS (Moderate Resolution Imaging Spectroradiometer) satellite data for fire locations and the potential source contribution function analysis. The most potential source regions of biomass burning were the Primorsky and Amur regions in Far Eastern Russia and southeastern and southwestern Siberia, Russia. Further discussion on the source characteristics suggested that the high OC concentrations measured in the strong AD period were significantly affected by the smoldering phase of biomass burning. In addition to biomass burning, secondary OC (SOC) formed during atmospheric long-range transport should be also considered as an important source of OC concentration measured at Gosan. Although this study dealt with the episodic case of the concurrent increase of dust and biomass burning particles, understanding the characteristics of heterogeneous mixing aerosol is essential in assessing the radiative forcing of aerosol.

Laboratory Studies of Carbon Emission from Biomass Burning for use in Remote Sensing

NASA Technical Reports Server (NTRS)

Wald, Andrew E.; Kaufman, Yoram J.

1998-01-01

Biomass burning is a significant source of many trace gases in the atmosphere. Up to 25% of the total anthropogenic carbon dioxide added to the atmosphere annually is from biomass burning. However, this gaseous emission from fires is not directly detectable from satellite. Infrared radiance from the fires is. In order to see if infrared radiance can be used as a tracer for these emitted gases, we made laboratory measurements to determine the correlation of emitted carbon dioxide, carbon monoxide and total burned biomass with emitted infrared radiance. If the measured correlations among these quantities hold in the field, then satellite-observed infrared radiance can be used to estimate gaseous emission and total burned biomass on a global, daily basis. To this end, several types of biomass fuels were burned under controlled conditions in a large-scale combustion laboratory. Simultaneous measurements of emitted spectral infrared radiance, emitted carbon dioxide, carbon monoxide, and total mass loss were made. In addition measurements of fuel moisture content and fuel elemental abundance were made. We found that for a given fire, the quantity of carbon burned can be estimated from 11 (micro)m radiance measurements only within a factor of five. This variation arises from three sources, 1) errors in our measurements, 2) the subpixel nature of the fires, and 3) inherent differences in combustion of different fuel types. Despite this large range, these measurements can still be used for large-scale satellite estimates of biomass burned. This is because of the very large possible spread of fire sizes that will be subpixel as seen by Moderate Resolution Imaging Spectroradiometer (MODIS). Due to this large spread, even relatively low-precision correlations can still be useful for large-scale estimates of emitted carbon. Furthermore, such estimates using the MODIS 3.9 (micro)m channel should be even more accurate than our estimates based on 11 (micro)m radiance.

Fast-quench reactor for hydrogen and elemental carbon production from natural gas and other hydrocarbons

DOEpatents

Detering, Brent A.; Kong, Peter C.

2006-08-29

A fast-quench reactor for production of diatomic hydrogen and unsaturated carbons is provided. During the fast quench in the downstream diverging section of the nozzle, such as in a free expansion chamber, the unsaturated hydrocarbons are further decomposed by reheating the reactor gases. More diatomic hydrogen is produced, along with elemental carbon. Other gas may be added at different stages in the process to form a desired end product and prevent back reactions. The product is a substantially clean-burning hydrogen fuel that leaves no greenhouse gas emissions, and elemental carbon that may be used in powder form as a commodity for several processes.

Biomass burning a driver for global change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levine, J.S.; Cofer, W.R. III; Cahoon, D.R. Jr.

1995-03-01

Recent research has identified another biospheric process that has instantaneous and longer term effects on the production of atmospheric gases: biomass burning. Biomass burning includes the burning of the world`s vegetation-forests, savannas. and agricultural lands, to clear the land and change its use. Only in the past decade have researchers realized the important contributions of biomass burning to the global budgets of many radiatively and chemically active gases - carbon dioxide, methane, nitric oxide, tropospheric ozone, methyl chloride - and elemental carbon particulates. International field experiments and satellite data are yielding a clearer understanding of this important global source ofmore » atmospheric gases and particulates. It is seen that in addition to being a significant instantaneous global source of atmospheric gases and particulates, burning enhances the biogenic emissions of nitric oxide and nitrous oxide from the world`s soils. Biomass burning affects the reflectivity and emissivity of the Earth`s surface as well as the hydrological cycle by changing rates of land evaporation and water runoff. For these reasons, it appears that biomass burning is a significant driver of global change. 20 refs., 4 figs., 2 tabs.« less

Emissions from prescribed burning of timber slash piles in Oregon

NASA Astrophysics Data System (ADS)

Aurell, Johanna; Gullett, Brian K.; Tabor, Dennis; Yonker, Nick

2017-02-01

Emissions from burning piles of post-harvest timber slash (Douglas-fir) in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matter (PM2.5), black carbon, ultraviolet absorbing PM, elemental/organic carbon, filter-based metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins/dibenzofurans (PCDD/PCDF), and volatile organic compounds (VOCs) were sampled to determine emission factors, the amount of pollutant formed per amount of biomass burned. The effect on emissions from covering the piles with polyethylene (PE) sheets to prevent fuel wetting versus uncovered piles was also determined. Results showed that the uncovered ("wet") piles burned with lower combustion efficiency and higher emission factors for VOCs, PM2.5, PCDD/PCDF, and PAHs. Removal of the PE prior to ignition, variation of PE size, and changing PE thickness resulted in no statistical distinction between emissions. Results suggest that dry piles, whether covered with PE or not, exhibited statistically significant lower emissions than wet piles due to better combustion efficiency.

Fossil and non-fossil source contributions to atmospheric carbonaceous aerosols during extreme spring grassland fires in Eastern Europe

NASA Astrophysics Data System (ADS)

Ulevicius, Vidmantas; Byčenkienė, Steigvilė; Bozzetti, Carlo; Vlachou, Athanasia; Plauškaitė, Kristina; Mordas, Genrik; Dudoitis, Vadimas; Abbaszade, Gülcin; Remeikis, Vidmantas; Garbaras, Andrius; Masalaite, Agne; Blees, Jan; Fröhlich, Roman; Dällenbach, Kaspar R.; Canonaco, Francesco; Slowik, Jay G.; Dommen, Josef; Zimmermann, Ralf; Schnelle-Kreis, Jürgen; Salazar, Gary A.; Agrios, Konstantinos; Szidat, Sönke; El Haddad, Imad; Prévôt, André S. H.

2016-05-01

In early spring the Baltic region is frequently affected by high-pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ng m-3 and black carbon (BC) up to 17 µg m-3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf) was the dominant fraction of PM1, with the primary (POCnf) and secondary (SOCnf) fractions contributing 26-44 % and 13-23 % to the total carbon (TC), respectively. 5-8 % of the TC had a primary fossil origin (POCf), whereas the contribution of fossil secondary organic carbon (SOCf) was 4-13 %. Non-fossil EC (ECnf) and fossil EC (ECf) ranged from 13-24 and 7-13 %, respectively. Isotope ratios of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.

Fluid Chemistry Dynamics Before and After Fire in the Jemez River Basin Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Chorover, J.; Perdrial, J. N.; Field, J. P.; Pelletier, J. D.; Pohlmann, M. A.; Losleben, M. V.; Lasharr, K.; Amistadi, M.; Brooks, P. D.; McIntosh, J. C.; Meixner, T.; Gallery, R.; Rich, V. I.; Rasmussen, C.; Schaap, M. G.; Breshears, D. D.

2013-12-01

The largest wildfire in New Mexico state history (prior to the Whitewater-Baldy fire of 2012) burned the eastern portion of the Jemez River Basin Critical Zone Observatory (JRB CZO) in June-July 2011. This Los Conchas fire burned large stands of ponderosa pine and mixed conifer (MC) forest within the East Fork Jemez River watershed generating massive post-fire erosion. We asked the question: What are the implications of wildfire on pulsed carbon and other bio-active element redistributions in impacted soils and catchments? As soon as possible following the fire, our research group installed sensor and sampler instrumentation in soil profiles in an intensively burned zero order basin (ZOB), enabling the initiation of comparisons to a similarly instrumented, unburned MC ZOB. The signal of biomass combustion was propagated through soil and stream. Post-burn solute fluxes were dominated by highly-aromatic character DOM, as well as elevated DIC, sulfate, chloride and non-hydrolyzing cation (Ca, Mg, K) concentrations deriving from biomass combustion. Supporting an apparent trend of increasing wildfire in western montane forests, the Thompson Ridge wildfire burned MC forest throughout much of the western previously unburned portion of the Valles Caldera National Preserve in June 2013, including the (until then) "unburned" MC ZOB sites comprising CZO sensor and sampler network arrays. Post-burn soil samples were collected for geochemical, physical, and microbial composition characterizations. Solute and gas fluxes were monitored in situ to compare CZ response following this high intensity burn to three years of pre-burn data. Results indicate that the post-fire pulse of water soluble, biomass-derived ions and carbon into underlying and downslope soils is generating landscape-scale element distribution that could affect recolonization by biota in the ensuing secondary succession.

Light absorption of organic carbon emitted from burning wood, charcoal, and kerosene in household cookstoves.

PubMed

Xie, Mingjie; Shen, Guofeng; Holder, Amara L; Hays, Michael D; Jetter, James J

2018-05-02

Household cookstove emissions are an important source of carbonaceous aerosols globally. The light-absorbing organic carbon (OC), also termed brown carbon (BrC), from cookstove emissions can impact the Earth's radiative balance, but is rarely investigated. In this work, PM 2.5 filter samples were collected during combustion experiments with red oak wood, charcoal, and kerosene in a variety of cookstoves mainly at two water boiling test phases (cold start CS, hot start HS). Samples were extracted in methanol and extracts were examined using spectrophotometry. The mass absorption coefficients (MAC λ , m 2 g -1 ) at five wavelengths (365, 400, 450, 500, and 550 nm) were mostly inter-correlated and were used as a measurement proxy for BrC. The MAC 365 for red oak combustion during the CS phase correlated strongly to the elemental carbon (EC)/OC mass ratio, indicating a dependency of BrC absorption on burn conditions. The emissions from cookstoves burning red oak have an average MAC λ 2-6 times greater than those burning charcoal and kerosene, and around 3-4 times greater than that from biomass burning measured in previous studies. These results suggest that residential cookstove emissions could contribute largely to ambient BrC, and the simulation of BrC radiative forcing in climate models for biofuel combustion in cookstoves should be treated specifically and separated from open biomass burning. Copyright © 2018 Elsevier Ltd. All rights reserved.

Particle and Gas Emissions from an In Situ Burn of Crude Oil on the Ocean.

PubMed

Hobbs, John L Ross Ronald J Ferek And Peter V

1996-03-01

Burning is a very effective way of removing oil spills from the ocean; the tradeoff is the potential for significant air pollution. Airborne measurements are described for particles and gases from two test burns of crude oil offshore of St. Johns, Newfoundland during the Newfoundland Offshore Burn Experiment (NOBE). The smoke plumes from the burns initially rose 200-400 m into the air and then continued to rise and disperse laterally downwind. The concentrations of accumulation-mode particles in the smoke were ~45,000 cm -3 at 1.5 km from the fires, and they remained as high as ~4,000 cm -3 after an hour or more of travel time downwind. Total particle mass loadings in the plumes were over 1000 µg m -3 near the fires, but decreased to ~100 µg m -3 at 25 km downwind. For each kilogram of fuel consumed, ~770 g of carbon was released in the form of CO2, ~13 g of carbon as CO, -5 g as volatile organic compounds (VOCs), and -87 g as particles with diameters <3.5 µm, of which ~66 g was elemental carbon and ~7 g condensed organic carbon. Also, ~3 g of SO2 was released per kilogram of fuel burned. A relatively low combustion efficiency was indicated by the average molar ratio of the concentration of CO to excess CO2 of 0.017. The molar ratio of NOX to excess CO2 typically varied from 0.3 x 10 -3 to 0.4 x 10 -3 , implying little fixation of atmospheric nitrogen and low concentrations of NOX. For comparison, the total smoke particle production rate in the NOBE burns was about the same as that for a nineacre slash burn.

Fossil and non-fossil source contributions to atmospheric carbonaceous aerosols during extreme spring grassland fires in Eastern Europe

NASA Astrophysics Data System (ADS)

Ulevicius, V.; Byčenkienė, S.; Bozzetti, C.; Vlachou, A.; Plauškaitė, K.; Mordas, G.; Dudoitis, V.; Abbaszade, G.; Remeikis, V.; Garbaras, A.; Masalaite, A.; Blees, J.; Fröhlich, R.; Dällenbach, K. R.; Canonaco, F.; Slowik, J. G.; Dommen, J.; Zimmermann, R.; Schnelle-Kreis, J.; Salazar, G. A.; Agrios, K.; Szidat, S.; El Haddad, I.; Prévôt, A. S. H.

2015-09-01

In early spring the Baltic region is frequently affected by high pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ng m-3 and black carbon (BC) up to 17 μg m-3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf) was the dominant fraction of PM1, with the primary (POCnf) and secondary (SOCnf) fractions contributing 26-44 % and 13-23 % to the TC, respectively. 5-8 % of the TC had a primary fossil origin (POCf), whereas the contribution of fossil secondary organic carbon (SOCf) was 4-13 %. Non-fossil EC (ECnf) and fossil EC (ECf) ranged from 13-24 % and 7-12 %, respectively. Isotope ratio of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.

Impact of fire disturbance on soil thermal and carbon dynamics in Alaskan Tundra and Boreal forest ecosystems

NASA Astrophysics Data System (ADS)

Jiang, Y.; Rastetter, E.; Shaver, G. R.; Rocha, A. V.

2012-12-01

In Alaska, fire disturbance is a major component influencing the soil water and energy balance in both tundra and boreal forest ecosystems. Fire-caused changes in soil environment further affect both above- and below-ground carbon cycles depending on different fire severities. Understanding the effects of fire disturbance on soil thermal change requires implicit modeling work on the post-fire soil thawing and freezing processes. In this study, we model the soil temperature profiles in multiple burned and non-burned sites using a well-developed soil thermal model which fully couples soil water and heat transport. The subsequent change in carbon dynamics is analyzed based on site level observations and simulations from the Multiple Element Limitation (MEL) model. With comparison between burned and non-burned sites, we compare and contrast fire effects on soil thermal and carbon dynamics in continuous permafrost (Anaktuvik fire in north slope), discontinuous permafrost (Erickson Creek fire at Hess Creek) and non-permafrost zone (Delta Junction fire in interior Alaska). Then we check the post-fire recovery of soil temperature profiles at sites with different fire severities in both tundra and boreal forest fire areas. We further project the future changes in soil thermal and carbon dynamics using projected climate data from Scenarios Network for Alaska & Arctic Planning (SNAP). This study provides information to improve the understanding of fire disturbance on soil thermal and carbon dynamics and the consequent response under a warming climate.

Organic aerosols and inorganic species from post-harvest agricultural-waste burning emissions over northern India: impact on mass absorption efficiency of elemental carbon.

PubMed

Rajput, Prashant; Sarin, M M; Sharma, Deepti; Singh, Darshan

2014-01-01

Atmospheric PM2.5 (particulate matter with aerodynamic diameter of ≤ 2.5 μm), collected from a source region [Patiala: 30.2 °N; 76.3 °E; 250 m above mean sea level] of emissions from post-harvest agricultural-waste (paddy-residue) burning in the Indo-Gangetic Plain (IGP), North India, has been studied for its chemical composition and impact on regional atmospheric radiative forcing. On average, organic aerosol mass accounts for 63% of PM2.5, whereas the contribution of elemental carbon (EC) is ∼3.5%. Sulphate, nitrate and ammonium contribute up to ∼85% of the total water-soluble inorganic species (WSIS), which constitutes ∼23% of PM2.5. The potassium-to-organic carbon ratio from paddy-residue burning emissions (KBB(+)/OC: 0.05 ± 0.01) is quite similar to that reported from Amazonian and Savanna forest-fires; whereas non-sea-salt-sulphate-to-OC ratio (nss-SO4(2-)/OC: 0.21) and nss-SO4(2-)/EC ratio of 2.6 are significantly higher (by factor of 5 to 8). The mass absorption efficiency of EC (3.8 ± 1.3 m(2) g(-1)) shows significant decrease with a parallel increase in the concentrations of organic aerosols and scattering species (sulphate and nitrate). A cross plot of OC/EC and nss-SO4(2-)/EC ratios show distinct differences for post-harvest burning emissions from paddy-residue as compared to those from fossil-fuel combustion sources in south-east Asia.

Fossil and Nonfossil Sources of Organic and Elemental Carbon Aerosols in the Outflow from Northeast China.

PubMed

Zhang, Yan-Lin; Kawamura, Kimitaka; Agrios, Konstantinos; Lee, Meehye; Salazar, Gary; Szidat, Sönke

2016-06-21

Source quantification of carbonaceous aerosols in the Chinese outflow regions still remains uncertain despite their high mass concentrations. Here, we unambiguously quantified fossil and nonfossil contributions to elemental carbon (EC) and organic carbon (OC) of total suspended particles (TSP) from a regional receptor site in the outflow of Northeast China using radiocarbon measurement. OC and EC concentrations were lower in summer, representing mainly marine air, than in other seasons, when air masses mostly traveled over continental regions in Mongolia and northeast China. The annual-mean contribution from fossil-fuel combustion to EC was 76 ± 11% (0.1-1.3 μg m(-3)). The remaining 24 ± 11% (0.03-0.42 μg m(-3)) was attributed to biomass burning, with slightly higher contribution in the cold period (∼31%) compared to the warm period (∼21%) because of enhanced emissions from regional biomass combustion sources in China. OC was generally dominated by nonfossil sources, with an annual average of 66 ± 11% (0.5-2.8 μg m(-3)), approximately half of which was apportioned to primary biomass-burning sources (34 ± 6%). In winter, OC almost equally originated from primary OC (POC) emissions and secondary OC (SOC) formation from fossil fuel and biomass-burning sources. In contrast, summertime OC was dominated by primary biogenic emissions as well as secondary production from biogenic and biomass-burning sources, but fossil-derived SOC was the smallest contributor. Distinction of POC and SOC was performed using primary POC-to-EC emission ratios separated for fossil and nonfossil emissions.

Chemical and toxicological properties of emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

NASA Astrophysics Data System (ADS)

Yoon, Seungju; Hu, Shaohua; Kado, Norman Y.; Thiruvengadam, Arvind; Collins, John F.; Gautam, Mridul; Herner, Jorn D.; Ayala, Alberto

2014-02-01

Chemical and toxicological properties of emissions from compressed natural gas (CNG) fueled transit buses with stoichiometric combustion engines and three-way catalyst (TWC) exhaust control systems were measured using a chassis dynamometer testing facility and compared to the data from earlier CNG engine and exhaust control technologies. Gaseous and particulate matter emissions from buses with stoichiometric engines and TWC were significantly lower than the emissions from buses with lean-burn engines. Carbonyls and volatile organic compounds (VOCs) from buses with stoichiometric engines and TWC were lower by more than 99% compared to buses with lean-burn engines. Elemental and organic carbons (EC and OC), polycyclic aromatic hydrocarbons (PAHs), and trace elements from buses with stoichiometric engines and TWC were effectively controlled and significantly lower than the emissions from buses with lean-burn engines. Potential mutagenicity measured using a microsuspension modification of the Salmonella/microsome assay was lower by more than 99% for buses with stoichiometric engines and TWC, compared to buses with lean-burn engines and OxC.

Fireplace and woodstove fine particle emissions from combustion of western Mediterranean wood types

NASA Astrophysics Data System (ADS)

Alves, Célia; Gonçalves, Cátia; Fernandes, Ana Patrícia; Tarelho, Luís; Pio, Casimiro

2011-08-01

Wood from seven species of trees grown in the Portuguese forest ( Pinus pinaster, Eucalyptus globulus, Quercus suber, Acacia longifolia, Quercus faginea, Olea europea and Quercus ilex rotundifolia), and briquettes produced from forest biomass waste were burned in a fireplace and in a woodstove to determine the chemical composition of fine particle (PM 2.5) emissions. Samples were analysed for organic and elemental carbon (OC/EC), water soluble ions (Na +, NH 4+, K +, Mg 2+, Ca 2+, Cl -, NO 3- and SO 42-) and 67 elements. The PM 2.5 emission factors (g kg - 1 fuel burned, dry basis) were in the ranges 9.9-20.2 and 4.2-16.3, respectively, for the fireplace and the woodstove. Organic carbon contributed to about 50% of the fine particle mass in the emissions from every wood species studied in both burning appliances. The carbonaceous component of PM 2.5 was dominated by organic carbon, accounting for more than 85% of the total carbon (TC): OC/TC ranged from 0.85 to 0.96 (avg. 0.92) for the fireplace and from 0.86 to 0.97 (avg. 0.93) for the woodstove. The water-soluble ions accounted for 0.64 to 11.3% of the PM 2.5 mass emitted from the fireplace, whereas mass fractions between 0.53 and 13.6% were obtained for the woodstove. The golden wattle wood smoke showed a much higher ionic content than the emissions from the other wood types. Trace elements represented 0.4 to 2.5% and 0.2 to 2.2% of the PM 2.5 mass emitted, respectively, from the fireplace and the woodstove, which corresponded to average total emissions of 132 ± 77.3 mg kg - 1 and 93.4 ± 60.8 mg kg - 1 of wood burned. Among these, K, Pb, Al, Mn and Sr were present in all samples. From the emission profiles of the individual experiments, composite wood combustion profiles are suggested with the aid of a cluster analysis.

Smoke aerosol chemistry and aging of Siberian biomass burning emissions in a large aerosol chamber

NASA Astrophysics Data System (ADS)

Kalogridis, A.-C.; Popovicheva, O. B.; Engling, G.; Diapouli, E.; Kawamura, K.; Tachibana, E.; Ono, K.; Kozlov, V. S.; Eleftheriadis, K.

2018-07-01

Vegetation open fires constitute a significant source of particulate pollutants on a global scale and play an important role in both atmospheric chemistry and climate change. To better understand the emission and aging characteristics of smoke aerosols, we performed small-scale fire experiments using the Large Aerosol Chamber (LAC, 1800 m3) with a focus on biomass burning from Siberian boreal coniferous forests. A series of burn experiments were conducted with typical Siberian biomass (pine and debris), simulating separately different combustion conditions, namely, flaming, smoldering and mixed phase. Following smoke emission and dispersion in the combustion chamber, we investigated aging of aerosols under dark conditions. Here, we present experimental data on emission factors of total, elemental and organic carbon, as well as individual organic compounds, such as anhydrosugars, phenolic and dicarboxylic acids. We found that total carbon accounts for up to 80% of the fine mode (PM2.5) smoke aerosol. Higher PM2.5 emission factors were observed in the smoldering compared to flaming phase and in pine compared to debris smoldering phase. For low-temperature combustion, organic carbon (OC) contributed to more than 90% of total carbon, whereas elemental carbon (EC) dominated the aerosol composition in flaming burns with a 60-70% contribution to the total carbon mass. For all smoldering burns, levoglucosan (LG), a cellulose decomposition product, was the most abundant organic species (average LG/OC = 0.26 for pine smoldering), followed by its isomer mannosan or dehydroabietic acid (DA), an important constituent of conifer resin (DA/OC = 0.033). A levoglucosan-to-mannosan ratio of about 3 was observed, which is consistent with ratios reported for coniferous biomass and more generally softwood. The rates of aerosol removal for OC and individual organic compounds were investigated during aging in the chamber in terms of mass concentration loss rates over time under dark conditions and compared to the loss rate of EC. The latter is used as an inert tracer for estimating aerosol mechanical deposition and wall losses of the otherwise chemically conserved aerosol species. The OC/EC ratio increased with smoke aging for the flaming phase, suggesting a production/partitioning of organic compounds after emission. On the other hand, for smoldering burns OC/EC ratios decreased further with aging due to additional sinks of OC, other than those related to deposition and wall losses alone, such as evaporation of semi-volatile compounds. The chemical fingerprints of the major PM components of fresh and aged smoke found in this study are proposed to be used for the assessment of contributions from Siberian biomass burning to atmospheric pollution in source apportionment studies like those using molecular marker approaches.

Chemical characterization and oxidative potential of particles emitted from open burning of cereal straws and rice husk under flaming and smoldering conditions

NASA Astrophysics Data System (ADS)

Fushimi, Akihiro; Saitoh, Katsumi; Hayashi, Kentaro; Ono, Keisuke; Fujitani, Yuji; Villalobos, Ana M.; Shelton, Brandon R.; Takami, Akinori; Tanabe, Kiyoshi; Schauer, James J.

2017-08-01

Open burning of crop residue is a major source of atmospheric fine particle emissions. We burned crop residues (rice straws, barley straws, wheat straws, and rice husks produced in Japan) in an outdoor chamber and measured particle mass, composition (elemental carbon: EC, organic carbon: OC, ions, elements, and organic species), and oxidative potential in the exhausts. The fine particulate emission factors from the literature were within the range of our values for rice straws but were 1.4-1.9 and 0.34-0.44 times higher than our measured values for barley straw and wheat straw, respectively. For rice husks and wheat straws, which typically lead to combustion conditions that are relatively mild, the EC content of the particles was less than 5%. Levoglucosan seems more suitable as a biomass burning marker than K+, since levoglucosan/OC ratios were more stable than K+/particulate mass ratios among crop species. Stigmasterol and β-sitosterol could also be used as markers of biomass burning with levoglucosan or instead of levoglucosan. Correlation analysis between chemical composition and combustion condition suggests that hot or flaming combustions enhance EC, K+, Cl- and polycyclic aromatic hydrocarbons emissions, while low-temperature or smoldering combustions enhance levoglucosan and water-soluble organic carbon emissions. Oxidative potential, measured with macrophage-based reactive oxygen species (ROS) assay and dithiothreitol (DTT) assay, of open burning fine particles per particulate mass as well as fine particulate emission factors were the highest for wheat straws and second highest for rice husks and rice straws. Oxidative potential per particulate mass was in the lower range of vehicle exhaust and atmosphere. These results suggest that the contribution of open burning is relatively small to the oxidative potential of atmospheric particles. In addition, oxidative potential (both ROS and DTT activities) correlated well with water-insoluble organic species, suggesting that OC components, especially water-insoluble OC components emitted under non-flaming combustion, have a major impact on oxidative potential.

Impacts of springtime biomass burning in the northern Southeast Asia on marine organic aerosols over the Gulf of Tonkin, China.

PubMed

Zheng, Lishan; Yang, Xiaoyang; Lai, Senchao; Ren, Hong; Yue, Siyao; Zhang, Yingyi; Huang, Xin; Gao, Yuanguan; Sun, Yele; Wang, Zifa; Fu, Pingqing

2018-06-01

Fine particles (PM 2.5 ) samples, collected at Weizhou Island over the Gulf of Tonkin on a daytime and nighttime basis in the spring of 2015, were analyzed for primary and secondary organic tracers, together with organic carbon (OC), elemental carbon (EC), and stable carbon isotopic composition (δ 13 C) of total carbon (TC). Five organic compound classes, including saccharides, lignin/resin products, fatty acids, biogenic SOA tracers and phthalic acids, were quantified by gas chromatography/mass spectrometry (GC/MS). Levoglucosan was the most abundant organic species, indicating that the sampling site was under strong influence of biomass burning. Based on the tracer-based methods, the biomass-burning-derived fraction was estimated to be the dominant contributor to aerosol OC, accounting for 15.7% ± 11.1% and 22.2% ± 17.4% of OC in daytime and nighttime samples, respectively. In two episodes E1 and E2, organic aerosols characterized by elevated concentrations of levoglucosan as well as its isomers, sugar compounds, lignin products, high molecular weight (HMW) fatty acids and β-caryophyllinic acid, were attributed to the influence of intensive biomass burning in the northern Southeast Asia (SEA). However, the discrepancies in the ratios of levoglucosan to mannosan (L/M) and OC (L/OC) as well as the δ 13 C values suggest the type of biomass burning and the sources of organic aerosols in E1 and E2 were different. Hardwood and/or C 4 plants were the major burning materials in E1, while burning of softwood and/or C 3 plants played important role in E2. Furthermore, more complex sources and enhanced secondary contribution were found to play a part in organic aerosols in E2. This study highlights the significant influence of springtime biomass burning in the northern SEA to the organic molecular compositions of marine aerosols over the Gulf of Tonkin. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characterization of Arctic elemental carbon in Barrow, AK using radiocarbon source apportionment

NASA Astrophysics Data System (ADS)

Barrett, T. E.; Usenko, S.; Robinson, E. M.; Sheesley, R. J.

2013-12-01

Currently, the Arctic is one of the fastest warming regions on earth with surface temperatures increasing at a rate nearly double the global mean over recent decades. Despite the fact that atmospheric concentrations of elemental carbon (EC) are lower in the Arctic than in lower latitudes, deposition of EC on snow and ice may exacerbate regional warming by simultaneously decreasing albedo and increasing melt rates. Due to the intensifying Arctic oil exploration in areas such as the Beaufort and Chukchi seas, the impact of new emission sources such as heavy fuel and heavy diesel combustion on regional carbon needs to be assessed. The first step in developing mitigation strategies for reducing current and future EC emissions in the Arctic is to determine emission source contributions. This study aims to determine the relative contributions of fossil fuel and biomass combustion and to identify major source regions of EC to the Arctic. Radiocarbon analysis of both total organic carbon (TOC) and EC combined with organic tracer and back trajectory analysis has been applied to a set of wintertime coarse particulate matter (PM10) samples from Barrow, AK. Preliminary apportionment for January 2013 indicates roughly half of TOC is from biogenic/biomass burning emissions and one third of EC is due to biomass burning emissions. The radiocarbon results will be combined with organic tracer analysis (polycyclic aromatic hydrocarbons, petroleum biomarkers and normal alkanes), increasing the specificity of the relative contribution of both the fossil and modern (biogenic/biomass burning) carbon emission sources. This research represents the first reported radiocarbon values for Arctic EC, providing highly conclusive source apportionment prior to the influence of increased drilling operations and ship traffic in the Beaufort and Chukchi seas.

UH cosmic rays and solar system material - The elements just beyond iron

NASA Technical Reports Server (NTRS)

Wefel, J. P.; Schramm, D. N.; Blake, J. B.

1977-01-01

The nucleosynthesis of cosmic-ray elements between the iron peak and the rare-earth region is examined, and compositional changes introduced by propagation in interstellar space are calculated. Theories on the origin of elements heavier than iron are reviewed, a supernova model of explosive nucleosynthesis is adopted for the ultraheavy (UH) cosmic rays, and computational results for different source distributions are compared with experimental data. It is shown that both the cosmic-ray data and the nucleosynthesis calculations are not yet of sufficient precision to pinpoint the processes occurring in cosmic-ray source regions, that the available data do provide boundary conditions for cosmic-ray nucleosynthesis, and that these limits may apply to the origin of elements in the solar system. Specifically, it is concluded that solar-system abundances appear to be consistent with a superposition of the massive-star core-helium-burning s-process plus explosive-carbon-burning synthesis for the elements from Cu to As and are explained adequately by the s- and r-processes for heavier elements.

Chemical characterization of biomass fuel particulate deposits and ashes in households of Mt. Everest region (NEPAL).

PubMed

Ielpo, Pierina; Fermo, Paola; Comite, Valeria; Mastroianni, Domenico; Viviano, Gaetano; Salerno, Franco; Tartari, Gianni

2016-12-15

During a sampling campaign, carried out during June 2012, inside some traditional households located in four villages (Phakding, Namche, Pangboche and Tukla) of Mt. Everest region in southern part of the central Himalaya (Nepal), particulate matter (PM) depositions and ashes have been collected. Moreover, outdoor PM depositions have also been analyzed. Chemical characterization of PM depositions and ashes for major ions, organic carbon, elemental carbon (EC), metal content and PAHs (Polycyclic Aromatic Hydrocarbons) allowed identifying, as major contributes to indoor PM, the following sources: biomass burning, cooking and chimney ashes. These sources significantly affect outdoor PM depositions: in-house biomass burning is the major source for outdoor EC and K + as well as biomass burning and cooking activities are the major sources for Polycyclic Aromatic Hydrocarbons. Copyright © 2016 Elsevier B.V. All rights reserved.

Radiocarbon Analysis to Calculate New End-Member Values for Biomass Burning Source Samples Specific to the Bay Area

NASA Astrophysics Data System (ADS)

Yoon, S.; Kirchstetter, T.; Fairley, D.; Sheesley, R. J.; Tang, X.

2017-12-01

Elemental carbon (EC), also known as black carbon or soot, is an important particulate air pollutant that contributes to climate forcing through absorption of solar radiation and to adverse human health impacts through inhalation. Both fossil fuel combustion and biomass burning, via residential firewood burning, agricultural burning, wild fires, and controlled burns, are significant sources of EC. Our ability to successfully control ambient EC concentrations requires understanding the contribution of these different emission sources. Radiocarbon (14C) analysis has been increasingly used as an apportionment tool to distinguish between EC from fossil fuel and biomass combustion sources. However, there are uncertainties associated with this method including: 1) uncertainty associated with the isolation of EC to be used for radiocarbon analysis (e.g., inclusion of organic carbon, blank contamination, recovery of EC, etc.) 2) uncertainty associated with the radiocarbon signature of the end member. The objective of this research project is to utilize laboratory experiments to evaluate some of these uncertainties, particularly for EC sources that significantly impact the San Francisco Bay Area. Source samples of EC only and a mix of EC and organic carbon (OC) were produced for this study to represent known emission sources and to approximate the mixing of EC and OC that would be present in the atmosphere. These samples include a combination of methane flame soot, various wood smoke samples (i.e. cedar, oak, sugar pine, pine at various ages, etc.), meat cooking, and smoldering cellulose smoke. EC fractions were isolated using a Sunset Laboratory's thermal optical transmittance carbon analyzer. For 14C analysis, samples were sent to Woods Hole Oceanographic Institution for isotope analysis using an accelerated mass spectrometry. End member values and uncertainties for the EC isolation utilizing this method will be reported.

Uncertainty assessment of source attribution of PM(2.5) and its water-soluble organic carbon content using different biomass burning tracers in positive matrix factorization analysis--a case study in Beijing, China.

PubMed

Tao, Jun; Zhang, Leiming; Zhang, Renjian; Wu, Yunfei; Zhang, Zhisheng; Zhang, Xiaoling; Tang, Yixi; Cao, Junji; Zhang, Yuanhang

2016-02-01

Daily PM2.5 samples were collected at an urban site in Beijing during four one-month periods in 2009-2010, with each period in a different season. Samples were subject to chemical analysis for various chemical components including major water-soluble ions, organic carbon (OC) and water-soluble organic carbon (WSOC), element carbon (EC), trace elements, anhydrosugar levoglucosan (LG), and mannosan (MN). Three sets of source profiles of PM2.5 were first identified through positive matrix factorization (PMF) analysis using single or combined biomass tracers - non-sea salt potassium (nss-K(+)), LG, and a combination of nss-K(+) and LG. The six major source factors of PM2.5 included secondary inorganic aerosol, industrial pollution, soil dust, biomass burning, traffic emission, and coal burning, which were estimated to contribute 31±37%, 39±28%, 14±14%, 7±7%, 5±6%, and 4±8%, respectively, to PM2.5 mass if using the nss-K(+) source profiles, 22±19%, 29±17%, 20±20%, 13±13%, 12±10%, and 4±6%, respectively, if using the LG source profiles, and 21±17%, 31±18%, 19±19%, 11±12%, 14±11%, and 4±6%, respectively, if using the combined nss-K(+) and LG source profiles. The uncertainties in the estimation of biomass burning contributions to WSOC due to the different choices of biomass burning tracers were around 3% annually and up to 24% seasonally in terms of absolute percentage contributions, or on a factor of 1.7 annually and up to a factor of 3.3 seasonally in terms of the actual concentrations. The uncertainty from the major source (e.g. industrial pollution) was on a factor of 1.9 annually and up to a factor of 2.5 seasonally in the estimated WSOC concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Carbonaceous particles and aerosol mass closure in PM2.5 collected in a port city

NASA Astrophysics Data System (ADS)

Genga, A.; Ielpo, P.; Siciliano, T.; Siciliano, M.

2017-01-01

Mass concentrations of PM2.5, mineral dust, organic carbon (OC) and elemental carbon (EC), water-soluble organic carbon (WSOC), sea salts and anthropogenic metals have been studied in a city-port of south Italy (Brindisi). This city is characterized by different emission sources (ship, vehicular traffic, biomass burning and industrial emissions) and it is an important port and industrial site of the Adriatic sea. Based on diagnostic ratios of carbonaceous species we assess the presence of biomass burning emissions (BBE), fossil fuel emissions (FFE) and ship emission (SE). Our proposed conversion factors from OC to OM are higher than those reported in the literature for urban site: the reason of this could be due to the existence of aged combustion aerosols during the sampling campaign (WSOC/OC = 0.6 ± 0.3).

Chemical compositions and source identification of PM₂.₅ aerosols for estimation of a diesel source surrogate.

PubMed

Sahu, Manoranjan; Hu, Shaohua; Ryan, Patrick H; Le Masters, Grace; Grinshpun, Sergey A; Chow, Judith C; Biswas, Pratim

2011-06-01

Exposure to traffic-related pollution during childhood has been associated with asthma exacerbation, and asthma incidence. The objective of the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) is to determine if the development of allergic and respiratory disease is associated with exposure to diesel engine exhaust particles. A detailed receptor model analyses was undertaken by applying positive matrix factorization (PMF) and UNMIX receptor models to two PM₂.₅ data sets: one consisting of two carbon fractions and the other of eight temperature-resolved carbon fractions. Based on the source profiles resolved from the analyses, markers of traffic-related air pollution were estimated: the elemental carbon attributed to traffic (ECAT) and elemental carbon attributed to diesel vehicle emission (ECAD). Application of UNMIX to the two data sets generated four source factors: combustion related sulfate, traffic, metal processing and soil/crustal. The PMF application generated six source factors derived from analyzing two carbon fractions and seven factors from temperature-resolved eight carbon fractions. The source factors (with source contribution estimates by mass concentrations in parentheses) are: combustion sulfate (46.8%), vegetative burning (15.8%), secondary sulfate (12.9%), diesel vehicle emission (10.9%), metal processing (7.5%), gasoline vehicle emission (5.6%) and soil/crustal (0.7%). Diesel and gasoline vehicle emission sources were separated using eight temperature-resolved organic and elemental carbon fractions. Application of PMF to both datasets also differentiated the sulfate rich source from the vegetative burning source, which are combined in a single factor by UNMIX modeling. Calculated ECAT and ECAD values at different locations indicated that traffic source impacts depend on factors such as traffic volumes, meteorological parameters, and the mode of vehicle operation apart from the proximity of the sites to highways. The difference in ECAT and ECAD, however, was less than one standard deviation. Thus, a cost benefit consideration should be used when deciding on the benefits of an eight or two carbon approach. Published by Elsevier B.V.

Urban aerosol in Oporto, Portugal: Chemical characterization of PM10 and PM2.5

NASA Astrophysics Data System (ADS)

Custódio, Danilo; Ferreira, Catarina; Alves, Célia; Duarte, Mácio; Nunes, Teresa; Cerqueira, Mário; Pio, Casimiro; Frosini, Daniele; Colombi, Cristina; Gianelle, Vorne; Karanasiou, Angeliki; Querol, Xavier

2014-05-01

Several urban and industrial areas in Southern Europe are not capable of meeting the implemented EU standards for particulate matter. Efficient air quality management is required in order to ensure that the legal limits are not exceeded and that the consequences of poor air quality are controlled and minimized. Many aspects of the direct and indirect effects of suspended particulate matter on climate and public health are not well understood. The temporal variation of the chemical composition is still demanded, since it enables to adopt off-set strategies and to better estimate the magnitude of anthropogenic forcing on climate. This study aims to provide detailed information on concentrations and chemical composition of aerosol from Oporto city, an urban center in Southern Europe. This city is located near the coast line in the North of Portugal, being the country's second largest urban area. Moreover, Oporto city economic prospects depend heavily on a diversified industrial park, which contribute to air quality degradation. Another strong source of air pollution is traffic. The main objectives of this study are: 1) to characterize the chemical composition of PM10 and PM2.5 by setting up an orchestra of aerosol sampling devices in a strategic place in Oporto; 2) to identify the sources of particles exploring parameters such as organic and inorganic markers (e.g. sugars as tracers for biomass burning; metals and elemental carbon for industrial and vehicular emissions); 3) to evaluate long range transport of pollutants using back trajectory analysis. Here we present data obtained between January 2013 and January 2014 in a heavy traffic roadside sampling site located in the city center. Different PM10 and PM2.5 samplers were operated simultaneously in order to collect enough mass on different filter matrixes and to fulfill the requirements of analytical methodologies. More than 100 aerosol samples were collected and then analysed for their mass concentration and chemical composition of water soluble ions, carbon species (carbonates, organic carbon, elemental carbon and sugars) and metals. High concentrations, up to more than 80 µg.m-3 for PM2.5 and up to 90 µg.m-3 for PM10, during summer, were associated with wildfires. Peak concentrations of biomass burning tracers, such as potassium ion (1.2 µgm-3) and levoglucosan (1 µgm-3), were registered in this period as well as high organic carbon/elemental carbon ratios. High PM10 concentrations, of about 70 µg.m-3, were also recorded in winter under dry weather conditions. A significant increase of levoglucosan concentrations, reaching 3.5 µg.m-3, were observed during this season. This phenomenon was associated with emissions from residential biomass burning for heating purposes. Moreover, it is possible to highlight the increase of formic and oxalic acid concentrations (up to 250 ng.m-3 and 600 ng.m-3, respectively) during dry days, indicating aerosol aging in the urban atmosphere before they were blown away. It was possible also to express the contribution of sea salt in Porto aerosol. Analyses of organic and elemental carbon, as well as elements, allowed drawing a picture on sources of air pollution, either of regional/local origin (industry, traffic, biomass burning) or resulting from long range transport. In what concerns anthropogenic pollutants, it is important to emphasize the high concentrations of elemental carbon, Zn, Cu, Pb, Ba, Sn, Mn, V, Zr, Cr, and Sb. Zn, generally pointed out as a tracer of brake and tire wear, was found to be the most abundant metal in PM2.5 and PM10 samples. Acknowledgement: This work was funded by the European Commission through the projectLIFE11 ENV/ES/000584, AIRUSE - Testing and Development of Air Quality Mitigation Measures in Southern Europe. Danilo Custódio acknowledges the PhD grant from the Portuguese Science Foundation SFRH/BD/76283/2011.

Carbon stocks and carbon fluxes from a 10 year prescribed burning chronosequence on a UK blanket peat.

NASA Astrophysics Data System (ADS)

Clay, G. D.; Worrall, F.

2012-04-01

Prescribed burning is a common land management technique in many areas of the UK uplands. However, concern has been expressed at the impact of this management practice on carbon stocks and fluxes found in the carbon rich peat soils that underlie many of these areas. Existing data shows a range of results at differing spatial and temporal scales for a range of carbon pathways e.g. dissolved organic carbon (DOC), yet there are limited studies that monitor a suite of parameters under burning management. This study measured both carbon stocks and carbon fluxes from a chronosequence of prescribed burn sites in northern England. A range of carbon parameters were measured including: above-ground biomass and carbon stocks; net ecosystem exchange (NEE); ecosystem respiration (Reco); photosynthesis (Pg); and particulate organic carbon (POC). CO2 data was analysed using ANOVA to investigate any significant differences between burn years. Carbon budgets were also calculated using measured and modelled data. Analysis of the CO2 data showed that burning was a significant factor in measured CO2 readings but that other factors such as month of sampling explained a greater proportion of the variation in the data. Carbon budget results show that whilst all the sites were net sources of carbon, the most recent burns were smaller sources of carbon compared to the older burns (Burn year 2009: 85 ± 29 gC/m2/yr; Burn year 1999: 152 ± 12 gC/m2/yr). Additionally, the most recent burns were net sinks of gaseous CO2.

Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem. Revision

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazurek, M.A.; Cofer, W.R. III; Levine, J.S.

1990-10-01

The identity and ambient mass concentrations of radiatively important carbonaceous aerosols were measured for a boreal forest prescribed burn conducted in northern Ontario, CAN in August 1989. Nonsize-segregated airborne particles were collected for smoldering-fire and full-fire conditions using a helicopter sampling platform. Total carbon (TC), organic carbon (OC) and elemental carbon (EC) were measured. Smoke plume mass concentrations of the OC and EC particles were greatest for full-fire conditions and had ranges of 1.560 to 2.160 mg/m{sup {minus}1} (OC) and 0.120 to 0.160 mg/m{sup {minus}3} (EC) with OC:EC ratios of 10 to 18, respectively. Smoldering fire conditions showed smoke plumemore » OC and EC levels of 0.570--1.030 mg/m{sup {minus}3} (OC) and 0.006--0.050 mg/m{sup {minus}3} (EC) and much higher ratios of OC:EC (21 to 95). These aerosol data indicate the formation of EC particles is greatest during full-fire combustion of boreal forest material relative to smoldering combustion. However, EC particles comprise a minor fraction of the particulate carbon smoke aerosols for both full-fire and smoldering conditions; the major component of carbonaceous smoke aerosols emitted during the prescribed burn is OC. Overall, the OC and EC in-plume smoke aerosol data show nonuniform production of these particles during various stages of the prescribed burn, and major differences in the type of carbonaceous aerosol that is generated (OC versus EC).« less

Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazurek, M.A.; Cofer, W.R. III; Levine, J.S.

1990-10-01

The identity and ambient mass concentrations of radiatively important carbonaceous aerosols were measured for a boreal forest prescribed burn conducted in northern Ontario, CAN in August 1989. Nonsize-segregated airborne particles were collected for smoldering-fire and full-fire conditions using a helicopter sampling platform. Total carbon (TC), organic carbon (OC) and elemental carbon (EC) were measured. Smoke plume mass concentrations of the OC and EC particles were greatest for full-fire conditions and had ranges of 1.560 to 2.160 mg/m{sup {minus}1} (OC) and 0.120 to 0.160 mg/m{sup {minus}3} (EC) with OC:EC ratios of 10 to 18, respectively. Smoldering fire conditions showed smoke plumemore » OC and EC levels of 0.570--1.030 mg/m{sup {minus}3} (OC) and 0.006--0.050 mg/m{sup {minus}3} (EC) and much higher ratios of OC:EC (21 to 95). These aerosol data indicate the formation of EC particles is greatest during full-fire combustion of boreal forest material relative to smoldering combustion. However, EC particles comprise a minor fraction of the particulate carbon smoke aerosols for both full-fire and smoldering conditions; the major component of carbonaceous smoke aerosols emitted during the prescribed burn is OC. Overall, the OC and EC in-plume smoke aerosol data show nonuniform production of these particles during various stages of the prescribed burn, and major differences in the type of carbonaceous aerosol that is generated (OC versus EC).« less

Chemical characterization of biomass fuel smoke particles of rural kitchens of South Asia

NASA Astrophysics Data System (ADS)

Deka, Pratibha; Hoque, Raza Rafiqul

2015-05-01

Biomass fuel smoke particles (BFSPs) of rural kitchens collected during dry and wet seasons were characterized for elements, anions and carbon. The BFSPs of kitchens using varied biomass fuel types viz. cow dung stick, mixed biomass, cow-dung stick-mixed biomass and sugarcane bagasse were chosen for the study. The BFSPs from cow dung fuel stick showed higher levels of elements, anions and particulate carbon than other BFSPs. Calcium, K, Fe and Mg were the major elements found in all BFSPs, which did not vary much between the seasons. Sulphate was found to be the dominant anion present in all BFSPs followed by Clˉ and PO43-. Seasonal variation was pronounced in the case of abundance of anions and particulate carbon. The ratio OC/EC, often used as source signature of biomass burning, was found to be within 1.89-7.41 and 1.72-6.19 during dry and wet seasons respectively.

Evidence for Biomass Burning from 14C and 13C/12C Measurements at T-0 and T-1 during MILAGRO.

NASA Astrophysics Data System (ADS)

Gaffney, J. S.; Marley, N. A.; Tackett, M. J.; Sturchio, N. C.; Heraty, L. J.; Martinez, N.; Hardy, K.; Guilderson, T.

2007-12-01

Both stable carbon isotopic and radiocarbon characterizations of aerosols can yield important information regarding the sources of carbonaceous aerosols in urban and regional environments. Biomass derived materials are labeled due to their recent photochemical activity in radiocarbon and vary depending upon the photochemical pathway (either C-4 or C-3) in stable carbon-13 content. C-4 being enriched over C-3. During the MILAGRO campaign, quartz filter samples were taken at 12 hour intervals from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. These samples were taken at the two super-sites, T-0 (Instituto Mexicano de Petroleo in Mexico City) and T-1 (Universidad Technologica de Tecamac, State of Mexico). The total carbon content was analyzed for stable carbon isotopic composition as well as for radiocarbon. Stable isotope mass spectroscopy was used to determine the carbon-13 to carbon-12 isotopic ratios on carbon dioxide. The carbon dioxide was then converted to graphite for analysis by accelerator mass spectrometry at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory. Results are presented for the carbon-13 content relative to the PDB standard and radiocarbon is given relative to recent carbon. The results for total radiocarbon content show that the carbonaceous aerosol content in Mexico City has more than half of the carbon coming from biomass derived sources. These can include inflow of biomass burning aerosols into the T-0 site as well as the input from local burning of biofuels and trash containing biomass derived materials (paper, boxes, etc.). Data also indicate that at the T-1 site biomass burning of C-4 grasses appears to be significant in that the carbon-13 values observed are enriched. Also at T-1 the radiocarbon levels are also found to be slightly higher indicating regional biomass burning as a significant contributor to aerosol carbon in the 0.1 to 1.0 micron size fraction. Some day and night differences were observed that indicate secondary organic aerosols are contributing and that a significant fraction of these aerosols are biomass derived. Further analyses of organic carbon and elemental carbon fractions are underway. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX- Mex) under the support of the Atmospheric Science Program. This research was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64328.

Emission factors from different burning stages of agriculture wastes in Mexico.

PubMed

Santiago-De la Rosa, Naxieli; Mugica-Álvarez, Violeta; Cereceda-Balic, Francisco; Guerrero, Fabián; Yáñez, Karen; Lapuerta, Magin

2017-11-01

Open-air burning of agricultural wastes from crops like corn, rice, sorghum, sugar cane, and wheat is common practice in Mexico, which in spite limiting regulations, is the method to eliminate such wastes, to clear the land for further harvesting, to control grasses, weeds, insects, and pests, and to facilitate nutrient absorption. However, this practice generates air pollution and contributes to the greenhouse effect. Burning of straws derived from the said crops was emulated in a controlled combustion chamber, hence determining emission factors for particles, black carbon, carbon dioxide, carbon monoxide, and nitric oxide throughout the process, which comprised three apparent stages: pre-ignition, flaming, and smoldering. In all cases, maximum particle concentrations were observed during the flaming stage, although the maximum final contributions to the particle emission factors corresponded to the smoldering stage. The comparison between particle size distributions (from laser spectrometer) and black carbon (from an aethalometer) confirmed that finest particles were emitted mainly during the flaming stage. Carbon dioxide emissions were also highest during the flaming stage whereas those of carbon monoxide were highest during the smoldering stage. Comparing the emission factors for each straw type with their chemical analyses (elemental, proximate, and biochemical), some correlations were found between lignin content and particle emissions and either particle emissions or duration of the pre-ignition stage. High ash or lignin containing-straw slowed down the pre-ignition and flaming stages, thus favoring CO oxidation to CO 2 .

Source apportionment of carbonaceous aerosols in a megacity of northwest China: insights from radiocarbon measurement

NASA Astrophysics Data System (ADS)

Ni, Haiyan; Huang, Rujin; Dusek, Ulrike

2017-04-01

Fine particulate matter (PM2.5) samples were collected from 5 July 2008 to 27 June 2009 at Xi'an, a very polluted megacity in Northwest China. The 24 h averaged PM2.5concentrations (ranged from 32 μg m-3 to 339 μg m-3) were 1-14 times higher than the WHO guideline for 24 h PM2.5(25 μg m-3). In this work, we unambiguously quantify fossil (e.g., vehicle emissions, coal burning etc.) and non-fossil (e.g., biomass burning, cooking, biogenic emissions etc.) contributions to organic carbon (OC) and elemental carbon (EC) of PM2.5using radiocarbon (14C) measurement. In addition, we measured PM2.5 major components and source markers, including OC and EC, ions, trace elements, polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (o-PAHs), anhydrous sugars and hopanes. The preliminary results of radiocarbon measurements in OC and EC show that the annual mean contributions from fossil-fuel combustion to EC was 76 ± 8% (6 ± 2 μg m-3). The remaining 24 ± 8% (2 ± 1 μg m-3) was attributed to biomass burning, with higher contribution in the cold period (˜33%) compared to the warm period (˜21%), due to enhanced emissions from local biomass burning activities in winter. In contrast with EC, OC was dominated by non-fossil sources, with an annual average of 54 ± 8 % (13 ± 10 μg m-3). Clear seasonal variations were seen in OC concentrations both from fossil fuel (OCff), and from non-fossil sources (OCnf), with maxima in the cold period and minima in the warm period, because of enhanced fossil and non-fossil activities in winter, mainly biomass burning and domestic coal burning. Further source apportionment of OC, including primary/secondary fossil OC, primary/secondary non-fossil OC, will be conducted by combining 14C results with positive matrix factorization (PMF) analysis of organic matter (OM).

Estimation of lifetime of carbonaceous aerosol from open crop residue burning during Mount Tai Experiment 2006 (MTX2006)

NASA Astrophysics Data System (ADS)

Pan, X. L.; Kanaya, Y.; Wang, Z. F.; Komazaki, Y.; Taketani, F.; Akimoto, H.; Pochanart, P.; Liu, Y.

2012-06-01

Studying the emission ratios of carbonaceous aerosols (element carbon, EC, and organic carbon, OC) from open biomass burning helps to reduce uncertainties in emission inventories and provides necessary constraints for model simulations. We measured apparent elemental carbon (ECa) and OC concentrations at the summit of Mount Tai (Mt. Tai) during intensive open crop residue burning (OCRB) episodes using a Sunset OCEC analyzer. Equivalent black carbon (BCe) concentrations were determined using a Multiple Angle Absorption Photometer (MAAP). In the fine particle mode, OC and EC showed strong correlations (r > 0.9) with carbon monoxide (CO). Footprint analysis using the FLEXPART_WRF model indicated that OCRB in central east China (CEC) had a significant influence on ambient carbonaceous aerosol loadings at the summit of Mt. Tai. ΔECa/ΔCO ratios resulting from OCRB plumes were 14.3 ± 1.0 ng m-3 ppbv-1 at Mt. Tai. This ratio was more than three times those resulting from urban pollution in CEC, demonstrating that significant concentrations of soot particles were released from OCRB. ΔOC/ΔCO ratio from fresh OCRB plumes was found to be 41.9 ± 2.6 ng m-3 ppbv-1 in PM1. The transport time of smoke particles was estimated using the FLEXPART_WRF tracer model by releasing inert particles from the ground layer inside geographical regions where large numbers of hotspots were detected by a MODIS satellite sensor. Fitting regressions using the e-folding exponential function indicated that the removal efficiency of OC (normalized to CO) was much larger than that of ECa mass, with mean lifetimes of 27 h (1.1 days) for OC and 105 h (4.3 days) for ECa, respectively. The lifetime of black carbon estimated for the OCRB events in east China was comparably lower than the values normally adopted in the transport models. Short lifetime of organic carbon highlighted the vulnerability of OC to cloud scavenging in the presence of water-soluble organic species from biomass combustion.

Apportionment of urban aerosol sources in Chongqing (China) using synergistic on-line techniques

NASA Astrophysics Data System (ADS)

Chen, Yang; Yang, Fumo

2016-04-01

The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Chongqing (southwestern China) have been determined. Aerosol chemical composition analyses were performed using multiple on-line techniques, such as single particle aerosol mass spectrometer (SPAMS) for single particle chemical composition, on-line elemental carbon-organic carbon analyzer (on-line OC-EC), on-line X-ray fluorescence (XRF) for elements, and in-situ Gas and Aerosol Compositions monitor (IGAC) for water-soluble ions in PM2.5. All the datasets from these techniques have been adjusted to a 1-h time resolution for receptor model input. Positive matrix factorization (PMF) has been used for resolving aerosol sources. At least six sources, including domestic coal burning, biomass burning, dust, traffic, industrial and secondary/aged factors have been resolved and interpreted. The synergistic on-line techniques were helpful for identifying aerosol sources more clearly than when only employing the results from the individual techniques. This results are useful for better understanding of aerosol sources and atmospheric processes.

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): Emissions of particulate matter from wood and dung cooking fires, brick kilns, generators, trash and crop residue burning

NASA Astrophysics Data System (ADS)

Stone, Elizabeth; Jayarathne, Thilina; Stockwell, Chelsea; Christian, Ted; Bhave, Prakash; Siva Praveen, Puppala; Panday, Arnico; Adhikari, Sagar; Maharjan, Rashmi; Goetz, Doug; DeCarlo, Peter; Saikawa, Eri; Yokelson, Robert

2016-04-01

The Nepal Ambient Monitoring and Source Testing Experiment (NAMASTE) field campaign targeted the in situ characterization of widespread and under-sampled combustion sources. In Kathmandu and the Terai, southern Nepal's flat plains, samples of fine particulate matter (PM2.5) were collected from wood and dung cooking fires (n = 22), generators (n = 2), groundwater pumps (n = 2), clamp kilns (n = 3), zig-zag kilns (n = 3), trash burning (n = 4), one heating fire, and one crop residue fire. Co-located measurements of carbon dioxide, carbon monoxide, and volatile organic compounds allowed for the application of the carbon mass balance approach to estimate emission factors for PM2.5, elemental carbon, organic carbon, and water-soluble inorganic ions. Organic matter was chemically speciated using gas chromatography - mass spectrometry for polycyclic aromatic hydrocarbons, sterols, n-alkanes, hopanes, steranes, and levoglucosan, which accounted for 2-8% of the measured organic carbon. These data were used to develop molecular-marker based profiles for use in source apportionment modeling. This study provides quantitative emission factors for particulate matter and its constituents for many important combustion sources in Nepal and South Asia.

Influence of fuel mass load, oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning.

PubMed

Shen, Guofeng; Xue, Miao; Wei, Siye; Chen, Yuanchen; Wang, Bin; Wang, Rong; Shen, Huizhong; Li, Wei; Zhang, Yanyan; Huang, Ye; Chen, Han; Wei, Wen; Zhao, Qiuyue; Li, Bin; Wu, Haisuo; Tao, Shu

2013-03-01

The uncertainty in emission estimation is strongly associated with the variation in emission factor (EF), which could be influenced by a variety of factors such as fuel properties, stove type, fire management and even methods used in measurements. The impacts of these factors are complicated and often interact with each other. Controlled burning experiments were conducted to investigate the influences of fuel mass load, air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter (PM) from indoor corn straw burning in a cooking stove. The results showed that the EFs of PM (EF(PM)), organic carbon (EFoc) and elemental carbon (EF(EC)) were independent of the fuel mass load. The differences among them under different burning rates or air supply amounts were also found to be insignificant (p > 0.05) in the tested circumstances. PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 microm, contributing 86.4% +/- 3.9% of the total. The size distribution of PM was influenced by the burning rate and air supply conditions. On average, EF(PM), EF(OC) and EF(EC) for corn straw burned in a residential cooking stove were (3.84 +/- 1.02), (0.846 +/- 0.895) and (0.391 +/- 0.350) g/kg, respectively. EF(PM), EF(OC) and EF(EC) were found to be positively correlated with each other (p < 0.05), but they were not significantly correlated with the EF of co-emitted CO, suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.

The influence of fuel mass load, oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning

PubMed Central

Shen, Guofeng; Xue, Miao; Wei, Siye; Chen, Yuanchen; Wang, Bing; Wang, Rong; Shen, Huizhong; Li, Wei; Zhang, Yanyan; Huang, Ye; Chen, Han; Wei, Wen; Zhao, Qiuyue; Li, Bin; Wu, Haisuo; Tao, Shu

2014-01-01

The uncertainty in emission estimation is strongly associated with the variation in emission factor which could be influenced by a variety of factors, like fuel property, stove type, fire management and even methods used in measurements. The impacts of these factors were usually complicated and often interacted with each other. In the present study, controlled burning experiments were conducted to investigate the influence of fuel mass load, air supply and burning rate on the emission of carbonaceous particulate matter (PM) from indoor corn straw burning. Their impacts on PM size distribution were also studied. The results showed that EFs of PM (EFPM), organic carbon (EFOC) and element carbon (EFEC) was independent of the fuel mass load. The differences among them under different burning rates or air supply amounts were also found to be insignificant (p > 0.05) in the tested circumstances. PM from the indoor corn straw burning was dominated by fine PM, and PM with diameter less than 2.1 μm contributed about 86.4±3.9% of the total. The size distribution of PM was also influenced by the burning rate and changed air supply conditions. On average, EFPM, EFOC and EFEC for corn straw burned in a residential cooking stove were 3.84±1.02, 0.846±0.895 and 0.391±0.350 g/kg, respectively. EFPM, EFOC and EFEC were found to be positively correlated with each other, but they were not significantly correlated with EF of co-emitted CO, suggesting a special attention should be paid to the use of CO acting as a surrogate for other incomplete pollutants. PMID:23923424

Environmental benefits of using magnesium carbonate minerals as new wildfire retardants instead of commercially available, phosphate-based compounds.

PubMed

Liodakis, S; Tsoukala, M

2010-10-01

A serial batch leaching experiment has been carried out to evaluate the release of elements from the ash of Pinus halepensis needles burned under two test conditions-with and without treatment of the forest species with the carbonate minerals (huntite and hydromagnesite) in aqueous solution (pH 6). The ash (before and after leaching) and leachates were analyzed using atomic absorption spectroscopy and X-ray diffraction. Compared with data from samples treated with the commercially available, phosphate-based fire retardant diammonium phosphate (DAP), we found that use of huntite or hydromagnesite was much more successful in obstructing the release of the toxic elements present in the ash, probably because of the alkaline conditions resulting from decomposition of the minerals during burning. In contrast, DAP tended to be more able to facilitate the extraction of some toxic metals (e.g., Zn, Cu, Mn), probably because of the acidic conditions resulting from its decomposition to phosphoric acid. Data from this study thus lend strong support to the use of magnesium carbonate minerals as new wildfire retardants, because they were shown to be more friendly to the environment (e.g., soil, ground, and underground water streams) than those currently in use (e.g., phosphate or sulfate salt type).

Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands

USGS Publications Warehouse

Turetsky, M.R.; Kane, E.S.; Harden, J.W.; Ottmar, R.D.; Manies, K.L.; Hoy, E.; Kasischke, E.S.

2011-01-01

Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult to assess. Here, we examined the depth of ground-layer combustion in 178 sites dominated by black spruce in Alaska, using data collected from 31 fire events between 1983 and 2005. We show that the depth of burning increased as the fire season progressed when the annual area burned was small. However, deep burning occurred throughout the fire season when the annual area burned was large. Depth of burning increased late in the fire season in upland forests, but not in peatland and permafrost sites. Simulations of wildfire-induced carbon losses from Alaskan black spruce stands over the past 60 years suggest that ground-layer combustion has accelerated regional carbon losses over the past decade, owing to increases in burn area and late-season burning. As a result, soils in these black spruce stands have become a net source of carbon to the atmosphere, with carbon emissions far exceeding decadal uptake.

Black carbon, mass and elemental measurements of airborne particles in the village of Serowe, Botswana

NASA Astrophysics Data System (ADS)

Moloi, K.; Chimidza, S.; Lindgren, E. Selin; Viksna, A.; Standzenieks, P.

Absorption of sunlight by sub-micron particles is an important factor in calculations of the radiation balance of the earth and thus in climate modelling. Carbon-containing particles are generally considered as the most important in this respect. Major sources of these particles are generally considered to be bio-mass burning and vehicle exhaust. In order to characterise size fractionated particulate matter in a rural village in Botswana with respect to light absorption and elemental content experiments were performed, in which simultaneous sampling was made with a dichotomous impactor and a laboratory-made sampler, made compatible with black carbon analysis by reflectometry. The dichotomous impactor was equipped with Teflon filters and the other sampler with glass fibre filters. Energy dispersive X-ray fluorescence was used for elemental analysis of both kinds of filters. It appeared that Teflon filters were the most suitable for the combination of mass-, elemental- and black carbon measurements. The black carbon content in coarse (2.5-10 μm) and fine (<2.5 μm) particles was determined separately and related to elemental content and emission source. The results show that the fine particle fraction in the aerosol has a much higher contribution of black particles than the coarse particle fraction. This observation is valid for the village in Botswana as well as for a typical industrialised city in Sweden, used as a reference location.

Light-absorbing organic carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions.

PubMed

Xie, Mingjie; Hays, Michael D; Holder, Amara L

2017-08-04

Light-absorbing organic carbon (OC), also termed brown carbon (BrC), from laboratory-based biomass burning (BB) has been studied intensively to understand the contribution of BB to radiative forcing. However, relatively few measurements have been conducted on field-based BB and even fewer measurements have examined BrC from anthropogenic combustion sources like motor vehicle emissions. In this work, the light absorption of methanol-extractable OC from prescribed and laboratory BB and gasoline vehicle emissions was examined using spectrophotometry. The light absorption of methanol extracts showed a strong wavelength dependence for both BB and gasoline vehicle emissions. The mass absorption coefficients at 365 nm (MAC 365 , m 2 g -1 C) - used as a measurement proxy for BrC - were significantly correlated (p < 0.05) to the elemental carbon (EC)/OC ratios when examined by each BB fuel type. No significant correlation was observed when pooling fuels, indicating that both burn conditions and fuel types may impact BB BrC characteristics. The average MAC 365 of gasoline vehicle emission samples is 0.62 ± 0.76 m 2  g -1 C, which is similar in magnitude to the BB samples (1.27 ± 0.76 m 2  g -1 C). These results suggest that in addition to BB, gasoline vehicle emissions may also be an important BrC source in urban areas.

The History and Impact of the CNO Cycles in Nuclear Astrophysics

NASA Astrophysics Data System (ADS)

Wiescher, Michael

2018-03-01

The carbon cycle, or Bethe-Weizsäcker cycle, plays an important role in astrophysics as one of the most important energy sources for quiescent and explosive hydrogen burning in stars. This paper presents the intellectual and historical background of the idea of the correlation between stellar energy production and the synthesis of the chemical elements in stars on the example of this cycle. In particular, it addresses the contributions of Carl Friedrich von Weizsäcker and Hans Bethe, who provided the first predictions of the carbon cycle. Further, the experimental verification of the predicted process as it developed over the following decades is discussed, as well as the extension of the initial carbon cycle to the carbon-nitrogen-oxygen (CNO) multi-cycles and the hot CNO cycles. This development emerged from the detailed experimental studies of the associated nuclear reactions over more than seven decades. Finally, the impact of the experimental and theoretical results on our present understanding of hydrogen burning in different stellar environments is presented, as well as the impact on our understanding of the chemical evolution of our universe.

Characterization of Emissions from Liquid Fuel and Propane Open Burns.

PubMed

Aurell, Johanna; Hubble, David; Gullett, Brian K; Holder, Amara; Washburn, Ephraim; Tabor, Dennis

2017-11-07

The effect of accidental fires are simulated to understand the response of items such as vehicles, fuel tanks, and military ordnance and to remediate the effects through re-design of the items or changes in operational procedures. The comparative combustion emissions of using jet propellant (JP-5) liquid fuel pools or a propane manifold grid to simulate the effects of accidental fires was investigated. A helium-filled tethered aerostat was used to maneuver an instrument package into the open fire plumes to measure CO, CO 2 , fine particulate matter (PM 2.5 ), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and elemental/organic/total carbon (EC/OC/TC). The results showed that all emissions except CO 2 were significantly higher from JP-5 burns than from propane. The major portion of the PM mass from fires of both fuels was less than 1 μm in diameter and differed in carbon content. The PM 2.5 emission factor from JP-5 burns (129 ± 23 g/kg Fuel c ) was approximately 150 times higher than the PM 2.5 emission factor from propane burns (0.89 ± 0.21 g/kg Fuel c ). The PAH emissions as well as some VOCs were more than one hundred times higher for the JP-5 burns than the propane burns. Using the propane test method to study flammability responses, the environmental impact of PM 2.5 , PAHs, and VOCs would be reduced by 2300, 700, and 100 times per test, respectively.

Chemical characterization and toxicity of particulate matter emissions from roadside trash combustion in urban India

NASA Astrophysics Data System (ADS)

Vreeland, Heidi; Schauer, James J.; Russell, Armistead G.; Marshall, Julian D.; Fushimi, Akihiro; Jain, Grishma; Sethuraman, Karthik; Verma, Vishal; Tripathi, Sachi N.; Bergin, Michael H.

2016-12-01

Roadside trash burning is largely unexamined as a factor that influences air quality, radiative forcing, and human health even though it is ubiquitously practiced across many global regions, including throughout India. The objective of this research is to examine characteristics and redox activity of fine particulate matter (PM2.5) associated with roadside trash burning in Bangalore, India. Emissions from smoldering and flaming roadside trash piles (n = 24) were analyzed for organic and elemental carbon (OC/EC), brown carbon (BrC), and toxicity (i.e. redox activity, measured via the dithiothreitol "DTT" assay). A subset of samples (n = 8) were further assessed for toxicity by a cellular assay (macrophage assay) and also analyzed for trace organic compounds. Results show high variability of chemical composition and toxicity between trash-burning emissions, and characteristic differences from ambient samples. OC/EC ratios for trash-burning emissions range from 0.8 to 1500, while ambient OC/EC ratios were observed at 5.4 ± 1.8. Trace organic compound analyses indicate that emissions from trash-burning piles were frequently composed of aromatic di-acids (likely from burning plastics) and levoglucosan (an indicator of biomass burning), while the ambient sample showed high response from alkanes indicating notable representation from vehicular exhaust. Volume-normalized DTT results (i.e., redox activity normalized by the volume of air pulled through the filter during sampling) were, unsurprisingly, extremely elevated in all trash-burning samples. Interestingly, DTT results suggest that on a per-mass basis, fresh trash-burning emissions are an order of magnitude less redox-active than ambient air (13.4 ± 14.8 pmol/min/μgOC for trash burning; 107 ± 25 pmol/min/μgOC for ambient). However, overall results indicate that near trash-burning sources, exposure to redox-active PM can be extremely high.

Logging debris matters: better soil, fewer invasive plants

Treesearch

John Kirkland; Timoth B. Harrington; David H. Peter; Robert A. Slesak; Stephen H. Schoenholtz

2012-01-01

The logging debris that remains after timber harvest traditionally has been seen as a nuisance. It can make subsequent tree planting more difficult and become fuel for wildfire. It is commonly piled, burned, or taken off site. Logging debris, however, contains significant amounts of carbon and nitrogen—elements critical to soil productivity. Its physical presence in...

Stellar helium burning in other universes: A solution to the triple alpha fine-tuning problem

NASA Astrophysics Data System (ADS)

Adams, Fred C.; Grohs, Evan

2017-01-01

Motivated by the possible existence of other universes, with different values for the fundamental constants, this paper considers stellar models in universes where 8Be is stable. Many previous authors have noted that stars in our universe would have difficulty producing carbon and other heavy elements in the absence of the well-known 12C resonance at 7.6 MeV. This resonance is necessary because 8Be is unstable in our universe, so that carbon must be produced via the triple alpha reaction to achieve the requisite abundance. Although a moderate change in the energy of the resonance (200-300 keV) will indeed affect carbon production, an even smaller change in the binding energy of beryllium (∼100 keV) would allow 8Be to be stable. A stable isotope with A = 8 would obviate the need for the triple alpha process in general, and the 12C resonance in particular, for carbon production. This paper explores the possibility that 8Be can be stable in other universes. Simple nuclear considerations indicate that bound states can be realized, with binding energy ∼ 0.1 - 1 MeV, if the fundamental constants vary by a ∼ few - 10 %. In such cases, 8Be can be synthesized through helium burning, and 12C can be produced later through nuclear burning of beryllium. This paper focuses on stellar models that burn helium into beryllium; once the universe in question has a supply of stable beryllium, carbon production can take place during subsequent evolution in the same star or in later stellar generations. Using both a semi-analytic stellar structure model as well as a state-of-the-art stellar evolution code, we find that viable stellar configurations that produce beryllium exist over a wide range of parameter space. Finally, we demonstrate that carbon can be produced during later evolutionary stages.

Sources of PM10 Air Pollution in Rural Area in the Vicinity of a Highway In Žilina Selfgoverning Region, Slovakia

NASA Astrophysics Data System (ADS)

Jandačka, Dušan

2015-05-01

Particulate matter results as an aftermath of numerous distinctive processes in the atmosphere and they become a part of everyday life. Their harmful effect and impact on the ambient environment is determined predominantly by the presence of various chemical substances and elements. The chemical composition of these particles (organic and elemental carbon, mineral dust, sea aerosols, secondary particles, especially sulphates and nitrates, heavy metals and further elements) is mainly impacted on by their origin, whereas the primary source of the particulate matter is determined and specified by the profile of chemical elements and substances. Particulate Matter (PM) may originate in various natural resources or anthropogenic sources. Among the natural sources sea salt is to be counted on, dust of the earth crust, pollen and volcanic ashes. Anthropogenic sources do include, predominantly, burning fossil fuels in the fossil-fuel power plants, local heating of households, burning liquefied fossil fuels in the combustion engines of vehicles, noncombustion related emissions as a result of vehicular traffic, resuspension of the road-traffic-related dust.

LUNA: Status and prospects

NASA Astrophysics Data System (ADS)

Broggini, C.; Bemmerer, D.; Caciolli, A.; Trezzi, D.

2018-01-01

The essential ingredients of nuclear astrophysics are the thermonuclear reactions which shape the life and death of stars and which are responsible for the synthesis of the chemical elements in the Universe. Deep underground in the Gran Sasso Laboratory the cross sections of the key reactions responsible for the hydrogen burning in stars have been measured with two accelerators of 50 and 400 kV voltage right down to the energies of astrophysical interest. As a matter of fact, the main advantage of the underground laboratory is the reduction of the background. Such a reduction has allowed, for the first time, to measure relevant cross sections at the Gamow energy. The qualifying features of underground nuclear astrophysics are exhaustively reviewed before discussing the current LUNA program which is mainly devoted to the study of the Big-Bang nucleosynthesis and of the synthesis of the light elements in AGB stars and classical novae. The main results obtained during the study of reactions relevant to the Sun are also reviewed and their influence on our understanding of the properties of the neutrino, of the Sun and of the Universe itself is discussed. Finally, the future of LUNA during the next decade is outlined. It will be mainly focused on the study of the nuclear burning stages after hydrogen burning: helium and carbon burning. All this will be accomplished thanks to a new 3.5 MV accelerator able to deliver high current beams of proton, helium and carbon which will start running under Gran Sasso in 2019. In particular, we will discuss the first phase of the scientific case of the 3.5 MV accelerator focused on the study of 12C+12C and of the two reactions which generate free neutrons inside stars: 13C(α,n)16O and 22Ne(α,n)25Mg.

Quantifying the variability of potential black carbon transport from cropland burning in Russia driven by atmospheric blocking events.

NASA Astrophysics Data System (ADS)

Hall, J.; Loboda, T. V.

2017-12-01

Short lived aerosols and pollutants transported from northern mid-latitudes have amplified the short term warming in the Arctic region. Specifically, black carbon is recognized as the second most important human emission in regards to climate forcing, behind carbon dioxide with a total climate forcing of +1.1Wm-2. Studies have suggested that cropland burning may be a large contributor to the black carbon emissions which are directly deposited on the snow in the Arctic region. However, accurate monitoring of cropland burning from existing active fire and burned area products is limited, thereby leading to an underestimation in black carbon emissions from cropland burning. This research focuses on 1) assessing the potential for the deposition of hypothetical black carbon emissions from known cropland burning in Russia through low-level transport, and 2) identifying a possible atmospheric pattern that may enhance the transport of black carbon emissions to the Arctic. Specifically, atmospheric blocking events present a potential mechanism that could act to enhance the likelihood of transport or accelerate the transport of pollutants to the snow-covered Arctic from Russian cropland burning based on their persistent wind patterns. This research study confirmed the importance of Russian cropland burning as a potential source of black carbon deposition on the Arctic snow in the spring despite the low injection heights associated with cropland burning. Based on the successful transport pathways, this study identified the potential transport of black carbon from Russian cropland burning beyond 80°N which has important implications for permanent sea ice cover. Further, based on the persistent wind patterns of blocking events, this study identified that blocking events are able to accelerate potential transport and increase the success of transport of black carbon emissions to the snow-covered Arctic during spring when the impact on the snow/ice albedo is at its highest. The enhanced transport of black carbon has important implications for the efficacy of deposited black carbon. Therefore, understanding these relationships could lead to possible mitigation strategies for reducing the impact of deposition of black carbon from crop residue burning in the Arctic.

Characterization of Emissions and Residues from Simulations ...

EPA Pesticide Factsheets

The surface oil burns conducted by the U.S. Coast Guard from April to July 2010 during the Deepwater Horizon disaster in the Gulf of Mexico were simulated by small scale burns to characterize the pollutants, determine emission factors, and gather particulate matter for subsequent toxicity testing. A representative crude oil (Bayou Sweet) was burned in ocean-salinity seawater and emissions were collected from the plume by means of a crane-suspended emission sampling platform. A comprehensive array of emissions was characterized, accounting for over 92% by mass of the combustion products even without accounting for H2O. The particulate matter emissions were 70 g/kg (±8.3) of oil consumed, composed of 81% (±8) elemental carbon, and 80% were 1 µm in diameter or less. The particulate matter emissions were strongly light absorbing and had a single scattering albedo of 0.4 (±0.01) at 532 nm. Emissions of the 16 polycyclic aromatic hydrocarbons (PAHs) were approximately 1 g/kg of oil consumed. While the oil burn particles were highly PAH-enriched, less than 30% of the PAHs were particle-bound, the rest being in the gas phase. Formation of polychlorinated dibenzodioxin/dibenzofuran (PCDD/DF) was observed at 1.2 ng toxic equivalency (TEQ)/kg of oil consumed. Analysis of the particles showed the major elements to be Na, S, Cl and Si with no other elements, including metals, exceeding 5 mg/kg oil consumed. The unburned oil mass was 29% of the original crude oil mas

Local Burn-Up Effects in the NBSR Fuel Element

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown N. R.; Hanson A.; Diamond, D.

2013-01-31

This study addresses the over-prediction of local power when the burn-up distribution in each half-element of the NBSR is assumed to be uniform. A single-element model was utilized to quantify the impact of axial and plate-wise burn-up on the power distribution within the NBSR fuel elements for both high-enriched uranium (HEU) and low-enriched uranium (LEU) fuel. To validate this approach, key parameters in the single-element model were compared to parameters from an equilibrium core model, including neutron energy spectrum, power distribution, and integral U-235 vector. The power distribution changes significantly when incorporating local burn-up effects and has lower power peakingmore » relative to the uniform burn-up case. In the uniform burn-up case, the axial relative power peaking is over-predicted by as much as 59% in the HEU single-element and 46% in the LEU single-element with uniform burn-up. In the uniform burn-up case, the plate-wise power peaking is over-predicted by as much as 23% in the HEU single-element and 18% in the LEU single-element. The degree of over-prediction increases as a function of burn-up cycle, with the greatest over-prediction at the end of Cycle 8. The thermal flux peak is always in the mid-plane gap; this causes the local cumulative burn-up near the mid-plane gap to be significantly higher than the fuel element average. Uniform burn-up distribution throughout a half-element also causes a bias in fuel element reactivity worth, due primarily to the neutronic importance of the fissile inventory in the mid-plane gap region.« less

Characteristics and formation mechanism of a heavy air pollution episode caused by biomass burning in Chengdu, Southwest China.

PubMed

Chen, Yuan; Xie, Shao-Dong

2014-03-01

To track the chemical characteristics and formation mechanism of biomass burning pollution, the hourly variations of meteorological factors and pollutant concentrations during a heavy pollution on 18-21 May, 2012 in Chengdu are presented in this study. The episode was the heaviest and most long-lasting pollution event in the historical record of Chengdu caused by a combination of stagnant dispersion conditions and enhanced PM2.5 emission from intensive biomass burning, with peak values surpassing 500 μg m(-3). The event was characterized by three nighttime peaks, relating to the burning practice and decreased boundary layer height at night. The prevailing northeasterly wind during nighttime preferentially brought more pollutants to the urban regions from northern suburbs of Chengdu, where dense fire spots were observed. Due to the obstruction of hilly topography and weak wind speed, minor regional features were reflected from the PM10 variations in nearby cities, whereas the long-distance transport of the plume impacted extensive regions in northern and eastern China. Carbon monoxide (CO) concentrations increased by more than 200%, while exceptionally high PM2.5 levels of 190.1 and 268.4 μg m(-3) on 17 May and 18 May, were observed and showed high correlation with CO (r=0.75). The relative contribution of biomass burning smoke to organic carbon was estimated from OC/EC ratios (organic carbon/elemental carbon) and elevated to 81.3% during the episode, indicating a significant impact on urban aerosol levels. The occurrence of high PM2.5/PM10 ratios (>0.80) and K(+)/EC ratios (>1.0), along with the increased carbonaceous concentrations and their fraction in PM2.5 (>40%) and high OC/EC ratios (about 8), could be used as immediate indicators for biomass burning pollution in cities. In addition, the heavy pollution involved a mixture of anthropogenic sources, reflected from the high SOR and NOR values and increases in the EFs (enrichment factors) of Mo, Zn, Cd, and Pb. Copyright © 2013 Elsevier B.V. All rights reserved.

Macro-particle charcoal C content following prescribed burning in a mixed-conifer forest, Sierra Nevada, California.

PubMed

Wiechmann, Morgan L; Hurteau, Matthew D; Kaye, Jason P; Miesel, Jessica R

2015-01-01

Fire suppression and changing climate have resulted in increased large wildfire frequency and severity in the western United States, causing carbon cycle impacts. Forest thinning and prescribed burning reduce high-severity fire risk, but require removal of biomass and emissions of carbon from burning. During each fire a fraction of the burning vegetation and soil organic matter is converted into charcoal, a relatively stable carbon form. We sought to quantify the effects of pre-fire fuel load and type on charcoal carbon produced by biomass combusted in a prescribed burn under different thinning treatments and to identify more easily measured predictors of charcoal carbon mass in a historically frequent-fire mixed-conifer forest. We hypothesized that charcoal carbon produced from coarse woody debris (CWD) during prescribed burning would be greater than that produced from fine woody debris (FWD). We visually quantified post-treatment charcoal carbon content in the O-horizon and the A-horizon beneath CWD (> 30 cm diameter) and up to 60 cm from CWD that was present prior to treatment. We found no difference in the size of charcoal carbon pools from CWD (treatment means ranged from 0.3-2.0 g m-2 of A-horizon and 0.0-1.7 g m-2 of O-horizon charcoal) and FWD (treatment means ranged from 0.2-1.7 g m-2 of A-horizon and 0.0-1.5 g m-2 of O-horizon charcoal). We also compared treatments and found that the burn-only, understory-thin and burn, and overstory-thin and burn treatments had significantly more charcoal carbon than the control. Charcoal carbon represented 0.29% of total ecosystem carbon. We found that char mass on CWD was an important predictor of charcoal carbon mass, but only explained 18-35% of the variation. Our results help improve our understanding of the effects forest restoration treatments have on ecosystem carbon by providing additional information about charcoal carbon content.

Black carbon content in a ponderosa pine forest of eastern Oregon with varying seasons and intervals of prescribed burns

NASA Astrophysics Data System (ADS)

Matosziuk, L.; Hatten, J. A.

2016-12-01

Soil carbon represents a significant component of the global carbon cycle. While fire-based disturbance of forest ecosystems acts as a carbon source, the increased temperatures can initiate molecular changes to forest biomass that convert fast cycling organic carbon into more stable forms such as black carbon (BC), a product of incomplete combustion that contains highly-condensed aromatic structures and very low hydrogen and oxygen content. Such forms of carbon can remain in the soil for hundred to thousands of years, effectively creating a long-term carbon sink. The goal of this project is to understand how specific characteristics of prescribed burns, specifically the season of burn and the interval between burns, affect the formation, structure, and retention of these slowly degrading forms of carbon in the soil. Both O-horizon (forest floor) and mineral soil (0-15 cm cores) samples were collected from a season and interval of burn study in Malheur National Forest. The study area is divided into six replicate units, each of which is sub-divided into four treatment areas and a control. Beginning in 1997, each treatment area was subjected to: i) spring burns at five-year intervals, ii) fall burns at five-year intervals, iii) spring burns at 15-year intervals, or iv) fall burns at 15-year intervals. The bulk density, pH, and C/N content of each soil were measured to assess the effect of the burn treatments on the soil. Additionally, the amount and molecular structure of BC in each sample was quantified using the distribution of specific molecular markers (benzene polycarboxylic acids or BPCAs) that are present in the soil following acid digestion.

Chemical Signature of Biomass Burning Emitted PM2.5 as Revealed by a C/N/S Multi- Elemental Scanning Thermal Analysis (MESTA) Technique

NASA Astrophysics Data System (ADS)

Hsieh, Y.; Bugna, G.

2006-12-01

Uncertainty of black carbon (BC) research is often plagued by the analytical difficulty associated with separating carbon components in solid samples. A rapid and sensitive multi-elemental scanning thermal analysis (MESTA), originally developed for organic matter analysis in solid samples, was applied to this study. The objective was to identify the chemical signature of biomass burning emitted PM2.5 (aerosols less than 2.5 micron) for tracing purposes. We collected PM2.5 from the burning of various biomass of a pine forest and from the ambient air of an urban campus using a PM sampler. The MESTA provides simultaneous C, N and S thermograms of the PM2.5 samples that can be used for characterization and identification purposes. This study showed that the PM2.5 samples produced from the burning of forest biomass can be characterized by a high temperature (greater than 350 oC) volatile organic component with high C/N ratio and no S content while those produced from the ambient air can be characterized by a low temperature (less than 350 oC) volatile organic component with low C/N ratio and high S content. Burning of the soaked woody debris, however, produced significant amount of the low-temperature volatile organic component similar to that of the ambient air in C/N ratio but different in S content. Most PM2.5 samples have a very low temperature (less than 110 oC) volatile N component that is identified as absorbed ammonia. The absorbed ammonia is most significant in the PM2.5 of the ambient air and the burning of soaked woody debris. All PM2.5 samples have significant amount of BC which volatilized above 500 oC with very high C/N ratio. This study also shows that MESTA can provide an objective means to present the chemical signature of the whole spectrum of OC/BC in the PM2.5 samples.

Sources and formation mechanisms of carbonaceous aerosol at a regional background site in the Netherlands: insights from a year-long radiocarbon study

NASA Astrophysics Data System (ADS)

Dusek, Ulrike; Hitzenberger, Regina; Kasper-Giebl, Anne; Kistler, Magdalena; Meijer, Harro A. J.; Szidat, Sönke; Wacker, Lukas; Holzinger, Rupert; Röckmann, Thomas

2017-03-01

We measured the radioactive carbon isotope 14C (radiocarbon) in various fractions of the carbonaceous aerosol sampled between February 2011 and March 2012 at the Cesar Observatory in the Netherlands. Based on the radiocarbon content in total carbon (TC), organic carbon (OC), water-insoluble organic carbon (WIOC), and elemental carbon (EC), we estimated the contribution of major sources to the carbonaceous aerosol. The main source categories were fossil fuel combustion, biomass burning, and other contemporary carbon, which is mainly biogenic secondary organic aerosol material (SOA). A clear seasonal variation is seen in EC from biomass burning (ECbb), with lowest values in summer and highest values in winter, but ECbb is a minor fraction of EC in all seasons. WIOC from contemporary sources is highly correlated with ECbb, indicating that biomass burning is a dominant source of contemporary WIOC. This suggests that most biogenic SOA is water soluble and that water-insoluble carbon stems mainly from primary sources. Seasonal variations in other carbon fractions are less clear and hardly distinguishable from variations related to air mass history. Air masses originating from the ocean sector presumably contain little carbonaceous aerosol from outside the Netherlands, and during these conditions measured carbon concentrations reflect regional sources. In these situations absolute TC concentrations are usually rather low, around 1.5 µg m-3, and ECbb is always very low ( ˜ 0.05 µg m-3), even in winter, indicating that biomass burning is not a strong source of carbonaceous aerosol in the Netherlands. In continental air masses, which usually arrive from the east or south and have spent several days over land, TC concentrations are on average by a factor of 3.5 higher. ECbb increases more strongly than TC to 0.2 µg m-3. Fossil EC and fossil WIOC, which are indicative of primary emissions, show a more moderate increase by a factor of 2.5 on average. An interesting case is fossil water-soluble organic carbon (WSOC, calculated as OC-WIOC), which can be regarded as a proxy for SOA from fossil precursors. Fossil WSOC has low concentrations when regional sources are sampled and increases by more than a factor of 5 in continental air masses. A longer residence time of air masses over land seems to result in increased SOA concentrations from fossil origin.

Transported vs. local contributions from secondary and biomass burning sources to PM2.5

NASA Astrophysics Data System (ADS)

Kim, Bong Mann; Seo, Jihoon; Kim, Jin Young; Lee, Ji Yi; Kim, Yumi

2016-11-01

The concentration of fine particulates in Seoul, Korea has been lowered over the past 10 years, as a result of the city's efforts in implementing environmental control measures. Yet, the particulate concentration level in Seoul remains high as compared to other urban areas globally. In order to further improve fine particulate air quality in the Korea region and design a more effective control strategy, enhanced understanding of the sources and contribution of fine particulates along with their chemical compositions is necessary. In turn, relative contributions from local and transported sources on Seoul need to be established, as this city is particularly influenced by sources from upwind geographic areas. In this study, PM2.5 monitoring was conducted in Seoul from October 2012 to September 2013. PM2.5 mass concentrations, ions, metals, organic carbon (OC), elemental carbon (EC), water soluble OC (WSOC), humic-like substances of carbon (HULIS-C), and 85 organic compounds were chemically analyzed. The multivariate receptor model SMP was applied to the PM2.5 data, which then identified nine sources and estimated their source compositions as well as source contributions. Prior studies have identified and quantified the transported and local sources. However, no prior studies have distinguished contributions of an individual source between transported contribution and locally produced contribution. We differentiated transported secondary and biomass burning sources from the locally produced secondary and biomass burning sources, which was supported with potential source contribution function (PSCF) analysis. Of the total secondary source contribution, 32% was attributed to transported secondary sources, and 68% was attributed to locally formed secondary sources. Meanwhile, the contribution from the transported biomass burning source was revealed as 59% of the total biomass burning contribution, which was 1.5 times higher than that of the local biomass burning source. Four-season average source contributions from the transported and the local sources were 28% and 72%, respectively.

Source apportionment of PM2.5 organic carbon in the San Joaquin Valley using monthly and daily observations and meteorological clustering.

PubMed

Skiles, Matthew J; Lai, Alexandra M; Olson, Michael R; Schauer, James J; de Foy, Benjamin

2018-06-01

Two hundred sixty-three fine particulate matter (PM 2.5 ) samples collected on 3-day intervals over a 14-month period at two sites in the San Joaquin Valley (SJV) were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), and organic molecular markers. A unique source profile library was applied to a chemical mass balance (CMB) source apportionment model to develop monthly and seasonally averaged source apportionment results. Five major OC sources were identified: mobile sources, biomass burning, meat smoke, vegetative detritus, and secondary organic carbon (SOC), as inferred from OC not apportioned by CMB. The SOC factor was the largest source contributor at Fresno and Bakersfield, contributing 44% and 51% of PM mass, respectively. Biomass burning was the only source with a statistically different average mass contribution (95% CI) between the two sites. Wintertime peaks of biomass burning, meat smoke, and total OC were observed at both sites, with SOC peaking during the summer months. Exceptionally strong seasonal variation in apportioned meat smoke mass could potentially be explained by oxidation of cholesterol between source and receptor and trends in wind transport outlined in a Residence Time Analysis (RTA). Fast moving nighttime winds prevalent during warmer months caused local emissions to be replaced by air mass transported from the San Francisco Bay Area, consisting of mostly diluted, oxidized concentrations of molecular markers. Good agreement was observed between SOC derived from the CMB model and from non-biomass burning WSOC mass, suggesting the CMB model is sufficiently accurate to assist in policy development. In general, uncertainty in monthly mass values derived from daily CMB apportionments were lower than that of CMB results produced with monthly marker composites, further validating daily sampling methodologies. Strong seasonal trends were observed for biomass and meat smoke OC apportionment, and monthly mass averages had lowest uncertainty when derived from daily CMB apportionments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Constraints on CEMP-no progenitors from nuclear astrophysics

NASA Astrophysics Data System (ADS)

Choplin, Arthur; Maeder, André; Meynet, Georges; Chiappini, Cristina

2016-09-01

Context. The CEMP-no stars are long-lived small mass stars presenting a very low iron content and overabundances of carbon with no sign or only very weak signs of s- or r-elements. Although the origin of this abundance pattern is still a matter of debate, it was very likely inherited from a previous massive star, which we call the source star. Aims: We rely on a recent classification of CEMP-no stars arguing that some of them are made of a material processed by hydrogen burning that was enriched in products of helium burning during the nuclear life of the source star. We examine the possibility of forming CEMP-no stars with this material. Methods: We study the nucleosynthesis of the CNO cycle and the Ne-Na Mg-Al chains in a hydrogen burning single zone while injecting the helium burning products 12C, 16O, 22Ne, and 26Mg. We investigate the impact of changing density, temperature and the injection rate. The nuclear reaction rates involving the creation and destruction of 27Al are also examined. Results: 14N, 23Na, 24Mg, and 27Al are formed when injecting 12C, 16O, 22Ne, and 26Mg in the hydrogen burning zone. The 12C/13C ratio is constant under various conditions in the hydrogen burning zone. The predicted [Al/Fe] ratio varies up to ~ 2 dex depending on the prescription used for the reaction rates involving 27Al. Conclusions: The experiments we carried out support the view that some CEMP-no stars are made of a material processed by hydrogen burning that comes from a massive star experiencing mild to strong rotational mixing. During its burning, this material was likely enriched in helium burning products. No material coming from the carbon-oxygen rich core of the source star should be added to form the daughter star, otherwise the 12C/13C ratio would be largely above the observed range of values.

Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands

Treesearch

Merritt R. Turetsky; Evan S. Kane; Jennifer W. Harden; Roger D. Ottmar; Kristen L. Maines; Elizabeth Hoy; Eric S. Kasischke

2010-01-01

Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult...

Challenges to the Standardization of Burn Data Collection: A Call for Common Data Elements for Burn Care.

PubMed

Schneider, Jeffrey C; Chen, Liang; Simko, Laura C; Warren, Katherine N; Nguyen, Brian Phu; Thorpe, Catherine R; Jeng, James C; Hickerson, William L; Kazis, Lewis E; Ryan, Colleen M

2018-02-20

The use of common data elements (CDEs) is growing in medical research; CDEs have demonstrated benefit in maximizing the impact of existing research infrastructure and funding. However, the field of burn care does not have a standard set of CDEs. The objective of this study is to examine the extent of common data collected in current burn databases.This study examines the data dictionaries of six U.S. burn databases to ascertain the extent of common data. This was assessed from a quantitative and qualitative perspective. Thirty-two demographic and clinical data elements were examined. The number of databases that collect each data element was calculated. The data values for each data element were compared across the six databases for common terminology. Finally, the data prompts of the data elements were examined for common language and structure.Five (16%) of the 32 data elements are collected by all six burn databases; additionally, five data elements (16%) are present in only one database. Furthermore, there are considerable variations in data values and prompts used among the burn databases. Only one of the 32 data elements (age) contains the same data values across all databases.The burn databases examined show minimal evidence of common data. There is a need to develop CDEs and standardized coding to enhance interoperability of burn databases.

Carbon and water fluxes from ponderosa pine forests disturbed by wildfire and thinning.

PubMed

Dore, S; Kolb, T E; Montes-Helu, M; Eckert, S E; Sullivan, B W; Hungate, B A; Kaye, J P; Hart, S C; Koch, G W; Finkral, A

2010-04-01

Disturbances alter ecosystem carbon dynamics, often by reducing carbon uptake and stocks. We compared the impact of two types of disturbances that represent the most likely future conditions of currently dense ponderosa pine forests of the southwestern United States: (1) high-intensity fire and (2) thinning, designed to reduce fire intensity. High-severity fire had a larger impact on ecosystem carbon uptake and storage than thinning. Total ecosystem carbon was 42% lower at the intensely burned site, 10 years after burning, than at the undisturbed site. Eddy covariance measurements over two years showed that the burned site was a net annual source of carbon to the atmosphere whereas the undisturbed site was a sink. Net primary production (NPP), evapotranspiration (ET), and water use efficiency were lower at the burned site than at the undisturbed site. In contrast, thinning decreased total ecosystem carbon by 18%, and changed the site from a carbon sink to a source in the first posttreatment year. Thinning also decreased ET, reduced the limitation of drought on carbon uptake during summer, and did not change water use efficiency. Both disturbances reduced ecosystem carbon uptake by decreasing gross primary production (55% by burning, 30% by thinning) more than total ecosystem respiration (TER; 33-47% by burning, 18% by thinning), and increased the contribution of soil carbon dioxide efflux to TER. The relationship between TER and temperature was not affected by either disturbance. Efforts to accurately estimate regional carbon budgets should consider impacts on carbon dynamics of both large disturbances, such as high-intensity fire, and the partial disturbance of thinning that is often used to prevent intense burning. Our results show that thinned forests of ponderosa pine in the southwestern United States are a desirable alternative to intensively burned forests to maintain carbon stocks and primary production.

Macro-Particle Charcoal C Content following Prescribed Burning in a Mixed-Conifer Forest, Sierra Nevada, California

PubMed Central

Wiechmann, Morgan L.; Hurteau, Matthew D.; Kaye, Jason P.; Miesel, Jessica R.

2015-01-01

Fire suppression and changing climate have resulted in increased large wildfire frequency and severity in the western United States, causing carbon cycle impacts. Forest thinning and prescribed burning reduce high-severity fire risk, but require removal of biomass and emissions of carbon from burning. During each fire a fraction of the burning vegetation and soil organic matter is converted into charcoal, a relatively stable carbon form. We sought to quantify the effects of pre-fire fuel load and type on charcoal carbon produced by biomass combusted in a prescribed burn under different thinning treatments and to identify more easily measured predictors of charcoal carbon mass in a historically frequent-fire mixed-conifer forest. We hypothesized that charcoal carbon produced from coarse woody debris (CWD) during prescribed burning would be greater than that produced from fine woody debris (FWD). We visually quantified post-treatment charcoal carbon content in the O-horizon and the A-horizon beneath CWD (> 30 cm diameter) and up to 60 cm from CWD that was present prior to treatment. We found no difference in the size of charcoal carbon pools from CWD (treatment means ranged from 0.3–2.0 g m-2 of A-horizon and 0.0–1.7 g m-2 of O-horizon charcoal) and FWD (treatment means ranged from 0.2–1.7 g m-2 of A-horizon and 0.0–1.5 g m-2 of O-horizon charcoal). We also compared treatments and found that the burn-only, understory-thin and burn, and overstory-thin and burn treatments had significantly more charcoal carbon than the control. Charcoal carbon represented 0.29% of total ecosystem carbon. We found that char mass on CWD was an important predictor of charcoal carbon mass, but only explained 18–35% of the variation. Our results help improve our understanding of the effects forest restoration treatments have on ecosystem carbon by providing additional information about charcoal carbon content. PMID:26258533

PM2.5 source apportionment with organic markers in the Southeastern Aerosol Research and Characterization (SEARCH) study.

PubMed

Watson, John G; Chow, Judith C; Lowenthal, Douglas H; Antony Chen, L-W; Shaw, Stephanie; Edgerton, Eric S; Blanchard, Charles L

2015-09-01

Positive matrix factorization (PMF) and effective variance (EV) solutions to the chemical mass balance (CMB) were applied to PM(2.5) (particulate matter with an aerodynamic diameter <2.5 μm) mass and chemically speciated measurements for samples taken from 2008 to 2010 at the Atlanta, Georgia, and Birmingham, Alabama, sites. Commonly measured PM(2.5) mass, elemental, ionic, and thermal carbon fraction concentrations were supplemented with detailed nonpolar organic speciation by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). Source contribution estimates were calculated for motor vehicle exhaust, biomass burning, cooking, coal-fired power plants, road dust, vegetative detritus, and secondary sulfates and nitrates for Atlanta. Similar sources were found for Birmingham, with the addition of an industrial source and the separation of biomass burning into open burning and residential wood combustion. EV-CMB results based on conventional species were qualitatively similar to those estimated by PMF-CMB. Secondary ammonium sulfate was the largest contributor, accounting for 27-38% of PM(2.5), followed by biomass burning (21-24%) and motor vehicle exhaust (9-24%) at both sites, with 4-6% of PM(2.5) attributed to coal-fired power plants by EV-CMB. Including organic compounds in the EV-CMB reduced the motor vehicle exhaust and biomass burning contributions at both sites, with a 13-23% deficit for PM(2.5) mass. The PMF-CMB solution showed mixing of sources within the derived factors, both with and without the addition of speciated organics, as is often the case with complex source mixtures such as those at these urban-scale sites. The nonpolar TD-GC/MS compounds can be obtained from existing filter samples and are a useful complement to the elements, ions, and carbon fractions. However, they should be supplemented with other methods, such as TD-GC/MS on derivitized samples, to obtain a wider range of polar compounds such as sterols, sugars, and organic acids. The PMF and EV solutions to the CMB equations are complementary to, rather than replacements for, each other, as comparisons of their results reveal uncertainties that are not otherwise evident. Organic markers can be measured on currently acquired PM(2.5) filter samples by thermal methods. These markers can complement element, ion, and carbon fraction measurements from long-term speciation networks. Applying the positive matrix factorization and effective variance solutions for the chemical mass balance equations provides useful information on the accuracy of the source contribution estimates. Nonpolar compounds need to be complemented with polar compounds to better apportion cooking and secondary organic aerosol contributors.

Chemical characterization of fine particulate matter emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

NASA Astrophysics Data System (ADS)

Jayarathne, Thilina; Stockwell, Chelsea E.; Gilbert, Ashley A.; Daugherty, Kaitlyn; Cochrane, Mark A.; Ryan, Kevin C.; Putra, Erianto I.; Saharjo, Bambang H.; Nurhayati, Ati D.; Albar, Israr; Yokelson, Robert J.; Stone, Elizabeth A.

2018-02-01

Fine particulate matter (PM2.5) was collected in situ from peat smoke during the 2015 El Niño peat fire episode in Central Kalimantan, Indonesia. Twenty-one PM samples were collected from 18 peat fire plumes that were primarily smoldering with modified combustion efficiency (MCE) values of 0.725-0.833. PM emissions were determined and chemically characterized for elemental carbon (EC), organic carbon (OC), water-soluble OC, water-soluble ions, metals, and organic species. Fuel-based PM2.5 mass emission factors (EFs) ranged from 6.0 to 29.6 g kg-1 with an average of 17.3 ± 6.0 g kg-1. EC was detected only in 15 plumes and comprised ∼ 1 % of PM mass. Together, OC (72 %), EC (1 %), water-soluble ions (1 %), and metal oxides (0.1 %) comprised 74 ± 11 % of gravimetrically measured PM mass. Assuming that the remaining mass is due to elements that form organic matter (OM; i.e., elements O, H, N) an OM-to-OC conversion factor of 1.26 was estimated by linear regression. Overall, chemical speciation revealed the following characteristics of peat-burning emissions: high OC mass fractions (72 %), primarily water-insoluble OC (84 ± 11 %C), low EC mass fractions (1 %), vanillic to syringic acid ratios of 1.9, and relatively high n-alkane contributions to OC (6.2 %C) with a carbon preference index of 1.2-1.6. Comparison to laboratory studies of peat combustion revealed similarities in the relative composition of PM but greater differences in the absolute EF values. The EFs developed herein, combined with estimates of the mass of peat burned, are used to estimate that 3.2-11 Tg of PM2.5 was emitted to atmosphere during the 2015 El Niño peatland fire event in Indonesia. Combined with gas-phase measurements of CO2, CO, CH4, and volatile organic carbon from Stockwell et al. (2016), it is determined that OC and EC accounted for 2.1 and 0.04 % of total carbon emissions, respectively. These in situ EFs can be used to improve the accuracy of the representation of Indonesian peat burning in emission inventories and receptor-based models.

Black Carbon in the Arctic: Assessment of and efforts to reduce black carbon emissions from wildfires and agricultural burning in Russia

NASA Astrophysics Data System (ADS)

Kinder, B.; Hao, W. M.; Larkin, N. K.; McCarty, G.; O'neal, K. J.; Gonzalez, O.; Luxenberg, J.; Rosenblum, M.; Petkov, A.

2011-12-01

Black carbon and other short-lived climate forcers exert a warming effect on the climate but remain in the atmosphere for short time periods when compared to carbon dioxide. Black carbon is a significant contributor to increasing temperatures in the Arctic region, which has warmed at twice the global rate over the past 100 years. Black carbon warms the Arctic by absorbing incoming solar radiation while in the atmosphere and, when deposited onto Arctic ice, leading to increased atmospheric temperatures and snow and ice melt. Black carbon remains in the atmosphere for a short time period ranging from days to weeks; therefore, local atmospheric conditions at the time of burning determine the amount of black carbon transport to the Arctic. Most black carbon transport and deposition in the Arctic results from the occurrence of wildfires, prescribed forest fires, and agricultural burning at latitudes greater than 40 degrees north latitude. Wildfire affects some 10-15 million hectares of forest, forest steppe, and grasslands in Russia each year. In addition to wildfire, there is widespread cropland burning in Russia occurring in the fall following harvest and in the spring prior to tilling. Agricultural burning is common practice for crop residue removal as well as suppression of weeds, insects and residue-borne diseases. The goal of the United States Department of Agriculture (USDA) Black Carbon Initiative is to assess black carbon emissions from agricultural burning and wildfires in Russia and explore practical options and opportunities for reducing emissions from these two sources. The emissions assessment combines satellite-derived burned area measurements of forest and agricultural fires, burn severity information, ancillary geospatial data, vegetation and land cover maps, fuels data, fire emissions data, fire/weather relationship information, and smoke transport models to estimate black carbon transport and deposition in the Arctic. The assessment addresses necessary improvements to fire and burned area detection algorithms to improve agricultural burned area mapping accuracy. Efforts to explore practical options for reducing black carbon emissions from wildfires and agricultural burning in Russia have been focused on designing community-based fire prevention and education programs in Siberia and the Russia Far East, two regions prone to frequent human-caused fires. The initiative also seeks to identify practical alternatives to reduce black carbon emissions from agricultural burning and to help promote these alternatives through outreach to farmers and other agricultural organizations. This submission will explore the initial findings and results of the emissions assessment and discuss the progress and challenges associated with implementation of local-level fire prevention and mitigation efforts in Russia. The results of this initiative will help inform future policy and management tools to address black carbon emissions from wildfires and agricultural burning in Russia and perhaps additional interested countries.

Molecular Chemistry of Atmospheric Brown Carbon Inferred from a Nationwide Biomass Burning Event

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Peng; Bluvshtein, Nir; Rudich, Yinon

Lag Ba'Omer, a nationwide bonfire festival in Israel, was chosen as a case study to investigate the influence of a major biomass burning event on the light absorption properties of atmospheric brown carbon (BrC). The chemical composition and optical properties of BrC chromophores were investigated using a high performance liquid chromatography (HPLC) platform coupled to photo diode array (PDA) and high resolution mass spectrometry (HRMS) detectors. Substantial increase of BrC light absorption coefficient was observed during the night-long biomass burning event. Most chromophores observed during the event were attributed to nitroaromatic compounds, comprising 28 elemental formulas of at least 63more » structural isomers. The NAC, in combination, accounted for 50-80% of the total visible light absorption (> 400 nm) by solvent extractable BrC. The results highlight that NAC, particular nitrophenols, are important light absorption contributors of biomass burning organic aerosol (BBOA), suggesting that night time chemistry of ·NO 3 and N 2O 5 with particles may play a significant role in atmospheric transformations of BrC. Nitrophenols and related compounds were especially important chromophores of BBOA. The absorption spectra of the BrC chromophores are influenced by the extraction solvent and solution pH, implying that the aerosol acidity is an important factor controlling the light absorption properties of BrC.« less

Molecular Chemistry of Atmospheric Brown Carbon Inferred from a Nationwide Biomass Burning Event

DOE PAGES

Lin, Peng; Bluvshtein, Nir; Rudich, Yinon; ...

2017-08-26

Lag Ba'Omer, a nationwide bonfire festival in Israel, was chosen as a case study to investigate the influence of a major biomass burning event on the light absorption properties of atmospheric brown carbon (BrC). The chemical composition and optical properties of BrC chromophores were investigated using a high performance liquid chromatography (HPLC) platform coupled to photo diode array (PDA) and high resolution mass spectrometry (HRMS) detectors. Substantial increase of BrC light absorption coefficient was observed during the night-long biomass burning event. Most chromophores observed during the event were attributed to nitroaromatic compounds, comprising 28 elemental formulas of at least 63more » structural isomers. The NAC, in combination, accounted for 50-80% of the total visible light absorption (> 400 nm) by solvent extractable BrC. The results highlight that NAC, particular nitrophenols, are important light absorption contributors of biomass burning organic aerosol (BBOA), suggesting that night time chemistry of ·NO 3 and N 2O 5 with particles may play a significant role in atmospheric transformations of BrC. Nitrophenols and related compounds were especially important chromophores of BBOA. The absorption spectra of the BrC chromophores are influenced by the extraction solvent and solution pH, implying that the aerosol acidity is an important factor controlling the light absorption properties of BrC.« less

PM2.5 Emission Elemental Composition from Diverse Combustion Sources in the Metropolitan Area of Mexico City

PubMed Central

Mugica, V.; Mugica, F.; Torres, M.; Figueroa, J.

2008-01-01

A field study was carried out from 2003 to 2004 with the aim to develop the PM2.5 emission source profiles from light-duty gasoline and heavy-duty diesel vehicles, as well as emission source profiles from waste incineration, wood burning, LP gas combustion, and meat broiling. Over 25 chemical species were quantified from the fine particles emitted by the different combustion sources investigated, including organic and elemental carbon, ions, and elements. The OC/TC ratio found in the different PM2.5 profiles was dissimilar as well as the sulfate, nitrate, ammonium, soil species, and trace element content. Consequently, these combustion emission profiles could be used in source reconciliation studies for fine particles. PMID:18379705

Influence of fire frequency on carbon consumption in Alaskan blackspruce forests

NASA Astrophysics Data System (ADS)

Hoy, E.; Kasischke, E. S.

2014-12-01

Increasing temperatures and drier conditions within the boreal forests of Alaska have resulted in increases in burned area and fire frequency, which alter carbon storage and emissions. In particular, analyses of satellite remote sensing data showed that >20% of the area impacted by fires in interior Alaska occurred in areas that had previously burned since 1950 (e.g., short to intermediate interval fires). Field studies showed that in immature black spruce forests ~ 35 to 55 years old organic layers experienced deep burning regardless of topographic position or seasonality of burning, factors that control depth of burning in mature black spruce forests. Here, refinements were made to a carbon consumption model to account for variations in fuel loads and fraction of carbon consumed associated with fire frequency based on quantifying burned area in recently burned sites using satellite imagery. An immature black spruce (Picea mariana) fuel type (including stands of ~0-50 years) was developed which contains new ground-layer carbon consumption values in order to more accurately account for differences between various age classes of black spruce forest. Both versions of the model were used to assess carbon consumption during 100 fire events (over 4.4 x 10^6 ha of burned area) from two recent ultra-large fire years (2004 and 2005). Using the improved model to better attribute fuel type and consumption resulted in higher ground-layer carbon consumption (4.9% in 2004 and 6.8% in 2005) than previously estimated. These adjustments in ground-layer burning resulted in total carbon consumption within 2004 and 2005 of 63.5 and 42.0 Tg of carbon, respectively. Results from this research could be incorporated into larger scale modeling efforts to better assess changes in the climate-fire-vegetation dynamics in interior Alaskan boreal forests, and to understand the impacts of these changes on carbon consumption and emissions.

A Comparison of Mass-Based Emission Factors from Laboratory Combustion of Boreal and Sub-Tropical Peat

NASA Astrophysics Data System (ADS)

Knue, J.; Yatavelli, R. L. N.; Chen, L. W. A. A.; Samburova, V.; Gyawali, M. S.; Watts, A.; Chakrabarty, R. K.; Moosmuller, H.; Wang, X.; Zielinska, B.; Chow, J. C.; Watson, J. G.; Tsibart, A.

2014-12-01

Peatlands cover approximately 3% of the Earth's surface, but account for approximately one-third of terrestrial soil carbon. This carbon is also much older, collected over hundreds to thousands of years, than other commonly encountered wildfire fuels such as Ponderosa Pine (i.e., years to decades). Due to the moisture and mineral content of peat it has a propensity to smolder, unlike Ponderosa Pine which has an intense flaming period when burning. To better understand the emission from peat fires, in comparison to Ponderosa Pine, a series of experiments were performed in the 8 m3 combustion chamber located at the Desert Research Institute in Reno, NV. Peat from Alaska and Florida (USA) and Siberia (Russia) were burned at two moisture content levels (25 & 50%). Ponderosa Pine needles from Sierra Nevada sites were burned at one moisture content level (8.2%). Real-time measurements included gaseous carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOx = NO + NO2), and ozone (O3) concentration, as well as particulate matter (PM) mass, size distribution, and black carbon concentration. In addition, Teflon-membrane and quartz-fiber filters as well as Teflon-impregnated glass fiber (TIGF) filters followed by XAD-4 cartridges were collected for detailed PM chemical speciation. Changes in fuel mass and combustion temperature were continuously monitored during each experiment. We will present a comparison of mass-based emission factors of inorganic gases, PM and black carbon mass concentrations, organic and elemental carbon, and a number of intermediate-volatility (300

Organic molecular tracers in the atmospheric aerosols from Lumbini, Nepal, in the northern Indo-Gangetic Plain: influence of biomass burning

NASA Astrophysics Data System (ADS)

Wan, Xin; Kang, Shichang; Li, Quanlian; Rupakheti, Dipesh; Zhang, Qianggong; Guo, Junming; Chen, Pengfei; Tripathee, Lekhendra; Rupakheti, Maheswar; Panday, Arnico K.; Wang, Wu; Kawamura, Kimitaka; Gao, Shaopeng; Wu, Guangming; Cong, Zhiyuan

2017-07-01

To better understand the characteristics of biomass burning in the northern Indo-Gangetic Plain (IGP), total suspended particles were collected in a rural site, Lumbini, Nepal, during April 2013 to March 2014 and analyzed for the biomass burning tracers (i.e., levoglucosan, mannosan, vanillic acid). The annual average concentration of levoglucosan was 734 ± 1043 ng m-3 with the maximum seasonal mean concentration during post-monsoon season (2206 ± 1753 ng m-3), followed by winter (1161 ± 1347 ng m-3), pre-monsoon (771 ± 524 ng m-3) and minimum concentration during monsoon season (212 ± 279 ng m-3). The other biomass burning tracers (mannosan, galactosan, p-hydroxybenzoic acid, vanillic acid, syringic acid and dehydroabietic acid) also showed the similar seasonal variations. There were good correlations among levoglucosan, organic carbon (OC) and elemental carbon (EC), indicating significant impact of biomass burning activities on carbonaceous aerosol loading throughout the year in Lumbini area. According to the characteristic ratios, levoglucosan / mannosan (lev / man) and syringic acid / vanillic acid (syr / van), we deduced that the high abundances of biomass burning products during non-monsoon seasons were mainly caused by the burning of crop residues and hardwood while the softwood had less contribution. Based on the diagnostic tracer ratio (i.e., lev / OC), the OC derived from biomass burning constituted large fraction of total OC, especially during post-monsoon season. By analyzing the MODIS fire spot product and 5-day air-mass back trajectories, we further demonstrated that organic aerosol composition was not only related to the local agricultural activities and residential biomass usage but also impacted by the regional emissions. During the post-monsoon season, the emissions from rice residue burning in western India and eastern Pakistan could impact particulate air pollution in Lumbini and surrounding regions in southern Nepal. Therefore, our finding is meaningful and has a great importance for adopting the appropriate mitigation measures, not only at the local level but also by involving different regions and nations, to reduce the biomass burning emissions in the broader IGP region nations.

Trace gas and particle emissions from domestic and industrial biofuel use and garbage burning in central Mexico

Treesearch

T. J. Christian; R. J. Yokelson; B. Cardenas; L. T. Molina; G. Engling; S.-C. Hsu

2009-01-01

In central Mexico during the spring of 2007 we measured the initial emissions of 12 gases and the aerosol speciation for elemental and organic carbon (EC, OC), anhydrosugars, Cl-, NO-3 , and 20 metals from 10 cooking fires, four garbage fires, three brick making kilns, three charcoal making kilns, and two crop residue fires. Biofuel use has been estimated at over 2600...

Trace gas and particle emissions from domestic and industrial biofuel use and garbage burning in central Mexico

Treesearch

T. J. Christian; R. J. Yokelson; B. Cardenas; L. T. Molina; G. Engling; S.-C. Hsu

2010-01-01

In central Mexico during the spring of 2007 we measured the initial emissions of 12 gases and the aerosol speciation for elemental and organic carbon (EC, OC), anhydrosugars, Cl-, NO-3 , and 20 metals from 10 cooking fires, four garbage fires, three brick making kilns, three charcoal making kilns, and two crop residue fires. Global biofuel use has been...

Chemistry of burning the forest floor during the FROSTFIRE experimental burn, interior Alaska, 1999

USGS Publications Warehouse

Harden, J.W.; Neff, J.C.; Sandberg, D.V.; Turetsky, M.R.; Ottmar, R.; Gleixner, G.; Fries, T.L.; Manies, K.L.

2004-01-01

Wildfires represent one of the most common disturbances in boreal regions, and have the potential to reduce C, N, and Hg stocks in soils while contributing to atmospheric emissions. Organic soil layers of the forest floor were sampled before and after the FROSTFIRE experimental burn in interior Alaska, and were analyzed for bulk density, major and trace elements, and organic compounds. Concentrations of carbon, nutrients, and several major and trace elements were significantly altered by the burn. Emissions of C, N, and Hg, estimated from chemical mass balance equations using Fe, Al, and Si as stable constituents, indicated that 500 to 900 g C and up to 0 to 4 ?? 10-4 g Hg/M2 were lost from the site. Calculations of nitrogen loss range from -4 to +6 g/m2 but were highly variable (standard deviation 19), with some samples showing increased N concentrations post-burn potentially from canopy ash. Noncombustible major nutrients such as Ca and K also were inherited from canopy ash. Thermogravimetry indicates a loss of thermally labile C and increase of lignin-like C in char and ash relative to unburned counterparts. Overall, atmospheric impacts of boreal fires include large emissions of C, N and Hg that vary greatly as a function of severe fire weather and its access to deep organic layers rich in C, N, and Hg. In terrestrial systems, burning rearranges the vertical distribution of nutrients in fuels and soils, the proximity of nutrients and permafrost to surface biota, and the chemical composition of soil including its nutrient and organic constituents, all of which impact C cycling. Copyright 2004 by the American Geophysical Union.

Long term atmospheric aerosol characterization in the Amazon Basin

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Gerab, Fábio; Yamasoe, Marcia A.

This chapter presents a characterization of atmospheric aerosols collected in different places in the Amazon Basin. Both the biogenic aerosol emission from the forest and the particulate material which is emitted to the atmosphere due to the large scale man-made burns during the dry season were studied. The samples were collected during a three year period at three different locations in the Amazon (Cuiabá, Alta Floresta and Serra do Navio), using stacked filter units. Aerosol samples were also collected directly over fires of cerrado vegetation and tropical primary forest burns The samples were analyzed using several techniques for a number of elements. Gravimetric analyses were used to determine the total atmospheric aerosol concentration. Multivariate statistical analysis was used in order to identify and characterize the sources of the atmospheric aerosol present in the sampled regions. Cerrado burning emissions were enriched compared to forest ones, specially for Cl, K and Zn. High atmospheric aerosol concentrations were observed in large amazonian areas due to emissions from man-made burns in the period from June to September. The emissions from burns dominate the fine fraction of the atmospheric aerosol with characteristic high contents of black carbon, S and K. Aerosols emitted in biomass burning process are correlated to the increase in the aerosol optical thickness of the atmosphere during the Amazonian dry season. The Serra do Navio aerosol is characterized by biogenic emissions with strong marine influence. The presence of trace elements characteristic of soil particulate associated with this marine contribution indicates the existence of aerosol transport from Africa to South America. Similar composition characteristics were observed in the biogenic emission aerosols from Serra do Navio and Alta Floresta.

Black carbon measurements during winter 2013-2014 in Athens and intercomparison between different techniques

NASA Astrophysics Data System (ADS)

Liakakou, Eleni; Stravroulas, Jason; Roukounakis, Nikolaos; Paraskevopoulou, Despina; Fourtziou, Luciana; Psiloglou, Vassilis; Gerasopoulos, Evangelos; Sciare, Jean; Mihalopoulos, Nikolaos

2014-05-01

Black carbon (BC) is a particulate pollutant species emitted from the combustion of fuels, biomass burning for agricultural purposes and forest fires, with the first two anthropogenic sources being the major contributors to the atmospheric burden of BC. The presence of BC is important due to its direct and indirect physicochemical effects and its use as a tracer of burning and subsequent transport processes. Black carbon measurements took place during winter 2013 -2014 in the frame of a pollution monitoring experiment conducted at the urban site of Thissio, Athens (city center) at the premises of the National Observatory of Athens. The economic crisis in Greece and the resulting turn of Athens inhabitants to wood burning for domestic heating, has led to increased daily concentrations of BC in the range of 2-6 μg m-3, peaking at night time (15-20 μg m-3). Three different optical methods were used for the determination of BC. A Particle Soot Absorption Photometer (PSAP; Radiance Research) commercial instrument was used to monitor the light absorption coefficient (σap) at 565 nm of ambient aerosols, with 1 minute resolution. During parts of the campaign, a portable Aethalometer (AE-42; Magee Scientific) was also used to provide measurement of the aerosol BC content at 7 wavelengths over 5 minutes intervals. Exploiting the measurements at different wavelengths is was feasible to separate wood burning BC from BC related to fossil fuel. Two Multi Angle Absorption Photometers (MAAP; Thermo) were also operated as reference. Finally, aerosol samples were collected on 12-hour basis using a sequential dichotomous sampler for the sampling of PM2.5, PM2.5-10and PM10 fractions of aerosols on quartz filters, and the filters were analyzed for elemental carbon (EC) by a thermal - optical transmission technique. The main objective of the study is the intercomparison of the different BC monitoring techniques under a large range of ambient concentrations achieved due to the special circumstance occurring in Athens with the rapid increase of BC emission due to wood burning. In parallel, the BC measurements are used for the estimation of the contribution of wood burning in fireplaces and wood-stoves in ambient PM levels, compared to other known sources of local pollution (e.g. traffic, central heating).

Variations of carbonaceous aerosols from open crop residue burning with transport and its implication to estimate their lifetimes

NASA Astrophysics Data System (ADS)

Pan, X. L.; Kanaya, Y.; Wang, Z. F.; Komazaki, Y.; Taketani, F.; Akimoto, H.; Pochanart, P.

2013-08-01

Studying the correlations of carbonaceous aerosols (element carbon, EC, and organic carbon, OC) from open biomass burning helps to reduce uncertainties in emission inventories and provides necessary constraints for model simulations. In the present study, we measured apparent elemental carbon (ECa) and OC concentrations at the summit of Mount Tai (Mt. Tai) during intensive open crop residue burning (OCRB) episodes using a Sunset OCEC analyzer. In the fine particle mode, OC and ECa showed strong correlations (r > 0.9) with carbon monoxide (CO). Footprint analysis using the FLEXPART_WRF model indicated that OCRB in Central East China had a significant influence on ambient carbonaceous aerosol loadings at the summit of Mt. Tai. During campaign, ΔECa/ΔCO ratios of OCRB plumes were found to be 14.3 ± 1.0 ng m-3 ppbv at Mt. Tai. This ratio was twice larger than those for urban pollution in CEC, demonstrating that significant emissions of soot particles emitted from OCRB. ΔOC/ΔCO ratio of OCRB plumes was found to be 41.9 ± 2.6 ng m-3 ppbv averagely. The transport time of smoke particles was estimated using the FLEXPART_WRF tracer model by releasing particles from the ground layer inside geographical regions where large numbers of hotspots were detected by the MODIS sensor. The relationship between transport time and observed ΔECa/ΔCO and ΔOC/ΔCO ratios was fitted by an e-folding exponential function. Results showed that the loss rate of OC (normalized by CO) with transport was much quicker than that of ECa mass, and the corresponding lifetime of OC mass was estimated to be 28.0-44.2 h (1.2-1.8 days), much shorter than that 98.4-136.9 h (4.1-5.7 days) of ECa. Lifetime of ECa estimated for the OCRB events in CEC in the study was comparably lower than the values normally calculated by the transport models. Short lifetime of OC highlighted its vulnerability to cloud scavenging in the presence of water-soluble organic species from biomass combustion.

Quantification of Absorption Due to Black and Brown Carbon from Biomass Burning and Parameterizations for Comparison to Climate Models Result

NASA Astrophysics Data System (ADS)

Pokhrel, Rudra Prasad

This dissertation examines the optical properties of fresh and aged biomass burning aerosols, parameterization of these properties, and development of new instrumentation and calibration techniques to measure aerosol optical properties. Data sets were collected from the fourth Fire Lab at Missoula Experiment (FLAME-4) that took place from October 15 to November 16, 2012. Biomass collected from the various parts of the world were burned under controlled laboratory conditions and fresh emissions from different stages of burning were measured and analyzed. Optical properties of aged aerosol under different conditions was also explored. A photoacoustic absorption spectrometer (PAS) was built and integrated with a newly designed thermal denuder to improve upon observations made during Flame-4. A novel calibration technique for the PAS was developed. Single scattering albedo (SSA) and absorption Angstrom exponent (AAE) from 12 different fuels with 41 individual burns were estimated and parameterized with modified combustion efficiency (MCE) and the ratio of elemental carbon (EC) to organic carbon (OC) mass. The EC / OC ratio has better capability to parameterize SSA and AAE than MCE. The simple linear regression model proposed in this study accurately predicts SSA during the first few hours of plume aging with the ambient data from a biomass burning event. In addition, absorption due to brown carbon (BrC) can significantly lower the SSA at 405 nm resulting in a wavelength dependence of SSA. Furthermore, smoldering dominated burns have larger AAE values while flaming dominated burns have smaller AAE values indicating a large fraction of BrC is emitted during the smoldering stage of the burn. Enhancement in BC absorption (EAbs) due to coating by absorbing and non-absorbing substances is estimated at 405 nm and 660 nm. Relatively smaller values of EAbs at 660 nm compared to 405 nm suggests lensing is a less important contributor to biomass burning aerosol absorption at lower wavelengths. Multiple burns of the same fuel produced significantly different EAbs values at 405 nm, but show good correlation with the EC/OC ratio indicating less dependency on fuel type and more dependency on burn conditions. In addition, absorption due to BrC can contribute up to 92 % of the total biomass burning aerosol absorption at 405 nm and up to 58 % of the total absorption at 532 nm. Indicating BrC absorption in biomass burning emissions is equally or more important than the absorption due to BC at short wavelengths. Furthermore, fractional absorption due to BrC shows reasonably good correlation with EC/OC ratio and AAE. Primary organic aerosol is found to be more volatile than secondary organic aerosol and it is found that the thermal denuder deployed in this study removes less organic aerosol if secondary organic aerosol is present. SSA at 532 nm remains constant during different conditions of aging while SSA at 405 nm increases under certain conditions suggesting the degradation of BrC. Decreases in AAE under the same experiment further support the proposed BrC degradation. The novel thermal denuder designed completely removes non-refractory material and can be used under higher flow rates (maximum of 5 LPM) than the most commercially available thermal denuders. The new calibration techniques proposed for the photoacousitc absorption spectrometer will reduce uncertainty during calibration compared to the conventional calibration methods.

Mercury (Hg) emissions from domestic biomass combustion for space heating.

PubMed

Huang, Jiaoyan; Hopke, Philip K; Choi, Hyun-Deok; Laing, James R; Cui, Huailue; Zananski, Tiffany J; Chandrasekaran, Sriraam Ramanathan; Rattigan, Oliver V; Holsen, Thomas M

2011-09-01

Three mercury (Hg) species (gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and fine particulate-bound mercury (PBM(2.5))) were measured in the stack of a small scale wood combustion chamber at 400°C, in the stack of an advanced wood boiler, and in two areas influenced by wood combustion. The low temperature process (lab-scale) emitted mostly GEM (∼99% when burning wood pellets and ∼95% when burning unprocessed wood). The high temperature wood boiler emitted a greater proportion of oxidized Hg (approximately 65%) than the low temperature system. In field measurements, mean PBM(2.5) concentrations at the rural and urban sites in winter were statistically significantly higher than in warmer seasons and were well correlated with Delta-C concentrations, a wood combustion indictor measured by an aethalometer (UV-absorbable carbon minus black carbon). Overall the results suggest that wood combustion may be an important source of oxidized mercury (mostly in the particulate phase) in northern climates in winter. Copyright © 2011 Elsevier Ltd. All rights reserved.

Source apportionment of carbonaceous aerosol in Sao Paulo using 13C and 14C measurements

NASA Astrophysics Data System (ADS)

Oyama, Beatriz; Andrade, Maria de Fatima; Holzinger, Rupert; Röckmann, Thomas; Meijer, Harro A. J.; Dusek, Ulrike

2016-04-01

The Metropolitan Area of Sao Paulo is affected by high aerosol concentrations, which contain a large fraction of organic material. Up to date, not much is known about the composition and origin of the organic aerosol in this city. We present the first source apportionment of the carbonaceous aerosol fraction in Sao Paulo, using stable (13C) and radioactive carbon isotopes (14C). 14C provides a clear-cut distinction between fossil sources, which contain no 14C, and contemporary sources such as biofuels, biomass burning, or biogenic sources, which contain a typical contemporary 14C/12C ratio. 13C can be used to distinguish C3 plants, such as maize and sugarcane, from C4 plants. This can help to identify a possible impact of sugarcane field burning in the rural areas of Sao Paulo State on the aerosol carbon in the city. In the first part of the study, we compare two tunnel studies: Tunnel 1 is frequented only by light duty vehicles, which run mainly on mixtures of gasoline with ethanol (gasohol, 25% ethanol and 85% gasoline) or hydrated ethanol (5% water and 95% ethanol). Tunnel 2 contains a significant fraction of heavy-duty diesel vehicles, and therefore the fraction of biofuels in the average fleet is lower. Comparison of 14C in organic and elemental carbon (OC and EC) shows that in both tunnels there is no significant contribution of biofuels to EC. Combusting ethanol-gasoline fuels in a vehicle engine does apparently not result in significant EC formation from ethanol. Biofuels contribute around 45% to OC in Tunnel 1 an only 20% in Tunnel 2, reflecting a strong impact of diesel vehicles in Tunnel 2. In the second part of the study we conduct a source apportionment of ambient aerosol carbon collected in a field study during winter (July-August) 2012. Ambient EC has two main sources, vehicular emissions and biomass burning. We estimate a contribution of vehicular sources to EC of roughly 90% during weekdays and 80% during weekends, using the 14C values measured in the tunnel studies. The absolute concentration of biomass burning EC is roughly 0.5 μg/m3 both during weekend and weekdays, whereas vehicular EC concentrations almost double during weekdays, increasing from 1.8 to 3.7 μg/m3 on average. OC concentrations are dominated by secondary carbon from vehicular emissions, both on weekdays and during weekends, however primary OC from biomass burning and contemporary secondary OC (from both biogenic and biomass burning emissions) are important fractions as well. Overall, primary biomass burning contributes between 10 and 30% to the carbonaceous aerosol in Sao Paulo. 13C measurements indicate that sugarcane burning could account for up to 15% of OC in the Sao Paulo metropolitan area.

Size distributions of dicarboxylic acids, ketoacids, α-dicarbonyls, sugars, WSOC, OC, EC and inorganic ions in atmospheric particles over Northern Japan: implication for long-range transport of Siberian biomass burning and East Asian polluted aerosols

NASA Astrophysics Data System (ADS)

Agarwal, S.; Aggarwal, S. G.; Okuzawa, K.; Kawamura, K.

2010-03-01

To better understand the size-segregated chemical composition of aged organic aerosols in the western Pacific rim, day- and night-time aerosol samples were collected in Sapporo, Japan during summer 2005 using Andersen impactor sampler with 5 size bins: <1.1, 1.1-2.0, 2.0-3.3, 3.3-7.0, >7.0 μm. Samples were analyzed for the molecular compositions of dicarboxylic acids, ketoacids, α-dicarbonyls, and sugars, together with water-soluble organic carbon (WSOC), organic carbon (OC), elemental carbon (EC) and inorganic ions. Based on the analyses of backward trajectory and chemical tracers, we found that during campaign, the air masses were arrived from Siberia (biomass burning source region) on 8-9 August, China (anthropogenic source region) on 9-10 August and from the East China Sea/Sea of Japan (a mixed source receptor region) on 10-11 August. Most of the diacids, ketoacids, dicarbonyls, levoglucosan, WSOC, and inorganic ions, i.e., SO42-, NH42+ and K+ were enriched in fine particles (PM1.1) whereas Ca2+, Mg2+ and Cl- peaked in coarse sizes (>1.1 μm). Interestingly, OC, most sugar compounds and NO4

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): Emissions of particulate matter from garbage burning, wood and dung cooking fires, motorcycles and brick kilns

NASA Astrophysics Data System (ADS)

Jayarathne, T. S.; Rathnayake, C.; Stockwell, C.; Daugherty, K.; Islam, R. M.; Christian, T. J.; Bhave, P.; Praveen, P. S.; Panday, A. K.; Adhikari, S.; Rasmi, M.; Goetz, D.; DeCarlo, P. F.; Saikawa, E.; Yokelson, R. J.; Stone, E. A.

2016-12-01

The Nepal Ambient Monitoring and Source Testing Experiment (NAMASTE) field campaign targeted the in-situ characterization of widespread and under-sampled combustion sources in South Asia by determining emission factors (EF) for fine particulate matter (PM2.5), organic carbon (OC), elemental carbon, inorganic ions, trace metals, and organic species. Garbage burning had the highest EF PM2.5 among the sampled sources ranging 7-124 g kg-1, with maximum EFs for garbage burned under higher moisture conditions. Garbage burning emissions contained high concentrations of polycyclic aromatic compounds (PAHs) and heavy metals (Pb, Cd, Zn) that are associated with acute and chronic health effects. Triphenylbenzene and antimony (Sb) were unique to garbage burning are good candidates for tracing this source. Cook stove emissions varied largely by stove technology (traditional mud stove, 3-stone cooking fire, chimney stove, etc.) and biomass fuel (dung, hardwood, twigs, and mixtures thereof). Burning dung consistently emitted more PM2.5 than burning wood and contained characteristic fecal sterols and stanols. Motorcycle emissions were evaluated before and after servicing, which decreased EF PM2.5 from 8.8 g kg-1 to 0.7 g kg-1. Organic species analysis indicated that this reduction in PM2.5­ is largely due to a decrease in emission of motor oil. For brick kilns, the forced draft zig-zag kilns had higher EF PM2.5 (12-19 g kg-1) compared to clamp kilns (8-13 g kg-1) and also exhibited chemical differences. PM2.5 emitted from the zig-zag kiln were mainly OC (7%), sulfate (32%) and uncharacterized chemical components (60%), while clamp kiln emissions were dominated by OC (64%) and ammonium sulfate (36%). The quantitative emission factors developed in this study may be used for source apportionment and to update regional emission inventories.

Linking Aerosol Optical Properties Between Laboratory, Field, and Model Studies

NASA Astrophysics Data System (ADS)

Murphy, S. M.; Pokhrel, R. P.; Foster, K. A.; Brown, H.; Liu, X.

2017-12-01

The optical properties of aerosol emissions from biomass burning have a significant impact on the Earth's radiative balance. Based on measurements made during the Fourth Fire Lab in Missoula Experiment, our group published a series of parameterizations that related optical properties (single scattering albedo and absorption due to brown carbon at multiple wavelengths) to the elemental to total carbon ratio of aerosols emitted from biomass burning. In this presentation, the ability of these parameterizations to simulate the optical properties of ambient aerosol is assessed using observations collected in 2017 from our mobile laboratory chasing wildfires in the Western United States. The ambient data includes measurements of multi-wavelength absorption, scattering, and extinction, size distribution, chemical composition, and volatility. In addition to testing the laboratory parameterizations, this combination of measurements allows us to assess the ability of core-shell Mie Theory to replicate observations and to assess the impact of brown carbon and mixing state on optical properties. Finally, both laboratory and ambient data are compared to the optical properties generated by a prominent climate model (Community Earth System Model (CESM) coupled with the Community Atmosphere Model (CAM 5)). The discrepancies between lab observations, ambient observations and model output will be discussed.

Quantifying the potential for low-level transport of black carbon emissions from cropland burning in Russia to the snow-covered Arctic.

NASA Astrophysics Data System (ADS)

Hall, Joanne V.; Loboda, Tatiana V.

2017-12-01

Short-lived aerosols and pollutants transported from northern mid-latitudes have amplified the short term warming in the Arctic region. Among those black carbon is recognized as the second most important human emission in regards to climate forcing, behind carbon dioxide, with a total climate forcing of +1.1Wm-2. Studies have suggested that cropland burning may be a large contributor to the black carbon emissions which are directly deposited on the snow in the Arctic. However, commonly applied atmospheric transport models rely on estimates of black carbon emissions from cropland burning which are known to be highly inaccurate in both the amount and the timing of release. Instead, this study quantifies the potential for the deposition of hypothetical black carbon emissions from known cropland burning in Russia, identified by the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire detections, through low-level transport to the snow in the Arctic using wind vectors from the European Centre for Medium-Range Weather Forecasts’ ERA-Interim Reanalysis product. Our results confirm that Russian cropland burning is a potentially significant source of black carbon deposition on the Arctic snow in the spring despite the low injection heights associated with cropland burning. Approximately 10% of the observed spring (March - May) cropland active fires (7% annual) likely contribute to black carbon deposition on the Arctic snow from as far south as at least 40°N. Furthermore, our results show that potential spring black carbon emissions from cropland burning in Russia can be deposited beyond 80°N, however, the majority ( 90% - depending on injection height) of all potential spring deposition occurs below 75°N.

Particulate matter chemical component concentrations and sources in settings of household solid fuel use.

PubMed

Secrest, M H; Schauer, J J; Carter, E M; Baumgartner, J

2017-11-01

Particulate matter (PM) air pollution derives from combustion and non-combustion sources and consists of various chemical species that may differentially impact human health and climate. Previous reviews of PM chemical component concentrations and sources focus on high-income urban settings, which likely differ from the low- and middle-income settings where solid fuel (ie, coal, biomass) is commonly burned for cooking and heating. We aimed to summarize the concentrations of PM chemical components and their contributing sources in settings where solid fuel is burned. We searched the literature for studies that reported PM component concentrations from homes, personal exposures, and direct stove emissions under uncontrolled, real-world conditions. We calculated weighted mean daily concentrations for select PM components and compared sources of PM determined by source apportionment. Our search criteria yielded 48 studies conducted in 12 countries. Weighted mean daily cooking area concentrations of elemental carbon, organic carbon, and benzo(a)pyrene were 18.8 μg m -3 , 74.0 μg m -3 , and 155 ng m -3 , respectively. Solid fuel combustion explained 29%-48% of principal component/factor analysis variance and 41%-87% of PM mass determined by positive matrix factorization. Multiple indoor and outdoor sources impacted PM concentrations and composition in these settings, including solid fuel burning, mobile emissions, dust, and solid waste burning. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

SEM/EDS Characterization of Ambient PM during Agricultural Burns

NASA Astrophysics Data System (ADS)

Wagner, J.; Wall, S.

2010-12-01

Ambient particulate matter (PM) samples were collected with UNC passive samplers during agricultural burns in Imperial Valley, California. Four Bermuda grass field burn events were sampled at 3-8 locations surrounding each burn. Sampling began at the start of each burn (30-60 min) and continued for 24-120 hours. During 3 of the 4 burn events, winds were calm and plumes were observed to travel straight up to the inversion layer. In one event, winds created a ground-level plume that enveloped two UNC samplers mounted on telephone poles very close to the field (0.2-0.3 miles away). Computer-controlled scanning electron microscopy / energy-dispersive x-ray spectroscopy (CCSEM/EDS) was used to measure particle sizes and elemental composition, from which mass concentrations and size distributions were calculated. The median PM2.5 and PM10 levels measured in this study were 3.4 and 20 ug/m3, respectively. To determine quantitative accuracy, UNC sampler PM2.5 results (PM< 2.5 um) were compared to PM2.5 results from four co-located, continuous-reading beta-attenuation monitors (EBAMs). The median agreement (EBAM - UNC) was 3.8 ug/m3. Manual SEM/EDS detected various distinctive species in these samples, including sea salt, spores, plant fragments, and large soot agglomerates. During the ‘plume event’, 24-hour PM2.5 exposures downwind were up to 17 times higher than that measured upwind. Numerous submicron combustion particles with carbon and oxygen only were directly observed by manual SEM/EDS in the two plume-impacted samples, along with larger ash particles enriched in potassium, sulfur, chlorine, calcium, sodium, and phosphorus. CCSEM/EDS data from this event was grouped into 5 particle classes to generate size-fraction-specific pie charts. Burn-related particle types contributed 95% of the PM2.5 in the location directly impacted by the ground-level plume, compared to only 12% in the upwind location. A sample of Imperial County Bermuda grass analyzed in bulk and partially-burned states was found to contain similar inorganic elements as the air samples impacted by the burn plume, as well as mold spores found at trace levels in various air samples.

Emission Factors from Aerial and Ground Measurements of Field and Laboratory Forest Burns in the Southeastern U.S.: PM2.5, Black and Brown Carbon, VOC, and PCDD/PCDF

EPA Science Inventory

Aerial- and ground-sampled emissions from three prescribed forest burns in the southeastern U.S. were compared to emissions from laboratory open burn tests using biomass from the same locations. A comprehensive array of emissions, including PM2.5, black carbon (BC), brown carbon ...

Carbon decomposition process of the residual biomass in the paddy soil of a single-crop rice field

NASA Astrophysics Data System (ADS)

Okada, K.; Iwata, T.

2014-12-01

In cultivated fields, residual organic matter is plowed into soil after harvest and decaying in fallow season. Greenhouse gases such as CO2 and CH4 is generated by the decomposition of the substantial organic matter and released into the atmosphere. In some fields, open burning is carried out by tradition, when carbon in residual matter is released into atmosphere as CO2. However, burning effect on carbon budget between crop lands and atmosphere is not entirely considered yet. In this study, coarse organic matter (COM) in paddy soil of a single-crop rice field was sampled on regular intervals between January, 2011 and August, 2014 The amount of carbon release from residual matter was estimated by analyzing of the variations in carbon content of COM. Effects of soil temperature (Ts) and soil water content (SWC) at the paddy field on the rate of carbon decomposition was investigated. Though decreasing rate of COM was much smaller in winter season, it is accelerated at the warming season between April and June every year. Decomposition was resisted for next rice cultivated season despite of highest soil temperature. In addition, the observational field was divided into two areas, and three time open burning experiments were conducted in November, 2011, 2012, and 2013. In each year, three sampling surveys, or plants before harvest and residuals before and after the burning experiment, were done. From these surveys, it is suggested that about 48±2% of carbon contents of above-ground plant was yield out as grain by harvest, and about 27±2% of carbon emitted as CO2 by burning. Carbon content of residuals plowed into soil after the harvest was estimated 293±1 and 220±36gC/m2 in no-burned and burned area, respectively, based on three-years average. It is estimated that 70 and 60% of the first input amount of COM was decomposed after a year in no-burned and burned area, respectively.

Ubiquitous influence of wildfire emissions and secondary organic aerosol on summertime atmospheric aerosol in the forested Great Lakes region

NASA Astrophysics Data System (ADS)

Gunsch, Matthew J.; May, Nathaniel W.; Wen, Miao; Bottenus, Courtney L. H.; Gardner, Daniel J.; VanReken, Timothy M.; Bertman, Steven B.; Hopke, Philip K.; Ault, Andrew P.; Pratt, Kerri A.

2018-03-01

Long-range aerosol transport affects locations hundreds of kilometers from the point of emission, leading to distant particle sources influencing rural environments that have few major local sources. Source apportionment was conducted using real-time aerosol chemistry measurements made in July 2014 at the forested University of Michigan Biological Station near Pellston, Michigan, a site representative of the remote forested Great Lakes region. Size-resolved chemical composition of individual 0.5-2.0 µm particles was measured using an aerosol time-of-flight mass spectrometer (ATOFMS), and non-refractory aerosol mass less than 1 µm (PM1) was measured with a high-resolution aerosol mass spectrometer (HR-AMS). The field site was influenced by air masses transporting Canadian wildfire emissions and urban pollution from Milwaukee and Chicago. During wildfire-influenced periods, 0.5-2.0 µm particles were primarily aged biomass burning particles (88 % by number). These particles were heavily coated with secondary organic aerosol (SOA) formed during transport, with organics (average O/C ratio of 0.8) contributing 89 % of the PM1 mass. During urban-influenced periods, organic carbon, elemental carbon-organic carbon, and aged biomass burning particles were identified, with inorganic secondary species (ammonium, sulfate, and nitrate) contributing 41 % of the PM1 mass, indicative of atmospheric processing. With current models underpredicting organic carbon in this region and biomass burning being the largest combustion contributor to SOA by mass, these results highlight the importance for regional chemical transport models to accurately predict the impact of long-range transported particles on air quality in the upper Midwest, United States, particularly considering increasing intensity and frequency of Canadian wildfires.

Chemical signatures of urban, open burning and dust transportation in an urban environment- megacity in South Asia

NASA Astrophysics Data System (ADS)

Priyadharshini, B.; Verma, S.

2016-12-01

A sub-micron aerosol sampler (SAS) consisting of two parallel stacked filter units (SFU) was deployed at an urban location (Kolkata) to study the sub-micron aerosols (water soluble inorganic ions (WSII) and carbonaceous aerosols (elemental carbon (EC) and organic carbon (OC)) collected over a year (September 2010 to August 2011). Quantification of 10 WSII species using Ion Chromatograph (IC) indicated alkaline nature of aerosols with calcium (Ca2+) being the major neutralizing factor of acidity at the study site. In terms of WSII percentage contribution, the most abundant were crustal species (Ca2+, magnesium (Mg2+) and marine species (chloride (Cl-)), followed by the secondary species sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+) . Ca2+ (fugitive and transported dust) was dominant throughout the study period with K+ concentrations exhibiting seasonality with agricultural residue burning. Further, results of carbonaceous aerosols analyzed using the OC-EC aerosol analyzer following Interagency Monitoring of Protected Visual Environment (IMPROVE) protocol exhibited pronounced seasonality in OC than EC with the overall mean concentration of OC being three folds than EC. Primary organic carbon (POC) and secondary organic carbon concentrations (SOC) estimated using EC tracer method showed 57% (43%) of POC (SOC) from various emission sources. Investigation of OC/EC ratio along with non-sea salt potassium (nss-K+) values revealed influence of season specific anthropogenic activities on both OC and EC concentrations (viz. Open burning (OB)) besides fossil fuel (FF) and biofuel (BF) usage for cooking and heating prevalent over the region. Source apportionment was discerned using positive matrix factorization (PMF) with four major factors (crustal, agricultural, anthropogenic sources and mixed source (crustal + agriculture + anthropogenic) as the primary contributors to the sub-micron aerosols at the study site.

Elemental and carbon isotope composition of total particulate matter in the urban atmosphere of Krakow, southern Poland: summer-winter contrast

NASA Astrophysics Data System (ADS)

Zimnoch, Miroslaw; Samek, Lucyna; Morawski, Filip; Rozanski, Kazimierz; Bartyzel, Jakub

2017-04-01

Deterioration of air quality in urban agglomerations is a growing problem of global significance [1]. This spurs research towards better understanding of parameters controlling air quality in urban environment (sources of particulate matter and gaseous contaminants, spatial and temporal variability of air quality, impact of atmospheric dynamics on the air quality, and several others). Krakow belongs to four largest cities in Poland. With nearly one million inhabitants, rapidly growing car traffic and significant industrial activities, Krakow agglomeration represents a typical urban environment in the eastern Europe. Characteristic features of the local climate are generally weak winds (annual average around 2.7 m s-1) and frequent inversions, extending sometimes over several days, particularly during winter seasons, favor accumulation of pollutants originating from surface emissions in the atmosphere over the city. Krakow ranks among the most polluted cities in Europe. There is an ongoing discussion on the role of different sources of total suspended particulate matter (TSPM) in the city's atmosphere, such as traffic, low- and high-level emissions related to burning of coal for heating purposes, resuspension of street dust, and some others. The presented work was aimed at exploring possibilities of using carbon isotope composition of total particulate matter collected in Krakow atmosphere, for better characterization of TSPM sources in the city, with the focus on seasonal changes of the character and intensity of those sources. Archived samples of TSPM deposited on filters (sampling interval between 5 and 20 days) and spanning the period 2005 - 2010 [3] were used for this purpose. For each year one pair of filters representing summer and winter conditions was selected. The work comprised also multi-elemental analysis of available TSPM samples using EDXRF technique. The measurements of 13C and 14C content in the total elemental carbon collected on filters revealed large seasonal variability of these two parameters. The mean fossil-fuel carbon fraction (pFF) derived from AMS radiocarbon analyses was 66.2 and 38.1%, for winter and summer samples, respectively. There was a strong positive correlation of pFF with δ13C, suggesting intensified burning of coal as the main source of fossil fuel derived carbon during winter in the city. Intensified burning of fossil fuels during winter was also reflected in larger percentage of fossil carbon in gaseous CO2 present in the city atmosphere (ffCO2) during winter. The linear relationship observed between pFF and ffCO2, when extrapolated to ffCO2 = 0 suggest that the main source of fossil carbon in TSPM during summer (extrapolated pFF value of ca. 30%) is related to transport (wearing of car tires and asphalt). The elemental composition of the analysed TSPM samples also showed distinct seasonal variability. This concerns mostly Cl, K, Zn, As, Br and Pb. References: [1] WHO's Urban Ambient Air Pollution database - Update 2016 (www.who.int/phe). [2] M. Zimnoch, P. Wach, L. Chmura, Z. Gorczyca, K. Rozanski, J. Godlowska, J. Mazur, K. Kozak, A. Jeričević. Factors controlling temporal variability of near-ground atmospheric 222Rn concentration over central Europe.Atmospheric Chemistry and Physics, 14 (2014) 9567-9581.

Stable carbon isotopes and levoglucosan for PM2.5 elemental carbon source apportionments in the largest city of Northwest China

NASA Astrophysics Data System (ADS)

Zhao, Zhuzi; Cao, Junji; Zhang, Ting; Shen, Zhenxing; Ni, Haiyan; Tian, Jie; Wang, Qiyuan; Liu, Suixin; Zhou, Jiamao; Gu, Jian; Shen, Ganzhou

2018-07-01

Stable carbon isotopes provide information on aerosol sources, but no extensive long-term studies of these isotopes have been conducted in China, and they have mainly been used for qualitative rather than quantitative purposes. Here, 24 h PM2.5 samples (n = 58) were collected from July 2008 to June 2009 at Xi'an, China. The concentrations of organic and elemental carbon (OC and EC), water-soluble OC, and the stable carbon isotope abundances of OC and EC were determined. In spring, summer, autumn and winter, the mean stable carbon isotope in OC (δ13COC) were -26.4 ± 0.6, -25.8 ± 0.7, -25.0 ± 0.6 and -24.4 ± 0.8‰, respectively, and the corresponding δ13CEC values were -25.5 ± 0.4, -25.5 ± 0.8, -25.2 ± 0.7 and -23.7 ± 0.6‰. Large δ13CEC and δ13COC values in winter can be linked to the burning coal for residential heating. Less biomass is burned during spring and summer than winter or fall (manifested in the levels of levoglucosan, i.e., 178, 85, 370, 935 ng m-3 in spring, summer, autumn, and winter), and the more negative δ13COC in the warmer months can be explained by the formation of secondary organic aerosols. A levoglucosan tracer method combined with an isotope mass balance analysis indicated that biomass burning accounted for 1.6-29.0% of the EC, and the mean value in winter (14.9 ± 7.5%) was 7 times higher than summer (2.1 ± 0.4%), with intermediate values of 6.1 ± 5.6 and 4.5 ± 2.4% in autumn and spring. Coal combustion accounted for 45.9 ± 23.1% of the EC overall, and the percentages were 63.0, 37.2, 36.7, and 33.7% in winter, autumn, summer and spring respectively. Motor vehicles accounted for 46.6 ± 26.5% of the annual EC, and these contributed over half (56.7-61.8%) of the EC in all seasons except winter. Correlations between motor vehicle-EC and coal combustion-EC with established source indicators (B(ghi)P and As) support the source apportionment results. This paper describes a simple and accurate method for apportioning the sources of EC, and the results may be beneficial for developing model simulations as well as controlling strategies in future.

Year-round Source Contributions of Fossil Fuel and Biomass Combustion to Elemental Carbon on the North Slope Alaska Utilizing Radiocarbon Analysis

NASA Astrophysics Data System (ADS)

Barrett, T. E.; Gustafsson, O.; Winiger, P.; Moffett, C.; Back, J.; Sheesley, R. J.

2015-12-01

It is well documented that the Arctic has undergone rapid warming at an alarming rate over the past century. Black carbon (BC) affects the radiative balance of the Arctic directly and indirectly through the absorption of incoming solar radiation and by providing a source of cloud and ice condensation nuclei. Among atmospheric aerosols, BC is the most efficient absorber of light in the visible spectrum. The solar absorbing efficiency of BC is amplified when it is internally mixed with sulfates. Furthermore, BC plumes that are fossil fuel dominated have been shown to be approximately 100% more efficient warming agents than biomass burning dominated plumes. The renewal of offshore oil and gas exploration in the Arctic, specifically in the Chukchi Sea, will introduce new BC sources to the region. This study focuses on the quantification of fossil fuel and biomass combustion sources to atmospheric elemental carbon (EC) during a year-long sampling campaign in the North Slope Alaska. Samples were collected at the Department of Energy Atmospheric Radiation Measurement (ARM) climate research facility in Barrow, AK, USA. Particulate matter (PM10) samples collected from July 2012 to June 2013 were analyzed for EC and sulfate concentrations combined with radiocarbon (14C) analysis of the EC fraction. Radiocarbon analysis distinguishes fossil fuel and biomass burning contributions based on large differences in end members between fossil and contemporary carbon. To perform isotope analysis on EC, it must be separated from the organic carbon fraction of the sample. Separation was achieved by trapping evolved CO2 produced during EC combustion in a cryo-trap utilizing liquid nitrogen. Radiocarbon results show an average fossil contribution of 85% to atmospheric EC, with individual samples ranging from 47% to 95%. Source apportionment results will be combined with back trajectory (BT) analysis to assess geographic source region impacts on the EC burden in the western Arctic.

Mercury content of Illinois soils

USGS Publications Warehouse

Dreher, G.B.; Follmer, L.R.

2004-01-01

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

Characterization of fine and carbonaceous particles emissions from pelletized biomass-coal blends combustion: Implications on residential crop residue utilization in China

NASA Astrophysics Data System (ADS)

Xu, Yue; Wang, Yan; Chen, Yingjun; Tian, Chongguo; Feng, Yanli; Li, Jun; Zhang, Gan

2016-09-01

Bulk biofuel, biomass pellets and pelletized biomass-coal blends were combusted in a typical rural conventional household stove and a high-efficiency stove. Reductions in PM2.5, organic carbon (OC) and elemental carbon (EC) emissions were evaluated by comparing emission factors (EFs) among 19 combinations of biofuel/residential stove types measured using a dilution sampling system. In the low-efficiency stove, the average EFs of PM2.5, OC, and EC of biomass pellets were 2.64 ± 1.56, 0.42 ± 0.36, and 0.30 ± 0.11 g/kg, respectively, significantly lower than those burned in bulk form. EFPM2.5 and EFOC of pelletized biomass combustion in the high-efficiency stove were lower than those of the same biofuel burned in the low-efficiency stove. Furthermore, pelletized corn residue and coal blends burned in the high-efficiency stove could significantly decrease emissions. Compared with the bulk material burned in the low-efficiency stove, the reduction rates of PM2.5, OC and EC from pelletized blends in the high-efficiency stove can reach 84%, 96% and 93%, respectively. If the annually produced corn residues in 2010 had been blended with 10% anthracite coal powder and burnt as pellets, it would have reduced about 82% of PM2.5, 90-96% of OC and 81-92% of EC emission in comparison with burning raw materials in conventional household stoves. Given the low cost, high health benefit and reduction effect on atmospheric pollutants, pelletized blends could be a promising alternative to fossil fuel resources or traditional bulk biofuel.

Is torrefaction of polysaccharides-rich biomass equivalent to carbonization of lignin-rich biomass?

PubMed

Bilgic, E; Yaman, S; Haykiri-Acma, H; Kucukbayrak, S

2016-01-01

Waste biomass species such as lignin-rich hazelnut shell (HS) and polysaccharides-rich sunflower seed shell (SSS) were subjected to torrefaction at 300°C and carbonization at 600°C under nitrogen. The structural variations in torrefied and carbonized biomasses were compared. Also, the burning characteristics under dry air and pure oxygen (oxy-combustion) conditions were investigated. It was concluded that the effects of carbonization on HS are almost comparable with the effects of torrefaction on SSS in terms of devolatilization and deoxygenation potentials and the increases in carbon content and the heating value. Consequently, it can be proposed that torrefaction does not provide efficient devolatilization from the lignin-rich biomass while it is relatively more efficient for polysaccharides-rich biomass. Heat-induced variations in biomass led to significant changes in the burning characteristics under both burning conditions. That is, low temperature reactivity of biomass reduced considerably and the burning shifted to higher temperatures with very high burning rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

Controls upon biomass losses and char production from prescribed burning on UK moorland.

PubMed

Worrall, Fred; Clay, Gareth D; May, Richard

2013-05-15

Prescribed burning is a common management technique used across many areas of the UK uplands. However, there are few data sets that assess the loss of biomass during burning and even fewer data on the effect of burning on above-ground carbon stocks and production of char. During fire the production of char occurs which represents a transfer of carbon from the short term bio-atmospheric cycle to the longer term geological cycle. However, biomass is consumed leading to the reduction in litter formation which is the principal mechanism for peat formation. This study aims to solve the problem of whether loss of biomass during a fire is ever outweighed by the production of refractory forms of carbon during the fire. This study combines both a laboratory study of char production with an assessment of biomass loss from a series of field burns from moorland in the Peak District, UK. The laboratory results show that there are significant effects due to ambient temperature but the most important control on dry mass loss is the maximum burn temperature. Burn temperature was also found to be linearly related to the production of char in the burn products. Optimisation of dry mass loss, char production and carbon content shows that the production of char from certain fires could store more carbon in the ecosystem than if there had been no fire. Field results show that approximately 75% of the biomass and carbon were lost through combustion, a figure comparable to other studies of prescribed fire in other settings. Char-C production was approximately 2.6% of the carbon consumed during the fire. This study has shown that there are conditions (fast burns at high temperatures) under which prescribed fire may increase C sequestration through char production and that these conditions are within existing management options available to practitioners. Copyright © 2013 Elsevier Ltd. All rights reserved.

Combining charcoal and elemental black carbon analysis in sedimentary archives: Implications for past fire regimes, the pyrogenic carbon cycle, and the human-climate interactions

NASA Astrophysics Data System (ADS)

Thevenon, Florian; Williamson, David; Bard, Edouard; Anselmetti, Flavio S.; Beaufort, Luc; Cachier, Hélène

2010-07-01

This paper addresses the quantification of combustion-derived products in oceanic and continental sediments by optical and chemical approaches, and the interest of combining such methods for reconstructing past biomass burning activity and the pyrogenic carbon cycle. In such context, the dark particles > 0.2 µm 2 remaining after the partial digestion of organic matter are optically counted by automated image analysis and defined as charcoal, while the elemental carbon remaining after thermal and chemical oxidative treatments is quantified as black carbon (BC). The obtained pyrogenic carbon records from three sediment core-based case studies, (i) the Late Pleistocene equatorial Pacific Ocean, (ii) the mid-Holocene European Lake Lucerne, and (iii) the Late Holocene African Lake Masoko, are interpreted as proxy records of regional transportation mechanisms and biomass burning activities. The results show that the burial of dark carbon-rich particles in the 360 kyr-long record from the west equatorial Pacific is controlled by the combination of sea-level changes and low-latitude atmospheric circulation patterns (summer monsoon dynamics). However, the three fold increases in charcoal and BC sediment influxes between 53-43 and 12-10 kyr BP suggest that major shifts in fire activity occur synchronously with human colonization in the Indo/Pacific region. The coarse charcoal distribution from a 7.2 kyr record from Lake Lucerne in Switzerland closely matches the regional timing of major technical, land-use, and socio-economic changes during the Neolithic (between ca. 5.7 and 5.2 kyr BP and 4.9-4.5 kyr BP), the Bronze and Iron Ages (at ca. 3.3 and 2.4 kyr BP, respectively), and the industrialization (after AD 1838), pointing to the key impact of human activities on the sources, transportation processes and reservoirs of refractory carbon during the Holocene. In the tropical Masoko maar lake in Tanzania, where charcoal and BC records are highly sensitive to the local climate and environment, surface runoffs from forested areas and/or aerial transportation over short distances are also important sources for detrital charred particles. However, this 4.3 kyr-long record exhibits a major increase in charcoal and BC sediment influxes between 1.8 and 0.6 kyr BP, synchronously with the regional extent of Late Iron Age and agricultural innovations. Therefore, in both marine and terrestrial depositional environments, the climate- and vegetation-controlled fire regimes appear to be strongly associated to societal changes, or directly affected by human practices. In fact, the anthropogenic effect associated to past human activities (e.g. settlement, agriculture, and metallurgy) has temporarily at least tripled the emissions of pyrogenic carbon in the environment. However, the data from the three Late Pleistocene to Holocene sequences also show that the redistribution of fossil particles by runoff and erosion processes is a significant source of pyrogenic carbon that should be understood as a prerequisite for interpreting sedimentary records of biomass burning.

Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands

NASA Astrophysics Data System (ADS)

Kolb, Thomas; Dore, Sabina; Montes-Helu, Mario

2013-03-01

We assessed the impacts of extreme late-summer drought on carbon balance in a semi-arid forest region in Arizona. To understand drought impacts over extremes of forest cover, we measured net ecosystem production (NEP), gross primary production (GPP), and total ecosystem respiration (TER) with eddy covariance over five years (2006-10) at an undisturbed ponderosa pine (Pinus ponderosa) forest and at a former forest converted to grassland by intense burning. Drought shifted annual NEP from a weak source of carbon to the atmosphere to a neutral carbon balance at the burned site and from a carbon sink to neutral at the undisturbed site. Carbon fluxes were particularly sensitive to drought in August. Drought shifted August NEP at the undisturbed site from sink to source because the reduction of GPP (70%) exceeded the reduction of TER (35%). At the burned site drought shifted August NEP from weak source to neutral because the reduction of TER (40%) exceeded the reduction of GPP (20%). These results show that the lack of forest recovery after burning and the exposure of undisturbed forests to late-summer drought reduce carbon sink strength and illustrate the high vulnerability of forest carbon sink strength in the southwest US to predicted increases in intense burning and precipitation variability.

Inferring Absorbing Organic Carbon Content from AERONET Data

NASA Technical Reports Server (NTRS)

Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

2011-01-01

Black carbon, light-absorbing organic carbon (often called brown carbon) and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated globally the amount of light absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South-America and Africa are relatively high (about 15-20 magnesium per square meters during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 magnesium per square meters during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while opposite is true in urban areas in India and China.

Evaluation of the Impact of Kerojet (trademark) Aquarius Water Scavenger Additive on the Thermal Stability of Jet A Fuels

DTIC Science & Technology

2014-12-01

113 Figure 64 - Elemental Analysis, Typical TMS Post - Test , Post Carbon Burn-off, Hexane rinsed ............ 114 Figure 65 – SEM (20X...Agency’s Wright-Patterson Aerospace Fuels Laboratory AFRL Air Force Research Laboratory AFTSTU Aviation Fuel Thermal Stability Test Unit ARSFSS Advanced...Approved for public release; distribution unlimited. For all ARSFSS testing , SV hysteresis is measure pre- and post - test and is defined by relating

SiO2/TiO2 Composite for Removing Hg from Combustion Exhaust

NASA Technical Reports Server (NTRS)

Mazyck, David; Londeree, Danielle; Wu, Chang-Yu; Powers, Kevin; Pitoniak, Erik

2008-01-01

Pellets made of a high-surface-area composite of silica and titania have shown promise as means of removing elemental mercury from flue gases. With further technical development and commercialization, this material could become economically attractive as a more effective, less-expensive alternative to activated carbons for removing mercury from exhaust streams of coal-burning power plants, which are the sources of more than 90 percent of all anthropogenic airborne mercury.

Modified carbon fibers to improve composite properties. [sizing fibers for reduced electrical conductivity and adhesion during combustion

NASA Technical Reports Server (NTRS)

Shepler, R. E.

1979-01-01

Thin coatings, 5 to 10 wt. percent, were applied to PAN-based carbon fibers. These coatings were intended to make the carbon fibers less electrically conductive or to cause fibers to stick together when a carbon fiber/epoxy composite burned. The effectiveness of the coatings in these regards was evaluated in burn tests with a test rig designed to simulate burning, impact and wind conditions which might release carbon fibers. The effect of the coatings on fiber and composite properties and handling was also investigated. Attempts at sizing carbon fibers with silicon dioxide, silicon carbide and boron nitride meet with varying degrees of success; however, none of these materials provided an electrically nonconductive coating. Coatings intended to stick carbon fibers together after a composite burned were sodium silicate, silica gel, ethyl silicate, boric acid and ammonium borate. Of these, only the sodium silicate and silica gel provided any sticking together of fibers. The amount of sticking was insufficient to achieve the desired objectives.

Organic tracer-based source analysis of PM2.5 organic and elemental carbon: A case study at Dongguan in the Pearl River Delta, China

NASA Astrophysics Data System (ADS)

Wang, Qiong Qiong; Huang, X. H. Hilda; Zhang, Ting; Zhang, Qingyan; Feng, Yongming; Yuan, Zibing; Wu, Dui; Lau, Alexis K. H.; Yu, Jian Zhen

2015-10-01

Organic carbon (OC) and elemental carbon (EC) are major constituents of PM2.5 and their source apportionment remains a challenging task due to the great diversity of their sources and lack of source-specific tracer data. In this work, sources of OC and EC are investigated using positive matrix factorization (PMF) analysis of PM2.5 chemical composition data, including major ions, OC, EC, elements, and organic molecular source markers, for a set of 156 filter samples collected over three years from 2010 to 2012 at Dongguan in the Pearl River Delta, China. The key organic tracers include levoglucosan, mannosan, hopanes, C27-C33n-alkanes, and polycyclic aromatic hydrocarbons (PAHs). Using these species as input for the PMF model, nine factors were resolved. Among them, biomass burning and coal combustion were significant sources contributing 15-17% of OC and 24-30% and 34-35% of EC, respectively. Industrial emissions and ship emissions, identified through their characteristic metal signatures, contributed 16-24% and 7-8% of OC and 8-11% and 16-17% of EC, respectively. Vehicle exhaust was a less significant source, accounting for 3-4% of OC and 5-8% of EC. Secondary OC, taken to be the sum of OC present in secondary sulfate and nitrate formation source factors, made up 27-36% of OC. Plastic burning, identified through 1,3,5-triphenylbenzene as a tracer, was a less important source for OC(≤4%) and EC (5-10%), but a significant source for PAHs at this site. The utility of organic source tracers was demonstrated by comparing PMF runs with different combinations of organic tracers removed from the input species list. Levoglucosan and mannosan were important additions to distinguish biomass burning from coal combustion by reducing collinearity among source profiles. Inclusion of hopanes and 1,3,5-triphenylbenzene was found to be necessary in resolving the less significant sources vehicle exhaust and plastic burning. Inclusion of C27-C33n-alkanes and PAHs can influence the source profiles resolved by PMF and thereby affect the source contributions to OC and EC. Considerably more OC (44% vs. 27% of OC) was apportioned to the secondary factors when only major components were considered in comparison with the PMF analysis with the full suite of organic tracers, mainly at the expense of coal combustion and industrial emissions. EC apportionment to the few major combustion sources was found more sensitive to inclusion of organic tracers than OC apportionment, with PAHs playing a prominent role. This work demonstrates the importance of having distinct organic tracers in identifying and quantifying OC and EC sources.

Shifts in Aboveground and Forest Floor Carbon and Nitrogen Pools After Felling and Burning in the Southern Appalachians

Treesearch

Barton D. Clinton; James M. Vose; Wayne T. Swank

1996-01-01

Changes in aboveground and forest floor mass, carbon (C), and nitrogen (N) pools were quantified on three sites in the southern Appalachians 2 yr after felling and burning. Before felling and burning, stands were characterized by sparse overstories and dense Kalmia latifolia L. understories. Two years after burning, foliar C and N pools had reached 25% and 29% of...

Sources of the PM10 aerosol in Flanders, Belgium, and re-assessment of the contribution from wood burning.

PubMed

Maenhaut, Willy; Vermeylen, Reinhilde; Claeys, Magda; Vercauteren, Jordy; Roekens, Edward

2016-08-15

From 30 June 2011 to 2 July 2012 PM10 aerosol samples were simultaneously taken every 4th day at four urban background sites in Flanders, Belgium. The sites were in Antwerpen, Gent, Brugge, and Oostende. The PM10 mass concentration was determined by weighing; organic and elemental carbon (OC and EC) were measured by thermal-optical analysis, the wood burning tracers levoglucosan, mannosan and galactosan were determined by gas chromatography/mass spectrometry, 8 water-soluble ions were measured by ion chromatography, and 15 elements were determined by a combination of inductively coupled plasma atomic emission spectrometry and mass spectrometry. The multi-species dataset was subjected to receptor modeling by PMF. The 10 retained factors (with their overall average percentage contributions to the experimental PM10 mass) were wood burning (9.5%), secondary nitrate (24%), secondary sulfate (12.6%), sea salt (10.0%), aged sea salt (19.2%), crustal matter (9.7%), non-ferrous metals (1.81%), traffic (10.3%), non-exhaust traffic (0.52%), and heavy oil burning (3.0%). The average contributions of wood smoke for the four sites were quite substantial in winter and ranged from 12.5 to 20% for the PM10 mass and from 47 to 64% for PM10 OC. Wood burning appeared to be also a notable source of As, Cd, and Pb. The contribution from wood burning to the PM10 mass and OC was also assessed by making use of levoglucosan as single marker compound and the conversion factors of Schmidl et al. (2008), as done in our previous study on wood burning in Flanders (Maenhaut et al., 2012). However, the apportionments were much lower than those deduced from PMF. It seems that the conversion factors of Schmidl et al. (2008) may not be applicable to wood burning in Flanders. From scatter plots of the PMF-derived wood smoke OC and PM versus levoglucosan, we arrived at conversion factors of 9.7 and 22.6, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013

NASA Astrophysics Data System (ADS)

Zhang, Y.-L.; Huang, R.-J.; El Haddad, I.; Ho, K.-F.; Cao, J.-J.; Han, Y.; Zotter, P.; Bozzetti, C.; Daellenbach, K. R.; Canonaco, F.; Slowik, J. G.; Salazar, G.; Schwikowski, M.; Schnelle-Kreis, J.; Abbaszade, G.; Zimmermann, R.; Baltensperger, U.; Prévôt, A. S. H.; Szidat, S.

2015-02-01

During winter 2013, extremely high concentrations (i.e., 4-20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) mass concentrations (24 h samples) were found in four major cities in China including Xi'an, Beijing, Shanghai and Guangzhou. Statistical analysis of a combined data set from elemental carbon (EC), organic carbon (OC), 14C and biomass-burning marker measurements using Latin hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. Based on 14C measurements of EC fractions (six samples each city), we found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% across all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xi'an (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10 and 48 ± 9% of OC and total carbon (TC), respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8, 48 ± 18, 53 ± 4 and 65 ± 26% of non-fossil OC for Xi'an, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately to heavily polluted days according to particulate matter mass. Despite a significant increase of the absolute mass concentrations of primary emissions from both fossil and non-fossil sources during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

Filter-based measurement of light absorption by brown carbon in PM2.5 in a megacity in South China.

PubMed

Li, Sheng; Zhu, Ming; Yang, Weiqiang; Tang, Mingjin; Huang, Xueliang; Yu, Yuegang; Fang, Hua; Yu, Xu; Yu, Qingqing; Fu, Xiaoxin; Song, Wei; Zhang, Yanli; Bi, Xinhui; Wang, Xinming

2018-08-15

Carbonaceous aerosols represent an important nexus between air pollution and climate change. Here we collected filter-based PM 2.5 samples during summer and autumn in 2015 at one urban and two rural sites in Guangzhou, a megacity in southern China, and got the light absorption by black carbon (BC) and brown carbon (BrC) resolved with a DRI Model 2015 multi-wavelength thermal/optical carbon analyzer apart from determining the organic carbon (OC) and elemental carbon (EC) contents. On average BrC contributed 12-15% of the measured absorption at 405nm (LA 405 ) during summer and 15-19% during autumn with significant increase in the LA 405 by BrC at the rural sites. Carbonaceous aerosols, identified as total carbon (TC), yielded average mass absorption efficiency at 405nm (MAE 405 ) that were approximately 45% higher in autumn than in summer, an 83% increase was noted in the average MAE 405 for OC, compared with an increase of only 14% in the average MAE 405 for EC. The LA 405 by BrC showed a good correlation (p<0.001) with the ratios of secondary OC to PM 2.5 in summer. However, this correlation was poor (p>0.1) in autumn, implying greater secondary formation of BrC in summer. The correlations between levoglucosan (a marker of biomass burning) and the LA 405 by BrC were significant during autumn but insignificant during summer, suggesting that the observed increase in the LA 405 by BrC during autumn in rural areas was largely related to biomass burning. The measurements of light absorption at 550nm presented in this study indicated that the use of the IMPROVE algorithm with an MAE value of 10m 2 /g for EC to approximate light absorption may be appropriate in areas not strongly affected by fossil fuel combustion; however, this practice would underestimate the absorption of light by PM 2.5 in areas heavily affected by vehicle exhausts and coal burning. Copyright © 2018 Elsevier B.V. All rights reserved.

The Influence of Fuel Properties on Combustion Efficiency and the Partitioning of Pyrogenic Carbon

NASA Astrophysics Data System (ADS)

Urbanski, S. P.; Baker, S. P.; Lincoln, E.; Richardson, M.

2016-12-01

The partitioning of volatized pyrogenic carbon into CO2, CO, CH4, non-methane organic carbon, and particulate organic carbon (POC) and elemental carbon (PEC) depends on the combustion characteristics of biomass fires which are influenced by the moisture content, structure and arrangement of the fuels. Flaming combustion is characterized by efficient conversion of volatized carbon into CO2. In contrast, smoldering is less efficient and produces incomplete combustion products like CH4 and carbonaceous particles. This paper presents a laboratory study that has examined the relationship between the partitioning of volatized pyrogenic carbon and specific fuel properties. The study focused on fuel beds composed of simple fuel particles — ponderosa pine needles. Ponderosa pine was selected because it contains a common wildland fuel component, conifer needles, which can be easily arranged into fuel beds of variable structure (bulk density and depth) and moisture contents that are both representative of natural conditions and are easily replicated. Modified combustion efficiency (MCE, ΔCO2/[ΔCO2+ ΔCO]) and emission factors (EF) for CO2, CO, CH4, POC, and PEC were measured over a range of needle moisture content and fuel bed bulk density and depth representative of naturally occurring fuel beds. We found that, as expected, MCE decreases as the fuel bed bulk density increases and emissions of CO, CH4, PM2.5, and POC increased. However, fuel bed depth did not appear to have an effect on how effect on MCE or emission factors. Surprisingly, a consistent relationship between the needle moisture content and emissions was not identified. At the high bulk densities, moisture content had a strong influence on MCE which explained variability in EFCH4. However, moisture content appeared to have an influence EFPOC and EFPEC that was independent of MCE. These findings may have significant implications since many models of biomass burning assume that litter fuels, such as ponderosa pine needles, burn almost exclusively via flaming combustion with a high efficiency. Our results indicate that for fuel bed properties typical of many conifer forests, pollutants generated from fires will be higher than that predicted using standard biomass burning models.

The Burning of Surface and Deep Peat during Boreal Forest and Peatland Fires: Implications for Fire Behaviour and Global Carbon Cycling

NASA Astrophysics Data System (ADS)

Turetsky, M. R.

2015-12-01

Fire is increasingly appreciated as a threat to peatlands and their carbon stocks. The global peatland carbon pool exceeds that of global vegetation and is similar to the current atmospheric carbon pool. Under pristine conditions, most of the peat carbon stock is protected from burning, and resistance to fire has increased peat carbon storage in high latitude regions over long time scales. This, in part, is due to the high porosity and storage coefficient of surface peat, which minimizes water table variability and maintains wet conditions even during drought. However, higher levels of disturbance associated with warming and increasing human activities are triggering state changes and the loss of resiliency in some peatland systems. This presentation will summarize information on burn area and severity in peatlands under undisturbed scenarios of hydrologic self-regulation, and will assess the consequences of warming and drying on peatland vegetation and wildfire behaviour. Our goal is to predict where and when peatlands will become more vulnerable to deep smouldering, given the importance of deep peat layers to global carbon cycling, permafrost stability, and a variety of other ecosystem services in northern regions. Results from two major wildfire seasons (2004 in Alaska and 2014 in the Northwest Territories) show that biomass burning in peatlands releases similar amounts of carbon to the atmosphere as patterns of burning in upland forests, but that peatlands are less vulnerable to severe burning that tends to occur in boreal forests during late season fire activity.

Oxygenated Interface on Biomass Burn Tar Balls Determined bySingle Particle Scanning Transmission X-ray Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tivanski, A.V.; Hopkins, R.J.; Tyliszczak, T.

2007-06-21

Carbonaceous particles originating from biomass burning canaccount for a large fraction of organic aerosols in a local environment.Presently, their composition, physical and chemical properties, as wellas their environmental effects are largely unknown. Tar balls, a distincttype of highly spherical carbonaceous biomass burn particles, have beenobserved in a number of field campaigns. The Yosemite AerosolCharacterization Study that took place in summer 2002 occurred during anactive fire season in the western United States; tar balls collectedduring this field campaign are described in this article. Scanningtransmission X-ray microscopy and near-edge X-ray absorption finestructure spectroscopy are used to determine the shape, structure, andsize-dependent chemicalmore » composition of ~;150 individual sphericalparticles ranging in size from 0.15 to 1.2mu m.The elemental compositionof tar balls is ~;55 percent atomic carbon and ~;45 percent atomicoxygen. Oxygen is present primarily as carboxylic carbonyls andoxygen-substituted alkyl (O-alkyl-C) functional groups, followed bymoderate amounts of ketonic carbonyls. The observed chemical composition,density, and carbon functional groups are distinctly different from sootor black carbon and more closely resemble high molecular weight polymerichumic-like substances, which could account for their reported opticalproperties. A detailed examination of the carboxylic carbonyl andO-alkyl-C functional groups as a function of particle size reveals a thinoxygenated interface layer. The high oxygen content, as well as thepresence of water-soluble carboxylic carbonyl groups, could account forthe reported hygroscopic properties of tar balls. The presence of theoxygenated layer is attributed to atmospheric processing of biomass burnparticles.« less

Mechanistic approach for nitride fuel evolution and fission product release under irradiation

NASA Astrophysics Data System (ADS)

Dolgodvorov, A. P.; Ozrin, V. D.

2017-01-01

A model for describing uranium-plutonium mixed nitride fuel pellet burning was developed. Except fission products generating, the model includes impurities of oxygen and carbon. Nitrogen behaviour in nitride fuel was analysed and the nitrogen chemical potential in solid solution with uranium-plutonium nitride was constructed. The chemical program module was tested with the help of thermodynamic equilibrium phase distribution calculation. Results were compared with analogous data in literature, quite good agreement was achieved, especially for uranium sesquinitride, metallic species and some oxides. Calculation of a process of nitride fuel burning was also conducted. Used mechanistic approaches for fission product evolution give the opportunity to find fission gas release fractions and also volumes of intergranular secondary phases. Calculations present that the most massive secondary phases are the oxide and metallic phases. Oxide phase contain approximately 1 % wt of substance over all time of burning with slightly increasing of content. Metallic phase has considerable rising of mass and by the last stage of burning it contains about 0.6 % wt of substance. Intermetallic phase has less increasing rate than metallic phase and include from 0.1 to 0.2 % wt over all time of burning. The highest element fractions of released gaseous fission products correspond to caesium and iodide.

Source apportionment and dynamic changes of carbonaceous aerosols during the haze bloom-decay process in China based on radiocarbon and organic molecular tracers

NASA Astrophysics Data System (ADS)

Liu, Junwen; Li, Jun; Liu, Di; Ding, Ping; Shen, Chengde; Mo, Yangzhi; Wang, Xinming; Luo, Chunling; Cheng, Zhineng; Szidat, Sönke; Zhang, Yanlin; Chen, Yingjun; Zhang, Gan

2016-03-01

Fine carbonaceous aerosols (CAs) is the key factor influencing the currently filthy air in megacities in China, yet few studies simultaneously focus on the origins of different CAs species using specific and powerful source tracers. Here, we present a detailed source apportionment for various CAs fractions, including organic carbon (OC), water-soluble OC (WSOC), water-insoluble OC (WIOC), elemental carbon (EC) and secondary OC (SOC) in the largest cities of North (Beijing, BJ) and South China (Guangzhou, GZ), using the measurements of radiocarbon and anhydrosugars. Results show that non-fossil fuel sources such as biomass burning and biogenic emission make a significant contribution to the total CAs in Chinese megacities: 56 ± 4 in BJ and 46 ± 5 % in GZ, respectively. The relative contributions of primary fossil carbon from coal and liquid petroleum combustions, primary non-fossil carbon and secondary organic carbon (SOC) to total carbon are 19, 28 and 54 % in BJ, and 40, 15 and 46 % in GZ, respectively. Non-fossil fuel sources account for 52 in BJ and 71 % in GZ of SOC, respectively. These results suggest that biomass burning has a greater influence on regional particulate air pollution in North China than in South China. We observed an unabridged haze bloom-decay process in South China, which illustrates that both primary and secondary matter from fossil sources played a key role in the blooming phase of the pollution episode, while haze phase is predominantly driven by fossil-derived secondary organic matter and nitrate.

Source apportionment and dynamic changes of carbonaceous aerosols during the haze bloom-decay process in China based on radiocarbon and organic molecular tracers

NASA Astrophysics Data System (ADS)

Liu, J.; Li, J.; Liu, D.; Ding, P.; Shen, C.; Mo, Y.; Wang, X.; Luo, C.; Cheng, Z.; Szidat, S.; Zhang, Y.; Chen, Y.; Zhang, G.

2015-12-01

Fine carbonaceous aerosols (CAs) is the key factor influencing the currently filthy air in megacities of China, yet seldom study simultaneously focuses on the origins of different CAs species using specific and powerful source tracers. Here, we present a detailed source apportionment for various CAs fractions, including organic carbon (OC), water-soluble OC (WSOC), water-insoluble OC (WIOC), elemental carbon (EC) and secondary OC (SOC) in the largest cities of North (Beijing, BJ) and South China (Guangzhou, GZ), respectively, using the measurements of radiocarbon and anhydrosugars. Results show that non-fossil fuel sources such as biomass burning and biogenic emission make a significant contribution to the total CAs in Chinese megacities: 56 ± 4 % in BJ and 46 ± 5 % in GZ, respectively. The relative contributions of primary fossil carbon from coal and liquid petroleum combustions, primary non-fossil carbon and secondary organic carbon (SOC) to total carbon are 19, 28 and 54 % in BJ, and 40, 15 and 46 % in GZ, respectively. Non-fossil fuel sources account for 52 % in BJ and 71 % in GZ of SOC, respectively. These results suggest that biomass burning has a greater influence on regional particulate air pollution in North China than in South China. We observed an unabridged haze bloom-decay process in South China, which illustrates that both primary and secondary matter from fossil sources played a key role in the blooming phase of the pollution episode, while haze phase is predominantly driven by fossil-derived secondary organic matter and nitrate.

Soils Data Related to the 1999 FROSTFIRE Burn

USGS Publications Warehouse

Manies, K.L.; Harden, J.W.; Ottmar, R.

2011-01-01

This report describes the sample collection and processing for U.S. Geological Survey efforts at FROSTFIRE, an experimental burn that occurred in Alaska in 1999. Data regarding carbon, water, and energy dynamics pre-fire, during, and post-fire were obtained in this landscape-scale prescribed burn. U.S. Geological Survey investigators measured changes in the stocks of carbon (C), nitrogen (N), mercury (Hg), and other components in pre- and post-burn soils of this watershed.

Radiocarbon-based impact assessment of open biomass burning on regional carbonaceous aerosols in North China.

PubMed

Zong, Zheng; Chen, Yingjun; Tian, Chongguo; Fang, Yin; Wang, Xiaoping; Huang, Guopei; Zhang, Fan; Li, Jun; Zhang, Gan

2015-06-15

Samples of total suspended particulates (TSPs) and fine particulate matter (PM2.5) were collected from 29th May to 1st July, 2013 at a regional background site in Bohai Rim, North China. Mass concentrations of particulate matter and carbonaceous species showed a total of 50% and 97% of the measured TSP and PM2.5 levels exceeded the first grade national standard of China, respectively. Daily concentrations of organic carbon (OC) and elemental carbon (EC) were detected 7.3 and 2.5 μg m(-3) in TSP and 5.2 and 2.0 μg m(-3) in PM2.5, which accounted 5.8% and 2.0% of TSP while 5.6% and 2.2% for PM2.5, respectively. The concentrations of OC, EC, TSP and PM2.5 were observed higher in the day time than those in the night time. The observations were associated with the emission variations from anthropogenic activities. Two merged samples representing from south and north source areas were selected for radiocarbon analysis. The radiocarbon measurements showed 74% of water-insoluble OC (WINSOC) and 59% of EC in PM2.5 derived from biomass burning and biogenic sources when the air masses were from south region, and 63% and 48% for the air masses from north, respectively. Combined with backward trajectories and daily burned area, open burning of agricultural wastes was found to be predominating, which was confirmed by the potential source contribution function (PSCF). Copyright © 2015 Elsevier B.V. All rights reserved.

Chemical characterization of fine organic aerosol for source apportionment at Monterrey, Mexico

NASA Astrophysics Data System (ADS)

Mancilla, Y.; Mendoza, A.; Fraser, M. P.; Herckes, P.

2015-07-01

Primary emissions from anthropogenic and biogenic sources as well as secondary formation are responsible for the pollution levels of ambient air in major urban areas. These sources release fine particles into the air that negatively impact human health and the environment. Organic molecular markers, which are compounds that are unique to specific PM2.5 sources, can be utilized to identify the major emission sources in urban areas. In this study, 43 representative PM2.5 samples, for both daytime and nighttime periods, were built from individual samples collected in an urban site of the Monterrey Metropolitan Area (MMA) during the spring and fall of 2011 and 2012. The samples were analyzed for organic carbon, elemental carbon, and organic molecular markers. Several diagnostic tools were employed for the preliminary identification of emission sources. Organic compounds for eight compound classes were quantified. The n-alkanoic acids were the most abundant, followed by n-alkanes, wood smoke markers, and levoglucosan/alkenoic acids. Polycyclic aromatic hydrocarbons (PAHs) and hopanes were less abundant. The carbon preference index (0.7-2.6) for n-alkanes indicate a major contribution of anthropogenic and mixed sources during the fall and the spring, respectively. Hopanes levels confirmed the contribution from gasoline and diesel engines. In addition, the contribution of gasoline and diesel vehicle exhaust was confirmed and identified by the PAH concentrations in PM2.5. Diagnostic ratios of PAH showed emissions from burning coal, wood, biomass, and other fossil fuels. The total PAH and elemental carbon (EC) were correlated (r2 = 0.39-0.70) across the monitoring periods, reinforcing that motor vehicles are the major contributors of PAH. Cholesterol levels remained constant during the spring and fall, showing evidence of the contribution of meat cooking operations, while the isolated concentrations of levoglucosan suggested occasional biomass burning events. Finally, source attribution results obtained using the CMB model indicate that emissions from motor vehicle exhausts are the most important, accounting for the 64 % of the PM2.5. The vegetative detritus and biomass burning had the smallest contribution (2.2 % of the PM2.5). To our knowledge, this is the second study to explore the broad chemical characterization of fine organic aerosol in Mexico and the first for the MMA.

Emission factors of atmospheric and climatic pollutants from crop residues burning.

PubMed

Santiago-De La Rosa, Naxieli; González-Cardoso, Griselda; Figueroa-Lara, José de Jesús; Gutiérrez-Arzaluz, Mirella; Octaviano-Villasana, Claudia; Ramírez-Hernández, Irma Fabiola; Mugica-Álvarez, Violeta

2018-04-13

Biomass burning is a common agricultural practice, because it allows elimination of postharvesting residues; nevertheless, it involves an inefficient combustion process that generates atmospheric pollutants emission, which has implications on health and climate change. This work focuses on the estimation of emission factors (EFs) of PM 2.5 , PM 10 , organic carbon (OC), elemental carbon (EC), carbon monoxide (CO), carbon dioxide (CO 2 ), and methane (CH 4 ) of residues from burning alfalfa, barley, beans, cotton, maize, rice, sorghum, and wheat in Mexico. Chemical characteristics of the residues were determined to establish their relationship with EFs, as well as with the modified combustion efficiency (MCE). Essays were carried out in an open combustion chamber with isokinetic sampling, following modified EPA 201-A method. EFs did not present statistical differences among different varieties of the same crop, but were statistically different among different crops, showing that generic values of EFs for all the agricultural residues can introduce significant uncertainties when used for climatic and atmospheric pollutant inventories. EFs of PM 2.5 ranged from 1.19 to 11.30 g kg -1 , and of PM 10 from 1.77 to 21.56 g kg -1 . EFs of EC correlated with lignin content, whereas EFs of OC correlated inversely with carbon content. EFs of EC and OC in PM 2.5 ranged from 0.15 to 0.41 g kg -1 and from 0.33 to 5.29 g kg -1 , respectively, and in PM 10 , from 0.17 to 0.43 g kg -1 and from 0.54 to 11.06 g kg -1 . CO 2 represented the largest gaseous emissions volume with 1053.35-1850.82 g kg -1 , whereas the lowest was CH 4 with 1.61-5.59 g kg -1 . CO ranged from 28.85 to 155.71 g kg -1 , correlating inversely with carbon content and MCE. EFs were used to calculate emissions from eight agricultural residues burning in the country during 2016, to know the potential mitigation of climatic and atmospheric pollutants, provided this practice was banned. The emission factors of particles, short-lived climatic pollutants, and atmospheric pollutants from the crop residues burning of eight agricultural wastes crops, determined in this study using a standardized method, provides better knowledge of the emissions of those species in Latin America and other developing countries, and can be used as inputs in air quality models and climatic studies. The EFs will allow the development of more accurate inventories of aerosols and gaseous pollutants, which will lead to the design of effective mitigation strategies and planning processes for sustainable agriculture.

The carbon balance of reducing wildfire risk and restoring process: an analysis of 10-year post-treatment carbon dynamics in a mixed-conifer forest

Treesearch

Morgan L. Wiechmann; Matthew D. Hurteau; Malcolm P. North; George W. Koch; Lucie Jerabkova

2015-01-01

Forests sequester carbon from the atmosphere, helping mitigate climate change. In fire-prone forests, burn events result in direct and indirect emissions of carbon. High fire-induced tree mortality can cause a transition from a carbon sink to source, but thinning and prescribed burning can reduce fire severity and carbon loss when wildfire occurs. However, treatment...

Source apportionment of organic compounds in Berlin using positive matrix factorization - assessing the impact of biogenic aerosol and biomass burning on urban particulate matter.

PubMed

Wagener, Sandra; Langner, Marcel; Hansen, Ute; Moriske, Heinz-Jörn; Endlicher, Wilfried R

2012-10-01

Source apportionment of 13 organic compounds, elemental carbon and organic carbon of ambient PM(10) and PM(1) was performed with positive matrix factorization (PMF). Samples were collected at three sites characterized by different vegetation influences in Berlin, Germany in 2010. The aim was to determine organic, mainly biogenic sources and their impact on urban aerosol collected in a densely populated region. A 6-factor solution provided the best data fit for both PM-fractions, allowing the sources isoprene- and α-pinene-derived secondary organic aerosol (SOA), bio primary, primarily attributable to fungal spores, bio/urban primary including plant fragments in PM(10) and cooking and traffic emissions in PM(1), biomass burning and combustion fossil to be identified. With mean concentrations up to 2.6 μg Cm(-3), biomass burning dominated the organic fraction in cooler months. Concentrations for α-pinene-derived SOA exceeded isoprene-derived concentrations. Estimated secondary organic carbon contributions to total organic carbon (OC) were between 7% and 42% in PM(10) and between 11% and 60% in PM(1), which is slightly lower than observed for US- or Asian cities. Primary biogenic emissions reached up to 33% of OC in the PM(10)-fraction in the late summer and autumn months. Temperature-dependence was found for both SOA-factors, correlations with ozone and mix depth only for the α-pinene-derived SOA-factor. Latter indicated input of α-pinene from the borders, highlighting differences in the origin of the precursors of both factors. Most factors were regionally distributed. High regional distribution was found to be associated with stronger influence of ambient parameters and higher concentrations at the background station. A significant contribution of biogenic emissions and biomass burning to urban organic aerosol could be stated. This indicates a considerable impact on PM concentrations also in cities in a densely populated area, and should draw the attention concerning health aspects not only to cardio-vascular diseases but also to allergy issues. Copyright © 2012 Elsevier B.V. All rights reserved.

Size distributions of dicarboxylic acids, ketoacids, α-dicarbonyls, sugars, WSOC, OC, EC and inorganic ions in atmospheric particles over Northern Japan: implication for long-range transport of Siberian biomass burning and East Asian polluted aerosols

NASA Astrophysics Data System (ADS)

Agarwal, S.; Aggarwal, S. G.; Okuzawa, K.; Kawamura, K.

2010-07-01

To better understand the size-segregated chemical composition of aged organic aerosols in the western North Pacific rim, day- and night-time aerosol samples were collected in Sapporo, Japan during summer 2005 using an Andersen impactor sampler with 5 size bins: Dp<1.1, 1.1-2.0, 2.0-3.3, 3.3-7.0, >7.0 μm. Samples were analyzed for the molecular composition of dicarboxylic acids, ketoacids, α-dicarbonyls, and sugars, together with water-soluble organic carbon (WSOC), organic carbon (OC), elemental carbon (EC) and inorganic ions. Based on the analyses of backward trajectories and chemical tracers, we found that during the campaign, air masses arrived from Siberia (a biomass burning source region) on 8-9 August, from China (an anthropogenic source region) on 9-10 August, and from the East China Sea/Sea of Japan (a mixed source receptor region) on 10-11 August. Most of the diacids, ketoacids, dicarbonyls, levoglucosan, WSOC, and inorganic ions (i.e., SO42-, NH4+ and K+) were enriched in fine particles (PM1.1) whereas Ca2+, Mg2+ and Cl- peaked in coarse sizes (>1.1 μm). Interestingly, OC, most sugar compounds and NO3- showed bimodal distributions in fine and coarse modes. In PM1.1, diacids in biomass burning-influenced aerosols transported from Siberia (mean: 252 ng m-3) were more abundant than those in the aerosols originating from China (209 ng m-3) and ocean (142 ng m-3), whereas SO42- concentrations were highest in the aerosols from China (mean: 3970 ng m-3) followed by marine- (2950 ng m-3) and biomass burning-influenced (1980 ng m-3) aerosols. Higher loadings of WSOC (2430 ng m-3) and OC (4360 ng m-3) were found in the fine mode, where biomass-burning products such as levoglucosan are abundant. This paper presents a case study of long-range transported aerosols illustrating that biomass burning episodes in the Siberian region have a significant influence on the chemical composition of carbonaceous aerosols in the western North Pacific rim.

Radiocarbon-based source apportionment of carbonaceous aerosols at a regional background site on Hainan Island, South China.

PubMed

Zhang, Yan-Lin; Li, Jun; Zhang, Gan; Zotter, Peter; Huang, Ru-Jin; Tang, Jian-Hui; Wacker, Lukas; Prévôt, André S H; Szidat, Sönke

2014-01-01

To assign fossil and nonfossil contributions to carbonaceous particles, radiocarbon ((14)C) measurements were performed on organic carbon (OC), elemental carbon (EC), and water-insoluble OC (WINSOC) of aerosol samples from a regional background site in South China under different seasonal conditions. The average contributions of fossil sources to EC, OC and WINSOC were 38 ± 11%, 19 ± 10%, and 17 ± 10%, respectively, indicating generally a dominance of nonfossil emissions. A higher contribution from fossil sources to EC (∼51%) and OC (∼30%) was observed for air-masses transported from Southeast China in fall, associated with large fossil-fuel combustion and vehicle emissions in highly urbanized regions of China. In contrast, an increase of the nonfossil contribution by 5-10% was observed during the periods with enhanced open biomass-burning activities in Southeast Asia or Southeast China. A modified EC tracer method was used to estimate the secondary organic carbon from fossil emissions by determining (14)C-derived fossil WINSOC and fossil EC. This approach indicates a dominating secondary component (70 ± 7%) of fossil OC. Furthermore, contributions of biogenic and biomass-burning emissions to contemporary OC were estimated to be 56 ± 16% and 44 ± 14%, respectively.

“Comprehensive emission measurements from prescribed ...

EPA Pesticide Factsheets

Simultaneous aerial- and ground-based emission sampling was conducted during prescribed burns at Eglin Air Force Base in November 2012 on a short grass/shrub field and a pine forest. Cumulative emission samples for volatile organic comounds, elemental carbon, organic carbon, chlorinated dioxins and furans, and PM2.5 and continuous samples for black carbon, particle size, and CO2 were taken. Aerial instruments were lofted using a 5 m diameter, helium-filled aerostat that was maneuvered with two remotely-controlled tethers mounted on all-terrain vehicles. A parallel set of instruments on the ground made simultaneous measurements, allowing for a comparison of ground level versus elevated measurements. Ground instruments were supplemented by additional measurements of polycyclic aromatic hydrocarbons and particle aerosol absorption and light scattering. Raw biomass was also gathered on site and tested in a laboratory combustion facility using the same array of instruments. This work compares emissions derived from aerial and ground sampling as well as field and laboratory results. This abstract will likely be the first ever prescribed burn study to compare laboratory and field emission results with results from aerial and and ground sampling. As such it will inform sampling methods for future events and determine the ability of laboratory simulations to mimic events inthe field.

Light absorbing organic carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

EPA Science Inventory

The light absorption of carbonaceous aerosols plays an important role in the atmospheric radiation balance. Light-absorbing organic carbon (OC), also called brown carbon (BrC), from laboratory-based biomass burning (BB) has been studied intensively to understand the contribution ...

The Betelgeuse Project II: Asteroseismology

NASA Astrophysics Data System (ADS)

Nance, S.; Sullivan, J. M.; Diaz, M.; Wheeler, J. Craig

2018-06-01

We explore the question of whether the interior state of massive red supergiant supernova progenitors can be effectively probed with asteroseismology. We have computed a suite of ten models with ZAMS masses from 15 to 25 M⊙ in intervals of 1 M⊙ including the effects of rotation, with the stellar evolutionary code MESA. We estimate characteristic frequencies and convective luminosities of convective zones at two illustrative stages, core helium burning and off-center convective carbon burning. We also estimate the power that might be delivered to the surface to modulate the luminous output considering various efficiencies and dissipation mechanisms. The inner convective regions should generate waves with characteristic periods of ˜ 20 days in core helium burning, ˜10 days in helium shell burning, and 0.1 to 1 day in shell carbon burning. Acoustic waves may avoid both shock and diffusive dissipation relatively early in core helium burning throughout most of the structure. In shell carbon burning, years before explosion, the signal generated in the helium shell might in some circumstances be weak enough to avoid shock dissipation, but is subject to strong thermal dissipation in the hydrogen envelope. Signals from a convective carbon-burning shell are very likely to be even more severely damped by within the envelope. In the most optimistic case, early in core helium burning, waves arriving close to the surface could represent luminosity fluctuations of a few millimagnitudes, but the conditions in the very outer reaches of the envelope suggest severe thermal damping there.

Dicarboxylic acids and levoglucosan in aerosols from Indo-Gangetic Plain: Inferences from day night variability during wintertime.

PubMed

Sorathia, Fena; Rajput, Prashant; Gupta, Tarun

2018-05-15

This study assesses daytime and nighttime atmospheric abundance and molecular distribution of dicarboxylic acids (DCA: C 2 -C 10 ) and biomass burning tracers (levoglucosan and biomass burning derived potassium: K + BB ) in PM 10 (particulate matter with aerodynamic diameter≤10μm) from an urban location, Kanpur (in central Indo-Gangetic Plain: IGP) during wintertime (December 2015-February 2016). In this study, PM 10 varied from 130 to 242 and 175-388μgm -3 during daytime and nighttime, respectively. The average ratios of OC/EC (day: 12.3; night: 9.3) and WSOC/OC (day: 0.74; night: 0.48) were relatively high during daytime (OC: organic carbon; EC: elemental carbon; WSOC: water-soluble organic carbon). Strong linear correlations (R 2 ≥0.6; p<0.05) of OC with levoglucosan and K + BB suggest biomass burning emission as predominant source of organic aerosols over the IGP. The measured concentrations of total DCA (ΣC 2 -C 10 ) showed pronounced diurnal variability with a higher concentration during nighttime (2510±1025ngm -3 ) as compared to that in daytime (1499±562ngm -3 ). Concentrations of oxalic acid (C 2 ), succinic acid (C 4 ) and malonic acid (C 3 ) were predominantly high as compared to other congeners of DCA (C 2 -C 10 ) over central IGP. Relatively higher mass fraction (73.4%) of C 2 in total DCA during nighttime than that in daytime (61.5%) indicates role of secondary organic aerosols (SOAs) formation involving aqueous-phase chemistry. Strong linear correlations of C 2 with C 3 and C 4 plausibly suggest that C 2 can have predominant formation pathways via decomposition of higher congeners of DCA. Overall, strong linear correlations of C 2 with levoglucosan and sulphate suggest that biomass burning emission and secondary transformations are predominant sources of DCA over IGP during wintertime. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of micron size carbon fibers released from burning graphite composites

NASA Technical Reports Server (NTRS)

Sussholz, B.

1980-01-01

Quantitative estimates were developed of micron carbon fibers released during the burning of graphite composites. Evidence was found of fibrillated particles which were the predominant source of the micron fiber data obtained from large pool fire tests. The fibrillation phenomena were attributed to fiber oxidation effects caused by the fire environment. Analysis of propane burn test records indicated that wind sources can cause considerable carbon fiber oxidation. Criteria estimates were determined for the number of micron carbon fibers released during an aircraft accident. An extreme case analysis indicated that the upper limit of the micron carbon fiber concentration level was only about half the permissible asbestos ceiling concentration level.

Aerosol composition and microstructure in the smoky atmosphere of Moscow during the August 2010 extreme wildfires

NASA Astrophysics Data System (ADS)

Popovicheva, O. B.; Kistler, M.; Kireeva, E. D.; Persiantseva, N. M.; Timofeev, M. A.; Shoniya, N. K.; Kopeikin, V. M.

2017-01-01

This is a comprehensive study of the physicochemical characterization of multicomponent aerosols in the smoky atmosphere of Moscow during the extreme wildfires of August 2010 and against the background atmosphere of August 2011. Thermal-optical analysis, liquid and ion chromatography, IR spectroscopy, and electron microscopy were used to determine the organic content (OC) and elemental content (EC) of carbon, organic/inorganic and ionic compounds, and biomass burning markers (anhydrosaccharides and the potassium ion) and study the morphology and elemental composition of individual particles. It has been shown that the fires are characterized by an increased OC/EC ratio and high concentrations of ammonium, potassium, and sulfate ions in correlation with an increased content of levoglucosan as a marker of biomass burning. The organic compounds containing carbonyl groups point to the process of photochemical aging and the formation of secondary organic aerosols in the urban atmosphere when aerosols are emitted from forest fires. A cluster analysis of individual particles has indicated that when the smokiest atmosphere is characterized by prevailing soot/tar ball particles, which are smoke-emission micromarkers.

Monitoring firefighter exposure to air toxins at prescribed burns of forest and range biomass.

Treesearch

Timothy E. Reinhardt

1991-01-01

A variety of potent air toxins are in the smoke produced by burning forest and range biomass. Preliminary data on flrefighter exposures to carbon monoxide and formaldehyde at four prescribed burns of Western United States natural fuels are presented. Formaldehyde may be correlated to carbon monoxide emissions. The firefighters' exposures to these compounds...

Comprehensive assessment of PM2.5 physicochemical properties during the Southeast Asia dry season (southwest monsoon)

NASA Astrophysics Data System (ADS)

Khan, Md Firoz; Sulong, Nor Azura; Latif, Mohd Talib; Nadzir, Mohd Shahrul Mohd; Amil, Norhaniza; Hussain, Dini Fajrina Mohd; Lee, Vernon; Hosaini, Puteri Nurafidah; Shaharom, Suhana; Yusoff, Nur Amira Yasmin Mohd; Hoque, Hossain Mohammed Syedul; Chung, Jing Xiang; Sahani, Mazrura; Mohd Tahir, Norhayati; Juneng, Liew; Maulud, Khairul Nizam Abdul; Abdullah, Sharifah Mastura Syed; Fujii, Yusuke; Tohno, Susumu; Mizohata, Akira

2016-12-01

A comprehensive assessment of fine particulate matter (PM2.5) compositions during the Southeast Asia dry season is presented. Samples of PM2.5 were collected between 24 June and 14 September 2014 using a high-volume sampler. Water-soluble ions, trace species, rare earth elements, and a range of elemental carbon (EC) and organic carbon were analyzed. The characterization and source apportionment of PM2.5 were investigated. The results showed that the 24 h PM2.5 concentration ranged from 6.64 to 68.2 µg m-3. Meteorological driving factors strongly governed the diurnal concentration of aerosol, while the traffic in the morning and evening rush hours coincided with higher levels of CO and NO2. The correlation analysis for non sea-salt K+-EC showed that EC is potentially associated with biomass burning events, while the formation of secondary organic carbon had a moderate association with motor vehicle emissions. Positive matrix factorization (PMF) version 5.0 identified the sources of PM2.5: (i) biomass burning coupled with sea salt [I] (7%), (ii) aged sea salt and mixed industrial emissions (5%), (iii) road dust and fuel oil combustion (7%), (iv) coal-fired combustion (25%), (v) mineral dust (8%), (vi) secondary inorganic aerosol (SIA) coupled with F- (15%), and (vii) motor vehicle emissions coupled with sea salt [II] (24%). Motor vehicle emissions, SIA, and coal-fired power plant are the predominant sources contributing to PM2.5. The response of the potential source contribution function and Hybrid Single-Particle Lagrangian Integrated Trajectory backward trajectory model suggest that the outline of source regions were consistent to the sources by PMF 5.0.

Restoring forest structure and process stabilizes forest carbon in wildfire-prone southwestern ponderosa pine forests.

PubMed

Hurteau, Matthew D; Liang, Shuang; Martin, Katherine L; North, Malcolm P; Koch, George W; Hungate, Bruce A

2016-03-01

Changing climate and a legacy of fire-exclusion have increased the probability of high-severity wildfire, leading to an increased risk of forest carbon loss in ponderosa pine forests in the southwestern USA. Efforts to reduce high-severity fire risk through forest thinning and prescribed burning require both the removal and emission of carbon from these forests, and any potential carbon benefits from treatment may depend on the occurrence of wildfire. We sought to determine how forest treatments alter the effects of stochastic wildfire events on the forest carbon balance. We modeled three treatments (control, thin-only, and thin and burn) with and without the occurrence of wildfire. We evaluated how two different probabilities of wildfire occurrence, 1% and 2% per year, might alter the carbon balance of treatments. In the absence of wildfire, we found that thinning and burning treatments initially reduced total ecosystem carbon (TEC) and increased net ecosystem carbon balance (NECB). In the presence of wildfire, the thin and burn treatment TEC surpassed that of the control in year 40 at 2%/yr wildfire probability, and in year 51 at 1%/yr wildfire probability. NECB in the presence of wildfire showed a similar response to the no-wildfire scenarios: both thin-only and thin and burn treatments increased the C sink. Treatments increased TEC by reducing both mean wildfire severity and its variability. While the carbon balance of treatments may differ in more productive forest types, the carbon balance benefits from restoring forest structure and fire in southwestern ponderosa pine forests are clear.

Sensitivity of global terrestrial carbon cycle dynamics to variability in satellite-observed burned area

NASA Astrophysics Data System (ADS)

Poulter, Benjamin; Cadule, Patricia; Cheiney, Audrey; Ciais, Philippe; Hodson, Elke; Peylin, Philippe; Plummer, Stephen; Spessa, Allan; Saatchi, Sassan; Yue, Chao; Zimmermann, Niklaus E.

2015-02-01

Fire plays an important role in terrestrial ecosystems by regulating biogeochemistry, biogeography, and energy budgets, yet despite the importance of fire as an integral ecosystem process, significant advances remain to improve its prognostic representation in carbon cycle models. To recommend and to help prioritize model improvements, this study investigates the sensitivity of a coupled global biogeography and biogeochemistry model, LPJ, to observed burned area measured by three independent satellite-derived products, GFED v3.1, L3JRC, and GlobCarbon. Model variables are compared with benchmarks that include pantropical aboveground biomass, global tree cover, and CO2 and CO trace gas concentrations. Depending on prescribed burned area product, global aboveground carbon stocks varied by 300 Pg C, and woody cover ranged from 50 to 73 Mkm2. Tree cover and biomass were both reduced linearly with increasing burned area, i.e., at regional scales, a 10% reduction in tree cover per 1000 km2, and 0.04-to-0.40 Mg C reduction per 1000 km2. In boreal regions, satellite burned area improved simulated tree cover and biomass distributions, but in savanna regions, model-data correlations decreased. Global net biome production was relatively insensitive to burned area, and the long-term land carbon sink was robust, 2.5 Pg C yr-1, suggesting that feedbacks from ecosystem respiration compensated for reductions in fuel consumption via fire. CO2 transport provided further evidence that heterotrophic respiration compensated any emission reductions in the absence of fire, with minor differences in modeled CO2 fluxes among burned area products. CO was a more sensitive indicator for evaluating fire emissions, with MODIS-GFED burned area producing CO concentrations largely in agreement with independent observations in high latitudes. This study illustrates how ensembles of burned area data sets can be used to diagnose model structures and parameters for further improvement and also highlights the importance in considering uncertainties and variability in observed burned area data products for model applications.

Experimental Constraints on Iron Mobilization into Biomass Burning Aerosols

NASA Astrophysics Data System (ADS)

Sherry, A. M.; Romaniello, S. J.; Herckes, P.; Anbar, A. D.

2017-12-01

Atmospheric deposition of iron (Fe) can limit marine primary productivity and, therefore, carbon dioxide uptake. Recent modeling studies suggest that biomass burning aerosols may contribute a significant amount of soluble Fe to the surface ocean. To address this hypothesis, we collected foliage samples from species representative of several biomes impacted by severe fire events. Existing studies of burn-induced trace element mobilization have often collected both entrained soil particles along with material from burning biomass, making it difficult to determine the actual source of aerosolized trace metals. In order to better constrain the importance of biomass vs. entrained soil as a source of trace metals in burn aerosols, we conducted burn experiments using soil-free foliage representative of a variety of fire-impacted ecosystems. The resulting burn aerosols were collected in two stages (PM > 2.5 μm and PM < 2.5 μm) on cellulose filters using a high-volume air sampler equipped an all-Teflon impactor. Unburned foliage and burn aerosols were analyzed for Fe and other trace metals using inductively coupled plasma mass spectrometry (ICP-MS). Our results show that 0.06-0.86 % of Fe in plant biomass is likely mobilized as atmospheric aerosols during biomass burning events, depending on the type of foliage. We used these results and estimates of annual global wildfire area to estimate the impact of biomass burning aerosols on total atmospheric Fe flux to the ocean. We estimate that biomass-derived Fe likely contributes 3% of the total soluble Fe flux from aerosols. Prior studies, which implicitly included both biomass and soil-derived Fe, concluded that biomass burning contributed as much as 7% of the total marine soluble Fe flux from aerosols. Together, these studies suggest that biomass and fire-entrained soil probably contribute equally to the total fire-derived Fe aerosol flux. Further study of solubility differences between plant- and soil-derived Fe is needed to improve estimates of the soluble Fe contribution from biomass burning to the marine soluble Fe flux.

The First 3D Simulations of Carbon Burning in a Massive Star

NASA Astrophysics Data System (ADS)

Cristini, A.; Meakin, C.; Hirschi, R.; Arnett, D.; Georgy, C.; Viallet, M.

2017-11-01

We present the first detailed three-dimensional hydrodynamic implicit large eddy simulations of turbulent convection for carbon burning. The simulations start with an initial radial profile mapped from a carbon burning shell within a 15 M⊙ stellar evolution model. We considered 4 resolutions from 1283 to 10243 zones. These simulations confirm that convective boundary mixing (CBM) occurs via turbulent entrainment as in the case of oxygen burning. The expansion of the boundary into the surrounding stable region and the entrainment rate are smaller at the bottom boundary because it is stiffer than the upper boundary. The results of this and similar studies call for improved CBM prescriptions in 1D stellar evolution models.

Prescribed fire as a means of reducing forest carbon emissions in the western United States.

PubMed

Wiedinmyer, Christine; Hurteau, Matthew D

2010-03-15

Carbon sequestration by forested ecosystems offers a potential climate change mitigation benefit. However, wildfire has the potential to reverse this benefit In the western United States, climate change and land management practices have led to increases in wildfire intensity and size. One potential means of reducing carbon emissions from wildfire is the use of prescribed burning,which consumes less biomass and therefore releases less carbon to the atmosphere. This study uses a regional fire emissions model to estimate the potential reduction in fire emissions when prescribed burning is applied in dry, temperate forested systems of the western U.S. Daily carbon dioxide (CO(2)) fire emissions for 2001-2008 were calculated for the western U.S. for two cases: a default wildfire case and one in which prescribed burning was applied. Wide-scale prescribed fire application can reduce CO(2) fire emissions for the western U.S. by 18-25%1 in the western U.S., and by as much as 60% in specific forest systems. Although this work does not address important considerations such as the feasibility of implementing wide-scale prescribed fire management or the cumulative emissions from repeated prescribed burning, it does provide constraints on potential carbon emission reductions when prescribed burning is used.

Important sources and chemical species of ambient fine particles related to adverse health effects

NASA Astrophysics Data System (ADS)

Heo, J.

2017-12-01

Although many epidemiological studies have reported that exposure to ambient fine particulate matter (PM2.5) has been linked to increases in mortality and mobidity health outcomes, the key question of which chemical species and sources of PM2.5 are most harmful to public health remains unanswered in the air pollution research area. This study was designed to address the key question with evaluating the risks of exposure to chemical species and source-specific PM2.5 mass on morbidity. Hourly measurements of PM2.5 mass and its major chemical species, including organic carbon, elemental carbon, ions, and trace elements, were observed from January 1 to December 31, 2013 at four of the PM2.5 supersites in urban environments in Korea and the reuslts were used in a positive matrix factorization to estimate source contributions to PM2.5 mass. Nine sources, including secondary sulfate, secondary nitrate, mobile, biomass burning, roadway emission, industry, oil combustion, soil, and aged sea salt, were identified and secondary inorganic aerosol factors (i.e. secondary sulfalte, and secondary nitrate) were the dominant sources contributing to 40% of the total PM2.5 mass in the study region. In order to evaluate the risks of exposure to chemical species and sources of PM2.5 on morbidity, emergency room visits for cardivascular disease and respiratory disease were considered. Hourly health outcomes were compared with hourly measurments of the PM2.5 chemical species and sources using a poission generalized linear model incorporating natural splines, as well as time-stratified case-crossover design. The PM2.5 mass and speveral chemical components, such as organic carbon, elemetal carbon, zinc, and potassium, were strongly associated with morbidity. Source-apporitionmened PM2.5 mass derived from biomass burning, and mobile sources, was significantly associated with cardiovascular and respiratory diseases. The findings represent that local combustion may be particularly important contributor to PM2.5, leading to adverse human health effects.

Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic.

PubMed

Valavanidis, Athanasios; Iliopoulos, Nikiforos; Gotsis, George; Fiotakis, Konstantinos

2008-08-15

The production and use of polymeric materials worldwide has reached levels of 150 million tonnes per year, and the majority of plastic materials are discarded in waste landfills where are burned generating toxic emissions. In the present study we conducted laboratory experiments for batch combustion/burning of commercial polymeric materials, simulating conditions of open fire combustion, with the purpose to analyze their emissions for chemical characteristics of toxicological importance. We used common types of plastic materials: poly(vinyl chloride) (PVC), low and high density poly(ethylene) (LDPE, HDPE), poly(styrene) (PS), poly(propylene) (PP) and poly(ethylene terephthalate) (PET). Samples of particulate smoke (soot) collected on filters and residue solid ash produced by controlled burning conditions at 600-750 degrees C are used for analysis. Emissions of particulate matter, persistent free radicals embedded in the carbonaceous polymeric matrix, heavy metals, other elements and PAHs were determined in both types of samples. Results showed that all plastics burned easily generating charred residue solid ash and black airborne particulate smoke. Persistent carbon- and oxygen-centered radicals, known for their toxic effects in inhalable airborne particles, were detected in both particulate smoke emissions and residue solid ash. Concentrations of heavy metals and other elements (determined by Inductively Coupled Plasma Emission Spectrometry, ICP, method) were measured in the airborne soot and residue ash. Toxic heavy metals, such as Pb, Zn, Cr, Ni, and Cd were relatively at were found at low concentrations. High concentrations were found for some lithophilic elements, such as Na, Ca, Mg, Si and Al in particulate soot and residue solid ash. Measurements of PAHs showed that low molecular weight PAHs were at higher concentrations in the airborne particulate soot than in the residue solid ash for all types of plastic. Higher-ringed PAHs were detected at higher concentrations in the residue solid ash of PVC as compared to those from the other types of plastic. The open-air burning of plastic material and their toxic emissions is of growing concern in areas of municipal solid waste where open-fires occur intentionally or accidentally. Another problem is building fires in which victims may suffer severe smoke inhalation from burning plastic materials in homes and in working places.

Coal-Quality Information - Key to the Efficient and Environmentally Sound Use of Coal

USGS Publications Warehouse

Finkleman, Robert B.

1997-01-01

The rock that we refer to as coal is derived principally from decomposed organic matter (plants) consisting primarily of the element carbon. When coal is burned, it produces energy in the form of heat, which is used to power machines such as steam engines or to drive turbines that produce electricity. Almost 60 percent of the electricity produced in the United States is derived from coal combustion. Coal is an extraordinarily complex material. In addition to organic matter, coal contains water (up to 40 or more percent by weight for some lignitic coals), oils, gases (such as methane), waxes (used to make shoe polish), and perhaps most importantly, inorganic matter (fig. 1). The inorganic matter--minerals and trace elements--cause many of the health, environmental, and technological problems attributed to coal use (fig. 2). 'Coal quality' is the term used to refer to the properties and characteristics of coal that influence its behavior and use. Among the coal-quality characteristics that will be important for future coal use are the concentrations, distribution, and forms of the many elements contained in the coal that we intend to burn. Knowledge of these quality characteristics in U.S. coal deposits may allow us to use this essential energy resource more efficiently and effectively and with less undesirable environmental impact.

Impact of Wildfire on Solute Release in Forested Catchments, Jemez River, New Mexico, USA

NASA Astrophysics Data System (ADS)

Sanchez, R. A.; Meixner, T.; McIntosh, J. C.; Chorover, J.

2017-12-01

Wildfires represent a large disturbance to the hydrology and biogeochemistry of forested catchments. The number, size and severity of wildfires have significantly increased in the western United States since 1990. Nutrients and other elements (e.g. Ca) that were taken up and stored by biomass are released from burned vegetation during forest fires and transported downgradient via overland flow, shallow subsurface flow, and/or deep groundwater flow. Ash accumulations on hillslopes may also store particulate carbon and contain elevated concentrations of elements that maybe leached into surface and ground water over extended periods of time. In 2013, the Thompson Ridge wildfire burned headwater catchments in the Jemez River Basin Critical Zone Observatory (JRB-CZO) within the Valles Caldera National Preserve, New Mexico USA. The burn severity and area impacted were different in the three headwater catchments. This study investigated the impact of the wildfire on surface water quality, including how the fire-induced impacts evolved with time, and how biogeochemical processes controlled post-fire solute concentrations in the surface water. Comparison of pre- and post-fire surface water solute chemistry shows increases in major cations and anions following fire. Increases in nitrate and sulfate concentrations in streams after the wildfire were likely from leaching of burned biomass. The elevated NO3- and SO42- concentrations persisted for over two years, and were even higher during spring snowmelt. Meanwhile, base cation concentrations increased immediately, within a few weeks after the fire, likely related to leaching from combusted organic matter; and, over a period of approximately two months, base cation concentrations returned to pre-fire levels. Trace element behavior was also altered by fire. For example, while pre-fire aluminum concentrations in stream flow increased significantly during the wet seasons (snowmelt and monsoons), the post-fire observations do not show significant changes with increase in discharge.

Management of forest fires to maximize carbon sequestration in temperate and boreal forests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guggenheim, D.E.

1996-12-31

This study examines opportunities for applying prescribed burning strategies to forest stands to enhance net carbon sequestration and compared prescribed burning strategies with more conventional forestry-based climate change mitigation alternatives, including fire suppression and afforestation. Biomass burning is a major contributor to greenhouse gas accumulation in the atmosphere. Biomass burning has increased by 50% since 1850. Since 1977, the annual extent of burning in the northern temperate and boreal forests has increased dramatically, from six- to nine-fold. Long-term suppression of fires in North America, Russia, and other parts of the world has led to accumulated fuel load and an increasemore » in the destructive power of wildfires. Prescribed burning has been used successfully to reduce the destructiveness of wildfires. However, across vast areas of Russia and other regions, prescribed burning is not a component of forest management practices. Given these factors and the sheer size of the temperate-boreal carbon sink, increasing attention is being focused on the role of these forests in mitigating climate change, and the role of fire management strategies, such as prescribed burning, which could work alongside more conventional forestry-based greenhouse gas offset strategies, such as afforestation.« less

Radiocarbon determination of fossil and contemporary carbon contribution to aerosol in the Pacific Islands.

PubMed

Isley, C F; Nelson, P F; Taylor, M P; Williams, A A; Jacobsen, G E

2018-06-21

Combustion emissions are of growing concern across all Pacific Island Countries, which account for >10,000 km 2 of the earth's surface area; as for many other small island states globally. Apportioning emissions inputs for Suva, the largest Pacific Island city, will aid in development of emission reduction strategies. Total suspended particulate (TSP) and fine particulate (PM 2.5 ) samples were collected for Suva City, a residential area (Kinoya, TSP) and a mainly ocean-influenced site (Suva Point, TSP) from 2014 to 2015. Percentages of contemporary and fossil carbon were determined by radiocarbon analysis (accelerator mass spectrometry); for non‑carbonate carbon (NCC), elemental carbon (EC) and organic carbon (OC). Source contributions to particulate matter were identified and the accuracy of previous emissions inventory and source apportionment studies was evaluated. Suva Point NCC concentrations (2.7 ± 0.4 μg/m 3 ) were four times lower than for City (13 ± 2 μg/m 3 in TSP) and Kinoya (13 ± 1 μg/m 3 in TSP); demonstrating the contribution of land-based emissions activities in city and residential areas. In Suva City, total NCC in air was 81% (79%-83%) fossil carbon, from vehicles, shipping, power generation and industry; whilst in the residential area, 48% (46%-50%) of total NCC was contemporary carbon; reflecting the higher incidence of biomass and waste burning and of cooking activities. Secondary organic fossil carbon sources contributed >36% of NCC mass at the city and >29% at Kinoya; with biogenic carbon being Kinoya's most significant source (approx. 30% of NCC mass). These results support the previous source apportionment studies for the city area; yet show that, in line with emissions inventory studies, biomass combustion contributes more PM 2.5 mass in residential areas. Hence air quality management strategies need to target open burning activities as well as fossil fuel combustion. Copyright © 2018 Elsevier B.V. All rights reserved.

Combustion studies of coal derived solid fuels by thermogravimetric analysis. III. Correlation between burnout temperature and carbon combustion efficiency

USGS Publications Warehouse

Rostam-Abadi, M.; DeBarr, J.A.; Chen, W.T.

1990-01-01

Burning profiles of 35-53 ??m size fractions of an Illinois coal and three partially devolatilized coals prepared from the original coal were obtained using a thermogravimetric analyzer. The burning profile burnout temperatures were higher for lower volatile fuels and correlated well with carbon combustion efficiencies of the fuels when burned in a laboratory-scale laminar flow reactor. Fuels with higher burnout temperatures had lower carbon combustion efficiencies under various time-temperature conditions in the laboratory-scale reactor. ?? 1990.

Origin of the Elements

NASA Astrophysics Data System (ADS)

Truran, J. W., Jr.; Heger, A.

2003-12-01

Nucleosynthesis is the study of the nuclear processes responsible for the formation of the elements which constitute the baryonic matter of the Universe. The elements of which the Universe is composed indeed have a quite complicated nucleosynthesis history, which extends from the first three minutes of the Big Bang through to the present. Contemporary nucleosynthesis theory associates the production of certain elements/isotopes or groups of elements with a number of specific astrophysical settings, the most significant of which are: (i) the cosmological Big Bang, (ii) stars, and (iii) supernovae.Cosmological nucleosynthesis studies predict that the conditions characterizing the Big Bang are consistent with the synthesis only of the lightest elements: 1H, 2H, 3He, 4He, and 7Li (Burles et al., 2001; Cyburt et al., 2002). These contributions define the primordial compositions both of galaxies and of the first stars formed therein. Within galaxies, stars and supernovae play the dominant role both in synthesizing the elements from carbon to uranium and in returning heavy-element-enriched matter to the interstellar gas from which new stars are formed. The mass fraction of our solar system (formed ˜4.6 Gyr ago) in the form of heavy elements is ˜1.8%, and stars formed today in our galaxy can be a factor 2 or 3 more enriched (Edvardsson et al., 1993). It is the processes of nucleosynthesis operating in stars and supernovae that we will review in this chapter. We will confine our attention to three broad categories of stellar and supernova site with which specific nucleosynthesis products are understood to be identified: (i) intermediate mass stars, (ii) massive stars and associated type II supernovae, and (iii) type Ia supernovae. The first two of these sites are the straightforward consequence of the evolution of single stars, while type Ia supernovae are understood to result from binary stellar evolution.Stellar nucleosynthesis resulting from the evolution of single stars is a strong function of stellar mass (Woosley et al., 2002). Following phases of hydrogen and helium burning, all stars consist of a carbon-oxygen core. In the mass range of the so-called "intermediate mass" stars (1<˜M/M⊙<˜10), the temperatures realized in their degenerate cores never reach levels at which carbon ignition can occur. Substantial element production occurs in such stars during the asymptotic giant branch (AGB) phase of evolution, accompanied by significant mass loss, and they evolve to white dwarfs of carbon-oxygen (or, less commonly, oxygen-neon) composition. In contrast, the increased pressures that are experienced in the cores of stars of masses M>˜10M⊙ yield higher core temperatures that enable subsequent phases of carbon, neon, oxygen, and silicon burning to proceed. Collapse of an iron core devoid of further nuclear energy then gives rise to a type II supernova and the formation of a neutron star or black hole remnant (Heger et al., 2003). The ejecta of type IIs contain the ashes of nuclear burning of the entire life of the star, but are also modified by the explosion itself. They are the source of most material (by mass) heavier than helium.Observations reveal that binary stellar systems comprise roughly half of all stars in our galaxy. Single star evolution, as noted above, can leave in its wake compact stellar remnants: white dwarfs, neutron stars, and black holes. Indeed, we have evidence for the occurrence of all three types of condensed remnant in binaries. In close binary systems, mass transfer can take place from an evolving companion onto a compact object. This naturally gives rise to a variety of interesting phenomena: classical novae (involving hydrogen thermonuclear runaways in accreted shells on white dwarfs (Gehrz et al., 1998)), X-ray bursts (hydrogen/helium thermonuclear runaways on neutron stars (Strohmayer and Bildsten, 2003)), and X-ray binaries (accretion onto black holes). For some range of conditions, accretion onto carbon-oxygen white dwarfs will permit growth of the CO core to the Chandrasekhar limit MCh=1.4M⊙, and a thermonuclear runaway in to core leads to a type Ia supernova.In this chapter, we will review the characteristics of thermonuclear processing in the three environments we have identified: (i) intermediate-mass stars; (ii) massive stars and type II supernovae; and (iii) type Ia supernovae. This will be followed by a brief discussion of galactic chemical evolution, which illustrates how the contributions from each of these environments are first introduced into the interstellar media of galaxies. Reviews of nucleosynthesis processes include those by Arnett (1995), Trimble (1975), Truran (1984), Wallerstein et al. (1997), and Woosley et al. (2002). An overview of galactic chemical evolution is presented by Tinsley (1980).

A neutron star with a carbon atmosphere in the Cassiopeia A supernova remnant.

PubMed

Ho, Wynn C G; Heinke, Craig O

2009-11-05

The surface of hot neutron stars is covered by a thin atmosphere. If there is accretion after neutron-star formation, the atmosphere could be composed of light elements (H or He); if no accretion takes place or if thermonuclear reactions occur after accretion, heavy elements (for example, Fe) are expected. Despite detailed searches, observations have been unable to confirm the atmospheric composition of isolated neutron stars. Here we report an analysis of archival observations of the compact X-ray source in the centre of the Cassiopeia A supernova remnant. We show that a carbon atmosphere neutron star (with low magnetic field) produces a good fit to the spectrum. Our emission model, in contrast with others, implies an emission size consistent with theoretical predictions for the radius of neutron stars. This result suggests that there is nuclear burning in the surface layers and also identifies the compact source as a very young ( approximately 330-year-old) neutron star.

Source Apportionment of PM2.5 in Delhi, India Using PMF Model.

PubMed

Sharma, S K; Mandal, T K; Jain, Srishti; Saraswati; Sharma, A; Saxena, Mohit

2016-08-01

Chemical characterization of PM2.5 [organic carbon, elemental carbon, water soluble inorganic ionic components, and major and trace elements] was carried out for a source apportionment study of PM2.5 at an urban site of Delhi, India from January, 2013, to December, 2014. The annual average mass concentration of PM2.5 was 122 ± 94.1 µg m(-3). Strong seasonal variation was observed in PM2.5 mass concentration and its chemical composition with maxima during winter and minima during monsoon. A receptor model, positive matrix factorization (PMF) was applied for source apportionment of PM2.5 mass concentration. The PMF model resolved the major sources of PM2.5 as secondary aerosols (21.3 %), followed by soil dust (20.5 %), vehicle emissions (19.7 %), biomass burning (14.3 %), fossil fuel combustion (13.7 %), industrial emissions (6.2 %) and sea salt (4.3 %).

Molecular-Size-Separated Brown Carbon Absorption for Biomass-Burning Aerosol at Multiple Field Sites.

PubMed

Di Lorenzo, Robert A; Washenfelder, Rebecca A; Attwood, Alexis R; Guo, Hongyu; Xu, Lu; Ng, Nga L; Weber, Rodney J; Baumann, Karsten; Edgerton, Eric; Young, Cora J

2017-03-21

Biomass burning is a known source of brown carbon aerosol in the atmosphere. We collected filter samples of biomass-burning emissions at three locations in Canada and the United States with transport times of 10 h to >3 days. We analyzed the samples with size-exclusion chromatography coupled to molecular absorbance spectroscopy to determine absorbance as a function of molecular size. The majority of absorption was due to molecules >500 Da, and these contributed an increasing fraction of absorption as the biomass-burning aerosol aged. This suggests that the smallest molecular weight fraction is more susceptible to processes that lead to reduced light absorption, while larger-molecular-weight species may represent recalcitrant brown carbon. We calculate that these large-molecular-weight species are composed of more than 20 carbons with as few as two oxygens and would be classified as extremely low volatility organic compounds (ELVOCs).

Ground based chemical characterization of submicron aerosol during the South American Biomass Burning Analysis (SAMBBA) field experiment

NASA Astrophysics Data System (ADS)

Brito, Joel; Artaxo, Paulo; Varanda Rizzo, Luciana; Johnson, Ben; Haywood, Jim; Longo, Karla; Freitas, Saulo; Coe, Hugh

2013-04-01

This work presents the results of an Aerosol Chemical Speciation Monitor (ACSM) which was successfully operated at a ground station in Porto Velho, Brazil, during the South American Biomass Burning Analysis (SAMBBA). SAMBBA is an international research project based on experimental and modeling activities designed to investigate the impacts of biomass burning emissions on climate, air quality and numerical weather prediction over South America. The measurement program was headed by the deployment of UK's Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft over Brazil during the dry season of 2012. The aircraft operation was coordinated with ground-based measurements at Porto Velho, operated by the University of Sao Paulo. Besides the aerosol chemical speciation, continuous measurements of aerosol size distribution and optical properties were carried out at the ground station, together with CO, CO2 and O3. Filters for trace elements measured by XRF and for OC/EC determined using a Sunset instrument were also collected at the ground based component of SAMBBA. The ACSM collected data for three weeks during September 2012. This period included a strong biomass burning event which showed a marked peak in f60, linked with Levoglucosan, a well-known biomass burning marker. During the biomass burning event, organics concentrations rose up to 80 μg/m3, black carbon close to 6 μg/m3 and CO mixing ratio above 2 ppmv. Fast biomass burning aerosol processing in the atmosphere could be observed through the relative contributions of C2H3O+ vs. CO2+ relative to total organic mass (f44 vs. f43). A clear diurnal variation throughout the sampling period has been observed for organic aerosols with a median peak of 9 μg/m3 at 04:00 LT and a minima of 5 μg/m3 at 18:00 LT. Preliminary results indicate that organics are responsible for 85% of PM1 non-refractory aerosols. The data set will allow the study of interactions between biomass burning and biogenic emissions, focusing on changes in the radiation balance, atmospheric chemistry and effects on the terrestrial biosphere including carbon uptake by the Amazonian forest.

Wildland fire emissions, carbon, and climate: wildland fire detection and burned area in the United States

Treesearch

Wei Min Hao; Narasimhan K. Larkin

2014-01-01

Biomass burning is a major source of greenhouse gases, aerosols, black carbon, and atmospheric pollutants that affects regional and global climate and air quality. The spatial and temporal extent of fires and the size of burned areas are critical parameters in the estimation of fire emissions. Tremendous efforts have been made in the past 12 years to characterize the...

Indoor Spatial Monitoring of Combustion Generated Pollutants (TSP, CO, and BaP) by Indian Cookstoves

DTIC Science & Technology

1988-07-01

various building materials and consumer products, and combustion appliances. People and pets normally emit C02 , moisture, odors, and microbes. Tobacco ...fuels Group II. Sources both indoor and outdoor: Nitric oxide, nitrogen dioxide Fuel-burning, tobacco smoke Polycyclic hydrocarbons Fuel-burning, tobacco ...smoke Carbon monoxide Fuel-burning, tobacco smoke Carbon dioxide Metabolic activity, combustion Suspended particulate matter Resuspension

Characteristics and sources of carbonaceous aerosols from Shanghai, China

NASA Astrophysics Data System (ADS)

Cao, J.-J.; Zhu, C.-S.; Tie, X.-X.; Geng, F.-H.; Xu, H.-M.; Ho, S. S. H.; Wang, G.-H.; Han, Y.-M.; Ho, K.-F.

2013-01-01

An intensive investigation of carbonaceous PM2.5 and TSP (total suspended particles) from Pudong (China) was conducted as part of the MIRAGE-Shanghai (Megacities Impact on Regional and Global Environment) experiment in 2009. Data for organic and elemental carbon (OC and EC), organic species, including C17 to C40 n-alkanes and 17 polycyclic aromatic hydrocarbons (PAHs), and stable carbon isotopes OC (δ13COC) and EC (δ13CEC) were used to evaluate the aerosols' temporal variations and identify presumptive sources. High OC/EC ratios indicated a large fraction of secondary organic aerosol (SOA); high char/soot ratios indicated stronger contributions to EC from motor vehicles and coal combustion than biomass burning. Diagnostic ratios of PAHs indicated that much of the SOA was produced via coal combustion. Isotope abundances (δ13COC = -24.5 ± 0.8‰ and δ13CEC = -25.1 ± 0.6‰) indicated that fossil fuels were the most important source for carbonaceous PM2.5 (particulate matter less than 2.5 micrometers in diameter), with lesser impacts from biomass burning and natural sources. An EC tracer system and isotope mass balance calculations showed that the relative contributions to total carbon from coal combustion, motor vehicle exhaust, and SOA were 41%, 21%, and 31%; other primary sources such as marine, soil and biogenic emissions contributed 7%. Combined analyses of OC and EC, n-alkanes and PAHs, and stable carbon isotopes provide a new way to apportion the sources of carbonaceous particles.

3D hydrodynamic simulations of carbon burning in massive stars

NASA Astrophysics Data System (ADS)

Cristini, A.; Meakin, C.; Hirschi, R.; Arnett, D.; Georgy, C.; Viallet, M.; Walkington, I.

2017-10-01

We present the first detailed 3D hydrodynamic implicit large eddy simulations of turbulent convection of carbon burning in massive stars. Simulations begin with radial profiles mapped from a carbon-burning shell within a 15 M⊙ 1D stellar evolution model. We consider models with 1283, 2563, 5123, and 10243 zones. The turbulent flow properties of these carbon-burning simulations are very similar to the oxygen-burning case. We performed a mean field analysis of the kinetic energy budgets within the Reynolds-averaged Navier-Stokes framework. For the upper convective boundary region, we find that the numerical dissipation is insensitive to resolution for linear mesh resolutions above 512 grid points. For the stiffer, more stratified lower boundary, our highest resolution model still shows signs of decreasing sub-grid dissipation suggesting it is not yet numerically converged. We find that the widths of the upper and lower boundaries are roughly 30 per cent and 10 per cent of the local pressure scaleheights, respectively. The shape of the boundaries is significantly different from those used in stellar evolution models. As in past oxygen-shell-burning simulations, we observe entrainment at both boundaries in our carbon-shell-burning simulations. In the large Péclet number regime found in the advanced phases, the entrainment rate is roughly inversely proportional to the bulk Richardson number, RiB (∝RiB-α, 0.5 ≲ α ≲ 1.0). We thus suggest the use of RiB as a means to take into account the results of 3D hydrodynamics simulations in new 1D prescriptions of convective boundary mixing.

Spatial variability of carbonaceous aerosol concentrations in East and West Jerusalem.

PubMed

von Schneidemesser, Erika; Zhou, Iiabin; Stone, Elizabeth A; Schauer, James I; Shpund, Jacob; Brenner, Shmuel; Qasrawi, Radwan; Abdeen, Ziad; Sarnat, Jeremy A

2010-03-15

Carbonaceous aerosol concentrations and sources were compared during a year long study at two sites in East and West Jerusalem that were separated by a distance of approximately 4 km. One in six day 24-h PM(2.5) elemental and organic carbon concentrations were measured, along with monthly average concentrations of particle-phase organic compound tracers for primary and secondary organic aerosol sources.Tracer compounds were used in a chemical mass balance ICMB) model to determine primary and secondary source contributions to organic carbon. The East Jerusalem sampling site at Al Quds University experienced higher concentrations of organic carbon (OC) and elemental carbon (EC) compared to the West Jerusalem site at Hebrew University. The annual average concentrations of OC and EC at the East Jerusalem site were 5.20 and 2.19 μg m(-3), respectively, and at the West Jerusalem site were 4.03 and 1.14 μg m(-3), respectively. Concentrations and trends of secondary organic aerosol and vegetative detritus were similar at both sites, but large differences were observed in the concentrations of organic aerosol from fossil fuel combustion and biomass burning, which was the cause of the large differences in OC and EC concentrations observed at the two sites.

LUNA: Nuclear Astrophysics Deep Underground

NASA Astrophysics Data System (ADS)

Broggini, Carlo; Bemmerer, Daniel; Guglielmetti, Alessandra; Menegazzo, Roberto

2010-11-01

Nuclear astrophysics strives for a comprehensive picture of the nuclear reactions responsible for synthesizing chemical elements and for powering the stellar evolution engine. Deep underground in the Gran Sasso National Laboratory, the cross sections of the key reactions of the proton-proton chain and of the carbon-nitrogen-oxygen cycle have been measured right down to the energies of astrophysical interest. The salient features of underground nuclear astrophysics are summarized here. We review the main results obtained by LUNA during the past 20 years and discuss their influence on our understanding of the properties of the neutrino, the Sun, and the universe itself. Future directions of underground nuclear astrophysics toward the study both of helium and carbon burning and of stellar neutron sources in stars are outlined.

Characterization of PM2.5 and identification of transported secondary and biomass burning contribution in Seoul, Korea.

PubMed

Kim, Yumi; Seo, Jihoon; Kim, Jin Young; Lee, Ji Yi; Kim, Hwajin; Kim, Bong Mann

2018-02-01

The chemical and seasonal characteristics of fine particulates in Seoul, Korea, were investigated based on 24-h integrated PM 2.5 measurements made over four 1-month periods in each season between October 2012 and September 2013. The four-season average concentration of PM 2.5 was 37 μg m -3 , and the major chemical components were secondary inorganic aerosol (SIA) species of sulfate, nitrate, and ammonium (49%), followed by organic matter (34%). The mass concentration and most of the chemical components of PM 2.5 showed clear seasonal variation, with a winter-high and summer-low pattern. The winter-to-summer sulfate ratio and the winter organic carbon (OC)-to-elemental carbon (EC) ratio were unusually high compared with those in previous studies. Strong correlations of both the sulfate level and the sulfur oxidation ratio with relative humidity, and between water-soluble OC (WSOC) and SIA in winter, suggest the importance of aqueous phase chemistry for secondary aerosols. A strong correlation between non-sea salt sulfate and Na + levels, a high Cl - /Na + ratio, and an unusual positive correlation between the nitrogen oxidation ratio and temperature during the winter indicate the influence of transported secondary emission sources from upwind urban areas and from China across the Yellow Sea. Despite the absence of local forest fires and the regulation of wood burning, a high levoglucosan concentration and its correlations with OC and WSOC indicate that Seoul was affected by biomass burning sources in the winter. The unusually high water-insoluble OC (WIOC)-to-EC ratio in winter implies additional transported combustion sources of WIOC. The strong correlation between WIOC and levoglucosan suggests the likely influence of transported biomass burning sources on the high WIOC/EC ratio during the winter.

An analysis of burn-off impact on the structure microporous of activated carbons formation

NASA Astrophysics Data System (ADS)

Kwiatkowski, Mirosław; Kopac, Türkan

2017-12-01

The paper presents the results on the application of the LBET numerical method as a tool for analysis of the microporous structure of activated carbons obtained from a bituminous coal. The LBET method was employed particularly to evaluate the impact of the burn-off on the obtained microporous structure parameters of activated carbons.

Risk and Protective Factors for Fires, Burns, and Carbon Monoxide Poisoning in U.S. Households

PubMed Central

Runyan, Carol W.; Johnson, Renee M.; Yang, Jingzhen; Waller, Anna E.; Perkis, David; Marshall, Stephen W.; Coyne-Beasley, Tamera; McGee, Kara S.

2011-01-01

Background More needs to be known about the prevalence of risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households. Methods A random-digit-dial survey was conducted about home safety with 1003 respondents representing households in the continental United States. Descriptive statistics assess the prevalence of risk and protective factors for fires, burns, and carbon monoxide overall, and by demographic characteristics, household structure, region, and residential tenure. The data were weighted to adjust for nonresponse and to reflect the U.S. population. Results Although most respondents reported having a smoke alarm (97%), and 80% reported having one on each level of their home, <20% reported checking the alarm at least every 3 months. Seventy-one percent reported having a fire extinguisher, 29% had a carbon monoxide detector, and 51% of those living with at least one other person had a fire escape plan. Few could report the temperature of their hot water at the tap (9%), or the setting on the hot water heater (25%). Only 6% had an antiscald device. Conclusions Results suggest that there is much room for improvement regarding adoption of measures to prevent fires, burns, and carbon monoxide poisoning. Further investigations of the efficacy of carbon monoxide detectors, fire extinguishers, and escape plans, as well as effectiveness studies of fire and burn-prevention efforts are needed. PMID:15626564

Risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households.

PubMed

Runyan, Carol W; Johnson, Renee M; Yang, Jingzhen; Waller, Anna E; Perkis, David; Marshall, Stephen W; Coyne-Beasley, Tamera; McGee, Kara S

2005-01-01

More needs to be known about the prevalence of risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households. A random-digit-dial survey was conducted about home safety with 1003 respondents representing households in the continental United States. Descriptive statistics assess the prevalence of risk and protective factors for fires, burns, and carbon monoxide overall, and by demographic characteristics, household structure, region, and residential tenure. The data were weighted to adjust for nonresponse and to reflect the U.S. population. Although most respondents reported having a smoke alarm (97%), and 80% reported having one on each level of their home, <20% reported checking the alarm at least every 3 months. Seventy-one percent reported having a fire extinguisher, 29% had a carbon monoxide detector, and 51% of those living with at least one other person had a fire escape plan. Few could report the temperature of their hot water at the tap (9%), or the setting on the hot water heater (25%). Only 6% had an antiscald device. Results suggest that there is much room for improvement regarding adoption of measures to prevent fires, burns, and carbon monoxide poisoning. Further investigations of the efficacy of carbon monoxide detectors, fire extinguishers, and escape plans, as well as effectiveness studies of fire and burn-prevention efforts are needed.

Biomass burning in the Amazon region: Aerosol source apportionment and associated health risk assessment

NASA Astrophysics Data System (ADS)

de Oliveira Alves, Nilmara; Brito, Joel; Caumo, Sofia; Arana, Andrea; de Souza Hacon, Sandra; Artaxo, Paulo; Hillamo, Risto; Teinilä, Kimmo; Batistuzzo de Medeiros, Silvia Regina; de Castro Vasconcellos, Pérola

2015-11-01

The Brazilian Amazon represents about 40% of the world's remaining tropical rainforest. However, human activities have become important drivers of disturbance in that region. The majority of forest fire hotspots in the Amazon arc due to deforestation are impacting the health of the local population of over 10 million inhabitants. In this study we characterize western Amazonia biomass burning emissions through the quantification of 14 Polycyclic Aromatic Hydrocarbons (PAHs), Organic Carbon, Elemental Carbon and unique tracers of biomass burning such as levoglucosan. From the PAHs dataset a toxic equivalence factor is calculated estimating the carcinogenic and mutagenic potential of biomass burning emissions during the studied period. Peak concentration of PM10 during the dry seasons was observed to reach 60 μg m-3 on the 24 h average. Conversely, PM10 was relatively constant throughout the wet season indicating an overall stable balance between aerosol sources and sinks within the filter sampling resolution. Similar behavior is identified for OC and EC components. Levoglucosan was found in significant concentrations (up to 4 μg m-3) during the dry season. Correspondingly, the estimated lung cancer risk calculated during the dry seasons largely exceeded the WHO health-based guideline. A source apportionment study was carried out through the use of Absolute Principal Factor Analysis (APFA), identifying a three-factor solution. The biomass burning factor is found to be the dominating aerosol source, having 75.4% of PM10 loading. The second factor depicts an important contribution of several PAHs without a single source class and therefore was considered as mixed sources factor, contributing to 6.3% of PM10. The third factor was mainly associated with fossil fuel combustion emissions, contributing to 18.4% of PM10. This work enhances the knowledge of aerosol sources and its impact on climate variability and local population, on a site representative of the deforestation which occupies a significant fraction of the Amazon basin.

Global biomass burning - Atmospheric, climatic, and biospheric implications

NASA Technical Reports Server (NTRS)

Levine, Joel S.

1990-01-01

Topics discussed at the March 1990 American Geophysical Union's Conference on biomass burning which was attended by more than 175 participants representing 19 countries are presented. Conference highlights include discussion of remote sensing data concerning biomass burning (BB), gaseous and particle emissions resulting from BB in the tropics, BB in temperate and boreal ecosystems, the historic and prehistoric perspectives on BB, BB and global budgets for carbon, nitrogen, and oxygen, and the BB and the greenhouse effect. Global estimates of annual amounts of biomass burning and of the resulting release of carbon to the atmosphere and the mean gaseous emission ratios for fires in wetlands, chaparral, and boreal ecosystems are given. An overview is presented of some conference discussions including global burning from 1850-1980, the global impact of biomass burning, the great Chinese/Soviet fire of 1987, and burning and biogenic emissions.

Quantifying the variability of potential black carbon transport from cropland burning in Russia driven by atmospheric blocking events

NASA Astrophysics Data System (ADS)

Hall, Joanne; Loboda, Tatiana

2018-05-01

The deposition of short-lived aerosols and pollutants on snow above the Arctic Circle transported from northern mid-latitudes have amplified the short term warming in the Arctic region. Specifically, black carbon has received a great deal of attention due to its absorptive efficiency and its fairly complex influence on the climate. Cropland burning in Russia is a large contributor to the black carbon emissions deposited directly onto the snow in the Arctic region during the spring when the impact on the snow/ice albedo is at its highest. In this study, our focus is on identifying a possible atmospheric pattern that may enhance the transport of black carbon emissions from cropland burning in Russia to the snow-covered Arctic. Specifically, atmospheric blocking events are large-scale patterns in the atmospheric pressure field that are nearly stationary and act to block migratory cyclones. The persistent low-level wind patterns associated with these mid-latitude weather patterns are likely to accelerate potential transport and increase the success of transport of black carbon emissions to the snow-covered Arctic during the spring. Our results revealed that overall, in March, the transport time of hypothetical black carbon emissions from Russian cropland burning to the Arctic snow is shorter (in some areas over 50 hours less at higher injection heights) and the success rate is also much higher (in some areas up to 100% more successful) during atmospheric blocking conditions as compared to conditions without an atmospheric blocking event. The enhanced transport of black carbon has important implications for the efficacy of deposited black carbon. Therefore, understanding these relationships could lead to possible mitigation strategies for reducing the impact of deposition of black carbon from crop residue burning in the Arctic.

Estimation of black carbon content for biomass burning aerosols from multi-channel Raman lidar data

NASA Astrophysics Data System (ADS)

Talianu, Camelia; Marmureanu, Luminita; Nicolae, Doina

2015-04-01

Biomass burning due to natural processes (forest fires) or anthropical activities (agriculture, thermal power stations, domestic heating) is an important source of aerosols with a high content of carbon components (black carbon and organic carbon). Multi-channel Raman lidars provide information on the spectral dependence of the backscatter and extinction coefficients, embedding information on the black carbon content. Aerosols with a high content of black carbon have large extinction coefficients and small backscatter coefficients (strong absorption), while aerosols with high content of organic carbon have large backscatter coefficients (weak absorption). This paper presents a method based on radiative calculations to estimate the black carbon content of biomass burning aerosols from 3b+2a+1d lidar signals. Data is collected at Magurele, Romania, at the cross-road of air masses coming from Ukraine, Russia and Greece, where burning events are frequent during both cold and hot seasons. Aerosols are transported in the free troposphere, generally in the 2-4 km altitude range, and reaches the lidar location after 2-3 days. Optical data are collected between 2011-2012 by a multi-channel Raman lidar and follows the quality assurance program of EARLINET. Radiative calculations are made with libRadTran, an open source radiative model developed by ESA. Validation of the retrievals is made by comparison to a co-located C-ToF Aerosol Mass Spectrometer. Keywords: Lidar, aerosols, biomass burning, radiative model, black carbon Acknowledgment: This work has been supported by grants of the Romanian National Authority for Scientific Research, Programme for Research- Space Technology and Advanced Research - STAR, project no. 39/2012 - SIAFIM, and by Romanian Partnerships in priority areas PNII implemented with MEN-UEFISCDI support, project no. 309/2014 - MOBBE

The production of black carbon during managed burning of UK peatlands: could managed burning of peatlands lead to enhanced carbon storage?

NASA Astrophysics Data System (ADS)

Clay, G.; Worrall, F.

2008-12-01

Peatlands are the UK's largest single terrestrial carbon store with carbon stored in UK peatlands than in forests of Britain and France combined. Unlike most northern peatlands in the peat soils of the UK are heavily managed for recreation and agriculture and due to their proximity to major centres of population are under more anthropogenic pressure than most peatlands. A typical management strategy on UK upland peats is the use of managed fire to restrict vegetation. Fires are used upon a 10-25 year rotation and are described as "cool" as they are designed to remove the crown of the vegetation without scorching the litter layer or the underlying soil. In this case the fire destroys primary productivity and limits litter production but produces char. Char is a low volume, highly refractory, high carbon content product while litter is a high volume, decomposable, lower carbon content product. Therefore, the question is if there are fire conditions under which the production of char causes more carbon to be stored in the peat than would have been stored if no fire management had been employed. This study combines field studies of recent managed burns and wildfires along with detailed vegetation studies from a long term monitoring site in order to assess litter, biomass and black carbon production. In the laboratory experimental burns were undertaken in order to assess the amount and controls upon char production and the carbon content of that char. Results of field and laboratory observations are used to model carbon accumulation under a series of fire management scenarios and the modelling shows that cools burns at long rotations could lead to higher carbon storage than if no fire had occurred, further in several cases more carbon accumulation occurred even if less depth of peat was generated.

The nu-process

NASA Technical Reports Server (NTRS)

Woosley, S. E.; Hartmann, D. H.; Hoffman, R. D.; Haxton, W. C.

1990-01-01

As the core of a massive star collapses to form a neutron star, the flux of neutrinos in the overlying shells of heavy elements becomes so great that, despite the small cross section, substantial nuclear transmutation is induced. Neutrinos excite heavy elements and even helium to particle unbound levels. The evaporation of a single neutron or proton, and the back reaction of these nucleons on other species present, significantly alters the outcome of traditional nucleosynthesis calculations leading to a new process: nu-nucleosynthesis. Modifications to traditional hydrostatic and explosive varieties of helium, carbon, neon, oxygen, and silicon burning are considered. The results show that a large number of rare isotopes, including many of the odd-Z nuclei from boron through copper, owe much of their present abundance in nature to this process.

Stand restoration burning in oak-pine forests in the southern Applachians: effects on aboveground biomass and carbon and nitrogen cycling

Treesearch

Robert M. Hubbard; James M. Vose; Barton D. Clinton; Katherine J. Elliott; Jennifer D. Knoepp

2004-01-01

Understory prescribed burning is being suggested as a viable management tool for restoring degraded oak–pine forest communities in the southern Appalachians yet information is lacking on how this will affect ecosystem processes. Our objectives in this study were to evaluate the watershed scale effects of understory burning on total aboveground biomass, and the carbon...

Monitoring firefighter exposure to air toxins at prescribed burns of forest and range biomass. Forest Service research paper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reinhardt, T.E.

1991-10-01

A variety of potent air toxins are in the smoke produced by burning forest and range biomass. Preliminary data on firefighter exposures to carbon monoxide and formaldehyde at four prescribed burns of Western United States natural fuels are presented. Formaldehyde may be correlated to carbon monoxide emissions. The firefighters' exposures to these compounds relative to workplace standards are discussed.

AmeriFlux US-An2 Anaktuvuk River Moderate Burn

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hobbie, John; Rocha, Adrian; Shaver, Gaius

This is the AmeriFlux version of the carbon flux data for the site US-An2 Anaktuvuk River Moderate Burn. Site Description - The Anaktuvuk River fire on the North Slope of Alaska started on July 16, 2007 by lightning. It continued until the end of September when nearby lakes had already frozen over and burned >256,000 acres, creating a mosaic of patches that differed in burn severity. The Anaktuvuk River Severe Burn, Moderate Burn, and Unburned sites are 40 km to the west of the nearest road and were selected in late May 2008 to determine the effects of the firemore » on carbon, water, and energy exchanges during the growing season. Because the fire had burned through September of the previous year, initial deployment of flux towers occurred prior to any significant vegetative regrowth, and our sampling campaign captured the full growing season in 2008. The Moderate Burn site consisted of a large area with small patches of completely and partially burned tundra intermixed across the landscape.« less

SDSS 1240+6710: a partially burnt supernova remnant

NASA Astrophysics Data System (ADS)

Gaensicke, Boris

2016-10-01

We have recently (Kepler et al. 2016, Science 352, 6281, April 1 issue) identified SDSSJ124043.01+671034.68 as a white dwarf with most peculiar characterstics. Instead of the usual hydrogen or helium, its atmosphere is composed almost purely of oxygen, the only other trace elements detected are neon, magnesium, and silicon; and it has a large transverse velocity of 340km/s. The relatively low mass, 0.6Msun, and the non-detection of carbon strongly argue against SDSSJ1240+6710 being a canonical oxygen-neon core formed from the evolution of a single progenitor star with a mass of 6.5-10Msun. The detection of silicon suggests that the progenitor of this white dwarf may have initiated oxygen-burning, and we argue that SDSSJ1240+6710 is the partially burnt remnant of an unusual thermonuclear supernova, of which a variety have been discovered by the ongoing large transient surveys. We propose to obtain COS ultraviolet spectroscopy of SDSSJ1240+6710 to measure (1) the abundances of phosphorus and sulfur, two other products of oxygen-burning, (2) significantly improve the upper limits on hydrogen (from Ly alpha) and carbon (1330/1335A resonance lines), (3) probe for traces of other nuclear burning, including nitrogen, iron, and nickel, and (4) accurately measure its effective temperature and mass. SDSSJ1240+6710 provides so far the unique opportunity to test the predictions of the rapidly growing number of theoretical stellar explosion models producing gravitationally bound remnants.

Carbon Nanostructure of Diesel Soot Particles Emitted from 2 and 4 Stroke Marine Engines Burning Different Fuels.

PubMed

Lee, Won-Ju; Park, Seul-Hyun; Jang, Se-Hyun; Kim, Hwajin; Choi, Sung Kuk; Cho, Kwon-Hae; Cho, Ik-Soon; Lee, Sang-Min; Choi, Jae-Hyuk

2018-03-01

Diesel soot particles were sampled from 2-stroke and 4-stroke engines that burned two different fuels (Bunker A and C, respectively), and the effects of the engine and fuel types on the structural characteristics of the soot particle were analyzed. The carbon nanostructures of the sampled particles were characterized using various techniques. The results showed that the soot sample collected from the 4-stroke engine, which burned Bunker C, has a higher degree of order of the carbon nanostructure than the sample collected from the 2-stroke engine, which burned Bunker A. Furthermore, the difference in the exhaust gas temperatures originating from the different engine and fuel types can affect the nanostructure of the soot emitted from marine diesel engines.

The forest-bioenergy-carbon connection

Treesearch

Jay O' Laughlin

2010-01-01

Burning wood for energy is a back-to-the-future approach for solving modern problems. The burning of fossil fuels for energy and resultant carbon emissions are global concerns: “The world needs ever increasing energy supplies to sustain economic growth and development. But energy resources are under pressure and carbon dioxide (CO2) emissions from today’s energy use...

Nucleosynthesis in Thermonuclear Supernovae

NASA Astrophysics Data System (ADS)

Seitenzahl, Ivo Rolf; Townsley, Dean M.

The explosion energy of thermonuclear (type Ia) supernovae is derived from the difference in nuclear binding energy liberated in the explosive fusion of light "fuel" nuclei, predominantly carbon and oxygen, into more tightly bound nuclear "ash" dominated by iron and silicon group elements. The very same explosive thermonuclear fusion event is also one of the major processes contributing to the nucleosynthesis of the heavy elements, in particular the iron-group elements. For example, most of the iron and manganese in the sun and its planetary system were produced in thermonuclear supernovae. Here, we review the physics of explosive thermonuclear burning in carbon-oxygen white dwarf material and the methodologies utilized in calculating predicted nucleosynthesis from hydrodynamic explosion models. While the dominant explosion scenario remains unclear, many aspects of the nuclear combustion and nucleosynthesis are common to all models and must occur in some form in order to produce the observed yields. We summarize the predicted nucleosynthetic yields for existing explosion models, placing particular emphasis on characteristic differences in the nucleosynthetic signatures of the different suggested scenarios leading to type Ia supernovae. Following this, we discuss how these signatures compare with observations of several individual supernovae, remnants, and the composition of material in our galaxy and galaxy clusters.

Emissions from prescribed burning of timber slash piles in Oregon.

EPA Science Inventory

Emissions from burning piles of post-harvest timber slash (Douglas fir) in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matte...

Increasing fire severity, alternate successional trajectories, and the carbon balance of Alaskan boreal forests

NASA Astrophysics Data System (ADS)

Mack, M. C.; Alexander, H. D.; Jean, M.; Melvin, A. M.; Johnstone, J. F.

2016-12-01

Climate-sensitive disturbances, such as wildfire, can feed back positively to climate warming via the carbon (C) cycle if C released by disturbance is not replaced over post-fire succession. In boreal forests, burning of carbon in deep organic soils is not only an important determinate of ecosystem element balance over the disturbance cycle, but also sets the conditions that control plant recruitment, species dominance and successional trajectory. Species dominance, in turn, has the potential to exert strong control over the plant-soil-microbial feedbacks that determine C and nutrient coupling, C storage, and ultimately, replacement of combusted C. We examined the consequences of increasing fire severity for C balance and C and nitrogen (N) coupling in Alaskan boreal forests. We estimated combustion losses in 90 black spruce (conifer) stands that burned in 2004. Over the next decade, we followed natural tree seedling establishment in these stands and used seedling species dominance identify conifer versus deciduous successional trajectories. We assembled data from 120 stands that varied in time after fire and successional trajectory, and estimated C and N dynamics across 150 years of post-fire succession for each trajectory. Conifer stands that burned with high severity transitioned to deciduous tree dominance after fire. These stands had smaller ecosystem pools of C and N before fire, lost a larger proportion of these pools during the fire, and began succession with smaller residual pools than stands that returned to conifer dominance after fire. Over secondary succession, deciduous stands accumulated about 10 times more carbon in aboveground biomass than conifer stands. Belowground biomass and soil carbon accumulation, by contrast, was about three times higher in the black spruce stands than in deciduous stands. As a result, net ecosystem C accumulation over the 100 year inter-fire interval was three times higher in deciduous stands than in coniferous stands. Nitrogen accumulation did not differ between the trajectories; high C:N ratio biomass accumulation in deciduous stands balanced low C:N ratio soil organic matter accumulation in conifer stands. The timing of N accumulation, however, differed substantially, supporting the idea that deciduous stands mine N from degrading permafrost after fire.

Source characterization of ambient fine aerosol in Singapore during a haze episode in 2015

NASA Astrophysics Data System (ADS)

Hapsari Budisulistiorini, Sri; Riva, Matthieu; Williams, Michael; Miyakawa, Takuma; Komazaki, Yuichi; Chen, Jing; Surratt, Jason; Kuwata, Mikinori

2017-04-01

Recurring transboundary haze from Indonesia peatland fires in the previous decades has significantly elevated particulate matter (PM) concentration in Southeast Asia, particularly during the 2015 El Niño event. Previous studies have investigated chemical composition of particles emitted during haze episodes; however, they were limited to time-integrated samples and the number of identified compounds. Low time-resolution measurement results in co-variance of PM sources; therefore, higher time-resolution measurement is important in PM source apportionment. Between October 10-31, 2015, Aerodyne Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) was deployed for real-time chemical characterization of ambient submicron PM (NR-PM1) in Singapore. Simultaneously, PM2.5 filter samples were collected for molecular-level organic aerosol (OA) constituents, organic carbon (OC), elemental carbon (EC) and water-soluble OC (WSOC) analyses. OA constituents were quantified by gas chromatography interfaced to electron ionization mass spectrometry (GC/EI-MS) and ultra-performance liquid chromatography interfaced to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometer operated in the negative ion mode (UPLC/(-)ESI-HR-Q-TOFMS). OA and SO42- are dominant components of the haze particles, accounting for ˜77% and ˜12% of the total NR-PM1 mass, respectively. OC/EC ratio of 4.8 might indicate formation of secondary OA (SOA) and aerosols from biomass burning, including those from peat burning. OA fraction from ToF-ACSM measurements was analyzed for source apportionment using a bilinear model through multi-linear engine algorithm (ME-2) in graphical user interface SoFi (Source Finder). Five OA factors were identified: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), peat burning OA (PBOA), low-volatility oxygenated OA (LV-OOA), and semi-volatile oxygenated OA (SV-OOA). The HOA factor shows a distinct diurnal profile peaking in the morning and evening, suggesting traffic influences. The BBOA factor was identified based on factor profile of wood burning particles and correlated with known biomass burning tracers (i.e. levoglucosan and mannosan). The PBOA factor was identified based on factor profile of laboratory-generated peat burning particles. This factor would be further identified with OA constituents in peat burning particles, such as brown carbon constituents. The LV-OOA and SV-OOA factors peak in the afternoon indicating they were likely formed through photochemistry. The LV-OOA factor might be a product of biomass burning aerosol aging as indicated by temporal trend correlations with BBOA and PBOA factors (r2 = 0.7-0.8). Contributions of the HOA and SV-OOA factors to OA mass are ˜12% and ˜21%, respectively. The biomass burning-related factors (BBOA and PBOA) account for ˜29% of OA mass, which likely indicates a lower-bound estimate of the transboundary impacts of primary emissions from peatland fires. The transboundary impacts of secondary aerosol from peatland fires might be represented by the LV-OOA factor accounting for ˜37% of OA mass. Overall, the transboundary haze could contribute to ˜66% of OA concentration, suggesting the strong influence of Indonesia peatland fires on the air quality of Singapore.

Fire recurrence effects on aboveground plant and soil carbon stocks in Mediterranean shrublands with Aleppo pine

NASA Astrophysics Data System (ADS)

Herman, J.; den Ouden, J.; Mohren, G. M. J.; Retana, J.; Serrasolses, I.

2009-04-01

Changes in fire regime due to intensification of human influence during the last decades led to changes in vegetation structure and composition, productivity and carbon sink strength of Mediterranean shrublands and forests. It is anticipated that further climate warming and lower precipitation will enhance fire frequency, having consequences for the carbon budget and carbon storage in Mediterranean ecosystems. The purpose of this study was to determine whether fire recurrence modifies aboveground plant and soil carbon stocks, soil organic carbon content and total soil nitrogen content in shrublands with Aleppo pine on the Garraf Massif in Catalonia (Spain). Stands differing in fire frequency (1, 2 and 3 fires since 1957) were examined 13 years after the stand-replacing fire of 1994 and compared with control stands which were free of fire since 1957. Recurrent fires led to a decrease in total ecosystem carbon stocks. Control sites stored 12203 g m-2C which was 3.5, 5.0 and 5.5 times more than sites that burned 1, 2 and 3 times respectively. Carbon stored in the aboveground biomass exceeded soil carbon stocks in control plots, while soils were the dominant carbon pool in burned plots. An increasing fire frequency from 1 to 2 fires decreased total soil carbon stock. Control soils stored 3551 g m-2C, of which 70 % was recovered over 13 years in once burned soils and approximately 50 % in soils that had 2 or 3 fires. The soil litter (LF) layer carbon stock decreased with increasing fire frequency from 1 to 2 fires, whereas humus (H) layer and upper mineral soil carbon stocks did not change consistently with fire frequency. Fire decreased the organic carbon content in LF and H horizons, however no significant effect of fire frequency was found. Increasing fire frequency from 1 to 2 fires caused a decrease in the organic carbon content in the upper mineral soil. Total soil N content and C/N ratios were not significantly impacted by fire frequency. Recurrent fires had the greatest impact on aboveground plant carbon stocks. Aboveground plants in control plots amounted to 8652 g m-2C, of which 93 % was stored in trees, while carbon storage in the most frequently burned sites was only 509 g m-2C. Shrub carbon varied barely between fire frequencies, corroborating the high resilience of resprouting shrub species to fire recurrence. The most striking result was the immense decrease in Aleppo pine carbon stock which varied between 7770 g m-2in control plots and 25.6 g m-2in 3-fires plots. Differences between control and burned plots are principally explained by the age of the plots. The decrease in Aleppo pine carbon stock within burned plots was not associated with a growth reduction, but was due to a decrease in stem density. The results indeed indicate that the recruitment of Aleppo pine on more frequently burned plots is obstructed due to cumulative effects of short fire return-intervals (

Ecosystem Carbon Emissions from 2015 Forest Fires in Interior Alaska

NASA Technical Reports Server (NTRS)

Potter, Christopher S.

2018-01-01

In the summer of 2015, hundreds of wildfires burned across the state of Alaska, and consumed more than 1.6 million ha of boreal forest and wetlands in the Yukon-Koyukuk region. Mapping of 113 large wildfires using Landsat satellite images from before and after 2015 indicated that nearly 60% of this area was burned at moderate-to-high severity levels. Field measurements near the town of Tanana on the Yukon River were carried out in July of 2017 in both unburned and 2015 burned forested areas (nearly adjacent to one-another) to visually verify locations of different Landsat burn severity classes (low, moderate, or high). Results: Field measurements indicated that the loss of surface organic layers in boreal ecosystem fires is a major factor determining post-fire soil temperature changes, depth of thawing, and carbon losses from the mineral topsoil layer. Measurements in forest sites showed that soil temperature profiles to 30 cm depth at burned forest sites increased by an average of 8o - 10o C compared to unburned forest sites. Sampling and laboratory analysis indicated a 65% reduction in soil carbon content and a 58% reduction in soil nitrogen content in severely burned sample sites compared to soil mineral samples from nearby unburned spruce forests. Conclusions: Combined with nearly unprecedented forest areas severely burned in the Interior region of Alaska in 2015, total ecosystem fire emission of carbon to the atmosphere exceeded most previous estimates for the state.

A method for smoke marker measurements and its potential application for determining the contribution of biomass burning from wildfires and prescribed fires to ambient PM2.5 organic carbon

Treesearch

A. P. Sullivan; A. S. Holden; L. A. Patterson; G. R. McMeeking; S. M. Kreidenweis; W. C. Malm; W. M. Hao; C. E. Wold; J. L. Collett

2008-01-01

Biomass burning is an important source of particulate organic carbon (OC) in the atmosphere. Quantifying this contribution in time and space requires a means of routinely apportioning contributions of smoke from biomass burning to OC. Smoke marker (for example, levoglucosan) measurements provide the most common approach for making this determination. A lack of source...

Biomass burning losses of carbon estimated from ecosystem modeling and satellite data analysis for the Brazilian Amazon region

NASA Astrophysics Data System (ADS)

Potter, Christopher; Brooks Genovese, Vanessa; Klooster, Steven; Bobo, Matthew; Torregrosa, Alicia

To produce a new daily record of gross carbon emissions from biomass burning events and post-burning decomposition fluxes in the states of the Brazilian Legal Amazon (Instituto Brasileiro de Geografia e Estatistica (IBGE), 1991. Anuario Estatistico do Brasil, Vol. 51. Rio de Janeiro, Brazil pp. 1-1024). We have used vegetation greenness estimates from satellite images as inputs to a terrestrial ecosystem production model. This carbon allocation model generates new estimates of regional aboveground vegetation biomass at 8-km resolution. The modeled biomass product is then combined for the first time with fire pixel counts from the advanced very high-resolution radiometer (AVHRR) to overlay regional burning activities in the Amazon. Results from our analysis indicate that carbon emission estimates from annual region-wide sources of deforestation and biomass burning in the early 1990s are apparently three to five times higher than reported in previous studies for the Brazilian Legal Amazon (Houghton et al., 2000. Nature 403, 301-304; Fearnside, 1997. Climatic Change 35, 321-360), i.e., studies which implied that the Legal Amazon region tends toward a net-zero annual source of terrestrial carbon. In contrast, our analysis implies that the total source fluxes over the entire Legal Amazon region range from 0.2 to 1.2 Pg C yr -1, depending strongly on annual rainfall patterns. The reasons for our higher burning emission estimates are (1) use of combustion fractions typically measured during Amazon forest burning events for computing carbon losses, (2) more detailed geographic distribution of vegetation biomass and daily fire activity for the region, and (3) inclusion of fire effects in extensive areas of the Legal Amazon covered by open woodland, secondary forests, savanna, and pasture vegetation. The total area of rainforest estimated annually to be deforested did not differ substantially among the previous analyses cited and our own.

Biogeochemical patterns of intermittent streams over space and time as surface flows decrease

NASA Astrophysics Data System (ADS)

MacNeille, R. B.; Lohse, K. A.; Godsey, S.; McCorkle, E. P.; Parsons, S.; Baxter, C.

2016-12-01

Climate change in the western United States is projected to lead to earlier snowmelt, increasing fire risk and potentially transitioning perennial streams to intermittent ones. Differences between perennial and intermittent streams, especially the temporal and spatial patterns of carbon and nutrient dynamics during periods of drying, are understudied. We examined spatial and temporal patterns in surface water biogeochemistry in southwest Idaho and hypothesized that as streams dry, carbon concentrations would increase due to evapoconcentration and/or increased in-stream production. Furthermore, we expected that biogeochemical patterns of streams would become increasingly spatially heterogeneous with drying. Finally, we expected that these patterns would vary in response to fire. To test these hypotheses, we collected water samples every 50 meters from two intermittent streams, one burned and one unburned, in April, May and June, 2016 to determine surface water biogeochemistry. Results showed average concentrations of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) increased 3-fold from April to June in the burned site compared to the unburned site where concentrations remained relatively constant. Interestingly, average concentrations of total nitrogen (TN) dropped substantially for the burned site over these three months, but only decreased slightly for the unburned site over the same time period. We also assessed changes in spatial correlation between the burned and unburned site: carbon concentrations were less spatially correlated at the unburned site than at the burned site. Scatterplot matrices of DIC values indicated that at a lag distance of 300 m in April and June, the unburned site had r-values of 0.7416 and 0.5975, respectively, while the burned site had r-values of 0.9468 and 0.8783, respectively. These initial findings support our hypotheses that carbon concentrations and spatial heterogeneity increased over time.

Estimating the financial risks of Andropogon gayanus to greenhouse gas abatement projects in northern Australia

NASA Astrophysics Data System (ADS)

Adams, Vanessa M.; Setterfield, Samantha A.

2013-06-01

Financial mechanisms such as offsets are one strategy to abate greenhouse gas emissions, and the carbon market is expanding with a growing demand for offset products. However, in the case of carbon offsets, if the carbon is released due to intentional or unintentional reversal through environmental events such as fire, the financial liability to replace lost offsets will likely fall on the provider. This liability may have implications for future participation in programmes, but common strategies such as buffer pool and insurance products can be used to minimize this liability. In order for these strategies to be effective, an understanding of the spatial and temporal distributions of expected reversals is needed. We use the case study of savanna burning, an approved greenhouse gas abatement methodology under the Carbon Farming Initiative in Australia, to examine potential risks to carbon markets in northern Australia and quantify the financial risks. We focus our analysis on the threat of Andropogon gayanus (gamba grass) to savanna burning due to its documented impacts of increased fuel loads and altered fire regimes. We assess the spatial and financial extent to which gamba grass poses a risk to savanna burning programmes in northern Australia. We find that 75% of the eligible area for savanna burning is spatially coincident with the high suitability range for gamba grass. Our analysis demonstrates that the presence of gamba grass seriously impacts the financial viability of savanna burning projects. For example, in order to recuperate the annual costs of controlling 1 ha of gamba grass infestation, 290 ha of land must be enrolled in annual carbon abatement credits. Our results show an immediate need to contain gamba grass to its current extent to avoid future spread into large expanses of land, which are currently profitable for savanna burning.

Probing thermonuclear burning on accreting neutron stars

NASA Astrophysics Data System (ADS)

Keek, L.

2008-12-01

Neutron stars are the most compact stars that can be directly observed, which makes them ideal laboratories to study physics at extreme densities. Neutron stars in low-mass X-ray binaries accrete hydrogen and helium from a lower-mass companion star through Roche lobe overflow. This matter undergoes thermonuclear burning in the neutron star envelope, creating carbon and heavier elements. The fusion process may proceed in an unstable manner, resulting in a thermonuclear runaway. Within one second the entire surface is burned, which is observable as a sharp rise in the emitted X-ray flux: a type I X-ray burst. Afterwards the neutron star surface cools down on a timescale of ten to one hundred seconds. During these bursts the surface of an accreting neutron star can be observed directly, which makes them instrumental for studying this type of stars. We have studied rare kinds of X-ray bursts. One such rare burst is the superburst, which lasts a thousand times longer than an ordinary burst. Superbursts are thought to result from the explosive burning of a thick carbon layer, which lies deeper inside the neutron star, close to a layer known as the crust. A prerequisite for the occurrence of a superburst is a high enough temperature, which is set by the temperature of the crust and the heat conductivity of the envelope. The latter is lowered by the presence of heavy elements that are produced during normal X-ray bursts. Using a large set of observations from the Wide Field Camera's onboard the BeppoSAX satellite, we find that, at high accretion rate, sources which do not exhibit normal bursts likely have a longer superburst recurrence time, than the observed superburst recurrence time of one burster. We analyze in detail the first superburst from a transient source, which went into outburst only 55 days before the superburst. Recent models of the neutron star crust predict that this is too small a time to heat the crust sufficiently for superburst ignition, indicating that the models need to be extended with a new heat source. Another rare phenomenon is the occurrence of bursts with recurrence times of less than 30 minutes. In a long set of observations of the source EXO 0748-676 we find for the first time triple bursts, where three bursts occur within 30 minutes. This time is too short to accrete new fuel for the next burst, which suggests that not all hydrogen and helium is burned during the first burst. Finally, using a hydrodynamic stellar evolution code we create a multi-zone numerical model of the neutron star envelope. For the first time we include mixing due to rotation and a rotationally induced magnetic field. We find that thermonuclear burning proceeds in a stable manner at a lower heat flux of the crust for models including mixing. This may explain the observed transition of stable to unstable burning at a lower mass accretion rate than models previously predicted.

Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode in 2013

NASA Astrophysics Data System (ADS)

Zhang, Y.-L.; Huang, R.-J.; El Haddad, I.; Ho, K.-F.; Cao, J.-J.; Han, Y.; Zotter, P.; Bozzetti, C.; Daellenbach, K. R.; Canonaco, F.; Slowik, J. G.; Salazar, G.; Schwikowski, M.; Schnelle-Kreis, J.; Abbaszade, G.; Zimmermann, R.; Baltensperger, U.; Prévôt, A. S. H.; Szidat, S.

2014-10-01

During winter 2013, extremely high concentrations (i.e. 4-20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter <2.5 μm) were reported in several large cities in China. In this work, source apportionment of fine carbonaceous aerosols during this haze episode was conducted at four major cities in China including Xian, Beijing, Shanghai and Guangzhou. An effective statistical analysis of a combined dataset from elemental carbon (EC) and organic carbon (OC), radiocarbon (14C) and biomass-burning marker measurements using Latin-hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. We found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% at all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xian (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was rather from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10% and 48 ± 9% of OC and TC, respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8%, 48 ± 18%, 53 ± 4% and 65 ± 26% of non-fossil OC for Xian, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass-burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately with heavily polluted days according to particulate matter mass. Despite a significant increase of absolute mass concentrations of primary emissions from both, fossil and non-fossil sources, during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

Organic composition and source apportionment of fine aerosol at Monterrey, Mexico, based on organic markers

NASA Astrophysics Data System (ADS)

Mancilla, Y.; Mendoza, A.; Fraser, M. P.; Herckes, P.

2016-01-01

Primary emissions from anthropogenic and biogenic sources as well as secondary formation are responsible for the pollution levels of ambient air in major urban areas. These sources release fine particles into the air that negatively impact human health and the environment. Organic molecular markers, which are compounds that are unique to specific PM2.5 sources, can be utilized to identify the major emission sources in urban areas. In this study, 43 representative PM2.5 samples, for both daytime and nighttime periods, were built from individual samples collected in an urban site of the Monterrey metropolitan area (MMA) during the spring and fall of 2011 and 2012. The samples were analyzed for organic carbon, elemental carbon, and organic molecular markers. Several diagnostic tools were employed for the preliminary identification of emission sources. Organic compounds for eight compound classes were quantified. The n-alkanoic acids were the most abundant, followed by n-alkanes, wood smoke markers, and levoglucosan/alkenoic acids. Polycyclic aromatic hydrocarbons (PAHs) and hopanes were less abundant. The carbon preference index (0.7-2.6) for n-alkanes indicates a major contribution of anthropogenic and mixed sources during the fall and the spring, respectively. Hopanes levels confirmed the contribution from gasoline and diesel engines. In addition, the contribution of gasoline and diesel vehicle exhaust was confirmed and identified by the PAH concentrations in PM2.5. Diagnostic ratios of PAHs showed emissions from burning coal, wood, biomass, and other fossil fuels. The total PAHs and elemental carbon were correlated (r2 = 0.39-0.70) across the monitoring periods, reinforcing that motor vehicles are the major contributors of PAHs. Cholesterol levels remained constant during the spring and fall, showing evidence of the contribution of meat-cooking operations, while the isolated concentrations of levoglucosan suggested occasional biomass burning events. Finally, source attribution results obtained using the CMB (chemical mass balance) model indicate that emissions from motor vehicle exhausts are the most important, accounting for the 64 % of the PM2.5, followed by meat-cooking operations with 31 % The vegetative detritus and biomass burning had the smallest contribution (2.2 % of the PM2.5). To our knowledge, this is only the second study to explore the organic composition and source apportionment of fine organic aerosol based on molecular markers in Mexico and the first for the MMA. Particularly molecular marker were quantified by solvent extraction with dichloromethane, derivatization, and gas chromatography with mass spectrometry (GC/MS).

Physical and chemical properties and adsorption type of activated carbon prepared from plum kernels by NaOH activation.

PubMed

Tseng, Ru-Ling

2007-08-25

Activated carbon was prepared from plum kernels by NaOH activation at six different NaOH/char ratios. The physical properties including the BET surface area, the total pore volume, the micropore ratio, the pore diameter, the burn-off, and the scanning electron microscope (SEM) observation as well as the chemical properties, namely elemental analysis and temperature programmed desorption (TPD), were measured. The results revealed a two-stage activation process: stage 1 activated carbons were obtained at NaOH/char ratios of 0-1, surface pyrolysis being the main reaction; stage 2 activated carbons were obtained at NaOH/char ratios of 2-4, etching and swelling being the main reactions. The physical properties of stage 2 activated carbons were similar, and specific area was from 1478 to 1887m(2)g(-1). The results of reaction mechanism of NaOH activation revealed that it was apparently because of the loss ratio of elements C, H, and O in the activated carbon, and the variations in the surface functional groups and the physical properties. The adsorption of the above activated carbons on phenol and three kinds of dyes (MB, BB1, and AB74) were used for an isotherm equilibrium adsorption study. The data fitted the Langmuir isotherm equation. Various kinds of adsorbents showed different adsorption types; separation factor (R(L)) was used to determine the level of favorability of the adsorption type. In this work, activated carbons prepared by NaOH activation were evaluated in terms of their physical properties, chemical properties, and adsorption type; and activated carbon PKN2 was found to have most application potential.

Aerial sampling of emissions from biomass pile burns in Oregon

EPA Science Inventory

Emissions from burning piles of post-harvest timber slash in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matter (PM2.5 µm), ...

Aerial Sampling of Emissions from Biomass Pile Burns in Oregon

EPA Science Inventory

Emissions from burning piles of post-harvest timber slash in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matter (PM2.5 µm), ...

Adsorbents for capturing mercury in coal-fired boiler flue gas.

PubMed

Yang, Hongqun; Xu, Zhenghe; Fan, Maohong; Bland, Alan E; Judkins, Roddie R

2007-07-19

This paper reviews recent advances in the research and development of sorbents used to capture mercury from coal-fired utility boiler flue gas. Mercury emissions are the source of serious health concerns. Worldwide mercury emissions from human activities are estimated to be 1000 to 6000 t/annum. Mercury emissions from coal-fired power plants are believed to be the largest source of anthropogenic mercury emissions. Mercury emissions from coal-fired utility boilers vary in total amount and speciation, depending on coal types, boiler operating conditions, and configurations of air pollution control devices (APCDs). The APCDs, such as fabric filter (FF) bag house, electrostatic precipitator (ESP), and wet flue gas desulfurization (FGD), can remove some particulate-bound and oxidized forms of mercury. Elemental mercury often escapes from these devices. Activated carbon injection upstream of a particulate control device has been shown to have the best potential to remove both elemental and oxidized mercury from the flue gas. For this paper, NORIT FGD activated carbon was extensively studied for its mercury adsorption behavior. Results from bench-, pilot- and field-scale studies, mercury adsorption by coal chars, and a case of lignite-burned mercury control were reviewed. Studies of brominated carbon, sulfur-impregnated carbon and chloride-impregnated carbon were also reviewed. Carbon substitutes, such as calcium sorbents, petroleum coke, zeolites and fly ash were analyzed for their mercury-adsorption performance. At this time, brominated activated carbon appears to be the best-performing mercury sorbent. A non-injection regenerable sorbent technology is briefly introduced herein, and the issue of mercury leachability is briefly covered. Future research directions are suggested.

Short Term Soil Respiration Response to Fire in a Semi-arid Ecosystem

NASA Astrophysics Data System (ADS)

Rozin, A. G.

2015-12-01

In the Intermountain West (USA), fire is an important driver of carbon cycling in the environment. Increasing frequency and severity of fires, either through management actions or wildfires, is expected with changing climates in the Western United States. When burning is used as a management tool, it may be beneficial and control the growth of nuisance vegetation, promote the regeneration of grasses and forage species, and reduce hazardous fuel loads to minimize the risk of future wildfires. However, high intensity wildfires often have a negative effect, resulting in a loss of carbon storage and a shift of vegetation communities. This delays recovery of the ecosystem for years or decades and alters the historic fire regime. A 2000 acre prescribed burn in the Reynolds Creek Critical Zone Observatory provided the opportunity to quantify pre and post-burn soil carbon stores and soil carbon losses by heterotrophic respiration. Pre and post-burn soil samples were collected for physical and biogeochemical characterization to quantify substrate availability and possible limitations for heterotrophic respiration. CO2 fluxes were continuously monitored in situ before and immediately after the fire to understand the short-term response of soil respiration to varying burn severities.

A white dwarf with an oxygen atmosphere.

PubMed

Kepler, S O; Koester, Detlev; Ourique, Gustavo

2016-04-01

Stars born with masses below around 10 solar masses end their lives as white dwarf stars. Their atmospheres are dominated by the lightest elements because gravitational diffusion brings the lightest element to the surface. We report the discovery of a white dwarf with an atmosphere completely dominated by oxygen, SDSS J124043.01+671034.68. After oxygen, the next most abundant elements in its atmosphere are neon and magnesium, but these are lower by a factor of ≥25 by number. The fact that no hydrogen or helium are observed is surprising. Oxygen, neon, and magnesium are the products of carbon burning, which occurs in stars at the high-mass end of pre-white dwarf formation. This star, a possible oxygen-neon white dwarf, will provide a rare observational test of the evolutionary paths toward white dwarfs. Copyright © 2016, American Association for the Advancement of Science.

Reductions in Emissions of Carbonaceous Particulate Matter and Polycyclic Aromatic Hydrocarbons from Combustion of Biomass Pellets in Comparisonwith Raw Fuel Burning

PubMed Central

SHEN, Guofeng; TAO, Shu; WEI, Siye; ZHANG, Yanyan; WANG, Rong; WANG, Bin; LI, Wei; SHEN, Huizhong; HUANG, Ye; CHEN, Yuanchen; CHEN, Han; YANG, Yifeng; WANG, Wei; WEI, Wen; WANG, Xilong; LIU, Wenxing; WANG, Xuejun; SIMONICH, Staci L. Massey

2012-01-01

Biomass pellets are emerging as a cleaner alternative to traditional biomass fuels. The potential benefits of using biomass pellets include improving energy utilization efficiency and reducing emissions of air pollutants. To assess the environmental, climate, and health significance of replacing traditional fuels with biomass pellets, it is critical to measure the emission factors (EFs) of various pollutants from pellet burning. However, only a few field measurements have been conducted on the emissions of carbon monoxide (CO), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) from the combustion of pellets. In this study, pine wood and corn straw pellets were burned in a pellet burner (2.6 kW) and the EFs of CO, organic carbon, elemental carbon, PM, and PAHs (EFCO, EFOC, EFEC, EFPM, and EFPAH) were determined. The average EFCO, EFOC, EFEC, and EFPM were 1520±1170, 8.68±11.4, 11.2±8.7, and 188±87 mg/MJ for corn straw pellets, and 266±137, 5.74±7.17, 2.02±1.57, and 71.0±54.0 mg/MJ for pine wood pellets, respectively. Total carbonaceous carbon constituted 8 to 14% of the PM mass emitted. The measured values of EFPAH for the two pellets were 1.02±0.64 and 0.506±0.360 mg/MJ, respectively. The secondary side air supply in the pellet burner did not change the EFs of most pollutants significantly (p > 0.05). The only exceptions were EFOC and EFPM for pine wood pellets because of reduced combustion temperatures with the increased air supply. In comparison with EFs for the raw pine wood and corn straw, EFCO, EFOC, EFEC, and EFPM for pellets were significantly lower than those for raw fuels (p < 0.05). However, the differences in EFPAH were not significant (p > 0.05). Based on the measured EFs and thermal efficiencies, it was estimated that 95, 98, 98, 88, and 71% reductions in the total emissions of CO, OC, EC, PM, and PAHs could be achieved by replacing the raw biomass fuels combusted in traditional cooking stoves with pellets burned in modern pellet burners. PMID:22568759

Reductions in emissions of carbonaceous particulate matter and polycyclic aromatic hydrocarbons from combustion of biomass pellets in comparison with raw fuel burning.

PubMed

Shen, Guofeng; Tao, Shu; Wei, Siye; Zhang, Yanyan; Wang, Rong; Wang, Bin; Li, Wei; Shen, Huizhong; Huang, Ye; Chen, Yuanchen; Chen, Han; Yang, Yifeng; Wang, Wei; Wei, Wen; Wang, Xilong; Liu, Wenxing; Wang, Xuejun; Masse Simonich, Staci L y

2012-06-05

Biomass pellets are emerging as a cleaner alternative to traditional biomass fuels. The potential benefits of using biomass pellets include improving energy utilization efficiency and reducing emissions of air pollutants. To assess the environmental, climate, and health significance of replacing traditional fuels with biomass pellets, it is critical to measure the emission factors (EFs) of various pollutants from pellet burning. However, only a few field measurements have been conducted on the emissions of carbon monoxide (CO), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) from the combustion of pellets. In this study, pine wood and corn straw pellets were burned in a pellet burner (2.6 kW), and the EFs of CO, organic carbon, elemental carbon, PM, and PAHs (EF(CO), EF(OC), EF(EC), EF(PM), and EF(PAH)) were determined. The average EF(CO), EF(OC), EF(EC), and EF(PM) were 1520 ± 1170, 8.68 ± 11.4, 11.2 ± 8.7, and 188 ± 87 mg/MJ for corn straw pellets and 266 ± 137, 5.74 ± 7.17, 2.02 ± 1.57, and 71.0 ± 54.0 mg/MJ for pine wood pellets, respectively. Total carbonaceous carbon constituted 8 to 14% of the PM mass emitted. The measured values of EF(PAH) for the two pellets were 1.02 ± 0.64 and 0.506 ± 0.360 mg/MJ, respectively. The secondary side air supply in the pellet burner did not change the EFs of most pollutants significantly (p > 0.05). The only exceptions were EF(OC) and EF(PM) for pine wood pellets because of reduced combustion temperatures with the increased air supply. In comparison with EFs for the raw pine wood and corn straw, EF(CO), EF(OC), EF(EC), and EF(PM) for pellets were significantly lower than those for raw fuels (p < 0.05). However, the differences in EF(PAH) were not significant (p > 0.05). Based on the measured EFs and thermal efficiencies, it was estimated that 95, 98, 98, 88, and 71% reductions in the total emissions of CO, OC, EC, PM, and PAHs could be achieved by replacing the raw biomass fuels combusted in traditional cooking stoves with pellets burned in modern pellet burners.

Potential health impacts of burning coal beds and waste banks

USGS Publications Warehouse

Finkelman, R.B.

2004-01-01

Uncontrolled release of pollutants from burning coal beds and waste banks presents potential environmental and human health hazards. On a global scale, the emissions of large volumes of greenhouse gases from burning coal beds may contribute to climate change that alters ecosystems and patterns of disease occurrence. On regional and local scales, the emissions from burning coal beds and waste banks of acidic gases, particulates, organic compounds, and trace elements can contribute to a range of respiratory and other human health problems. Although there are few published reports of health problems caused by these emissions, the potential for problems can be significant. In India, large numbers of people have been displaced from their homes because of health problems caused by emissions from burning coal beds. Volatile elements such as arsenic, fluorine, mercury, and selenium are commonly enriched in coal deposits. Burning coal beds can volatilize these elements, which then can be inhaled, or adsorbed on crops and foods, taken up by livestock or bioaccumulated in birds and fish. Some of these elements can condense on dust particles that can be inhaled or ingested. In addition, selenium, arsenic, lead, tin, bismuth, fluorine, and other elements condense where the hot gaseous emissions come in contact with ambient air, forming mats of concentrated efflorescent minerals on the surface of the ground. These mats can be leached by rainwater and washed into local water bodies providing other potential routes of exposure. Although there are little data linking burning coal beds and waste banks to known health problems, a possibly analogous situation exists in rural China where mineralized coal burned in a residential environment has caused widespread and severe health problems such as fluorosis and arseniasis. ?? 2004 Elsevier B.V. All rights reserved.

Time-resolved analysis of particle emissions from residential biomass combustion - Emissions of refractory black carbon, PAHs and organic tracers

NASA Astrophysics Data System (ADS)

Nielsen, Ingeborg E.; Eriksson, Axel C.; Lindgren, Robert; Martinsson, Johan; Nyström, Robin; Nordin, Erik Z.; Sadiktsis, Ioannis; Boman, Christoffer; Nøjgaard, Jacob K.; Pagels, Joakim

2017-09-01

Time-resolved particle emissions from a conventional wood stove were investigated with aerosol mass spectrometry to provide links between combustion conditions, emission factors, mixing state of refractory black carbon and implications for organic tracer methods. The addition of a new batch of fuel results in low temperature pyrolysis as the fuel heats up, resulting in strong, short-lived, variable emission peaks of organic aerosol-containing markers of anhydrous sugars, such as levoglucosan (fragment at m/z 60). Flaming combustion results in emissions dominated by refractory black carbon co-emitted with minor fractions of organic aerosol and markers of anhydrous sugars. Full cycle emissions are an external mixture of larger organic aerosol-dominated and smaller thinly coated refractory black carbon particles. A very high burn rate results in increased full cycle mass emission factors of 66, 2.7, 2.8 and 1.3 for particulate polycyclic aromatic hydrocarbons, refractory black carbon, total organic aerosol and m/z 60, respectively, compared to nominal burn rate. Polycyclic aromatic hydrocarbons are primarily associated with refractory black carbon-containing particles. We hypothesize that at very high burn rates, the central parts of the combustion zone become air starved, leading to a locally reduced combustion temperature that reduces the conversion rates from polycyclic aromatic hydrocarbons to refractory black carbon. This facilitates a strong increase of polycyclic aromatic hydrocarbons emissions. At nominal burn rates, full cycle emissions based on m/z 60 correlate well with organic aerosol, refractory black carbon and particulate matter. However, at higher burn rates, m/z 60 does not correlate with increased emissions of polycyclic aromatic hydrocarbons, refractory black carbon and organic aerosol in the flaming phase. The new knowledge can be used to advance source apportionment studies, reduce emissions of genotoxic compounds and model the climate impacts of refractory black carbon, such as absorption enhancement by lensing.

Insights into organic-aerosol sources via a novel laser-desorption/ionization mass spectrometry technique applied to one year of PM10 samples from nine sites in central Europe

NASA Astrophysics Data System (ADS)

Daellenbach, Kaspar R.; El-Haddad, Imad; Karvonen, Lassi; Vlachou, Athanasia; Corbin, Joel C.; Slowik, Jay G.; Heringa, Maarten F.; Bruns, Emily A.; Luedin, Samuel M.; Jaffrezo, Jean-Luc; Szidat, Sönke; Piazzalunga, Andrea; Gonzalez, Raquel; Fermo, Paola; Pflueger, Valentin; Vogel, Guido; Baltensperger, Urs; Prévôt, André S. H.

2018-02-01

We assess the benefits of offline laser-desorption/ionization mass spectrometry in understanding ambient particulate matter (PM) sources. The technique was optimized for measuring PM collected on quartz-fiber filters using silver nitrate as an internal standard for m/z calibration. This is the first application of this technique to samples collected at nine sites in central Europe throughout the entire year of 2013 (819 samples). Different PM sources were identified by positive matrix factorization (PMF) including also concomitant measurements (such as NOx, levoglucosan, and temperature). By comparison to reference mass spectral signatures from laboratory wood burning experiments as well as samples from a traffic tunnel, three biomass burning factors and two traffic factors were identified. The wood burning factors could be linked to the burning conditions; the factors related to inefficient burns had a larger impact on air quality in southern Alpine valleys than in northern Switzerland. The traffic factors were identified as primary tailpipe exhaust and most possibly aged/secondary traffic emissions. The latter attribution was supported by radiocarbon analyses of both the organic and elemental carbon. Besides these sources, factors related to secondary organic aerosol were also separated. The contribution of the wood burning emissions based on LDI-PMF (laser-desorption/ionization PMF) correlates well with that based on AMS-PMF (aerosol mass spectrometer PMF) analyses, while the comparison between the two techniques for other components is more complex.

Interactive effects of frequent burning and timber harvesting on above ground carbon biomass in temperate eucalypt forests

NASA Astrophysics Data System (ADS)

Collins, Luke; Penman, Trent; Ximenes, Fabiano; Bradstock, Ross

2015-04-01

The sequestration of carbon has been identified as an important strategy to mitigate the effects of climate change. Fuel reduction burning and timber harvesting are two common co-occurring management practices within forests. Frequent burning and timber harvesting may alter forest carbon pools through the removal and redistribution of biomass and demographic and structural changes to tree communities. Synergistic and antagonistic interactions between frequent burning and harvesting are likely to occur, adding further complexity to the management of forest carbon stocks. Research aimed at understanding the interactive effects of frequent fire and timber harvesting on carbon biomass is lacking. This study utilised data from two long term (25 - 30 years) manipulative burning experiments conducted in southern Australia in temperate eucalypt forests dominated by resprouting canopy species. Specifically we examined the effect of fire frequency and harvesting on (i) total biomass of above ground carbon pools and (ii) demographic and structural characteristics of live trees. We also investigated some of the mechanisms driving these changes. Frequent burning reduced carbon biomass by up to 20% in the live tree carbon pool. Significant interactions occurred between fire and harvesting, whereby the reduction in biomass of trees >20 cm diameter breast height (DBH) was amplified by increased fire frequency. The biomass of trees <20 cm DBH increased with harvesting intensity in frequently burnt areas, but was unaffected by harvesting intensity in areas experiencing low fire frequency. Biomass of standing and fallen coarse woody debris was relatively unaffected by logging and fire frequency. Fire and harvesting significantly altered stand structure over the study period. Comparison of pre-treatment conditions to current conditions revealed that logged sites had a significantly greater increase in the number of small trees (<40 cm DBH) than unlogged sites. Logged sites showed a significant decrease in the number of large trees (>60 cm DBH) over the study period, while unlogged sites showed an increase. Frequently burnt logged sites showed the greatest reduction in large trees, presumably due to increased fire related mortality and collapse. Analysis of tree survival and growth data suggest that mortality rate is increased and growth rate reduced in frequently burnt areas compared to unburnt areas. Our findings suggest that future shifts towards more frequent fire (both prescribed fire and wildfire) could potentially lead to broad scale reductions in carbon sequestration in temperate forests and woodlands dominated by resprouting canopy species. Reductions in carbon sequestration associated with frequent burning will potentially be amplified in intensively harvested landscapes.

Mass distribution and elemental analysis of the resultant atmospheric aerosol particles generated in controlled biomass burning processes

NASA Astrophysics Data System (ADS)

Ordou, N.; Agranovski, I. E.

2017-12-01

Air contamination resulting from bushfires is becoming increasingly important research question, as such disasters frequently occur in many countries. The objectives of this project were focused on physical and chemical characterisations of particulate emission resulting from burning of common representatives of Australian vegetation under controlled laboratory conditions. It was found that leaves are burned mostly with flaming phase and producing black smoke resulting in larger particles compared to white smoke in case of branches and grass, dominated by smouldering phase, producing finer particles. Following elemental analysis determined nine main elements in three different size fractions of particulate matter for each category of burning material, ranging from 14.1 μm to particle sizes below 2.54 μm. Potassium was found to be one of the main biomass markers, and sulphur was the ubiquitous element among the smoke particles followed by less prevalent trace elements like Na, Al, Mg, Zn, Si, Ca, and Fe.

Modelling carbonaceous aerosol from residential solid fuel burning with different assumptions for emissions

NASA Astrophysics Data System (ADS)

Ots, Riinu; Heal, Mathew R.; Young, Dominique E.; Williams, Leah R.; Allan, James D.; Nemitz, Eiko; Di Marco, Chiara; Detournay, Anais; Xu, Lu; Ng, Nga L.; Coe, Hugh; Herndon, Scott C.; Mackenzie, Ian A.; Green, David C.; Kuenen, Jeroen J. P.; Reis, Stefan; Vieno, Massimo

2018-04-01

Evidence is accumulating that emissions of primary particulate matter (PM) from residential wood and coal combustion in the UK may be underestimated and/or spatially misclassified. In this study, different assumptions for the spatial distribution and total emission of PM from solid fuel (wood and coal) burning in the UK were tested using an atmospheric chemical transport model. Modelled concentrations of the PM components were compared with measurements from aerosol mass spectrometers at four sites in central and Greater London (ClearfLo campaign, 2012), as well as with measurements from the UK black carbon network.The two main alternative emission scenarios modelled were Base4x and combRedist. For Base4x, officially reported PM2.5 from the residential and other non-industrial combustion source sector were increased by a factor of four. For the combRedist experiment, half of the baseline emissions from this same source were redistributed by residential population density to simulate the effect of allocating some emissions to the smoke control areas (that are assumed in the national inventory to have no emissions from this source). The Base4x scenario yielded better daily and hourly correlations with measurements than the combRedist scenario for year-long comparisons of the solid fuel organic aerosol (SFOA) component at the two London sites. However, the latter scenario better captured mean measured concentrations across all four sites. A third experiment, Redist - all emissions redistributed linearly to population density, is also presented as an indicator of the maximum concentrations an assumption like this could yield.The modelled elemental carbon (EC) concentrations derived from the combRedist experiments also compared well with seasonal average concentrations of black carbon observed across the network of UK sites. Together, the two model scenario simulations of SFOA and EC suggest both that residential solid fuel emissions may be higher than inventory estimates and that the spatial distribution of residential solid fuel burning emissions, particularly in smoke control areas, needs re-evaluation. The model results also suggest the assumed temporal profiles for residential emissions may require review to place greater emphasis on evening (including discretionary) solid fuel burning.

Biomass burning dominates brown carbon absorption in the rural southeastern United States

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Guo, H.; Xu, L.; Weber, R. J.; Ng, N. L.; Allen, H. M.; Ayres, B. R.; Baumann, K.; Cohen, R. C.; Draper, D. C.; Duffey, K. C.; Edgerton, E.; Fry, J. L.; Hu, W. W.; Jimenez, J. L.; Palm, B. B.; Romer, P.; Stone, E. A.; Wooldridge, P. J.; Brown, S. S.

2015-01-01

carbon aerosol consists of light-absorbing organic particulate matter with wavelength-dependent absorption. Aerosol optical extinction, absorption, size distributions, and chemical composition were measured in rural Alabama during summer 2013. The field site was well located to examine sources of brown carbon aerosol, with influence by high biogenic organic aerosol concentrations, pollution from two nearby cities, and biomass burning aerosol. We report the optical closure between measured dry aerosol extinction at 365 nm and calculated extinction from composition and size distribution, showing agreement within experiment uncertainties. We find that aerosol optical extinction is dominated by scattering, with single-scattering albedo values of 0.94 ± 0.02. Black carbon aerosol accounts for 91 ± 9% of the total carbonaceous aerosol absorption at 365 nm, while organic aerosol accounts for 9 ± 9%. The majority of brown carbon aerosol mass is associated with biomass burning, with smaller contributions from biogenically derived secondary organic aerosol.

Mass retention efficiencies of He accretion onto carbon-oxygen white dwarfs and type Ia supernovae

NASA Astrophysics Data System (ADS)

Wu, C.; Wang, B.; Liu, D.; Han, Z.

2017-07-01

Context. Type Ia supernovae (SNe Ia) play a crucial role in studying cosmology and galactic chemical evolution. They are thought to be thermonuclear explosions of carbon-oxygen white dwarfs (CO WDs) when their masses reach the Chandrasekar mass limit in binaries. Previous studies have suggested that He novae may be progenitor candidates of SNe Ia. However, the mass retention efficiencies during He nova outbursts are still uncertain. Aims: In this article, we aim to study the mass retention efficiencies of He nova outbursts and to investigate whether SNe Ia can be produced through He nova outbursts. Methods: Using the stellar evolution code Modules for Experiments in Stellar Astrophysics, we simulated a series of multicycle He-layer flashes, in which the initial WD masses range from 0.7 to 1.35 M⊙ with various accretion rates. Results: We obtained the mass retention efficiencies of He nova outbursts for various initial WD masses, which can be used in the binary population synthesis studies. In our simulations, He nova outbursts can increase the mass of the WD to the Chandrasekar mass limit and the explosive carbon burning can be triggered in the center of the WD; this suggests that He nova outbursts can produce SNe Ia. Meanwhile, the mass retention efficiencies in the present work are lower than those of previous studies, which leads to a lower birthrates of SNe Ia through the WD + He star channel. Furthermore, we obtained the elemental abundances distribution at the moment of explosive carbon burning, which can be used as the initial input parameters in studying explosion models of SNe Ia.

Stable carbon and nitrogen isotopic compositions of ambient aerosols collected from Okinawa Island in the western North Pacific Rim, an outflow region of Asian dusts and pollutants

NASA Astrophysics Data System (ADS)

Kunwar, Bhagawati; Kawamura, Kimitaka; Zhu, Chunmao

2016-04-01

Stable carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured for total carbon (TC) and nitrogen (TN), respectively, in aerosol (TSP) samples collected at Cape Hedo, Okinawa, an outflow region of Asian pollutants, during 2009-2010. The averaged δ13C and δ15N ratios are -22.2‰ and +12.5‰, respectively. The δ13C values are similar in both spring (-22.5‰) and winter (-22.5‰), suggesting the similar sources and/or source regions. We found that δ13C from Okinawa aerosols are ca. 2‰ higher than those reported from Chinese megacities probably due to photochemical aging of organic aerosols. A strong correlation (r = 0.81) was found between nss-Ca and TSP, suggesting that springtime aerosols are influenced from Asian dusts. However, carbonates in the Asian dusts were titrated with acidic species such as sulfuric acid and oxalic acid during atmospheric transport although two samples suggested the presence of remaining carbonate. No correlations were found between δ13C and tracer compounds (levoglucosan, elemental carbon, oxalic acid, and Na+). During winter and spring, coal burning is significant source in China. Based on isotopic mass balance, contribution of coal burning origin particles to total aerosol carbon was estimated as ca. 97% in winter, which is probably associated with the high emissions in China. Contribution of NO3- to TN was on average 45% whereas that of NH4+ was 18%. These results suggest that vehicular exhaust is an important source of TN in Okinawa aerosols. Concentration of water-soluble organic nitrogen (WSON) is higher in summer, suggesting that WSON is more emitted from the ocean in warmer season whereas inorganic nitrogen is more emitted in winter and spring from pollution sources in the Asian continent.

Relative importance of black carbon, brown carbon, and absorption enhancement from clear coatings in biomass burning emissions

NASA Astrophysics Data System (ADS)

Pokhrel, Rudra P.; Beamesderfer, Eric R.; Wagner, Nick L.; Langridge, Justin M.; Lack, Daniel A.; Jayarathne, Thilina; Stone, Elizabeth A.; Stockwell, Chelsea E.; Yokelson, Robert J.; Murphy, Shane M.

2017-04-01

A wide range of globally significant biomass fuels were burned during the fourth Fire Lab at Missoula Experiment (FLAME-4). A multi-channel photoacoustic absorption spectrometer (PAS) measured dry absorption at 405, 532, and 660 nm and thermally denuded (250 °C) absorption at 405 and 660 nm. Absorption coefficients were broken into contributions from black carbon (BC), brown carbon (BrC), and lensing following three different methodologies, with one extreme being a method that assumes the thermal denuder effectively removes organics and the other extreme being a method based on the assumption that black carbon (BC) has an Ångström exponent of unity. The methodologies employed provide ranges of potential importance of BrC to absorption but, on average, there was a difference of a factor of 2 in the ratio of the fraction of absorption attributable to BrC estimated by the two methods. BrC absorption at shorter visible wavelengths is of equal or greater importance to that of BC, with maximum contributions of up to 92 % of total aerosol absorption at 405 nm and up to 58 % of total absorption at 532 nm. Lensing is estimated to contribute a maximum of 30 % of total absorption, but typically contributes much less than this. Absorption enhancements and the estimated fraction of absorption from BrC show good correlation with the elemental-carbon-to-organic-carbon ratio (EC / OC) of emitted aerosols and weaker correlation with the modified combustion efficiency (MCE). Previous studies have shown that BrC grows darker (larger imaginary refractive index) as the ratio of black to organic aerosol (OA) mass increases. This study is consistent with those findings but also demonstrates that the fraction of total absorption attributable to BrC shows the opposite trend: increasing as the organic fraction of aerosol emissions increases and the EC / OC ratio decreases.

Burning by prescription in chaparral

Treesearch

Lisle R. Green

1981-01-01

Prescribed burning is frequently suggested for reducing conflagration costs in chaparral. Preparation for a prescribed burn includes environmental impact reports, approval by higher levels of authority, and a burn plan. After objectives are stated, the prescription can be written. Elements of the burn prescription reflect fuel, weather, and other factors that determine...

Polar and non-polar organic aerosols from large-scale agricultural-waste burning emissions in Northern India: Implications to organic mass-to-organic carbon ratio.

PubMed

Rajput, Prashant; Sarin, M M

2014-05-01

This study focuses on characteristics of organic aerosols (polar and non-polar) and total organic mass-to-organic carbon ratio (OM/OC) from post-harvest agricultural-waste (paddy- and wheat-residue) burning emissions in Northern India. Aerosol samples from an upwind location (Patiala: 30.2°N, 76.3°E) in the Indo-Gangetic Plain were analyzed for non-polar and polar fractions of organic carbon (OC1 and OC2) and their respective mass (OM1 and OM2). On average, polar organic aerosols (OM2) contribute nearly 85% of the total organic mass (OM) from the paddy- and wheat-residue burning emissions. The water-soluble-OC (WSOC) to OC2 ratio, within the analytical uncertainty, is close to 1 from both paddy- and wheat-residue burning emissions. However, temporal variability and relatively low WSOC/OC2 ratio (Av: 0.67±0.06) is attributed to high moisture content and poor combustion efficiency during paddy-residue burning, indicating significant contribution (∼30%) of aromatic carbon to OC2. The OM/OC ratio for non-polar (OM1/OC1∼1.2) and polar organic aerosols (OM2/OC2∼2.2), hitherto unknown for open agricultural-waste burning emissions, is documented in this study. The total OM/OC ratio is nearly identical, 1.9±0.2 and 1.8±0.2, from paddy- and wheat-residue burning emissions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Radiocarbon of Respired CO2 Following Fire in Alaskan Boreal Forest: Can Disturbance Release Old Soil Carbon to the Atmosphere?

NASA Astrophysics Data System (ADS)

Schuur, E. A.; Randerson, J. A.; Fessenden, J.; Trumbore, S. E.

2002-12-01

Fire in the boreal forest releases carbon stored in vegetation and soil to the atmosphere. Following fire, microbial decomposition is stimulated by inputs of plant detritus and changes in soil microclimate, which can result in large losses of carbon. Furthermore, warmer summer soil temperatures and deeper thaw depths in burned ecosystems may make carbon that was previously climatically protected by low soil temperatures susceptible to decomposition. We used radiocarbon measurements to estimate the age of carbon released by soil respiration following fire in two black spruce (Picea mariana) forests in interior Alaska that burned during the summer of 1999. To isolate soil respiration, we established manipulated plots where vegetation was prevented from recolonizing, and paired control plots in nearby unburned forest. Soil respiration radiocarbon signatures in the burned manipulation ranged from +112\\permil to +192\\permil and differed significantly from the unburned controls that ranged from +100\\permil to +130\\permil. Burned plots appear to respire older carbon than unburned forest, which could either be due to the stimulation of decomposition of intermediate age soil organic matter pools, to the lack of plant respiration that reflects the atmospheric radiocarbon signature of +92\\permil, or both. At least during the initial phase following fire, these data suggest that carbon fluxes from soil are dominated by soil organic matter pools with decadal scale turnover times.

PM10 source apportionment in Milan (Italy) using time-resolved data.

PubMed

Bernardoni, Vera; Vecchi, Roberta; Valli, Gianluigi; Piazzalunga, Andrea; Fermo, Paola

2011-10-15

In this work Positive Matrix Factorization (PMF) was applied to 4-hour resolved PM10 data collected in Milan (Italy) during summer and winter 2006. PM10 characterisation included elements (Mg-Pb), main inorganic ions (NH(4)(+), NO(3)(-), SO(4)(2-)), levoglucosan and its isomers (mannosan and galactosan), and organic and elemental carbon (OC and EC). PMF resolved seven factors that were assigned to construction works, re-suspended dust, secondary sulphate, traffic, industry, secondary nitrate, and wood burning. Multi Linear Regression was applied to obtain the PM10 source apportionment. The 4-hour temporal resolution allowed the estimation of the factor contributions during peculiar episodes, which would have not been detected with the traditional 24-hour sampling strategy. Copyright © 2011 Elsevier B.V. All rights reserved.

Recent Progress and Emerging Issues in Measuring and Modeling Biomass Burning Emissions

NASA Astrophysics Data System (ADS)

Yokelson, R. J.; Stockwell, C.; Veres, P. R.; Hatch, L. E.; Barsanti, K. C.; Simpson, I. J.; Blake, D. R.; Alvarado, M.; Kreidenweis, S. M.; Robinson, A. L.; Akagi, S. K.; McMeeking, G. R.; Stone, E.; Gilman, J.; Warneke, C.; Sedlacek, A. J.; Kleinman, L. I.

2013-12-01

Nine recent multi-PI campaigns (6 airborne, 3 laboratory) have quantified biomass burning emissions and the subsequent smoke evolution in unprecedented detail. Among these projects were the Fourth Fire Lab at Missoula Experiment (FLAME-4) and the DOE airborne campaign BBOP (Biomass Burning Observation Project). Between 2009 and 2013 a large selection of fuels and ecosystems were probed including: (1) 21 US prescribed fires in pine forests, chaparral, and shrublands; (2) numerous wildfires in the Pacific Northwest of the US; (3) 77 lab fires burning fuels collected from the sites of the prescribed fires; and (4) 158 lab fires burning authentic fuels in traditional cooking fires and advanced stoves; peat from Indonesia, Canada, and North Carolina; savanna grasses from Africa; temperate grasses from the US; crop waste from the US; rice straw from Taiwan, China, Malaysia, and California; temperate and boreal forest fuels collected in Montana and Alaska; chaparral fuels from California; trash; and tires. Instrumentation for gases included: FTIR, PTR-TOF-MS, 2D-GC and whole air sampling. Particle measurements included filter sampling (with IC, elemental carbon (EC), organic carbon (OC), and GC-MS) and numerous real-time measurements such as: HR-AMS (high-resolution aerosol MS), SP-AMS (soot particle AMS), SP2 (single particle soot photometer), SP-MS (single particle MS), ice nuclei, CCN (cloud condensation nuclei), water soluble OC, size distribution, and optical properties in the UV-VIS. New data include: emission factors for over 400 gases, black carbon (BC), brown carbon (BrC), organic aerosol (OA), ions, metals, EC, and OC; and details of particle morphology, mixing state, optical properties, size distributions, and cloud nucleating activity. Large concentrations (several ppm) of monoterpenes were present in fresh smoke. About 30-70% of the initially emitted gas-phase non-methane organic compounds were semivolatile and could not be identified with current technology. The detection rate for the sampled US prescribed fires was zero by burned area and <30% by active fire detection. Smoke evolution was measured for numerous gas-phase precursors and products, ozone, OA, ions, and BC and BrC mixing state. BC particles were coated within one hour and the smoke evolution was, in general, strongly impacted by the unidentified low volatility gases. An informative synthesis of lab and field fire data with fuels from the same sites was carried out. A preliminary comparison of wildfire and prescribed fire emissions will be presented. Novel schemes are under development to summarize the new emissions data for models, with limited mechanisms and parameterize fast, sub-grid processes. Key current issues to be discussed include: packaging/parameterizing the recent explosion of emissions/evolution data for use in model mechanisms; addressing fires not detected from space; addressing the large amount of unidentified semi-volatile gases emitted by all fires; and developing appropriate airborne and ground-based sampling scales/strategies for local-global models. We briefly summarize a recently funded project that will sample emissions and quantify biomass consumption by peat fires in Indonesia and a pending proposal for comprehensive sampling of cooking fires, brick kilns, garbage burning, diesel super-emitters, etc. in South Asia.

Modeling biomass burning emissions for Amazon forest and pastures in Rondônia, Brazil.

Treesearch

Liane S. Guild; J. Boone Kauffman; Warren B. Cohen; Christine A. Hlavka; Darold E. Ward

2004-01-01

As a source of atmospheric carbon, biomass burning emissions associated with deforestation in the Amazon are globally significant. Once deforested, these lands continue to be sources of substantial burning emissions for many years due to frequent pasture burning. The objective of this research was to quantify biomass-burning emissions at a local scale. We estimated...

Vegetation management with fire modifies peatland soil thermal regime.

PubMed

Brown, Lee E; Palmer, Sheila M; Johnston, Kerrylyn; Holden, Joseph

2015-05-01

Vegetation removal with fire can alter the thermal regime of the land surface, leading to significant changes in biogeochemistry (e.g. carbon cycling) and soil hydrology. In the UK, large expanses of carbon-rich upland environments are managed to encourage increased abundance of red grouse (Lagopus lagopus scotica) by rotational burning of shrub vegetation. To date, though, there has not been any consideration of whether prescribed vegetation burning on peatlands modifies the thermal regime of the soil mass in the years after fire. In this study thermal regime was monitored across 12 burned peatland soil plots over an 18-month period, with the aim of (i) quantifying thermal dynamics between burned plots of different ages (from <2 to 15 + years post burning), and (ii) developing statistical models to determine the magnitude of thermal change caused by vegetation management. Compared to plots burned 15 + years previously, plots recently burned (<2-4 years) showed higher mean, maximum and range of soil temperatures, and lower minima. Statistical models (generalised least square regression) were developed to predict daily mean and maximum soil temperature in plots burned 15 + years prior to the study. These models were then applied to predict temperatures of plots burned 2, 4 and 7 years previously, with significant deviations from predicted temperatures illustrating the magnitude of burn management effects. Temperatures measured in soil plots burned <2 years previously showed significant statistical disturbances from model predictions, reaching +6.2 °C for daily mean temperatures and +19.6 °C for daily maxima. Soil temperatures in plots burnt 7 years previously were most similar to plots burned 15 + years ago indicating the potential for soil temperatures to recover as vegetation regrows. Our findings that prescribed peatland vegetation burning alters soil thermal regime should provide an impetus for further research to understand the consequences of thermal regime change for carbon processing and release, and hydrological processes, in these peatlands. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Could managed burning of peatlands lead to enhanced carbon storage?

NASA Astrophysics Data System (ADS)

Worrall, F.; Clay, G. D.

2009-04-01

Peatlands are the UK's largest single terrestrial carbon store with carbon stored in UK peatlands than in forests of Britain and France combined. Unlike most northern peatlands in the peat soils of the UK are heavily managed for recreation and agriculture and due to their proximity to major centres of population are under more anthropogenic pressure than most peatlands. A typical management strategy on UK upland peats is the use of managed fire to restrict vegetation. Fires are used upon a 10-25 year rotation and are described as "cool" as they are designed to remove the crown of the vegetation without scorching the litter layer or the underlying soil. In this case the fire destroys primary productivity and limits litter production but produces char. Char is a low volume, highly refractory, high carbon content product while litter is a high volume, decomposable, lower carbon content product. Therefore, the question is if there are fire conditions under which the production of char causes more carbon to be stored in the peat than would have been stored if no fire management had been employed. This study combines field studies of recent managed burns and wildfires along with detailed vegetation studies from a long term monitoring site in order to assess litter, biomass and black carbon production. In the laboratory experimental burns were undertaken in order to assess the amount and controls upon char production and the carbon content of that char. Results of field and laboratory observations are used to model carbon accumulation under a series of fire management scenarios and the modelling shows that cools burns at long rotations could lead to higher carbon storage than if no fire had occurred, further in several cases more carbon accumulation occurred even if less depth of peat was generated.

Biomass Burning Dominates Brown Carbon Absorption in the Rural Southeastern U.S.

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Brown, S. S.; Guo, H.; Weber, R. J. J.; Xu, L.; Ng, N. L.; Stone, E. A.; Edgerton, E. S.; Baumann, K.; Hu, W.; Palm, B. B.; Jimenez, J. L.; Fry, J.; Ayres, B. R.; Draper, D.; Allen, H.

2014-12-01

Aerosol scattering and absorption are still among the largest uncertainties in quantifying radiative forcing. Brown carbon has a wavelength-dependent absorption that increases in the UV spectral region, and its major atmospheric sources include biomass burning, anthropogenic combustion of fossil fuels, and secondary organic aerosol. The rural Southeastern U.S. is influenced by high isoprene concentrations and varying concentrations of biomass burning aerosol, making it an ideal place to compare the relative contributions of these two sources to the brown carbon absorption budget. During the Southern Oxidant and Aerosol Study in summer 2013, we deployed a new field instrument that uses cavity enhanced spectroscopy with a broadband light source to measure aerosol optical extinction as a function of wavelength. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We combine these data with direct absorption measurements of water-soluble organic carbon obtained from a novel UV/VIS-WSOC instrument, and with aerosol composition measurements. We examine these data sets to determine: 1) the optical closure between measured dry aerosol extinction and values calculated from aerosol composition and size distribution; 2) the magnitude of brown and black carbon absorption; 3) the relative contributions of biomass burning, anthropogenic, and secondary organic aerosol contributions to brown carbon absorption in the Southeast U.S. during the summer. We conclude that biomass burning is a major contributor to optical absorption by organic aerosol in the rural southeastern U.S.

Chemical characterization and source apportionment of fine and coarse particulate matter in Lahore, Pakistan

NASA Astrophysics Data System (ADS)

Stone, Elizabeth; Schauer, James; Quraishi, Tauseef A.; Mahmood, Abid

2010-03-01

Lahore, Pakistan is an emerging megacity that is heavily polluted with high levels of particle air pollution. In this study, respirable particulate matter (PM 2.5 and PM 10) were collected every sixth day in Lahore from 12 January 2007 to 19 January 2008. Ambient aerosol was characterized using well-established chemical methods for mass, organic carbon (OC), elemental carbon (EC), ionic species (sulfate, nitrate, chloride, ammonium, sodium, calcium, and potassium), and organic species. The annual average concentration (±one standard deviation) of PM 2.5 was 194 ± 94 μg m -3 and PM 10 was 336 ± 135 μg m -3. Coarse aerosol (PM 10-2.5) was dominated by crustal sources like dust (74 ± 16%, annual average ± one standard deviation), whereas fine particles were dominated by carbonaceous aerosol (organic matter and elemental carbon, 61 ± 17%). Organic tracer species were used to identify sources of PM 2.5 OC and chemical mass balance (CMB) modeling was used to estimate relative source contributions. On an annual basis, non-catalyzed motor vehicles accounted for more than half of primary OC (53 ± 19%). Lesser sources included biomass burning (10 ± 5%) and the combined source of diesel engines and residual fuel oil combustion (6 ± 2%). Secondary organic aerosol (SOA) was an important contributor to ambient OC, particularly during the winter when secondary processing of aerosol species during fog episodes was expected. Coal combustion alone contributed a small percentage of organic aerosol (1.9 ± 0.3%), but showed strong linear correlation with unidentified sources of OC that contributed more significantly (27 ± 16%). Brick kilns, where coal and other low quality fuels are burned together, are suggested as the most probable origins of unapportioned OC. The chemical profiling of emissions from brick kilns and other sources unique to Lahore would contribute to a better understanding of OC sources in this megacity.

Comprehensive characterization of PM2.5 aerosols in Singapore

NASA Astrophysics Data System (ADS)

Balasubramanian, R.; Qian, W.-B.; Decesari, S.; Facchini, M. C.; Fuzzi, S.

2003-08-01

A comprehensive characterization of PM2.5 aerosols collected in Singapore from January through December 2000 is presented. The annual average mass concentration of PM2.5 was 27.2 μg/m3. The atmospheric loading of PM2.5 was elevated sporadically from March through May, mainly due to advection of biomass burning (deliberate fires to clear plantation areas) impacted air masses from Sumatra, Indonesia. Satellite images of the area, trajectory calculations, and surface wind direction data are in support of the transport of pyrogenic products from Sumatra toward Singapore. Aerosol samples collected during the dry season were analyzed for water-soluble ions, water-soluble organic compounds (WSOC), elemental carbon (EC), organic carbon, and trace elements using a number of analytical techniques. The major components were sulfate, EC, water-soluble carbonaceous materials, and water-insoluble carbonaceous materials. Aerosol WSOC were characterized based on a combination of chromatographic separations by ion exchange chromatography, functional group investigation by proton nuclear magnetic resonance, and total organic carbon determination. The comprehensive chemical characterization of PM2.5 particles revealed that both non-sea-salt sufate (nss-SO42-) and carbonaceous aerosols mainly contributed to the increase in the mass concentration of aerosols during the smoke haze period. Using a mass closure test (a mass balance), we determined whether the physical measurement of gravimetric fine PM concentration of a sample is equal to the summed concentrations of the individually identified chemical constituents (measured or inferred) in the sample. The sum of the determined groups of aerosol components and the gravimetrically determined mass agreed reasonably well. Principal component analysis was performed from the combined data set, and five factors were observed: a soil dust component, a metallurgical industry factor, a factor representing emissions from biomass burning and automobiles, a sea-salt component, and an oil combustion factor.

Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity

NASA Astrophysics Data System (ADS)

Pellegrini, Adam F. A.; Ahlström, Anders; Hobbie, Sarah E.; Reich, Peter B.; Nieradzik, Lars P.; Staver, A. Carla; Scharenbroch, Bryant C.; Jumpponen, Ari; Anderegg, William R. L.; Randerson, James T.; Jackson, Robert B.

2018-01-01

Fire frequency is changing globally and is projected to affect the global carbon cycle and climate. However, uncertainty about how ecosystems respond to decadal changes in fire frequency makes it difficult to predict the effects of altered fire regimes on the carbon cycle; for instance, we do not fully understand the long-term effects of fire on soil carbon and nutrient storage, or whether fire-driven nutrient losses limit plant productivity. Here we analyse data from 48 sites in savanna grasslands, broadleaf forests and needleleaf forests spanning up to 65 years, during which time the frequency of fires was altered at each site. We find that frequently burned plots experienced a decline in surface soil carbon and nitrogen that was non-saturating through time, having 36 per cent (±13 per cent) less carbon and 38 per cent (±16 per cent) less nitrogen after 64 years than plots that were protected from fire. Fire-driven carbon and nitrogen losses were substantial in savanna grasslands and broadleaf forests, but not in temperate and boreal needleleaf forests. We also observe comparable soil carbon and nitrogen losses in an independent field dataset and in dynamic model simulations of global vegetation. The model study predicts that the long-term losses of soil nitrogen that result from more frequent burning may in turn decrease the carbon that is sequestered by net primary productivity by about 20 per cent of the total carbon that is emitted from burning biomass over the same period. Furthermore, we estimate that the effects of changes in fire frequency on ecosystem carbon storage may be 30 per cent too low if they do not include multidecadal changes in soil carbon, especially in drier savanna grasslands. Future changes in fire frequency may shift ecosystem carbon storage by changing soil carbon pools and nitrogen limitations on plant growth, altering the carbon sink capacity of frequently burning savanna grasslands and broadleaf forests.

Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity.

PubMed

Pellegrini, Adam F A; Ahlström, Anders; Hobbie, Sarah E; Reich, Peter B; Nieradzik, Lars P; Staver, A Carla; Scharenbroch, Bryant C; Jumpponen, Ari; Anderegg, William R L; Randerson, James T; Jackson, Robert B

2018-01-11

Fire frequency is changing globally and is projected to affect the global carbon cycle and climate. However, uncertainty about how ecosystems respond to decadal changes in fire frequency makes it difficult to predict the effects of altered fire regimes on the carbon cycle; for instance, we do not fully understand the long-term effects of fire on soil carbon and nutrient storage, or whether fire-driven nutrient losses limit plant productivity. Here we analyse data from 48 sites in savanna grasslands, broadleaf forests and needleleaf forests spanning up to 65 years, during which time the frequency of fires was altered at each site. We find that frequently burned plots experienced a decline in surface soil carbon and nitrogen that was non-saturating through time, having 36 per cent (±13 per cent) less carbon and 38 per cent (±16 per cent) less nitrogen after 64 years than plots that were protected from fire. Fire-driven carbon and nitrogen losses were substantial in savanna grasslands and broadleaf forests, but not in temperate and boreal needleleaf forests. We also observe comparable soil carbon and nitrogen losses in an independent field dataset and in dynamic model simulations of global vegetation. The model study predicts that the long-term losses of soil nitrogen that result from more frequent burning may in turn decrease the carbon that is sequestered by net primary productivity by about 20 per cent of the total carbon that is emitted from burning biomass over the same period. Furthermore, we estimate that the effects of changes in fire frequency on ecosystem carbon storage may be 30 per cent too low if they do not include multidecadal changes in soil carbon, especially in drier savanna grasslands. Future changes in fire frequency may shift ecosystem carbon storage by changing soil carbon pools and nitrogen limitations on plant growth, altering the carbon sink capacity of frequently burning savanna grasslands and broadleaf forests.

The Carbon Crisis in 90 Seconds

NASA Technical Reports Server (NTRS)

Griffith, Peter

2011-01-01

This is a banana; and this is a chunk of coal. The banana is sweet and delicious and fun to eat... the coal is ... none of those things. But they are much more alike than they seem. Both were made by plants and store energy from the sun and carbon gas from the air around us. When you eat the banana, you use the energy stored in the banana to run and jump; and you release carbon gas back into the air around you. Now, carbon in the banana is young fast carbon: just weeks ago the banana was carbon gas in the air, and hours after you eat it, you breathe out the same carbon back into the air. When we burn coal in power plants, we use the energy stored in the coal to generate electricity that powers our homes and factories; and we release carbon gas back into the air around us. But, the carbon in the coal is old slow carbon. Plants took the coal carbon out of the air hundreds of millions of years ago. That carbon has been locked up ever since, and would stay locked up, if people hadn't dug up the coal and burned it. So now by burning coal and oil, people are adding lots and lots of old carbon to the atmosphere, faster than plants and the oceans can take it out. Why do I care? Because carbon gas in the atmosphere acts like a blanket, trapping heat, and making the whole planet warmer. My name is Peter, and I'm a carbon cycle scientist at NASA. We use satellites to watch how the world is warming. We can see the glaciers and the ice caps melting; and the air, land, and oceans warming. So we know we all have to change the way we produce and use energy, to burn less coal and oil, to prevent the planet from getting too warm.

Improving global fire carbon emissions estimates by combining moderate resolution burned area and active fire observations

NASA Astrophysics Data System (ADS)

Randerson, J. T.; Chen, Y.; Giglio, L.; Rogers, B. M.; van der Werf, G.

2011-12-01

In several important biomes, including croplands and tropical forests, many small fires exist that have sizes that are well below the detection limit for the current generation of burned area products derived from moderate resolution spectroradiometers. These fires likely have important effects on greenhouse gas and aerosol emissions and regional air quality. Here we developed an approach for combining 1km thermal anomalies (active fires; MOD14A2) and 500m burned area observations (MCD64A1) to estimate the prevalence of these fires and their likely contribution to burned area and carbon emissions. We first estimated active fires within and outside of 500m burn scars in 0.5 degree grid cells during 2001-2010 for which MCD64A1 burned area observations were available. For these two sets of active fires we then examined mean fire radiative power (FRP) and changes in enhanced vegetation index (EVI) derived from 16-day intervals immediately before and after each active fire observation. To estimate the burned area associated with sub-500m fires, we first applied burned area to active fire ratios derived solely from within burned area perimeters to active fires outside of burn perimeters. In a second step, we further modified our sub-500m burned area estimates using EVI changes from active fires outside and within of burned areas (after subtracting EVI changes derived from control regions). We found that in northern and southern Africa savanna regions and in Central and South America dry forest regions, the number of active fires outside of MCD64A1 burned areas increased considerably towards the end of the fire season. EVI changes for active fires outside of burn perimeters were, on average, considerably smaller than EVI changes associated with active fires inside burn scars, providing evidence for burn scars that were substantially smaller than the 25 ha area of a single 500m pixel. FRP estimates also were lower for active fires outside of burn perimeters. In our analysis we quantified how including sub-500m burned area influenced global burned area, carbon emissions, and net ecosystem exchange (NEE) in different continental regions using the Global Fire Emissions Database (GFED) biogeochemical model. We conclude by discussing validation needs using higher resolution visible and thermal imagery.

Pollution technology program, can-annular combustor engines

NASA Technical Reports Server (NTRS)

Roberts, R.; Fiorentino, A. J.; Greene, W.

1976-01-01

A Pollution Reduction Technology Program to develop and demonstrate the combustor technology necessary to reduce exhaust emissions for aircraft engines using can-annular combustors is described. The program consisted of design, fabrication, experimental rig testing and assessment of results and was conducted in three program elements. The combustor configurations of each program element represented increasing potential for meeting the 1979 Environmental Protection Agency (EPA) emission standards, while also representing increasing complexity and difficulty of development and adaptation to an operational engine. Experimental test rig results indicate that significant reductions were made to the emission levels of the baseline JT8D-17 combustor by concepts in all three program elements. One of the Element I single-stage combustors reduced carbon monoxide to a level near, and total unburned hydrocarbons (THC) and smoke to levels below the 1979 EPA standards with little or no improvement in oxides of nitrogen. The Element II two-stage advanced Vorbix (vortex burning and mixing) concept met the standard for THC and achieved significant reductions in CO and NOx relative to the baseline. Although the Element III prevaporized-premixed concept reduced high power NOx below the Element II results, there was no improvement to the integrated EPA parameter relative to the Vorbix combustor.

Short-term degradation of air quality during major firework events in Delhi, India

NASA Astrophysics Data System (ADS)

Shivani; Gadi, Ranu; Saxena, Mohit; Sharma, Sudhir Kumar; Mandal, Tuhin Kumar

2018-04-01

The effect of firework events on air quality was assessed from ambient fine particulate matter (PM2.5) collected during the Diwali period in two consecutive years, i.e., November 2015 and October 2016. The extensive firework activities led to the short-term degradation of air quality during the Diwali days. PM2.5 samples were chemically characterised for elements, water-soluble ionic species, organic carbon (OC) and elemental carbon (EC). Ba, K, Sr, S, Mg and Na showed significant increases in concentration on Diwali days compared to pre-Diwali days which revealed their association with firecrackers. Concentration of SO4 2-, NO3 -, Cl-, K+ and NH4 + ions contributed to the increases in PM2.5 concentration on Diwali days. Higher OC/EC ratios indicated the formation of secondary organic carbon during the Diwali period. This study concludes that the high PM2.5 level during Diwali 2016 was a result of contribution from fireworks on the Diwali night, trans-regional movement of pollutants due to crop residue burning, low wind speed (0.15 m s-1), and high humidity. It was observed that short-term exposure to Diwali is plausible to generate 1.3% increase in non-carcinogenic hazard index due to elements Al and Ba during Diwali 2016, whereas no significant variation was observed for the carcinogenic risk due to Pb. However, in 2015, the increase in non-carcinogenic hazard index was appreciably lower as compared to 2016.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMeeking, Gavin R.; Kreidenweis, Sonia M.; Baker, Stephen

We characterized the gas- and speciated aerosol-phase emissions from the open combustion of 33 different plant species during a series of 255 controlled laboratory burns during the Fire Laboratory at Missoula Experiments (FLAME). The plant species we tested were chosen to improve the existing database for U.S. domestic fuels: laboratory-based emission factors have not previously been reported for many commonly-burned species that are frequently consumed by fires near populated regions and protected scenic areas. The plants we tested included the chaparral species chamise, manzanita, and ceanothus, and species common to the southeastern US (common reed, hickory, kudzu, needlegrass rush, rhododendron,more » cord grass, sawgrass, titi, and wax myrtle). Fire-integrated emission factors for gas-phase CO{sub 2}, CO, CH{sub 4}, C{sub 2-4} hydrocarbons, NH{sub 3}, SO{sub 2}, NO, NO{sub 2}, HNO{sub 3} and particle-phase organic carbon (OC), elemental carbon (EC), SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, Na{sup +}, K{sup +}, and NH{sub 4}{sup +} generally varied with both fuel type and with the fire-integrated modified combustion efficiency (MCE), a measure of the relative importance of flaming- and smoldering-phase combustion to the total emissions during the burn. Chaparral fuels tended to emit less particulate OC per unit mass of dry fuel than did other fuel types, whereas southeastern species had some of the largest observed EF for total fine particulate matter. Our measurements often spanned a larger range of MCE than prior studies, and thus help to improve estimates for individual fuels of the variation of emissions with combustion conditions.« less

Carbon and nitrogen in Type 2 supernova diamonds

NASA Astrophysics Data System (ADS)

Clayton, Donald D.; Eleid, Mounib; Brown, Lawrence E.

1993-03-01

Abundant diamonds found in meteorites seem either to have condensed within supernova interiors during their expansions and coolings or to have been present around those explosions. Either alternative allows implantation of Xe-HL prior to interstellar mixing. A puzzling feature is the near normalcy of the carbon isotopes, considering that the only C-rich matter, the He-burning shell, is pure C-12 in that region. That last fact has caused many to associate supernova carbon with C-12 carbon, so that its SUNOCONS have been anticipated as very C-12-rich. We show that this expectation is misleading because the C-13-rich regions of Type 2's have been largely overlooked in this thinking. We here follow the idea that the diamonds nucleated in the C-12-rich He shell, the only C-rich site for nucleation, but then attached C-13-rich carbon during turbulent encounters with overlying C-13-rich matter. That is, the initial diamonds continued to grow during the same collisional encounters that cause the Xe-HL implantation. Instead of interacting with the small carbon mass having 13/12 = 0.2 in the upper He zone, however, we have calculated the remnants of the initial H-burning core, which left behind C-13-rich matter as it receded during core hydrogen burning. Howard et al. described why the velocity mixing would be essential to understanding the implantation of both the Xe-H and Xe-L components. Velocity mixing is now known to occur from the X-ray and gamma-ray light curves of supernova 1987A. Using the stellar evolution code developed at Goettingen, we calculated at Clemson the evolution of a grid of massive stars up to the beginning of core He burning. We paid attention to all H-burning reactions throughout the star, to the treatment of both convection and semiconvection, and to the recession of the outer boundary of the convective H-burning core as the star expands toward a larger redder state. This program was to generate a careful map of the CNO isotope distribution as He burning begins. Our result for the 30 solar mass star is shown.

A common explosion mechanism for type Ia supernovae.

PubMed

Mazzali, Paolo A; Röpke, Friedrich K; Benetti, Stefano; Hillebrandt, Wolfgang

2007-02-09

Type Ia supernovae, the thermonuclear explosions of white dwarf stars composed of carbon and oxygen, were instrumental as distance indicators in establishing the acceleration of the universe's expansion. However, the physics of the explosion are debated. Here we report a systematic spectral analysis of a large sample of well-observed type Ia supernovae. Mapping the velocity distribution of the main products of nuclear burning, we constrain theoretical scenarios. We find that all supernovae have low-velocity cores of stable iron-group elements. Outside this core, nickel-56 dominates the supernova ejecta. The outer extent of the iron-group material depends on the amount of nickel-56 and coincides with the inner extent of silicon, the principal product of incomplete burning. The outer extent of the bulk of silicon is similar in all supernovae, having an expansion velocity of approximately 11,000 kilometers per second and corresponding to a mass of slightly over one solar mass. This indicates that all the supernovae considered here burned similar masses and suggests that their progenitors had the same mass. Synthetic light-curve parameters and three-dimensional explosion simulations support this interpretation. A single explosion scenario, possibly a delayed detonation, may thus explain most type Ia supernovae.

Electronic equipment vulnerability to fire released carbon fibers

NASA Technical Reports Server (NTRS)

Pride, R. A.; Mchatton, A. D.; Musselman, K. A.

1980-01-01

The vulnerability of electronic equipment to damage by carbon fibers released from burning aircraft type structural composite materials was investigated. Tests were conducted on commercially available stereo power amplifiers which showed that the equipment was damaged by fire released carbon fibers but not by the composite resin residue, soot and products of combustion of the fuel associated with burning the carbon fiber composites. Results indicate that the failure rates of the equipment exposed to the fire released fiber were consistent with predictions based on tests using virgin fibers.

Semi-coke briquettes: towards reducing emissions of primary PM2.5, particulate carbon, and carbon monoxide from household coal combustion in China

NASA Astrophysics Data System (ADS)

Li, Qing; Li, Xinghua; Jiang, Jingkun; Duan, Lei; Ge, Su; Zhang, Qi; Deng, Jianguo; Wang, Shuxiao; Hao, Jiming

2016-01-01

Direct household use of unprocessed raw coals for cooking and heating without any air pollution control device has caused serious indoor and outdoor environment problems by emitting particulate matter (PM) and gaseous pollutants. This study examined household emission reduction by switching from unprocessed bituminous and anthracite coals to processed semi-coke briquettes. Two typical stoves were used to test emission characteristics when burning 20 raw coal samples commonly used in residential heating activities and 15 semi-coke briquette samples which were made from bituminous coals by industrial carbonization treatment. The carbonization treatment removes volatile compounds from raw coals which are the major precursors for PM formation and carbon emission. The average emission factors of primary PM2.5, elemental carbon, organic carbon, and carbon monoxide for the tested semi-coke briquettes are much lower than those of the tested raw coals. Based on the current coal consumption data in China, switching to semi-coke briquettes can reduce average emission factors of these species by about 92%, 98%, 91%, and 34%, respectively. Additionally, semi-coke briquette has relatively lower price and higher burnout ratio. The replacement of raw coals with semi-coke briquettes is a feasible path to reduce pollution emissions from household activities.

Semi-coke briquettes: towards reducing emissions of primary PM2.5, particulate carbon, and carbon monoxide from household coal combustion in China

PubMed Central

Li, Qing; Li, Xinghua; Jiang, Jingkun; Duan, Lei; Ge, Su; Zhang, Qi; Deng, Jianguo; Wang, Shuxiao; Hao, Jiming

2016-01-01

Direct household use of unprocessed raw coals for cooking and heating without any air pollution control device has caused serious indoor and outdoor environment problems by emitting particulate matter (PM) and gaseous pollutants. This study examined household emission reduction by switching from unprocessed bituminous and anthracite coals to processed semi-coke briquettes. Two typical stoves were used to test emission characteristics when burning 20 raw coal samples commonly used in residential heating activities and 15 semi-coke briquette samples which were made from bituminous coals by industrial carbonization treatment. The carbonization treatment removes volatile compounds from raw coals which are the major precursors for PM formation and carbon emission. The average emission factors of primary PM2.5, elemental carbon, organic carbon, and carbon monoxide for the tested semi-coke briquettes are much lower than those of the tested raw coals. Based on the current coal consumption data in China, switching to semi-coke briquettes can reduce average emission factors of these species by about 92%, 98%, 91%, and 34%, respectively. Additionally, semi-coke briquette has relatively lower price and higher burnout ratio. The replacement of raw coals with semi-coke briquettes is a feasible path to reduce pollution emissions from household activities. PMID:26782059

Source Apportionment of Elemental Carbon in Beijing, China: Insights from Radiocarbon and Organic Marker Measurements.

PubMed

Zhang, Yan-Lin; Schnelle-Kreis, Jürgen; Abbaszade, Gülcin; Zimmermann, Ralf; Zotter, Peter; Shen, Rong-rong; Schäfer, Klaus; Shao, Longyi; Prévôt, André S H; Szidat, Sönke

2015-07-21

Elemental carbon (EC) or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In this study, radiocarbon ((14)C) based source apportionment is used to distinguish between fossil fuel and biomass burning sources of EC isolated from aerosol filter samples collected in Beijing from June 2010 to May 2011. The (14)C results demonstrate that EC is consistently dominated by fossil-fuel combustion throughout the whole year with a mean contribution of 79% ± 6% (ranging from 70% to 91%), though EC has a higher mean and peak concentrations in the cold season. The seasonal molecular pattern of hopanes (i.e., a class of organic markers mainly emitted during the combustion of different fossil fuels) indicates that traffic-related emissions are the most important fossil source in the warm period and coal combustion emissions are significantly increased in the cold season. By combining (14)C based source apportionment results and picene (i.e., an organic marker for coal emissions) concentrations, relative contributions from coal (mainly from residential bituminous coal) and vehicle to EC in the cold period were estimated as 25 ± 4% and 50 ± 7%, respectively, whereas the coal combustion contribution was negligible or very small in the warm period.

Fast and safe gas detection from underground coal fire by drone fly over.

PubMed

Dunnington, Lucila; Nakagawa, Masami

2017-10-01

Underground coal fires start naturally or as a result of human activities. Besides burning away the important non-renewable energy resource and causing financial losses, burning coal seams emit carbon dioxide, carbon monoxide, sulfur oxide and methane, and is a leading cause of smog, acid rain, global warming, and air toxins. In the U.S. alone, the combined cost of coal-fire remediation projects that have been completed, budgeted, or projected by the U.S. Department of the Interior's Office of Surface Mining Remediation and Enforcement (OSM), exceeds $1 billion. It is estimated that these fires generate as much as 3% of the world's annual carbon dioxide emissions and consume as much as 5% of its minable coal. Considering the magnitude of environmental impact and economic loss caused by burning underground coal seams, we have developed a new, safe, reliable surface measurement of coal fire gases to assess the nature of underground coal fires. We use a drone mounted with gas sensors. Drone collected gas concentration data provides a safe alternative for evaluating the rank of a burning coal seam. In this study, a new method of determining coal rank by gas ratios is developed. Coal rank is valuable for defining parameters of a coal seam such as burn temperature, burn rate, and volume of burning seam. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pyrogenic carbon from tropical savanna burning: production and stable isotope composition

NASA Astrophysics Data System (ADS)

Saiz, G.; Wynn, J. G.; Wurster, C. M.; Goodrick, I.; Nelson, P. N.; Bird, M. I.

2015-03-01

Widespread burning of mixed tree-grass ecosystems represents the major natural locus of pyrogenic carbon (PyC) production. PyC is a significant, pervasive and yet poorly understood "slow-cycling" form of carbon present in the atmosphere, hydrosphere, soils and sediments. We conducted 16 experimental burns on a rainfall transect through northern Australian savannas with C4 grasses ranging from 35 to 99% of total biomass. Residues from each fire were partitioned into PyC and further into recalcitrant (HyPyC) components, with each of these fluxes also partitioned into proximal components (>125 μm), likely to remain close to the site of burning, and distal components (<125 μm), likely to be transported from the site of burning. The median (range) PyC production across all burns was 16.0 (11.5) % of total carbon exposed (TCE), with HyPyC accounting for 2.5 (4.9) % of TCE. Both PyC and HyPyC were dominantly partitioned into the proximal flux. Production of HyPyC was strongly related to fire residence time, with shorter duration fires resulting in higher HyPyC yields. The carbon isotope (δ13C) compositions of PyC and HyPyC were generally lower by 1-3‰ relative to the original biomass, with marked depletion up to 7‰ for grasslands dominated by C4 biomass. δ13C values of CO2 produced by combustion were computed by mass balance and ranged from ~0.4 to 1.3‰. The depletion of 13C in PyC and HyPyC relative to the original biomass has significant implications for the interpretation of δ13C values of savanna soil organic carbon and of ancient PyC preserved in the geologic record, as well as for global 13C isotopic disequilibria calculations.

Quantifying Asian and biomass burning sources of mercury using the Hg/CO ratio in pollution plumes observed at the Mount Bachelor observatory

NASA Astrophysics Data System (ADS)

Weiss-Penzias, Peter; Jaffe, Dan; Swartzendruber, Phil; Hafner, William; Chand, Duli; Prestbo, Eric

Total airborne mercury (TAM) and carbon monoxide (CO) were measured in 22 pollution transport "events" at Mt. Bachelor Observatory (MBO), USA (2.8 km asl) between March 2004 and September 2005. Submicron particulate scattering ( σsp), ozone ( O3), and nitrogen oxides ( NOy) were also measured and enhancement ratios for each chemical and aerosol species with CO were calculated. Events were categorized based on their source regions, which were determined by a combination of back trajectories, satellite fire detections, chemical and aerosol enhancement ratios, and meteorology. The mean ΔTAM/ΔCO values for each source region are: East Asian industrial ( 0.0046±0.0013ngm-3ppbv-1, n=10 events, 236 h), Pacific Northwest U.S. (PNW) biomass burning ( 0.0013±0.008ngm-3ppbv-1, n=7 events, 173 h), and Alaska biomass burning ( 0.0014±0.0006ngm-3ppbv-1, n=3 events, 96 h). The ΔTAM/ΔCO means from Asian long-range transport (ALRT) and biomass burning events are combined with previous estimates of CO emissions from Chinese anthropogenic, global biomass burning, and global boreal biomass sources in order to estimate the emissions of gaseous elemental mercury (GEM) from these sources. The GEM emissions that we calculate here are: Chinese anthropogenic ( 620±180ty-1), global biomass burning (670±330ty-1), and global boreal biomass burning (168±75ty-1), with errors estimated from propagating the uncertainty in the mean enhancement ratios and CO emissions. A comparison of our results with published mercury (Hg) emissions inventories reveals that the Chinese GEM emissions from this study are higher by about a factor of two, while our estimate for global biomass burning is consistent with previous studies.

Development a minimum data set of the information management system for burns.

PubMed

Ahmadi, Maryam; Alipour, Jahanpour; Mohammadi, Ali; Khorami, Farid

2015-08-01

Burns are the most common and destructive injuries in across of the world and especially in developing countries. Nevertheless, a standard tool for collecting the data of burn injury has not been developed yet. The purpose of this study was to develop a minimum data set (MDS) of the information management system for burns in Iran. This descriptive and cross-sectional study was performed in 2014. Data were collected from hospitals affiliated with Hormozgan and Iran University of Medical Sciences and medical documents centers, emergency centers and legal medicine centers located in Bandar Abbas city, in addition to internet access and library. Investigated documents were burn injury records in 2013, and documents that retrieved from the internet, and printed materials. Records were selected randomly based on T20-T29 categories from ICD-10. Data were collected using a checklist. In order to make a consensus about the data elements the decision Delphi technique was applied using a questionnaire. The content validity and reliability of questionnaire were assessed by expert's opinions and test-retest method, respectively. An MDS of burns was developed. This MDS divided into two categories: administrative and clinical with six and 17 section and 161 and 311 data elements respectively. This study showed that comprehensive and uniform data elements about burns do not exist in Iran. Therefore a MDS was developed for burns in Iran. Development of an MDS will result in standardization and effective management of the data through providing uniform and comprehensive data elements for burns. Thus, comparability of the extracted information from different analyses and researches will be possible in various levels. In addition, establishment of policies and prevention and control of burns will be possible, which results in the improvement of the quality of care and containment of costs. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Chemical composition of PM2.5 at an urban site of Chengdu in southwestern China

NASA Astrophysics Data System (ADS)

Tao, Jun; Cheng, Tiantao; Zhang, Renjian; Cao, Junji; Zhu, Lihua; Wang, Qiyuan; Luo, Lei; Zhang, Leiming

2013-07-01

PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annual average of PM2.5 was 165 μg m-3, which is generally higher than measurements in other Chinese cities, suggesting serious particulate pollution issues in the city. Water soluble ions contributed 43.5% to the annual total PM2.5 mass, carbonaceous aerosols including elemental carbon and organic carbon contributed 32.0%, and trace elements contributed 13.8%. Distinct daily and seasonal variations were observed in the mass concentrations of PM2.5 and its components, reflecting the seasonal variations of different anthropogenic and natural sources. Weakly acidic to neutral particles were found for PM2.5. Major sources of PM2.5 identified from source apportionment analysis included coal combustion, traffic exhaust, biomass burning, soil dust, and construction dust emissions. The low nitrate: sulfate ratio suggested that stationary emissions were more important than vehicle emissions. The reconstructed masses of ammonium sulfate, ammonium nitrate, particulate carbonaceous matter, and fine soil accounted for 79% of the total measured PM2.5 mass; they also accounted for 92% of the total measured particle scattering.

Lipid Droplets and Peroxisomes: Key Players in Cellular Lipid Homeostasis or A Matter of Fat—Store ’em Up or Burn ’em Down

PubMed Central

Kohlwein, Sepp D.; Veenhuis, Marten; van der Klei, Ida J.

2013-01-01

Lipid droplets (LDs) and peroxisomes are central players in cellular lipid homeostasis: some of their main functions are to control the metabolic flux and availability of fatty acids (LDs and peroxisomes) as well as of sterols (LDs). Both fatty acids and sterols serve multiple functions in the cell—as membrane stabilizers affecting membrane fluidity, as crucial structural elements of membrane-forming phospholipids and sphingolipids, as protein modifiers and signaling molecules, and last but not least, as a rich carbon and energy source. In addition, peroxisomes harbor enzymes of the malic acid shunt, which is indispensable to regenerate oxaloacetate for gluconeogenesis, thus allowing yeast cells to generate sugars from fatty acids or nonfermentable carbon sources. Therefore, failure of LD and peroxisome biogenesis and function are likely to lead to deregulated lipid fluxes and disrupted energy homeostasis with detrimental consequences for the cell. These pathological consequences of LD and peroxisome failure have indeed sparked great biomedical interest in understanding the biogenesis of these organelles, their functional roles in lipid homeostasis, interaction with cellular metabolism and other organelles, as well as their regulation, turnover, and inheritance. These questions are particularly burning in view of the pandemic development of lipid-associated disorders worldwide. PMID:23275493

A Modeling Approach for Burn Scar Assessment Using Natural Features and Elastic Property

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsap, L V; Zhang, Y; Goldgof, D B

2004-04-02

A modeling approach is presented for quantitative burn scar assessment. Emphases are given to: (1) constructing a finite element model from natural image features with an adaptive mesh, and (2) quantifying the Young's modulus of scars using the finite element model and the regularization method. A set of natural point features is extracted from the images of burn patients. A Delaunay triangle mesh is then generated that adapts to the point features. A 3D finite element model is built on top of the mesh with the aid of range images providing the depth information. The Young's modulus of scars ismore » quantified with a simplified regularization functional, assuming that the knowledge of scar's geometry is available. The consistency between the Relative Elasticity Index and the physician's rating based on the Vancouver Scale (a relative scale used to rate burn scars) indicates that the proposed modeling approach has high potentials for image-based quantitative burn scar assessment.« less

Aerosol emissions by tropical forest and savanna biomass burning: Characteristic trace elements and fluxes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Echalar, F.; Gaudichet, A.; Cachier, H.

1995-11-15

This report characterizes and compares trace element emissions from fires of three different types of savannas and from the southwestern amazonian rain forest. This study tries to verify a fingerprint that may characterize savanna fires or tropical biomass burning.

The air pollution caused by the burning of fireworks during the lantern festival in Beijing

NASA Astrophysics Data System (ADS)

Wang, Ying; Zhuang, Guoshun; Xu, Chang; An, Zhisheng

The effects of the burning of fireworks on air quality in Beijing was firstly assessed from the ambient concentrations of various air pollutants (SO 2, NO 2, PM 2.5, PM 10 and chemical components in the particles) during the lantern festival in 2006. Eighteen ions, 20 elements, and black carbon were measured in PM 2.5 and PM 10, and the levels of organic carbon could be well estimated from the concentrations of dicarboxylic acids. Primary components of Ba, K, Sr, Cl -, Pb, Mg and secondary components of C 5H 6O 42-, C 3H 2O 42-, C 2O 42-, C 4H 4O 42-, SO 42-, NO 3- were over five times higher in the lantern days than in the normal days. The firework particles were acidic and of inorganic matter mostly with less amounts of secondary components. Primary aerosols from the burning of fireworks were mainly in the fine mode, while secondary formation of acidic anions mainly took place on the coarse particles. Nitrate was mainly formed through homogeneous gas-phase reactions of NO 2, while sulfate was largely from heterogeneous catalytic transformations of SO 2. Fe could catalyze the formation of nitrate through the reaction of α-Fe 2O 3 with HNO 3, while in the formation of sulfate, Fe is not only the catalyst, but also the oxidant. A simple method using the concentration of potassium and a modified method using the ratio of Mg/Al have been developed to quantify the source contribution of fireworks. It was found that over 90% of the total mineral aerosol and 98% of Pb, 43% of total carbon, 28% of Zn, 8% of NO 3-, and 3% of SO 42- in PM 2.5 were from the emissions of fireworks on the lantern night.

Influence of wildfires on atmospheric composition and carbon uptake of forest ecosystems in Central Siberia: the establishing of a long-term post-fire monitoring system

NASA Astrophysics Data System (ADS)

Panov, Alexey; Chi, Xuguang; Winderlich, Jan; Prokushkin, Anatoly; Bryukhanov, Alexander; Korets, Mikhail; Ponomarev, Evgenii; Timokhina, Anastasya; Andreae, Meinrat O.; Heimann, Martin

2014-05-01

Calculations of direct emissions of greenhouse gases from boreal wildfires remain uncertain due to problems with emission factors, available carbon, and imprecise estimates of burned areas. Even more varied and sparse are accurate in situ calculations of temporal changes in boreal forest carbon dynamics following fire. Linking simultaneous instrumental atmospheric observations, GIS-based estimates of burned areas, and ecosystem carbon uptake calculations is vital to fill this knowledge gap. Since 2006 the Zotino Tall Tower Observatory (ZOTTO; www.zottoproject.org) a research platform for large-scale climatic observations is operational in Central Siberia (60°48'N, 89°21'E). The data of ongoing greenhouse gases measurements at the tower are used in atmospheric inversions studies to infer the distribution of carbon sinks and sources over central Northern Eurasia. We present our contribution to reducing uncertainties in estimates of fire influence on atmospheric composition and post-fire ecosystem carbon uptake deduced from the large-scale fires that happened in 2012 in the tall tower footprint area. The burned areas were estimated from Landsat ETM 5,8 satellite images, while fires were detected from Terra/Aqua MODIS satellite data. The magnitude of ecological change caused by fires ("burn severity") was measured and mapped with a Normalized Burn Ratio (NBR) index and further calibrated by a complementary field based Composite Burn Index (CBI). Measures of fire radiative power (FRP) index provided information on fire heat release intensity and on the amount and completeness of biomass combustion. Based on the analyzed GIS data, the system of study plots was established in the 5 dominating ecosystem types for a long-term post-fire monitoring. On the plots the comprehensive estimation of ecosystem parameters and carbon pools and their mapping was organized with a laser-based field instrumentation system. The work was supported financially by ISTC Project # 2757p, project of RFBR # 13-05-98053, and grant of president of RF for young scientists MK-1691.2014.5.

Fire management and carbon sequestration in Pine Barren Forests

Treesearch

Kenneth L. Clark; Nicholas Skowronski; Michael Gallagher

2015-01-01

Prescribed burning is the major viable option that land managers have for reducing hazardous fuels and ensuring the regeneration of fire-dependent species in a cost-effective manner in Pine Barren ecosystems. Fuels management activities are directly linked to carbon (C) storage and rates of C sequestration by forests. To evaluate the effects of prescribed burning on...

Comparing soil carbon of short rotation poplar plantations with agricultural crops and woodlots in north central United States

Treesearch

Mark D. Coleman; J.G. Isebrands; David N. Tolsted; Virginia R. Tolbert

2004-01-01

Atmospheric carbon dioxide (CO2) has increased dramatically since the beginning of the Industrial Revolution as a result of human activities (Keeling and others 1995, Houghton and others 2001). The primary cause of CO2 increases are worldwide fossil fuel burning, biomass burning, and cement manufacturing. These activities...

The potential for damage from the accidental release of conductive carbon fibers from burning composites

NASA Technical Reports Server (NTRS)

Bell, V. L.

1980-01-01

The potential damage to electrical equipment caused by the release of carbon fibers from burning commercial airliners is assessed in terms of annual expected costs and maximum losses at low probabilities of occurrence. A materials research program to provide alternate or modified composite materials for aircraft structures is reviewed.

Decadal changes in aerosol absorption across Brazil resulting from changes in biomass burning practices

NASA Astrophysics Data System (ADS)

Coe, H.; Morgan, W.; Darbyshire, E.; Allan, J. D.; Flynn, M.; Liu, D.; Langridge, J.; Johnson, B. T.; Haywood, J. M.; Longo, K.; Artaxo, P.; Highwood, E.; Mollard, J.

2015-12-01

Open biomass burning makes a substantial contribution to the global budget of black carbon, yet models significantly underestimate absorption aerosol optical depth compared to observations by approximately a factor of two over South America. These large differences need to be addressed. Recent work has shown that the number of deforestation fires has decreased across Amazonia over the last decade, giving rise to a decrease in the abundance of biomass burning aerosol across the region. At the same time there has been an increase in the frequency of agricultural burning across regions that have previously been deforested, as well as increased burning in the east of Brazil in the Cerrado regions. We sampled both of these types of open burning extensively during a recent aircraft experiment. Significant concentrations of organic carbon as well as black carbon were observed, with this ratio providing the main control on the single scattering albedo (SSA).Deforestation fires and wild forest fires are prevalent across the south west of the Amazon Basin, where smouldering burning dominates. In the east of Brazil, agricultural burning proceeds via a much more efficient form of combustion and as a result, black carbon is a much larger fraction of the aerosol mass and SSAs are much lower than in the west. We have analysed MISR data across the region to show that whilst aerosol optical depths have decreased during the dry season over the last decade, with greater rates of reduction occurring over the south western margins of Amazonia, absorption aerosol optical depths have significantly increased over the Cerrado and remained constant over south western Amazonia. This has led to a decline in SSA across the whole of the region with greater reductions occurring over the eastern states. This finding is consistent with our aircraft measurements. We will discuss the implications of these changes for air quality and climate across the region.

Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

NASA Astrophysics Data System (ADS)

Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

2012-01-01

We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.

Modeling long-term changes in tundra carbon balance following wildfire, climate change, and potential nutrient addition.

PubMed

Jiang, Yueyang; Rastetter, Edward B; Shaver, Gaius R; Rocha, Adrian V; Zhuang, Qianlai; Kwiatkowski, Bonnie L

2017-01-01

To investigate the underlying mechanisms that control long-term recovery of tundra carbon (C) and nutrients after fire, we employed the Multiple Element Limitation (MEL) model to simulate 200-yr post-fire changes in the biogeochemistry of three sites along a burn severity gradient in response to increases in air temperature, CO 2 concentration, nitrogen (N) deposition, and phosphorus (P) weathering rates. The simulations were conducted for severely burned, moderately burned, and unburned arctic tundra. Our simulations indicated that recovery of C balance after fire was mainly determined by the internal redistribution of nutrients among ecosystem components (controlled by air temperature), rather than the supply of nutrients from external sources (e.g., nitrogen deposition and fixation, phosphorus weathering). Increases in air temperature and atmospheric CO 2 concentration resulted in (1) a net transfer of nutrient from soil organic matter to vegetation and (2) higher C : nutrient ratios in vegetation and soil organic matter. These changes led to gains in vegetation biomass C but net losses in soil organic C stocks. Under a warming climate, nutrients lost in wildfire were difficult to recover because the warming-induced acceleration in nutrient cycles caused further net nutrient loss from the system through leaching. In both burned and unburned tundra, the warming-caused acceleration in nutrient cycles and increases in ecosystem C stocks were eventually constrained by increases in soil C : nutrient ratios, which increased microbial retention of plant-available nutrients in the soil. Accelerated nutrient turnover, loss of C, and increasing soil temperatures will likely result in vegetation changes, which further regulate the long-term biogeochemical succession. Our analysis should help in the assessment of tundra C budgets and of the recovery of biogeochemical function following fire, which is in turn necessary for the maintenance of wildlife habitat and tundra vegetation. © 2016 by the Ecological Society of America.

Near-Infrared Spectra of Type Ia Supernovae

NASA Technical Reports Server (NTRS)

Marion, G. H.; Hoeflich, P.; Vacca, W. D.; Wheeler, J. C.

2003-01-01

We report near-infrared (NIR) spectroscopic observations of 12 'branch-normal' Type Ia supernovae (SNe Ia) that cover the wavelength region from 0.8 to 2.5 microns. Our sample more than doubles the number of SNe Ia with published NIR spectra within 3 weeks of maximum light. The epochs of observation range from 13 days before maximum light to 18 days after maximum light. A detailed model for a Type Ia supernovae is used to identify spectral features. The Doppler shifts of lines are measured to obtain the velocity and thus the radial distribution of elements. The NIR is an extremely useful tool to probe the chemical structure in the layers of SNe Ia ejecta. This wavelength region is optimal for examining certain products of the SNe Ia explosion that may be blended or obscured in other spectral regions. We identify spectral features from Mg II, Ca II, Si II, Fe II, Co II, Ni II, and possibly Mn II. We find no indications for hydrogen, helium, or carbon in the spectra. The spectral features reveal important clues about the physical characteristics of SNe Ia. We use the features to derive upper limits for the amount of unburned matter, to identify the transition regions from explosive carbon to oxygen burning and from partial to complete silicon burning, and to estimate the level of mixing during and after the explosion. Elements synthesized in the outer layers during the explosion appear to remain in distinct layers. That provides strong evidence for the presence of a detonation phase during the explosion as it occurs in delayed detonation or merger models. Mg II velocities are found to exceed 11,000 - 15,000 km/s, depending on the individual SNe Ia. That result suggests that burning during the explosion reaches the outermost layers of the progenitor and limits the amount of unburned material to less than 10% of the mass of the progenitor. Small residuals of unburned material are predicted by delayed detonation models but are inconsistent with pure deflagration or merger models. Differences in the spectra of the individual SNe Ia demonstrate the variety of these events.

Estimation of local and external contributions of biomass burning to PM2.5 in an industrial zone included in a large urban settlement.

PubMed

Benetello, Francesca; Squizzato, Stefania; Hofer, Angelika; Masiol, Mauro; Khan, Md Badiuzzaman; Piazzalunga, Andrea; Fermo, Paola; Formenton, Gian Maria; Rampazzo, Giancarlo; Pavoni, Bruno

2017-01-01

A total of 85 PM 2.5 samples were collected at a site located in a large industrial zone (Porto Marghera, Venice, Italy) during a 1-year-long sampling campaign. Samples were analyzed to determine water-soluble inorganic ions, elemental and organic carbon, and levoglucosan, and results were processed to investigate the seasonal patterns, the relationship between the analyzed species, and the most probable sources by using a set of tools, including (i) conditional probability function (CPF), (ii) conditional bivariate probability function (CBPF), (iii) concentration weighted trajectory (CWT), and (iv) potential source contribution function (PSCF) analyses. Furthermore, the importance of biomass combustions to PM 2.5 was also estimated. Average PM 2.5 concentrations ranged between 54 and 16 μg m -3 in the cold and warm period, respectively. The mean value of total ions was 11 μg m -3 (range 1-46 μg m -3 ): The most abundant ion was nitrate with a share of 44 % followed by sulfate (29 %), ammonium (14 %), potassium (4 %), and chloride (4 %). Levoglucosan accounted for 1.2 % of the PM 2.5 mass, and its concentration ranged from few ng m -3 in warm periods to 2.66 μg m -3 during winter. Average concentrations of levoglucosan during the cold period were higher than those found in other European urban sites. This result may indicate a great influence of biomass combustions on particulate matter pollution. Elemental and organic carbon (EC, OC) showed similar behavior, with the highest contributions during cold periods and lower during summer. The ratios between biomass burning indicators (K + , Cl - , NO 3 - , SO 4 2- , levoglucosan, EC, and OC) were used as proxy for the biomass burning estimation, and the contribution to the OC and PM 2.5 was also calculated by using the levoglucosan (LG)/OC and LG/PM 2.5 ratios and was estimated to be 29 and 18 %, respectively.

Characterization of emissions from South Asian biofuels and application to source apportionment of carbonaceous aerosol in the Himalayas

NASA Astrophysics Data System (ADS)

Stone, Elizabeth A.; Schauer, James J.; Pradhan, Bidya Banmali; Dangol, Pradeep Man; Habib, Gazala; Venkataraman, Chandra; Ramanathan, V.

2010-03-01

This study focuses on improving source apportionment of carbonaceous aerosol in South Asia and consists of three parts: (1) development of novel molecular marker-based profiles for real-world biofuel combustion, (2) application of these profiles to a year-long data set, and (3) evaluation of profiles by an in-depth sensitivity analysis. Emissions profiles for biomass fuels were developed through source testing of a residential stove commonly used in South Asia. Wood fuels were combusted at high and low rates, which corresponded to source profiles high in organic carbon (OC) or high in elemental carbon (EC), respectively. Crop wastes common to the region, including rice straw, mustard stalk, jute stalk, soybean stalk, and animal residue burnings, were also characterized. Biofuel profiles were used in a source apportionment study of OC and EC in Godavari, Nepal. This site is located in the foothills of the Himalayas and was selected for its well-mixed and regionally impacted air masses. At Godavari, daily samples of fine particulate matter (PM2.5) were collected throughout the year of 2006, and the annual trends in particulate mass, OC, and EC followed the occurrence of a regional haze in South Asia. Maximum concentrations occurred during the dry winter season and minimum concentrations occurred during the summer monsoon season. Specific organic compounds unique to aerosol sources, molecular markers, were measured in monthly composite samples. These markers implicated motor vehicles, coal combustion, biomass burning, cow dung burning, vegetative detritus, and secondary organic aerosol as sources of carbonaceous aerosol. A molecular marker-based chemical mass balance (CMB) model provided a quantitative assessment of primary source contributions to carbonaceous aerosol. The new profiles were compared to widely used biomass burning profiles from the literature in a sensitivity analysis. This analysis indicated a high degree of stability in estimates of source contributions to OC when different biomass profiles were used. The majority of OC was unapportioned to primary sources and was estimated to be of secondary origin, while biomass combustion was the next-largest source of OC. The CMB apportionment of EC to primary sources was unstable due to the diversity of biomass burning conditions in the region. The model results suggested that biomass burning and fossil fuel were important contributors to EC, but could not reconcile their relative contributions.

Particle and VOC emission factor measurements for anthropogenic sources in West Africa

NASA Astrophysics Data System (ADS)

Keita, Sekou; Liousse, Cathy; Yoboué, Véronique; Dominutti, Pamela; Guinot, Benjamin; Assamoi, Eric-Michel; Borbon, Agnès; Haslett, Sophie L.; Bouvier, Laetitia; Colomb, Aurélie; Coe, Hugh; Akpo, Aristide; Adon, Jacques; Bahino, Julien; Doumbia, Madina; Djossou, Julien; Galy-Lacaux, Corinne; Gardrat, Eric; Gnamien, Sylvain; Léon, Jean F.; Ossohou, Money; Touré N'Datchoh, E.; Roblou, Laurent

2018-06-01

A number of campaigns have been carried out to establish the emission factors of pollutants from fuel combustion in West Africa, as part of work package 2 (Air Pollution and Health) of the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) FP7 program. Emission sources considered here include wood (hevea and iroko) and charcoal burning, charcoal making, open trash burning, and vehicle emissions, including trucks, cars, buses and two-wheeled vehicles. Emission factors of total particulate matter (TPM), elemental carbon (EC), primary organic carbon (OC) and volatile organic compounds (VOCs) have been established. In addition, emission factor measurements were performed in combustion chambers in order to reproduce field burning conditions for a tropical hardwood (hevea), and obtain particulate emission factors by size (PM0.25, PM1, PM2.5 and PM10). Particle samples were collected on quartz fiber filters and analyzed using gravimetric method for TPM and thermal methods for EC and OC. The emission factors of 58 VOC species were determined using offline sampling on a sorbent tube. Emission factor results for two species of tropical hardwood burning of EC, OC and TPM are 0.98 ± 0.46 g kg-1 of fuel burned (g kg-1), 11.05 ± 4.55 and 41.12 ± 24.62 g kg-1, respectively. For traffic sources, the highest emission factors among particulate species are found for the two-wheeled vehicles with two-stroke engines (2.74 g kg-1 fuel for EC, 65.11 g kg-1 fuel for OC and 496 g kg-1 fuel for TPM). The largest VOC emissions are observed for two-stroke two-wheeled vehicles, which are up to 3 times higher than emissions from light-duty and heavy-duty vehicles. Isoprene and monoterpenes, which are usually associated with biogenic emissions, are present in almost all anthropogenic sources investigated during this work and could be as significant as aromatic emissions in wood burning (1 g kg-1 fuel). EC is primarily emitted in the ultrafine fraction, with 77 % of the total mass being emitted as particles smaller than 0.25 µm. The particles and VOC emission factors obtained in this study are generally higher than those in the literature whose values are discussed in this paper. This study underlines the important role of in situ measurements in deriving realistic and representative emission factors.

Carbon Monoxide (CO)

MedlinePlus

... burning appliances -- including furnaces, stoves, fireplaces, clothes dryers, water heaters, and space heaters -- to detect deadly carbon monoxide leaks. Underwriters' Laboratory Product Safety Tips - Carbon Monoxide Alarms ...

The origin of black carbon on speleothems in tourist caves in South Korea: Chemical characterization and source discrimination by radiocarbon measurement

NASA Astrophysics Data System (ADS)

Chang, Sae Jung; Jeong, Gi Young; Kim, Soo Jin

Since the Gosu, Ondal, and Sungryu karst caves in South Korea became open to the public several decades ago, the surface of their speleothems has been turning black due to pollutants. The black pollutant is concentrated at the surface of speleothems, and the surface black layer is 0.1 to several millimeters thick. Elemental measurements of three bulk, acid-dissolved and oxidized fractions of the surface black layer show that the black pigment is a black carbon. The black carbon correlates positively with sulfates, nitrates, manganese, and lead, which are typical tracers of industrial and urban emissions. The 14C-measurement of the black carbon, using accelerator mass spectrometry, shows that the black carbon was derived from both fossil-fuel combustion and biomass burning in roughly equal amounts, evidenced by fC value ranging from 0.340 to 0.592 (<±0.004, 1 σ). Therefore, protection of speleothems from black coloration requires control of anthropogenic black carbons carried by visitors. Suitable measures might include closure of caves, air cleaning of visitors and regulation of visitor numbers. The application of radiocarbon measurement of black carbon suggests that the fC is a valuable proxy for tracing the blackening phenomenon of natural and cultural heritage sites such as caves.

Black carbon in aerosol during BIBLE B

NASA Astrophysics Data System (ADS)

Liley, J. Ben; Baumgardner, D.; Kondo, Y.; Kita, K.; Blake, D. R.; Koike, M.; Machida, T.; Takegawa, N.; Kawakami, S.; Shirai, T.; Ogawa, T.

2003-02-01

The Biomass Burning and Lightning Experiment (BIBLE) A and B campaigns over the tropical western Pacific during springtime deployed a Gulfstream-II aircraft with systems to measure ozone and numerous precursor species. Aerosol measuring systems included a MASP optical particle counter, a condensation nucleus (CN) counter, and an absorption spectrometer for black carbon. Aerosol volume was very low in the middle and upper troposphere during both campaigns, and during BIBLE A, there was little aerosol enhancement in the boundary layer away from urban areas. In BIBLE B, there was marked aerosol enhancement in the lowest 3 km of the atmosphere. Mixing ratios of CN in cloud-free conditions in the upper troposphere were in general higher than in the boundary layer, indicating new particle formation from gaseous precursors. High concentrations of black carbon were observed during BIBLE B, with mass loadings up to 40 μg m-3 representing as much as one quarter of total aerosol mass. Strong correlations with hydrocarbon enhancement allow the determination of a black carbon emission ratio for the fires at that time. Expressed as elemental carbon, it is about 0.5% of carbon dioxide and 6% of carbon monoxide emissions from the same fires, comparable to methane production, and greater than that of other hydrocarbons.

Black carbon in aerosol during BIBLE B

NASA Astrophysics Data System (ADS)

Liley, J. Ben; Baumgardner, D.; Kondo, Y.; Kita, K.; Blake, D. R.; Koike, M.; Machida, T.; Takegawa, N.; Kawakami, S.; Shirai, T.; Ogawa, T.

2002-02-01

The Biomass Burning and Lightning Experiment (BIBLE) A and B campaigns over the tropical western Pacific during springtime deployed a Gulfstream-II aircraft with systems to measure ozone and numerous precursor species. Aerosol measuring systems included a MASP optical particle counter, a condensation nucleus (CN) counter, and an absorption spectrometer for black carbon. Aerosol volume was very low in the middle and upper troposphere during both campaigns, and during BIBLE A, there was little aerosol enhancement in the boundary layer away from urban areas. In BIBLE B, there was marked aerosol enhancement in the lowest 3 km of the atmosphere. Mixing ratios of CN in cloud-free conditions in the upper troposphere were in general higher than in the boundary layer, indicating new particle formation from gaseous precursors. High concentrations of black carbon were observed during BIBLE B, with mass loadings up to 40 μg m-3 representing as much as one quarter of total aerosol mass. Strong correlations with hydrocarbon enhancement allow the determination of a black carbon emission ratio for the fires at that time. Expressed as elemental carbon, it is about 0.5% of carbon dioxide and 6% of carbon monoxide emissions from the same fires, comparable to methane production, and greater than that of other hydrocarbons.

Full scale calcium bromide injection with subsequent mercury oxidation and removal within wet flue gas desulphurization system: Experience at a 700 MW coal-fired power facility

NASA Astrophysics Data System (ADS)

Berry, Mark Simpson

The Environmental Protection Agency promulgated the Mercury and Air Toxics Standards rule, which requires that existing power plants reduce mercury emissions to meet an emission rate of 1.2 lb/TBtu on a 30-day rolling average and that new plants meet a 0.0002 lb/GWHr emission rate. This translates to mercury removals greater than 90% for existing units and greater than 99% for new units. Current state-of-the-art technology for the control of mercury emissions uses activated carbon injected upstream of a fabric filter, a costly proposition. For example, a fabric filter, if not already available, would require a 200M capital investment for a 700 MW size unit. A lower-cost option involves the injection of activated carbon into an existing cold-side electrostatic precipitator. Both options would incur the cost of activated carbon, upwards of 3M per year. The combination of selective catalytic reduction (SCR) reactors and wet flue gas desulphurization (wet FGD) systems have demonstrated the ability to substantially reduce mercury emissions, especially at units that burn coals containing sufficient halogens. Halogens are necessary for transforming elemental mercury to oxidized mercury, which is water-soluble. Plants burning halogen-deficient coals such as Power River Basin (PRB) coals currently have no alternative but to install activated carbon-based approaches to control mercury emissions. This research consisted of investigating calcium bromide addition onto PRB coal as a method of increasing flue gas halogen concentration. The treated coal was combusted in a 700 MW boiler and the subsequent treated flue gas was introduced into a wet FGD. Short-term parametric and an 83-day longer-term tests were completed to determine the ability of calcium bromine to oxidize mercury and to study the removal of the mercury in a wet FGD. The research goal was to show that calcium bromine addition to PRB coal was a viable approach for meeting the Mercury and Air Toxics Standards rule for existing boilers. The use of calcium bromide injection as an alternative to activated carbon approaches could save millions of dollars. The technology application described herein has the potential to reduce compliance cost by $200M for a 700 MW facility burning PRB coal.

Effects of wildland fire on regional and global carbon stocks in a changing environment

Treesearch

Allen M. Solomon

2009-01-01

Every year tens of millions of hectares of forests, woodlands, and grasslands burn globally. Some are burned intentionally for land conversion, pasture renewal or hazard reduction, or wildlife habitat improvement, but most are burned by uncontrolled wildfire. Estimates of...

Characteristics of Ambient Black Carbon Mass and Size-Resolved Particle Number Concentrations during Corn Straw Open-Field Burning Episode Observations at a Rural Site in Southern Taiwan.

PubMed

Cheng, Yu-Hsiang; Yang, Li-Sing

2016-07-08

Information on the effect of open-field burning of agricultural residues on ambient black carbon (BC) mass and size-resolved particle number concentrations is scarce. In this study, to understand the effect of such open-field burning on short-term air quality, real-time variations of the BC mass and size-resolved particle number concentrations were monitored before and during a corn straw open-field burning episode at a rural site. Correlations between the BC mass and size-resolved particle number concentrations during the episode were investigated. Moreover, the particle number size distribution and absorption Ångström exponent were determined for obtaining the characteristics of aerosol emissions from the corn straw open-field burning. The results can be used to address public health concerns and as a reference for managing similar episodes of open-field burning of agricultural residues.

Characterization of atmospheric black carbon and co-pollutants in urban and rural areas of Spain

NASA Astrophysics Data System (ADS)

Becerril-Valle, M.; Coz, E.; Prévôt, A. S. H.; Močnik, G.; Pandis, S. N.; Sánchez de la Campa, A. M.; Alastuey, A.; Díaz, E.; Pérez, R. M.; Artíñano, B.

2017-11-01

A one-year black carbon (BC) experimental study was performed at three different locations (urban traffic, urban background, rural) in Spain with different equivalent BC (eBC) source characteristics by means of multi-wavelength Aethalometers. The Aethalometer model was used for the source apportionment study, based on the difference in absorption spectral dependence of emissions from biomass burning (bb) and fossil fuel (ff) combustion. Most studies use a single bb and ff absorption Ångström exponent (AAE) pair (AAEbb and AAEff), however in this work we use a range of AAE values associated with fossil fuel and biomass burning based on the available measurements, which represents more properly all conditions. A sensitivity analysis of the source specific AAE was carried out to determine the most appropriate AAE values, being site dependent and seasonally variable. Here we present a methodology for the determination of the ranges of AAEbb and AAEff by evaluating the correlations between the source apportionment of eBC using the Aethalometer model with four biomass burning tracers measured at the rural site. The best combination was AAEbb = [1.63-1.74] and AAEff = [0.97-1.12]. Mean eBC values (±SD) obtained during the period of study were 3.70 ± 3.73 μg m-3 at the traffic urban site, 2.33 ± 2.96 μg m-3 at the urban background location, and 2.61 ± 5.04 μg m-3 in the rural area. High contributions of eBC to the PM10 mass were found (values up to 21% in winter), but with high eBC/PM10 variability. The hourly mean eBCff and eBCbb concentrations varied from 0 to 51 μg m-3 and from 0 to 50 μg m-3 at the three sites, respectively, exhibiting distinct seasonal and daily patterns. The fossil fuel combustion was the dominant eBC source at the urban sites, while biomass burning dominated during the cold season (88% of eBCbb) in the rural area. Daily PM2.5 and PM10 samples were collected using high-volume air samplers and analyzed for OC and EC. Analysis of biomass burning tracers and organic (OC) and elemental (EC) carbon in the rural area indicate that biomass combustion is the main source, while OC and EC indicate a lower influence of this source at the urban site.

Uncontrolled burning of solid waste by households in Mexico is a significant contributor to climate change in the country.

PubMed

Reyna-Bensusan, Natalia; Wilson, David C; Smith, Stephen R

2018-05-01

Uncontrolled burning of municipal solid waste (MSW) is an important source of air pollution and is wide spread in many developing countries, but only limited data quantify the extent of domestic open burning of household waste. Here, we present some of the first field data to be reported on the uncontrolled domestic burning of waste. A representative community of Mexico (Huejutla de Reyes Municipality) was investigated and household surveys, interviews with waste operators and a waste characterisation analysis were completed to assess the extent of, and factors controlling, the open burning of waste. Waste collection provision to rural communities was very limited and, consequently 92% of households in rural areas reported that they disposed of waste by uncontrolled burning in backyards or unofficial dumps. Overall, 24% of the total MSW generated in the Municipality was disposed by uncontrolled burning. Urban and periurban areas received twice-weekly collections and the rate of uncontrolled burning was considerably smaller compared to rural households, corresponding to approximately 2% of total waste generation. Carbon equivalency calculations showed that burning waste in backyards represented approximately 6% of the total and 8.5% of fuel related CO 2 Eq emissions by the municipality. Moreover, the equivalent carbon dioxide (CO 2 Eq) from black carbon (BC) emitted by uncontrolled burning in backyards was over fifteen times larger compared to methane (CH 4 ) potentially released from equivalent amounts of combustible biodegradable waste disposal at the official dumpsite. An assessment of local respiratory health data showed the incidence of disease was higher in rural than in urban areas, when the opposite trend is typically observed in the international literature; given the high rate of burning activity found in rural areas we suggest that open burning of waste could be a major reason for the apparent poorer respiratory health status of the rural population and requires further investigation. The results emphasise the importance of including BC from uncontrolled burning of waste in international emission inventories of greenhouse gases and in the assessment of the health status of local communities in developing countries where this practice is prevalent. Copyright © 2018 Elsevier Inc. All rights reserved.

Mapping day-of-burning with coarse-resolution satellite fire-detection data

Treesearch

Sean A. Parks

2014-01-01

Evaluating the influence of observed daily weather on observed fire-related effects (e.g. smoke production, carbon emissions and burn severity) often involves knowing exactly what day any given area has burned. As such, several studies have used fire progression maps ­ in which the perimeter of an actively burning fire is mapped at a fairly high temporal resolution -...

AmeriFlux US-An1 Anaktuvuk River Severe Burn

DOE Data Explorer

Hobbie, John [Marine Biological Laboratory; Rocha, Adrian [Marine Biological Laboratory; Shaver, Gaius [Marine Biological Laboratory

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-An1 Anaktuvuk River Severe Burn. Site Description - The Anaktuvuk River fire on the North Slope of Alaska started on July 16, 2007 by lightning. It continued until the end of September when nearby lakes had already frozen over and burned >256,000 acres, creating a mosaic of patches that differed in burn severity. The Anaktuvuk River Severe Burn, Moderate Burn, and Unburned sites are 40 km to the west of the nearest road and were selected in late May 2008 to determine the effects of the fire on carbon, water, and energy exchanges during the growing season. Because the fire had burned through September of the previous year, initial deployment of flux towers occurred prior to any significant vegetative regrowth, and our sampling campaign captured the full growing season in 2008. The Severe Burn site consisted of a large area in which all of the green vegetation were consumed in the fire and some of the organic matter had burnt to the mineral soil in many places. A bear damaged the tower during the last week of August 2008, and it was repaired shortly after.

Trace elements in coal. Environmental and health significance

USGS Publications Warehouse

Finkelman, R.B.

1999-01-01

Trace elements can have profound adverse effects on the health of people burning coal in homes or living near coal deposits, coal mines, and coal- burning power plants. Trace elements such as arsenic emitted from coal- burning power plants in Europe and Asia have been shown to cause severe health problems. Perhaps the most widespread health problems are caused by domestic coal combustion in developing countries where millions of people suffer from fluorosis and thousands from arsenism. Better knowledge of coal quality characteristics may help to reduce some of these health problems. For example, information on concentrations and distributions of potentially toxic elements in coal may help delineate areas of a coal deposit to be avoided. Information on the modes of occurrence of these elements and the textural relations of the minerals in coal may help to predict the behavior of the potentially toxic trace metals during coal cleaning, combustion, weathering, and leaching.

AmeriFlux US-ARc ARM Southern Great Plains control site- Lamont

DOE Data Explorer

Torn, Margaret [Lawrence Berkeley National Laboratory

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-ARc ARM Southern Great Plains control site- Lamont. Site Description - The ARM SGP Control site is located in the native tallgrass prairies of the USDA Grazinglands Research Laboratory near El Reno, OK. One of two adjacent 35 ha plots with identical towers, measurements at the US-ARc unburned plot are used as the experimental control. The second plot, US-Arb, was burned on 2005/03/08. Measurement comparisons between the control and burn plot are used to address questions regarding the effects of burning activities on carbon fluxes. The region evaded burning activities for at least 15 years. Current disturbances consist of only light grazing activities.

Black Carbon Contribution to Organic Carbon Stocks in Urban Soil.

PubMed

Edmondson, Jill L; Stott, Iain; Potter, Jonathan; Lopez-Capel, Elisa; Manning, David A C; Gaston, Kevin J; Leake, Jonathan R

2015-07-21

Soil holds 75% of the total organic carbon (TOC) stock in terrestrial ecosystems. This comprises ecosystem-derived organic carbon (OC) and black carbon (BC), a recalcitrant product of the incomplete combustion of fossil fuels and biomass. Urban topsoils are often enriched in BC from historical emissions of soot and have high TOC concentrations, but the contribution of BC to TOC throughout the urban soil profile, at a regional scale is unknown. We sampled 55 urban soil profiles across the North East of England, a region with a history of coal burning and heavy industry. Through combined elemental and thermogravimetic analyses, we found very large total soil OC stocks (31-65 kg m(-2) to 1 m), exceeding typical values reported for UK woodland soils. BC contributed 28-39% of the TOC stocks, up to 23 kg C m(-2) to 1 m, and was affected by soil texture. The proportional contribution of the BC-rich fraction to TOC increased with soil depth, and was enriched in topsoil under trees when compared to grassland. Our findings establish the importance of urban ecosystems in storing large amounts of OC in soils and that these soils also capture a large proportion of BC particulates emitted within urban areas.

Wintertime Correlation Between Black Carbon and Particle Size in a Street and Rural Site in Santiago de Chile

NASA Astrophysics Data System (ADS)

Gramsch, E. V.; Reyes, F.; Oyola, P.

2013-05-01

We have studied the correlation between black carbon and particle size in three sites in the Metropolitan area of Santiago de Chile in the winter of 2009 and performed a detailed comparison. Two of the sites are located near busy streets in Santiago de Chile. The other site was located in a rural area about 30 km upwind from downtown with little influence from vehicles, but large influence from wood burning. The particle size distribution was measured with a DMPS (Whalin, 2001) in the range from 10 to 700 nm. Simultaneously, black carbon was measured with an optical monitor developed at the University of Santiago (Gramsch, 2004). It is well known that the smaller particles (~ 10 - 40 nm ) are emitted directly by the engines of vehicles, which later condensate or coagulate in the atmosphere to form larger particles. In our measurements, the street site is mostly influenced by diesel vehicles which emit large amounts of black carbon. We have divided the particle size measurements in four groups (10 - 40 nm, 41- 69 nm, 79 - 157 nm and 190 - 700 nm) in order to compare with the carbon monitor. The highest correlation (0.98) in the site near the street between black carbon and the particles was obtained with the 190 - 700 nm. The correlation with the 79 - 157 nm group was slightly less (0.93). A comparison between the hourly average curves for black carbon and the 190 - 700 nm group show a similar shape during the whole day. In the rural site, the number of particles in the 10 - 40 nm group was 10 times lower than in the street, but the number of particles in the 190 - 700 nm group was only two times smaller. This fact is an indication that wood burning does not generate particles smaller than ~ 80 - 100 nm. The best correlation in the rural site between the black carbon and the particles was also with the 190 - 700 nm group. However, the correlation was lower (0.86) than in the street site. The hourly average curves for black carbon and the 190 - 700 nm group show a similar shape during the night (10 PM - 6 AM), but differ during the day. These measurements indicate that black carbon measurements may be more sensitive to emission from diesel vehicles than wood burning. This work was supported by the University of Santiago (Dicyt), the National Commission for the Environment (CONAMA) and the Regional Government of the Metropolitan Region (GORE).. Gramsch, E., Cereceda-Balic, F., Ormeño, I., Palma, G., Oyola, P., 2004. Use of the light absorption coefficient to monitor elemental carbon and PM2.5. Example of Santiago de Chile. Journal of the Air and Waste Management Association 54, 799-808 Wahlin, P., Palmgren, F., Van Dingenen, R., 2001. Experimental studies of ultrafine particles in streets and the relationship to traffic. Atmospheric Environment 35 (Suppl. 1), 63-69..

Solar absorption by elemental and brown carbon determined from spectral observations.

PubMed

Bahadur, Ranjit; Praveen, Puppala S; Xu, Yangyang; Ramanathan, V

2012-10-23

Black carbon (BC) is functionally defined as the absorbing component of atmospheric total carbonaceous aerosols (TC) and is typically dominated by soot-like elemental carbon (EC). However, organic carbon (OC) has also been shown to absorb strongly at visible to UV wavelengths and the absorbing organics are referred to as brown carbon (BrC), which is typically not represented in climate models. We propose an observationally based analytical method for rigorously partitioning measured absorption aerosol optical depths (AAOD) and single scattering albedo (SSA) among EC and BrC, using multiwavelength measurements of total (EC, OC, and dust) absorption. EC is found to be strongly absorbing (SSA of 0.38) whereas the BrC SSA varies globally between 0.77 and 0.85. The method is applied to the California region. We find TC (EC + BrC) contributes 81% of the total absorption at 675 nm and 84% at 440 nm. The BrC absorption at 440 nm is about 40% of the EC, whereas at 675 nm it is less than 10% of EC. We find an enhanced absorption due to OC in the summer months and in southern California (related to forest fires and secondary OC). The fractions and trends are broadly consistent with aerosol chemical-transport models as well as with regional emission inventories, implying that we have obtained a representative estimate for BrC absorption. The results demonstrate that current climate models that treat OC as nonabsorbing are underestimating the total warming effect of carbonaceous aerosols by neglecting part of the atmospheric heating, particularly over biomass-burning regions that emit BrC.

Top-down estimates of biomass burning emissions of black carbon in the western United States

Treesearch

Y. H. Mao; Q. B. Li; D. Chen; L. Zhang; W. -M. Hao; K.-N. Liou

2014-01-01

We estimate biomass burning and anthropogenic emissions of black carbon (BC) in the western US for May-October 2006 by inverting surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network using a global chemical transport model. We first use active fire counts from the Moderate Resolution Imaging Spectroradiometer (MODIS...

Fingerprints of carbon, nitrogen, and silicon isotopes in small interstellar SiC grains from the Murchison meteorite

NASA Technical Reports Server (NTRS)

Hoppe, Peter; Geiss, Johannes; Buehler, Fritz; Neuenschwander, Juerg; Amari, Sachiko; Lewis, Roy S.

1993-01-01

We report ion microprobe determinations of the carbon, nitrogen, and silicon isotopic compositions of small SiC grains from the Murchison CM2 chondrite. Analyses were made on samples containing variable numbers of grains and on 14 individual grains. In some cases the multiple-grain sample compositions were probably dominated by only one or two grains. Total ranges observed are given. Only a few grains show values near the range limits. Both the total ranges of carbon and nitrogen isotopic compositions, and even the narrower ranges typical for the majority of the grains, are similar to those observed for larger SiC grains. Two rare components appear to be present in the smaller-size fraction, one characterized by C-12/C-13 about 12-16 and the other by very heavy nitrogen. The carbon and nitrogen isotopic compositions qualitatively may reflect hydrostatic H-burning via the CNO cycle and He-burning in red giants, as well as explosive H-burning in novae. The silicon isotopic compositions of most grains qualitatively show what is the signature of He-burning. The silicon isotopic composition of one grain, however, suggests a different process.

Meteorological Controls on Biomass Burning During Santa Ana Events in Southern California

NASA Technical Reports Server (NTRS)

Veraverbeke, Sander; Capps, Scott; Hook, Simon J.; Randerson, James T.; Jin, Yufang; Hall, Alex

2013-01-01

Fires occurring during Santa Ana (SA) events in southern California are driven by extreme fire weather characterized by high temperatures, low humidities, and high wind speeds. We studied the controls on burned area and carbon emissions during two intensive SA burning periods in 2003 and 2007. We therefore used remote sensing data in parallel with fire weather simulations of the Weather and Regional Forecast model. Total carbon emissions were approximately 1800 gigagrams in 2003 and 900 gigagrams in 2007, based on a daily burned area and a fire emission model that accounted for spatial variability in fuel loads and combustion completeness. On a regional scale, relatively strong positive correlations were found between the daily Fosberg fire weather index and burned area/emissions (probability is less than 0.01). Our analysis provides a quantitative assessment of relationships between fire activity and weather during severe SA fires in southern California.

Open-cycle magnetohydrodynamic power plant with CO.sub.2 recycling

DOEpatents

Berry, Gregory F.

1991-01-01

A method of converting the chemical energy of fossil fuel to electrical and mechanical energy with a MHD generator. The fossil fuel is mixed with preheated oxygen and carbon dioxide and a conducting seed of potassium carbonate to form a combustive and electrically conductive mixture which is burned in a combustion chamber. The burned combustion mixture is passed through a MHD generator to generate electrical energy. The burned combustion mixture is passed through a diffuser to restore the mixture approximately to atmospheric pressure, leaving a spent combustion mixture which is used to heat oxygen from an air separation plant and recycled carbon dioxide for combustion in a high temperature oxygen preheater and for heating water/steam for producing superheated steam. Relatively pure carbon dioxide is separated from the spent combustion mixture for further purification or for exhaust, while the remainder of the carbon dioxide is recycled from the spent combustion mixture to a carbon dioxide purification plant for removal of water and any nitrous oxides present, leaving a greater than 98% pure carbon dioxide. A portion of the greater then 98% pure carbon dioxide stream is recovered and the remainder is recycled to combine with the oxygen for preheating and combination with the fossil fuel to form a combustion mixture.

Nucleosynthesis during a Thermonuclear Supernova Explosion

NASA Astrophysics Data System (ADS)

Panov, I. V.; Glazyrin, S. I.; Röpke, F. K.; Blinnikov, S. I.

2018-05-01

Supernovae are such bright objects that they can be observed even at high redshifts. Some types of such events, for example, type Ia (thermonuclear), have peculiarities of the light curve, which allows them to be used for cosmological applications. The light curve is determined by the details of the explosion dynamics and nucleosynthesis: in particular, it depends on the amount of iron-peak elements produced during the explosion. We discuss the burning processes in such objects and the peculiarities of turbulence simulations in them, which is needed for a proper hydrodynamic description of the explosion process. A direct nucleosynthesis calculation is performed for the temperature and density profiles derived in the available 3D hydrodynamic explosion simulations. We show that in the supernova progenitor model considered the calculated abundances of elements from carbon to iron-peak elements are in good agreement both with the observations and with the calculations of other authors. At the same time, no r-elements are produced even at the maximum neutron excess for this model ( Y e 0.47) due to the slow evolution of the density and temperature.

Chemistry Characterization of Jet Aircraft Engine Particulate by XPS: Results from APEX III

NASA Technical Reports Server (NTRS)

Vander Wal, Randy L.; Bryg, Victoria M.

2014-01-01

This paper reports XPS analysis of jet exhaust particulate from a B737, Lear, ERJ, and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and platforms. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20 percent or more. By lower resolution survey scans various elements including transition metals are identified along with lighter elements such as S, N, and O in the form of oxides. Burning additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their presence can be used as a tracer for identifying soots from aircraft engines as well as diagnostic for monitoring engine performance and wear.

Comparison of two thermal-optical methods for the determination of organic carbon and elemental carbon: Results from the southeastern United States

NASA Astrophysics Data System (ADS)

Cheng, Yuan; Zheng, Mei; He, Ke-bin; Chen, Yingjun; Yan, Bo; Russell, Armistead G.; Shi, Wenyan; Jiao, Zheng; Sheng, Guoying; Fu, Jiamo; Edgerton, Eric S.

2011-02-01

A total of 333 PM 2.5 samples were collected at four sites in the southeastern Aerosol Research and Characterization Study (SEARCH) network during four seasons from 2003 to 2005 and were simultaneously analyzed by two common thermal-optical methods, the National Institute of Occupational Safety and Health (NIOSH) method and the Interagency Monitoring of Protected Visual Environments (IMPROVE) method. The concentrations of total carbon measured by the two methods were comparable, whereas the split of organic carbon (OC) and elemental carbon (EC) was significantly different. The NIOSH-defined EC was lower (up to 80%) than that defined by IMPROVE since the NIOSH method applied the transmittance charring correction and a much higher peak inert mode temperature. The discrepancy between NIOSH- and IMPROVE-defined EC showed distinct seasonal and spatial variations. Potential factors contributing to this discrepancy besides the analytical method were investigated. The discrepancy between NIOSH- and IMPROVE-defined EC was larger in the spring compared to winter due to the influence of biomass burning, which is known to emit significant amount of brown carbon that would complicate the split of OC and EC. The NIOSH-defined EC to IMPROVE-defined EC ratio reached its minimum (0.2-0.5) in the summer, when the largest discrepancy was observed. This was most likely to be attributed to the influence of secondary organic aerosol (SOA). Moreover, the discrepancy between NIOSH- and IMPROVE-defined EC was larger in the coastal and the rural sites where the presence of abundant SOA was found based on previous studies in this region, providing supporting evidence that SOA could contribute to the observed discrepancy in summer.

ON THE EFFECT OF EXPLOSIVE THERMONUCLEAR BURNING ON THE ACCRETED ENVELOPES OF WHITE DWARFS IN CATACLYSMIC VARIABLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sion, Edward M.; Sparks, Warren, E-mail: edward.sion@villanova.edu, E-mail: warrensparks@comcast.net

2014-11-20

The detection of heavy elements at suprasolar abundances in the atmospheres of some accreting white dwarfs in cataclysmic variables (CVs), coupled with the high temperatures needed to produce these elements, requires explosive thermonuclear burning. The central temperatures of any formerly more massive secondary stars in CVs undergoing hydrostatic CNO burning are far too low to produce these elements. Evidence is presented that at least some CVs contain donor secondaries that have been contaminated by white dwarf remnant burning during the common envelope phase and are transferring this material back to the white dwarf. This scenario does not exclude the channelmore » in which formerly more massive donor stars underwent CNO processing in systems with thermal timescale mass transfer. Implications for the progenitors of CVs are discussed and a new scenario for the white dwarf's accretion-nova-outburst is given.« less

Controlled burn and immediate mobilization of potentially toxic elements in soil, from a legacy mine site in Central Victoria, Australia.

PubMed

Abraham, Joji; Dowling, Kim; Florentine, Singarayer

2018-03-01

Conducting controlled burns in fire prone areas is an efficient and economic method for forest management, and provides relief from the incidence of high severity wild fires and the consequent damage to human property and ecosystems. However, similar to wild fires, controlled burns also affect many of the physical and biogeochemical properties of the forest soil and may facilitate remobilization of potentially toxic elements (PTEs) sequestered in vegetation and soil organic matter. The objective of the current study is to investigate the mobilization of PTEs, in Central Victorian forest soils in Australia after a controlled burn. Surface soil samples were collected two days before and after the controlled burn to determine the concentration of PTEs and to examine the physicochemical properties. Results show that As, Cd, Mn, Ni and Zn concentrations increased 1.1, 1.6, 1.7, 1.1 and 1.9 times respectively in the post-burn environment, whereas the concentrations of Hg, Cr and Pb decreased to 0.7, 0.9 and 0.9 times respectively, highlighting considerable PTE mobility during and after a controlled burn. Whilst these results do not identify very strong correlations between physicochemical properties of soil and PTEs in the pre- and post-burn environments, PTEs themselves demonstrated very strong and significant correlations. The mobilization of As, Hg and other toxic elements raise potential health concerns as the number of controlled burns are projected to increase in response to climate change. Due to this increased level of PTE release and remobilization, the use of any kinds of controlled burn must be carefully considered before being used as a forest management strategy in mining-affected landscapes which include areas with high PTE concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon dioxide emissions and energy balance closure before, during, and after biomass burning in mid-South rice fields

NASA Astrophysics Data System (ADS)

Fong, B.; Adviento-Borbe, A.; Reba, M. L.; Runkle, B.; Suvocarev, K.

2017-12-01

Biomass burning or field burning is a crop management practice that removes rice straw, reduces tillage, controls pests and releases nutrients for the next cropping season. Current field burning emissions are not included in agricultural field annual emissions largely because of the lack of studies, especially on the field scale. Field burning measurements are important for greenhouse gas emission inventories and quantifying the annual carbon footprint of rice. Paired eddy covariance systems were used to measure energy balance, CO2 fluxes, and H2O fluxes in mid-South US rice fields (total area of 25 ha) before, during and after biomass burning for 20 days after harvest. During the biomass burning, air temperatures increased 29°C, while ambient CO2 concentration increased from 402 to 16,567 ppm and H2O concentrations increased from 18.73 to 25.62 ppt. For the burning period, 67-86 kg CO2 ha-1 period-1 was emitted calculated by integrating fluxes over the biomass burning event. However, the estimated emission using aboveground biomass and combustion factors was calculated as 11,733 kg CO2 ha-1 period-1. Part of the difference could be attributed to sensor sensitivity decreasing 80% during burning for two minutes due to smoke. Net ecosystem exchange (NEE) increased by a factor of two, 1.14 before burning to 2.44 μmol m-2 s-1 possibly due to greater reduction of plant material and photosynthesis following burning. This study highlights the contribution of rice straw burning to total CO2 emissions from rice production.

Laboratory Studies of Water Uptake by Biomass Burning Smoke: Role of Fuel Inorganic Content, Combustion Phase and Aging

NASA Astrophysics Data System (ADS)

Dubey, M. K.; Bixler, S. L.; Romonosky, D.; Lam, J.; Carrico, C.; Aiken, A. C.

2017-12-01

Biomass burning aerosol emissions have substantially increased with observed warming and drying in the southwestern US. While wildfires are projected to intensify missing knowledge on the aerosols hampers assessments. Observations demonstrate that enhanced light absorption by coated black carbon and brown carbon can offset the cooling effects of organic aerosols in wildfires. However, if mixing processes that enhance this absorption reduce the aerosol lifetime it would lower their atmospheric burden. In order to elucidate mechanisms regulating this tradeoff we performed laboratory studies of smoke from biomass burning. We focus on aerosol optical properties and their hygroscopic response. Fresh emissions from burning 30 fuels under flaming and smoldering conditions were investigated. We measured aerosol absorption, scattering and extinction at multiple wavelengths, water uptake at 85% relative humidity (fRH85%) with a humidity controlled dual nephelometer, and black carbon mass with a SP2. Trace gases and the ionic content of the fuel and smoke were also measured We find that whereas the optical properties of smoke were strongly dictated by the flaming versus smoldering nature of the burn, the observed hygroscopicity was intimately linked to the chemical composition of the fuel. The mean hygroscopicity ranged from nearly hydrophobic (fRH85% = 1) to very hydrophilic (fRH85% = 2.1) values typical of pure deliquescent salts. The k values varied from 0.004 to 0.18 and correlated well with inorganic content. Inorganic fuel content was the key driver of hygroscopicity with combustion phase playing a secondary but important role ( 20%). Flaming combustion promoted hygroscopicity by generating refractory black carbon and ions. Smoldering combustion suppressed hygroscopicity by producing hydrogenated organic species. Wildfire smoke was hydrophobic since the evergreen species with low inorganic content dominated in these fires. We also quantify the mass absorption cross-sections at 780nm and 430nm to evaluate the absorbing species. We plan to extend our studies to aged biomass burning smoke with a potential aerosol mass reactor and monitor the ionic content of black carbon with a SP-AMS. Our analysis will develop a mechanistic framework of water uptake and optical properties of biomass burning aerosols.

Hydrogen and helium shell burning during white dwarf accretion

NASA Astrophysics Data System (ADS)

Cui, Xiao; Meng, Xiang-Cun; Han, Zhan-Wen

2018-05-01

Type Ia supernovae (SNe Ia) are believed to be thermonuclear explosions of carbon oxygen (CO) white dwarfs (WDs) with masses close to the Chandrasekhar mass limit. How a CO WD accretes matter and grows in mass to this limit is not well understood, hindering our understanding of SN Ia explosions and the reliability of using SNe Ia as a cosmological distance indicator. In this work, we employed the stellar evolution code MESA to simulate the accretion process of hydrogen-rich material onto a 1.0 M ⊙ CO WD at a high rate (over the Eddington limit) of 4.3 × 10‑7 M ⊙ yr‑1. The simulation demonstrates the characteristics of the double shell burning on top of the WD, with a hydrogen shell burning on top of a helium burning shell. The results show that helium shell burning is not steady (i.e. it flashes). Flashes from the helium shell are weaker than those in the case of accretion of helium-rich material onto a CO WD. The carbon to oxygen mass ratio resulting from the helium shell burning is higher than what was previously thought. Interestingly, the CO WD growing due to accretion has an outer part containing a small fraction of helium in addition to carbon and oxygen. The flashes become weaker and weaker as the accretion continues.

Resistance of the boreal forest to high burn rates.

PubMed

Héon, Jessie; Arseneault, Dominique; Parisien, Marc-André

2014-09-23

Boreal ecosystems and their large carbon stocks are strongly shaped by extensive wildfires. Coupling climate projections with records of area burned during the last 3 decades across the North American boreal zone suggests that area burned will increase by 30-500% by the end of the 21st century, with a cascading effect on ecosystem dynamics and on the boreal carbon balance. Fire size and the frequency of large-fire years are both expected to increase. However, how fire size and time since previous fire will influence future burn rates is poorly understood, mostly because of incomplete records of past fire overlaps. Here, we reconstruct the length of overlapping fires along a 190-km-long transect during the last 200 y in one of the most fire-prone boreal regions of North America to document how fire size and time since previous fire will influence future fire recurrence. We provide direct field evidence that extreme burn rates can be sustained by a few occasional droughts triggering immense fires. However, we also show that the most fire-prone areas of the North American boreal forest are resistant to high burn rates because of overabundant young forest stands, thereby creating a fuel-mediated negative feedback on fire activity. These findings will help refine projections of fire effect on boreal ecosystems and their large carbon stocks.

Resistance of the boreal forest to high burn rates

PubMed Central

Héon, Jessie; Arseneault, Dominique; Parisien, Marc-André

2014-01-01

Boreal ecosystems and their large carbon stocks are strongly shaped by extensive wildfires. Coupling climate projections with records of area burned during the last 3 decades across the North American boreal zone suggests that area burned will increase by 30–500% by the end of the 21st century, with a cascading effect on ecosystem dynamics and on the boreal carbon balance. Fire size and the frequency of large-fire years are both expected to increase. However, how fire size and time since previous fire will influence future burn rates is poorly understood, mostly because of incomplete records of past fire overlaps. Here, we reconstruct the length of overlapping fires along a 190-km-long transect during the last 200 y in one of the most fire-prone boreal regions of North America to document how fire size and time since previous fire will influence future fire recurrence. We provide direct field evidence that extreme burn rates can be sustained by a few occasional droughts triggering immense fires. However, we also show that the most fire-prone areas of the North American boreal forest are resistant to high burn rates because of overabundant young forest stands, thereby creating a fuel-mediated negative feedback on fire activity. These findings will help refine projections of fire effect on boreal ecosystems and their large carbon stocks. PMID:25201981

Carbon, water, and heat flux responses to experimental burning and drought in a tallgrass prarie.

USDA-ARS?s Scientific Manuscript database

Natural fires and prescribed burning represent long-standing and currently prevalent disturbances to biogeochemical cycling in grassland ecosystems. We report eddy covariance ecosystem-atmosphere fluxes and biometric variables measured in paired, burned and unburned plots in two paddocks in the US S...

Source apportionment revisited for long-term measurements of fine aerosol trace elements at two locations in southern Norway

NASA Astrophysics Data System (ADS)

Maenhaut, Willy

2018-02-01

Five-year-long (1991-1996) aerosol trace element data sets for the fine (PM2) size fraction from the sites of Birkenes and Skreådalen in southern Norway were reanalysed by US EPA positive matrix factorization PMF5 in order to assess the sources and their contribution to the PM2 aerosol. The data sets contained the concentrations of the particulate mass (PM), black carbon (BC) and 21 elements in over 700 samples for each of the two sites. The PM was obtained from weighing with a microbalance and BC was determined with a light reflectance technique. The data for the elements were obtained by a combination of particle-induced X-ray emission and instrumental neutron activation analysis. Eight source factors were retained for each site, i.e., (i) secondary sulfate, which accounted for around 40% of the average measured PM2 mass, (ii) wood burning, with BC, K, Zn and As, which accounted for about 17%, (iii) an iodine factor (with also Br and Se), which is probably related to a marine biogenic source and was responsible for about 6.5%, (iv) aged sea salt with Na, Mg, Cl and Ca, but heavily depleted in Cl; (v) a crustal factor containing Al, Si, Ca, Ti and Fe; (vi) a heavy oil burning factor with V and Ni in a ratio of 3-4; (vii) a general pollution factor (with Cu, Zn, As, Se, Sb and Pb), and (viii) an almost pure manganese factor, which is attributed to Mn and FeMn industries in southern Norway. The results were substantially different from those of an earlier PMF analysis, in which use was made of PMF2.

Source apportionment by PMF on elemental concentrations obtained by PIXE analysis of PM10 samples collected at the vicinity of lignite power plants and mines in Megalopolis, Greece

NASA Astrophysics Data System (ADS)

Manousakas, M.; Diapouli, E.; Papaefthymiou, H.; Migliori, A.; Karydas, A. G.; Padilla-Alvarez, R.; Bogovac, M.; Kaiser, R. B.; Jaksic, M.; Bogdanovic-Radovic, I.; Eleftheriadis, K.

2015-04-01

Particulate matter (PM) is an important constituent of atmospheric pollution especially in areas under the influence of industrial emissions. Megalopolis is a small city of 10,000 inhabitants located in central Peloponnese in close proximity to three coal opencast mines and two lignite fired power plants. 50 PM10 samples were collected in Megalopolis during the years 2009-11 for elemental and multivariate analysis. For the elemental analysis PIXE was used as one of the most effective techniques in APM analytical characterization. Altogether, the concentrations of 22 elements (Z = 11-33), whereas Black Carbon was also determined for each sample using a reflectometer. Factorization software was used (EPA PMF 3.0) for source apportionment analysis. The analysis revealed that major emission sources were soil dust 33% (7.94 ± 0.27 μg/m3), biomass burning 19% (4.43 ± 0.27 μg/m3), road dust 15% (3.63 ± 0.37 μg/m3), power plant emissions 13% (3.01 ± 0.44 μg/m3), traffic 12% (2.82 ± 0.37 μg/m3), and sea spray 8% (1.99 ± 0.41 μg/m3). Wind trajectories have suggested that metals associated with emission from the power plants came mainly from west and were connected with the locations of the lignite mines located in this area. Soil resuspension, road dust and power plant emissions increased during the warm season of the year, while traffic/secondary, sea spray and biomass burning become dominant during the cold season.

Seasonality of major aerosol species and their transformations in Cairo megacity

NASA Astrophysics Data System (ADS)

Favez, Olivier; Cachier, Hélène; Sciare, Jean; Alfaro, Stéphane C.; El-Araby, Tarek M.; Harhash, Maha A.; Abdelwahab, Magdy M.

Bulk aerosols sampled on a weekly basis at two Cairo (Egypt) urban sites from January 2003 to May 2006 were analysed for their chemical composition of major aerosol species (elemental carbon, water soluble/insoluble organic carbon, nitrate, sulphate, ammonium, chloride, sodium and calcium). Data subsequently obtained constitute one of the longest and more detailed dataset related to Cairo aerosols, and offer the opportunity to investigate seasonal trends. Dust aerosols (derived from calcium measurements) displayed maximum concentrations in spring and winter, due to frequent dust storms, but also high background concentration levels (˜50 μg m -3) all year long. Within these particles, about 40% on average of Ca 2+ was found to be associated with SO 42-, NO 3- and/or Cl -, pointing out "dust anthropization" processes and their subsequent climatic impact on a regional scale. Seasonal variations of non-dust aerosols, equally distributed between carbonaceous aerosols and ions, were also observed, with concentrations of the order of 100 μg m -3 in autumn and winter, and of 60 μg m -3 in spring and summer. High concentration levels of non-sea-salt chloride (up to 15 μg m -3 on a monthly basis), likely of industrial origin, were observed in autumn and winter. During the autumn "Black Cloud" event, biomass burning aerosols originating from rice straw burning in the Nile Delta have shown to account for 12%, 35% and 50% of Cairo EC, WIOC and WSOC mass concentrations, respectively. Finally, relatively low WSOC/OC ratios (˜1/3) were obtained all the year long, calling for more investigation on the water-solubility of organic aerosols originating from the burning of agricultural waste, and on that of secondary organic aerosols formed in dry urban atmospheres.

Oxidative potential of ambient fine aerosol over a semi-urban site in the Indo-Gangetic Plain

NASA Astrophysics Data System (ADS)

Patel, Anil; Rastogi, Neeraj

2018-02-01

Indo-Gangetic Plain (IGP) receives emissions from variety of pollutant sources such as post-harvest crop residue burning, vehicles, industries, power plants, and bio-fuel burning. Several studies have documented physical, chemical and optical properties of aerosol over the IGP; however, their oxidative potential (OP) has not yet documented. Present study reports the OP (measured through dithiothreitol (DTT) assay) of soluble particulate matter smaller than 2.5 μm aerodynamic diameter (PM2.5) over Patiala (30.3°N, 76.4°E, 249 m amsl), a semi-urban site located in the IGP, during winter 2014. Volume-normalized OP (range: 1.3-7.2 nmol DTT min-1 m-3, average: 3.8 ± 1.4, 1σ) is found to be ∼3 to 20 times higher, and mass-normalized OP (range: 13-50 pmol DTT min-1 μg-1, average: 27 ± 8, 1σ) is found to be similar or higher than those documented in literature. Further, observed OP is found to depend more on PM2.5 composition rather than mass concentration. Mass fractions of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) correlate positively whereas that of secondary inorganic aerosol (SIA, sum of the concentrations of SO42-, NO3- and NH4+) correlate negatively with OP μg-1 at considerable significance level (p < 0.05). Negative correlation of SIA with OP μg-1 has been assessed in laboratory experiment and attributed to their DTT inactive nature. It is suggested to use WSOC/SIA ratio as a measure of DTT activity of secondary particles over the study region. Further, biomass burning derived species are observed to be more DTT active than those derived from fossil fuel burning. It was also observed that the slope of OP μg-1 and WSOC/SIA ratio linear relationship enhances significantly in samples collected during days following foggy nights in comparison to that in samples collected during non-foggy period, which may be due to the production of redox-active species by fog processing. Such studies have implications in assessing the effect of ambient aerosol on atmospheric chemistry, air quality and human health.

Temporal and spatial changes in soil carbon and nitrogen after clearcutting and burning of an old-growth Douglas-fir forest.

Treesearch

Joseph A. Antos; Charles B. Halpern; Richard E. Miller; Kermit Cromack; Melora G. Halaj

2003-01-01

We used 135 permanent plots (4 m2) nested within 15 blocks (121 m2) to quantify changes in concentration and spatial variation of carbon (C) and nitrogen (N) in the mineral soil (0- to 10-cm depth) after logging and broadcast burning of an old-growth, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)...

Continuous flux of dissolved black carbon from a vanished tropical forest biome

NASA Astrophysics Data System (ADS)

Dittmar, Thorsten; de Rezende, Carlos Eduardo; Manecki, Marcus; Niggemann, Jutta; Coelho Ovalle, Alvaro Ramon; Stubbins, Aron; Bernardes, Marcelo Correa

2012-09-01

Humans have used fire extensively as a tool to shape Earth's vegetation. The slash-and-burn destruction of Brazil's Atlantic forest, which once covered over 1.3millionkm2 of present-day Brazil and was one of the largest tropical forest biomes on Earth, is a prime example. Here, we estimate the amount of black carbon generated by the burning of the Atlantic forest, using historical records of land cover, satellite data and black carbon conversion ratios. We estimate that before 1973, destruction of the Atlantic forest generated 200-500 million tons of black carbon. We then estimate the amount of black carbon exported from this relict forest between 1997 and 2008, using measurements of polycyclic aromatic black carbon collected from a large river draining the region, and a continuous record of river discharge. We show that dissolved black carbon (DBC) continues to be mobilized from the watershed each year in the rainy season, despite the fact that widespread forest burning ceased in 1973. We estimate that the river exports 2,700 tons of DBC to the ocean each year. Scaling our findings up, we estimate that 50,000-70,000 tons of DBC are exported from the former forest each year. We suggest that an increase in black carbon production on land could increase the size of the refractory pool of dissolved organic carbon in the deep ocean.

Net Acid Production, Acid Neutralizing Capacity, and Associated Mineralogical and Geochemical Characteristics of Animas River Watershed Igneous Rocks Near Silverton, Colorado

USGS Publications Warehouse

Yager, Douglas B.; Choate, LaDonna; Stanton, Mark R.

2008-01-01

This report presents results from laboratory and field studies involving the net acid production (NAP), acid neutralizing capacity (ANC), and magnetic mineralogy of 27 samples collected in altered volcanic terrain in the upper Animas River watershed near Silverton, Colo., during the summer of 2005. Sampling focused mainly on the volumetrically important, Tertiary-age volcanic and plutonic rocks that host base- and precious-metal mineralization in the study area. These rocks were analyzed to determine their potential for neutralization of acid-rock drainage. Rocks in the study area have been subjected to a regional propylitic alteration event, which introduced calcite, chlorite (clinochlore), and epidote that have varying amounts and rates of acid neutralizing capacity (ANC). Locally, hydrothermal alteration has consumed any ANC and introduced minerals, mainly pyrite, that have a high net acid production (NAP). Laboratory studies included hydrogen pyroxide (H2O2) acid digestion and subsequent sodium hydroxide (NaOH) titration to determine NAP, and sulfuric acid (H2SO4) acid titration experiments to determine ANC. In addition to these environmental rock-property determinations, mineralogical, chemical, and petrographic characteristics of each sample were determined through semiquantitative X-ray diffractometry (Rietveld method), optical mineralogy, wavelength dispersive X-ray fluorescence, total carbon-carbonate, and inductively coupled plasma?mass spectrometric analysis. An ANC ranking was assigned to rock samples based on calculated ANC quantity in kilograms/ton (kg/t) calcium carbonate equivalent and ratios of ANC to NAP. Results show that talus near the southeast Silverton caldera margin, composed of andesite clasts of the Burns Member of the Silverton Volcanics, has the highest ANC (>100 kg/t calcium carbonate equivalent) with little to no NAP. The other units found to have moderate to high ANC include (a) andesite lavas and volcaniclastic rocks of the San Juan Formation, west and northwest of the Silverton caldera, and (b) the Picayune Megabreccia Member of Sapinero Mesa Tuff along the western San Juan caldera margin. Sultan Mountain stock, composed of granitoid intrusive rocks, was shown to have low ANC and moderate NAP. Sequential leachate analyses on a suite of whole-rock samples from the current and a previous study indicate that host rock composition and mineralogy control leachate compositions. The most mafic volcanic samples had high leachate concentrations for Mg, Fe, and Ca, whereas silicic volcanic samples had lower ferromagnesiun compositions. Samples with high chlorite abundance also had high leachable Mg concentrations. Trace-element substitution, such as Sr for Ca in plagioclase, controls high Sr concentrations in those samples with high plagioclase abundance. High Ti abundance in leachate was observed in those samples with high magnetite concentrations. This is likely due to samples containing intergrown magnetite-ilmenite. Whole rocks having high trace-element concentrations have relatively high leachate trace-element abundances. Some lavas of the San Juan Formation and Burns Member of the Silverton Volcanics had elevated Zn-, Cd-, and Pb-leachate concentrations. Manganese was also elevated in one San Juan Formation sample. Other San Juan Formation and Burns Member lavas had low to moderate trace-element abundances. One sample of the pyroxene andesite member of the Silverton Volcanics had elevated concentrations for As and Mo. Most other pyroxene andesite member samples had low leachate trace-element abundances. Mine-waste-leachate analyses indicated that one mine-waste sample had elevated concentrations of Cu (1.5 orders of magnitude), Zn (1 order of magnitude), As (1 order of magnitude), Mo (1.5 to 2 orders of magnitude), Cd (1 to 2 orders of magnitude), and Pb (2 to 3 orders of magnitude) compared to whole rocks. These data indicate the importance of whole-rock geochemistry or leachate analys

Carbon and Water Vapor Fluxes of Different Ecosystems in Oklahoma

NASA Astrophysics Data System (ADS)

Wagle, P.; Gowda, P. H.; Northup, B. K.

2016-12-01

Information on exchange of energy, carbon dioxide (CO2), and water vapor (H2O) for major terrestrial ecosystems is vital to quantify carbon and water balances on a large-scale. It is also necessary to develop, test, and improve crop models and satellite-based production efficiency and evapotranspiration (ET) models, and to better understand the potential of terrestrial ecosystems to mitigate rising atmospheric CO2 concentration and climate change. A network (GRL-FLUXNET) of nine eddy flux towers has been established over a diverse range of terrestrial ecosystems, including native and improved perennial grasslands [unburned and grazed tallgrass prairie, burned and grazed tallgrass prairie, and burned Bermuda grass (Cynodon dactylon L.)], grazed and non-grazed winter wheat (Triticum aestivum L.), till and no-till winter wheat and canola (Brassica napus L.), alfalfa (Medicago sativa L.), and soybean (Glycine max L.), at the USDA-ARS, Grazinglands Research Laboratory, El Reno, OK. In this presentation, we quantify and compare net ecosystem CO2 exchange (NEE) and ET between recently burned and grazed tallgrass prairie and burned and non-grazed Bermuda grass pastures, alfalfa, and soybean. Preliminary results show monthly ensembles average NEE reached seasonal peak values of -29, -35, -25, and -20 µmol m-2 s-1 in burned tallgrass prairie pasture, burned Bermuda grass pasture, alfalfa, and soybean, respectively. Similarly, monthly ensembles average ET reached seasonal peak values of 0.22, 0.27, 0.25, 0.28 mm 30-min-1 in burned tallgrass prairie pasture, burned Bermuda grass pasture, alfalfa, and soybean, respectively. Seasonal patterns and daily magnitudes of NEE and ET and their responses to the similar climatic conditions will be further investigated.

The influence of burn severity on post-fire vegetation recovery and albedo change during early succession in North American boreal forests

NASA Astrophysics Data System (ADS)

Jin, Y.; Randerson, J. T.; Goetz, S. J.; Beck, P. S.; Loranty, M. M.; Goulden, M.

2011-12-01

Severity of burning can influence multiple aspects of forest composition, carbon cycling, and climate forcing. We quantified how burn severity affected vegetation recovery and albedo change during early succession in Canadian boreal regions by combining satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Canadian Large Fire Data Base (LFDB). We used the difference Normalized Burn Ratio (dNBR) and changes in spring albedo derived from MODIS 500m albedo product as measures of burn severity. We found that the most severe burns had the greatest reduction in summer EVI in first year after fire, indicating greater loss of vegetation cover immediately following fire. By 5-7 years after fire, summer EVI for all severity classes had recovered to within 90-110% of pre-fire levels. Burn severity had a positive effect on the increase of post-fire spring albedo during the first 7 years after fire, and a shift from low to moderate or moderate to severe fires led to amplification of the post-fire albedo increase by approximately 30%. Fire-induced increases in both spring and summer albedo became progressively larger with stand age from years 1-7, with the trend in spring albedo likely driven by continued losses of needles and branches from trees killed by the fire (and concurrent losses of black carbon coatings on remaining debris), and the summer trend associated with increases in leaf area of short-stature herbs and shrubs. Our results suggest that increases in burn severity and carbon losses observed in some areas of boreal forests (e.g., Turetsky et al., 2011) may be at least partly offset by increases in negative forcing associated with changes in surface albedo.

Impact of managed moorland burning on DOC concentrations in soil solutions and stream waters

NASA Astrophysics Data System (ADS)

Palmer, Sheila; Wearing, Catherine; Johnson, Kerrylyn; Holden, Joseph; Brown, Lee

2013-04-01

In the UK uplands, prescribed burning of moorland vegetation is a common practice to maintain suitable habitats for game birds. Many of these landscapes are in catchments covered by significant deposits of blanket peat (typically one metre or more in depth). There is growing interest in the effect of land management on the stability of these peatland carbon stores, and their contribution to dissolved and particulate organic carbon in surface waters (DOC and POC, respectively) and subsequent effects on stream biogeochemistry and ecology. Yet there are surprisingly few published catchment-scale studies on the effect of moorland burning on DOC and POC. As part of the EMBER project, stream chemistry data were collected approximately monthly in ten upland blanket peat catchments in the UK, five of which acted as controls and were not subject to burning. The other five catchments were subject to a history of prescribed burning, typically in small patches (300-900 m2) in rotations of 8-25 years. Soil solution DOC was also monitored at four depths at two intensively studied sites (one regularly burned and one control). At the two intensive sites, soil solution DOC was considerably higher at the burned site, particularly in surface solutions where concentrations in excess of 100 mg/L were recorded on several occasions (median 37 mg/L over 18 months). The high soil solution DOC concentrations at the burned site occurred in the most recently burned plots (less than 2 years prior to start of sampling) and the lowest DOC concentrations were observed in plots burned 15-25 years previously. On average, median stream DOC and POC concentrations were approximately 43% and 35% higher respectively in burned catchments relative to control catchments. All streams exhibited peak DOC in late summer/early autumn with higher peak DOC concentrations in burned catchments (20-66 mg/L) compared to control catchments (18-54 mg/L). During winter months, DOC concentrations were low in control catchments (typically less than 15 mg/L) but were highly variable in burned catchments (9-40 mg/L), implying some instability of peat carbon stores and/or fluctuation in source. The results offer strong evidence for an impact of burning on the delivery of DOC to streams, possibly through increased surface run-off from bare or partially vegetated patches.

Trace gas emissions to the atmosphere by biomass burning in the west African savannas

NASA Technical Reports Server (NTRS)

Frouin, Robert J.; Iacobellis, Samuel F.; Razafimpanilo, Herisoa; Somerville, Richard C. J.

1994-01-01

Savanna fires and atmospheric carbon dioxide (CO2) detection and estimating burned area using Advanced Very High Resolution Radiometer_(AVHRR) reflectance data are investigated in this two part research project. The first part involves carbon dioxide flux estimates and a three-dimensional transport model to quantify the effect of north African savanna fires on atmospheric CO2 concentration, including CO2 spatial and temporal variability patterns and their significance to global emissions. The second article describes two methods used to determine burned area from AVHRR data. The article discusses the relationship between the percentage of burned area and AVHRR channel 2 reflectance (the linear method) and Normalized Difference Vegetation Index (NDVI) (the nonlinear method). A comparative performance analysis of each method is described.

Chemical and Optical Properties of Water-Soluble Organic Aerosols from Biomass Burning Emissions

NASA Astrophysics Data System (ADS)

Yu, J. M.; Park, S.; Cho, S. Y.

2016-12-01

Light absorption property by organic aerosols is an important parameter to determine their radiative forcing on global and regional scales. However, the optical measurements by light absorbing aerosols from biomass burning emissions are rather lacking. This study explored the chemical and light-absorption properties of humic-like substances (HULIS) from biomass burning aerosols of three types; rice straw (RS), pine needles (PN), and sesame stem (SS). Water-soluble organic carbon (WSOC) contributed 42.5, 42.0, and 57.0% to the OC concentrations of the RS, PN, and SS emissions, respectively. Respective HULIS (=1.94´HULIS-C) concentrations accounted for 29.5±2.0, 15.3±3.1, and 25.8±4.0% of PM2.5, and contributed 63±5, 36±10, and 51±8% to WSOC concentration. Absorption Ångström exponents (AAEs) of the WSOC fitted between 300 and 400 nm wavelengths were 7.4-8.3, indicating no significant differences among the biomass types. These AAEs are similar to those reported for aqueous extracts of biomass burning HULIS and fresh secondary organic aerosols from ozonolysis of terpenes. HULIS, which is a hydrophobic part of WSOC and a significant fraction of brown carbon, showed absorption spectra similar to brown carbon. WSOC mass absorption efficiency (MAE365) at 365 nm were 1.37, 0.86, and 1.38 m2/g×C for RS, PN, and SS burning aerosols, respectively. The MAE values by WSOC were less than 10% of MAE caused by light-absorbing black carbon. The light absorption of the water extracts at 365 nm indicated that light absorption was more strongly associated with HULIS from biomass burning emissions than with the hydrophilic WSOC fraction.

Correlations Between Optical, Chemical and Physical Properties of Biomass Burn Aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopkins, Rebecca J.; Lewis, Keith M.; Dessiaterik, Yury

2007-09-20

Single scattering albedo (ω) and Angstrom absorption coefficient (αap) values are measured at 405, 532 and 870 nm for aerosols generated during controlled laboratory combustion of twelve wildland fuels. Considerable fuel dependent variation in these optical properties is observed at these wavelengths. Complementary microspectroscopy techniques are used to elucidate spatially resolved local chemical bonding, carbon-to-oxygen atomic ratios, percent of sp2 hybridization (graphitic nature), elemental composition, particle size and morphology. These parameters are compared directly with the corresponding optical properties for each combustion product, facilitating an understanding of the fuel dependent variability observed. Results indicate that combustion products can be dividedmore » into three categories based on chemical, physical and optical properties. Only materials displaying a high degree of sp2 hybridization, with chemical and physical properties characteristic of ‘soot’ or black carbon, exhibit ω and αap values that indicate a high light absorbing capacity.« less

Characteristics of size-segregated carbonaceous aerosols in the Beijing-Tianjin-Hebei region.

PubMed

Guo, Yuhong

2016-07-01

Mass concentrations of organic carbon (OC) and elemental carbon (EC) in size-resolved aerosols were investigated at four sites (three cities and one country) in the Beijing-Tianjin-Hebei region from September 2009 to August 2011. The size distributions of OC and EC presented large evolutions among rural and urban sites, and among four seasons, with highest peaks of OC and EC in fine mode in urban areas during winter. Geometric mean diameters (GMDs) of OC and EC in fine particles at urban sites during winter were lower than those at rural site mainly due to effects of fine particle coagulation and organic compound repartitioning. Fossil fuel emissions were a dominant source of OC and EC in urban areas, while biomass burning was a major source of OC and EC at rural site. Trajectory clustering and CWT analysis showed that regional transport was an important contributor to OC and EC in Beijing.

Planning and evaluating prescribed fires--a standard procedure

Treesearch

William C. Fischer

1978-01-01

Provides a standard format and checklist to guide the land manager through the important steps for prescribed burning. Describes the kind of information needed to prepare fire prescriptions and burning plans. Identifies the elements of a fire prescription, a burning plan, and a prescribed fire evaluation. A plan written for an actual prescribed burning is included as...

Dynamic variations of ultrafine, fine and coarse particles at the Lu-Lin background site in East Asia

NASA Astrophysics Data System (ADS)

Chen, Sheng-Chieh; Hsu, Shih-Chieh; Tsai, Chuen-Jinn; Chou, Charles C.-K.; Lin, Neng-Huei; Lee, Chung-Te; Roam, Gwo-Dong; Pui, David Y. H.

2013-10-01

The characteristics of atmospheric ultrafine particles (i.e. <100 nm, nanoparticles or PM0.1), PM2.5 and PM10 were studied at the Lulin Atmospheric Background Station (LABS, 2862 m a.s.l., Taiwan) as part of the 7SEAS/Dongsha campaign. Sampling was conducted in July and August of 2009 and September to November of 2010, during which two 96-h and four 72-h PM samples were taken. Real-time particle size distributions were measured continuously from July to August of 2009 and July to November of 2010. PM0.1, PM2.5 and PM10 were collected by using two MOUDIs (micro-orifice uniform deposit impactor, MSP 110) and a Dichotomous PM10 sampler (Andersen SA-241) while real-time size distributions of particles of 5.5-350 nm in diameter were measured by an SMPS (scanning mobility particle sizer, TSI 3936). Filter samples were analyzed for gravimetric mass and chemical compositions, including organic carbon (OC), element carbon (EC), water-soluble ions and trace elements. Meteorology parameters and gaseous O3 and CO concentrations were also monitored along with the SMPS data for studying particle nucleation, condensation, SOA (secondary organic aerosol) formation and long-range air pollutant transport at the LABS. SMPS data showed that nanoparticle concentrations at the LABS remained relatively stable at low level (˜300-500 #/cm3) during the nighttime (22:00-04:00), increased during daytime, and reached a maximum (˜2000-4000 #/cm3) in the afternoon (12:00-16:00). The NMD (number median diameter) showed an opposite trend with the peak number concentrations observed in the afternoon corresponding to the smallest NMD (20-40 nm). These results indicate the dominance of local sources rather than the transport from other atmospheric air because that the lifetime of nanoparticles was only few minutes. Chemical analysis of filter samples showed that the concentrations of trace elements K and Mn, which serve as biomass burning markers, were elevated in the fine particle fractions during November 9-12th when the air mass passed through South and Southeast Asia prior to reaching the LABS. The concentrations of K and Mn would have been low if the aerosols had local origins The biomass burning derived K was found in all fine particle samples at the LABS suggesting that the free troposphere around Taiwan is frequently impacted by the long-range transport of biomass burning plumes via the westerly winds.

Size-resolved chemical composition, effective density, and optical properties of biomass burning particles

NASA Astrophysics Data System (ADS)

Zhai, Jinghao; Lu, Xiaohui; Li, Ling; Zhang, Qi; Zhang, Ci; Chen, Hong; Yang, Xin; Chen, Jianmin

2017-06-01

Biomass burning aerosol has an important impact on the global radiative budget. A better understanding of the correlations between the mixing states of biomass burning particles and their optical properties is the goal of a number of current studies. In this work, the effective density, chemical composition, and optical properties of rice straw burning particles in the size range of 50-400 nm were measured using a suite of online methods. We found that the major components of particles produced by burning rice straw included black carbon (BC), organic carbon (OC), and potassium salts, but the mixing states of particles were strongly size dependent. Particles of 50 nm had the smallest effective density (1.16 g cm-3) due to a relatively large proportion of aggregate BC. The average effective densities of 100-400 nm particles ranged from 1.35 to 1.51 g cm-3 with OC and inorganic salts as dominant components. Both density distribution and single-particle mass spectrometry showed more complex mixing states in larger particles. Upon heating, the separation of the effective density distribution modes confirmed the external mixing state of less-volatile BC or soot and potassium salts. The size-resolved optical properties of biomass burning particles were investigated at two wavelengths (λ = 450 and 530 nm). The single-scattering albedo (SSA) showed the lowest value for 50 nm particles (0.741 ± 0.007 and 0.889 ± 0.006) because of the larger proportion of BC content. Brown carbon played an important role for the SSA of 100-400 nm particles. The Ångström absorption exponent (AAE) values for all particles were above 1.6, indicating the significant presence of brown carbon in all sizes. Concurrent measurements in our work provide a basis for discussing the physicochemical properties of biomass burning aerosol and its effects on the global climate and atmospheric environment.

Variable carbon losses from recurrent fires in drained tropical peatlands.

PubMed

Konecny, Kristina; Ballhorn, Uwe; Navratil, Peter; Jubanski, Juilson; Page, Susan E; Tansey, Kevin; Hooijer, Aljosja; Vernimmen, Ronald; Siegert, Florian

2016-04-01

Tropical peatland fires play a significant role in the context of global warming through emissions of substantial amounts of greenhouse gases. However, the state of knowledge on carbon loss from these fires is still poorly developed with few studies reporting the associated mass of peat consumed. Furthermore, spatial and temporal variations in burn depth have not been previously quantified. This study presents the first spatially explicit investigation of fire-driven tropical peat loss and its variability. An extensive airborne Light Detection and Ranging data set was used to develop a prefire peat surface modelling methodology, enabling the spatially differentiated quantification of burned area depth over the entire burned area. We observe a strong interdependence between burned area depth, fire frequency and distance to drainage canals. For the first time, we show that relative burned area depth decreases over the first four fire events and is constant thereafter. Based on our results, we revise existing peat and carbon loss estimates for recurrent fires in drained tropical peatlands. We suggest values for the dry mass of peat fuel consumed that are 206 t ha(-1) for initial fires, reducing to 115 t ha(-1) for second, 69 t ha(-1) for third and 23 t ha(-1) for successive fires, which are 58-7% of the current IPCC Tier 1 default value for all fires. In our study area, this results in carbon losses of 114, 64, 38 and 13 t C ha(-1) for first to fourth fires, respectively. Furthermore, we show that with increasing proximity to drainage canals both burned area depth and the probability of recurrent fires increase and present equations explaining burned area depth as a function of distance to drainage canal. This improved knowledge enables a more accurate approach to emissions accounting and will support IPCC Tier 2 reporting of fire emissions. © 2015 John Wiley & Sons Ltd.

Rethinking the distinction between black and brown carbon

NASA Astrophysics Data System (ADS)

Adler, G. A.; Franchin, A.; Lamb, K. D.; Manfred, K.; Middlebrook, A. M.; Schwarz, J. P.; Wagner, N.; Washenfelder, R. A.; Womack, C.; Murphy, D. M.

2017-12-01

Aerosol radiative properties contribute large uncertainty to modeling of the earth's radiative budget. Black carbon (BC) aerosols originate from combustion processes and substantially contribute to warming and uncertainty - ongoing efforts are focused on reducing their anthropogenic emissions even as their emissions from biomass burning sources, such as wildfire, may increase in the future. Quantifying the radiative effect of BC is challenging, in part due to its association with other light absorbing materials including Brown carbon organic aerosol (BrC) that absorbs primarily blue and ultraviolet light while BC absorbs broadly across the visible. Conventionally BrC is thought of a low volatility spherical particles, distinguishing it from BC, which has a distinctive agglomerate morphology and is refractory at high temperatures. However, the separation of BC and BrC is often operationally defined and dependent on the measurement method. Using measurements of aerosol morphology, mass, absorption, and refractory BC mass content we were able to identify a light absorbing contribution from biomass burning aerosol that does not correspond to either BC or BrC as conventionally defined. Our measurements were collected from realistic biomass burning fires at the Missoula Fire Sciences Laboratory as part of the NOAA FIREX project (2016) and from extensive natural wildfire sampled aloft during NASA SEAC4RS field study (2013). We coin the term Dark Brown Carbon (DBrC) to describe this material, which absorbs broadly across the visible and survives thermal denuding at 250°C but does not incandesce in laser induced incandesce (LII) measurements. DBrC may be an intermediate burning stage product between polycyclic aromatic hydrocarbons (PAHs) and the mature soot. DBrC deserves further study to quantify its abundance and aging in ambient biomass burning plumes, and its relationship to tar balls. Our findings show that more than half of the light absorption in biomass burning smoke could be potentially contributed to DBC, which may provide an explanation for some of the persistent inconsistencies in measurements of BC from biomass burning by different methods.

Dissolved organic carbon in rainwater from areas heavily impacted by sugar cane burning

NASA Astrophysics Data System (ADS)

Coelho, C. H.; Francisco, J. G.; Nogueira, R. F. P.; Campos, M. L. A. M.

This work reports on rainwater dissolved organic carbon (DOC) from Ribeirão Preto (RP) and Araraquara over a period of 3 years. The economies of these two cities, located in São Paulo state (Brazil), are based on agriculture and related industries, and the region is strongly impacted by the burning of sugar cane foliage before harvesting. Highest DOC concentrations were obtained when air masses traversed sugar cane fields burned on the same day as the rain event. Significant increases in the DOC volume weighted means (VWM) during the harvest period, for both sites, and a good linear correlation ( r = 0.83) between DOC and K (a biomass burning marker) suggest that regional scale organic carbon emissions prevail over long-range transport. The DOC VWMs and standard deviations were 272 ± 22 μmol L -1 ( n = 193) and 338 ± 40 μmol L -1 ( n = 80) for RP and Araraquara, respectively, values which are at least two times higher than those reported for other regions influenced by biomass burning, such as the Amazon. These high DOC levels are discussed in terms of agricultural activities, particularly the large usage of biogenic fuels in Brazil, as well as the analytical method used in this work, which includes volatile organic carbon when reporting DOC values. Taking into account rainfall volume, estimated annual rainwater DOC fluxes for RP (4.8 g C m -2 yr -1) and Araraquara (5.4 g C m -2 yr -1) were close to that previously found for the Amazon region (4.8 g C m -2 yr -1). This work also discusses whether previous calculations of the global rainwater carbon flux may have been underestimated, since they did not consider large inputs from biomass combustion sources, and suffered from a possible analytical bias.

Time-resolved characterization of primary emissions from residential wood combustion appliances.

PubMed

Heringa, M F; DeCarlo, P F; Chirico, R; Lauber, A; Doberer, A; Good, J; Nussbaumer, T; Keller, A; Burtscher, H; Richard, A; Miljevic, B; Prevot, A S H; Baltensperger, U

2012-10-16

Primary emissions from a log wood burner and a pellet boiler were characterized by online measurements of the organic aerosol (OA) using a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and of black carbon (BC). The OA and BC concentrations measured during the burning cycle of the log wood burner, batch wise fueled with wood logs, were highly variable and generally dominated by BC. The emissions of the pellet burner had, besides inorganic material, a high fraction of OA and a minor contribution of BC. However, during artificially induced poor burning BC was the dominating species with ∼80% of the measured mass. The elemental O:C ratio of the OA was generally found in the range of 0.2-0.5 during the startup phase or after reloading of the log wood burner. During the burnout or smoldering phase, O:C ratios increased up to 1.6-1.7, which is similar to the ratios found for the pellet boiler during stable burning conditions and higher than the O:C ratios observed for highly aged ambient OA. The organic emissions of both burners have a very similar H:C ratio at a given O:C ratio and therefore fall on the same line in the Van Krevelen diagram.

Wildfire and forest disease interaction lead to greater loss of soil nutrients and carbon.

PubMed

Cobb, Richard C; Meentemeyer, Ross K; Rizzo, David M

2016-09-01

Fire and forest disease have significant ecological impacts, but the interactions of these two disturbances are rarely studied. We measured soil C, N, Ca, P, and pH in forests of the Big Sur region of California impacted by the exotic pathogen Phytophthora ramorum, cause of sudden oak death, and the 2008 Basin wildfire complex. In Big Sur, overstory tree mortality following P. ramorum invasion has been extensive in redwood and mixed evergreen forests, where the pathogen kills true oaks and tanoak (Notholithocarpus densiflorus). Sampling was conducted across a full-factorial combination of disease/no disease and burned/unburned conditions in both forest types. Forest floor organic matter and associated nutrients were greater in unburned redwood compared to unburned mixed evergreen forests. Post-fire element pools were similar between forest types, but lower in burned-invaded compared to burned-uninvaded plots. We found evidence disease-generated fuels led to increased loss of forest floor C, N, Ca, and P. The same effects were associated with lower %C and higher PO4-P in the mineral soil. Fire-disease interactions were linear functions of pre-fire host mortality which was similar between the forest types. Our analysis suggests that these effects increased forest floor C loss by as much as 24.4 and 21.3 % in redwood and mixed evergreen forests, respectively, with similar maximum losses for the other forest floor elements. Accumulation of sudden oak death generated fuels has potential to increase fire-related loss of soil nutrients at the region-scale of this disease and similar patterns are likely in other forests, where fire and disease overlap.

Trace elements in stormflow, ash, and burned soil following the 2009 station fire in southern California

USGS Publications Warehouse

Burton, Carmen; Hoefen, Todd M.; Plumlee, Geoffrey S.; Baumberger, Katherine L.; Backlin, Adam R.; Gallegos, Elizabeth; Fisher, Robert N.

2016-01-01

Most research on the effects of wildfires on stream water quality has focused on suspended sediment and nutrients in streams and water bodies, and relatively little research has examined the effects of wildfires on trace elements. The purpose of this study was two-fold: 1) to determine the effect of the 2009 Station Fire in the Angeles National Forest northeast of Los Angeles, CA on trace element concentrations in streams, and 2) compare trace elements in post-fire stormflow water quality to criteria for aquatic life to determine if trace elements reached concentrations that can harm aquatic life. Pre-storm and stormflow water-quality samples were collected in streams located inside and outside of the burn area of the Station Fire. Ash and burned soil samples were collected from several locations within the perimeter of the Station Fire. Filtered concentrations of Fe, Mn, and Hg and total concentrations of most trace elements in storm samples were elevated as a result of the Station Fire. In contrast, filtered concentrations of Cu, Pb, Ni, and Se and total concentrations of Cu were elevated primarily due to storms and not the Station Fire. Total concentrations of Se and Zn were elevated as a result of both storms and the Station Fire. Suspended sediment in stormflows following the Station Fire was an important transport mechanism for trace elements. Cu, Pb, and Zn primarily originate from ash in the suspended sediment. Fe primarily originates from burned soil in the suspended sediment. As, Mn, and Ni originate from both ash and burned soil. Filtered concentrations of trace elements in stormwater samples affected by the Station Fire did not reach levels that were greater than criteria established for aquatic life. Total concentrations for Fe, Pb, Ni, and Zn were detected at concentrations above criteria established for aquatic life.

Trace Elements in Stormflow, Ash, and Burned Soil following the 2009 Station Fire in Southern California

PubMed Central

Burton, Carmen A.; Hoefen, Todd M.; Plumlee, Geoffrey S.; Baumberger, Katherine L.; Backlin, Adam R.; Gallegos, Elizabeth; Fisher, Robert N.

2016-01-01

Most research on the effects of wildfires on stream water quality has focused on suspended sediment and nutrients in streams and water bodies, and relatively little research has examined the effects of wildfires on trace elements. The purpose of this study was two-fold: 1) to determine the effect of the 2009 Station Fire in the Angeles National Forest northeast of Los Angeles, CA on trace element concentrations in streams, and 2) compare trace elements in post-fire stormflow water quality to criteria for aquatic life to determine if trace elements reached concentrations that can harm aquatic life. Pre-storm and stormflow water-quality samples were collected in streams located inside and outside of the burn area of the Station Fire. Ash and burned soil samples were collected from several locations within the perimeter of the Station Fire. Filtered concentrations of Fe, Mn, and Hg and total concentrations of most trace elements in storm samples were elevated as a result of the Station Fire. In contrast, filtered concentrations of Cu, Pb, Ni, and Se and total concentrations of Cu were elevated primarily due to storms and not the Station Fire. Total concentrations of Se and Zn were elevated as a result of both storms and the Station Fire. Suspended sediment in stormflows following the Station Fire was an important transport mechanism for trace elements. Cu, Pb, and Zn primarily originate from ash in the suspended sediment. Fe primarily originates from burned soil in the suspended sediment. As, Mn, and Ni originate from both ash and burned soil. Filtered concentrations of trace elements in stormwater samples affected by the Station Fire did not reach levels that were greater than criteria established for aquatic life. Total concentrations for Fe, Pb, Ni, and Zn were detected at concentrations above criteria established for aquatic life. PMID:27144270

Biomass Burning and the Production of Greenhouse Gases. Chapter 9

NASA Technical Reports Server (NTRS)

Levine, Joel S.

1994-01-01

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which regulates the lifetime of almost every atmospheric gas. Following biomass burning, biogenic emissions of nitrous oxide, nitric oxide, and methane are significantly enhanced. It is hypothesized that enhanced postburn biogenic emissions of these gases are related to fire-induced changes in soil chemistry and/or microbial ecology. Biomass burning, once believed to be a tropical phenomenon, has been demonstrated by satellite imagery to also be a regular feature of the world's boreal forests. One example of biomass burning is the extensive 1987 fire that destroyed more than 12 million acres of boreal forest in the People's Republic of China and across its border in the Soviet Union. Recent estimates indicate that almost all biomass burning is human-initiated and that it is increasing with time. With the formation of greenhouse and chemically active gases as direct combustion products and a longer-term enhancement of biogenic emissions of gases, biomass burning may be a significant driver for global change.

High-Resolution Mapping of Biomass Burning Emissions in Three Tropical Regions.

PubMed

Shi, Yusheng; Matsunaga, Tsuneo; Yamaguchi, Yasushi

2015-09-15

Biomass burning in tropical regions plays a significant role in atmospheric pollution and climate change. This study quantified a comprehensive monthly biomass burning emissions inventory with 1 km high spatial resolution, which included the burning of vegetation, human waste, and fuelwood for 2010 in three tropical regions. The estimations were based on the available burned area product MCD64A1 and statistical data. The total emissions of all gases and aerosols were 17382 Tg of CO2, 719 Tg of CO, 30 Tg of CH4, 29 Tg of NOx, 114 Tg of NMOC (nonmethane organic compounds), 7 Tg of SO2, 10 Tg of NH3, 79 Tg of PM2.5 (particulate matter), 45 Tg of OC (organic carbon), and 6 Tg of BC (black carbon). Taking CO as an example, vegetation burning accounted for 74% (530 Tg) of the total CO emissions, followed by fuelwood combustion and human waste burning. Africa was the biggest emitter (440 Tg), larger than Central and South America (113 Tg) and South and Southeast Asia (166 Tg). We also noticed that the dominant fire types in vegetation burning of these three regions were woody savanna/shrubland, savanna/grassland, and forest, respectively. Although there were some slight overestimations, our results are supported by comparisons with previously published data.

New perspectives on quantitative characterization of biomass burning (Invited)

NASA Astrophysics Data System (ADS)

Ichoku, C. M.

2010-12-01

Biomass burning (BB) occurs seasonally in different vegetated landscapes across the world, consuming large amounts of biomass, generating intense heat energy, and emitting corresponding amounts of smoke plumes that comprise aerosols and trace gases, which include carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), non-methane hydrocarbons, and numerous other trace compounds, many of which have adverse effects on human health, air quality, and environmental processes. Accurate estimates of these emissions are required as model inputs to evaluate and forecast smoke plume transport and impacts on air quality, human health, clouds, weather, radiation, and climate. The goal of this presentation is to highlight results of research activities that are aimed at advancing the quantitative characterization of various aspects of biomass burning (energetics, intensity, burn areas, burn severity, emissions, and fire weather) from aircraft and satellite measurements that can help advance our understanding of biomass burning and its overall effects. We will show recent results of analysis of fire radiative power (FRP), burned areas, fuel consumption, smoke emission rates, and plume heights from satellite measurements, as well as related aircraft calibration/validation activities. We will also briefly examine potential future plans and strategies for effective monitoring of biomass burning characteristics and emissions from aircraft and satellite.

Global Burned Area and Biomass Burning Emissions from Small Fires

NASA Technical Reports Server (NTRS)

Randerson, J. T.; Chen, Y.; vanderWerf, G. R.; Rogers, B. M.; Morton, D. C.

2012-01-01

In several biomes, including croplands, wooded savannas, and tropical forests, many small fires occur each year that are well below the detection limit of the current generation of global burned area products derived from moderate resolution surface reflectance imagery. Although these fires often generate thermal anomalies that can be detected by satellites, their contributions to burned area and carbon fluxes have not been systematically quantified across different regions and continents. Here we developed a preliminary method for combining 1-km thermal anomalies (active fires) and 500 m burned area observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) to estimate the influence of these fires. In our approach, we calculated the number of active fires inside and outside of 500 m burn scars derived from reflectance data. We estimated small fire burned area by computing the difference normalized burn ratio (dNBR) for these two sets of active fires and then combining these observations with other information. In a final step, we used the Global Fire Emissions Database version 3 (GFED3) biogeochemical model to estimate the impact of these fires on biomass burning emissions. We found that the spatial distribution of active fires and 500 m burned areas were in close agreement in ecosystems that experience large fires, including savannas across southern Africa and Australia and boreal forests in North America and Eurasia. In other areas, however, we observed many active fires outside of burned area perimeters. Fire radiative power was lower for this class of active fires. Small fires substantially increased burned area in several continental-scale regions, including Equatorial Asia (157%), Central America (143%), and Southeast Asia (90%) during 2001-2010. Globally, accounting for small fires increased total burned area by approximately by 35%, from 345 Mha/yr to 464 Mha/yr. A formal quantification of uncertainties was not possible, but sensitivity analyses of key model parameters caused estimates of global burned area increases from small fires to vary between 24% and 54%. Biomass burning carbon emissions increased by 35% at a global scale when small fires were included in GFED3, from 1.9 Pg C/yr to 2.5 Pg C/yr. The contribution of tropical forest fires to year-to-year variability in carbon fluxes increased because small fires amplified emissions from Central America, South America and Southeast Asia-regions where drought stress and burned area varied considerably from year to year in response to El Nino-Southern Oscillation and other climate modes.

Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dzepina, K.; Mazzoleni, C.; Fialho, P.

Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m above mean sea level on Pico Island of the Azores archipelago in the North Atlantic. The observatory is located ~ 3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 μg m -3. On average, organic aerosol components represent the largest mass fraction of the totalmore » measured aerosol (60 ± 51%), followed by sulfate (23 ± 28%), nitrate (13 ± 10%), chloride (2 ± 3%), and elemental carbon (2 ± 2%). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100–1000. The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled air masses were very aged (average plume age > 12 days). These aged aerosol WSOM compounds had an average O/C ratio of ~ 0.45, which is relatively low compared to O/C ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were more aged and influenced by marine emissions, as indicated by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for the two samples was corroborated by the changes in ethane, propane, and ozone, morphology of particles, as well as by the FLEXPART retroplume simulations. This paper presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere remote location and provides evidence of low oxygenation after long-range transport. We hypothesize this is a result of the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and fragmentation (e.g., photolysis) of components.« less

Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume

DOE PAGES

Dzepina, K.; Mazzoleni, C.; Fialho, P.; ...

2015-05-05

Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m above mean sea level on Pico Island of the Azores archipelago in the North Atlantic. The observatory is located ~ 3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 μg m -3. On average, organic aerosol components represent the largest mass fraction of the totalmore » measured aerosol (60 ± 51%), followed by sulfate (23 ± 28%), nitrate (13 ± 10%), chloride (2 ± 3%), and elemental carbon (2 ± 2%). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100–1000. The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled air masses were very aged (average plume age > 12 days). These aged aerosol WSOM compounds had an average O/C ratio of ~ 0.45, which is relatively low compared to O/C ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were more aged and influenced by marine emissions, as indicated by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for the two samples was corroborated by the changes in ethane, propane, and ozone, morphology of particles, as well as by the FLEXPART retroplume simulations. This paper presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere remote location and provides evidence of low oxygenation after long-range transport. We hypothesize this is a result of the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and fragmentation (e.g., photolysis) of components.« less

Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume

NASA Astrophysics Data System (ADS)

Dzepina, K.; Mazzoleni, C.; Fialho, P.; China, S.; Zhang, B.; Owen, R. C.; Helmig, D.; Hueber, J.; Kumar, S.; Perlinger, J. A.; Kramer, L. J.; Dziobak, M. P.; Ampadu, M. T.; Olsen, S.; Wuebbles, D. J.; Mazzoleni, L. R.

2015-05-01

Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m above mean sea level on Pico Island of the Azores archipelago in the North Atlantic. The observatory is located ~ 3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 μg m-3. On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51%), followed by sulfate (23 ± 28%), nitrate (13 ± 10%), chloride (2 ± 3%), and elemental carbon (2 ± 2%). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100-1000. The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled air masses were very aged (average plume age > 12 days). These aged aerosol WSOM compounds had an average O/C ratio of ~ 0.45, which is relatively low compared to O/C ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were more aged and influenced by marine emissions, as indicated by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for the two samples was corroborated by the changes in ethane, propane, and ozone, morphology of particles, as well as by the FLEXPART retroplume simulations. This paper presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere remote location and provides evidence of low oxygenation after long-range transport. We hypothesize this is a result of the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and fragmentation (e.g., photolysis) of components.

AmeriFlux US-Me1 Metolius - Eyerly burn

DOE Data Explorer

Law, Bev [Oregon State University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-Me1 Metolius - Eyerly burn. Site Description - An intermediate aged ponderosa pine forest that was severely burned in the 2002 Eyerly wildfire. All trees were killed (stand replacing event). Irvine et al (2007) GCB 13 (8), 1748–1760.

Trace gas emissions from burning Florida wetlands

NASA Technical Reports Server (NTRS)

Cofer, Wesley R., III; Levine, Joel S.; Lebel, Peter J.; Winstead, Edward L.; Koller, Albert M., Jr.; Hinkle, C. Ross

1990-01-01

Measurements of biomass burn-produced trace gases were obtained using a helicopter at low altitudes above burning Florida wetlands on November 9, 1987, and from both helicopter and light-aircraft samplings on November 7, 1988. Carbon dioxide normalized emission ratios for carbon monoxide, hydrogen, methane, total nonmethane hydrocarbons, and nitrous oxide were obtained over burning graminoid wetlands consisting primarily of Spartina bakeri and Juncus roemerianus. Some interspersed scrub oak and saw palmetto were also burned. No significant differences were observed in the emission ratios determined for these gases from samples collected over flaming, mixed, and smoldering phases of combustion during the 1987 fire. Combustion-categorized differences in emission ratios were small for the 1988 fire. Combustion efficiency was relatively good (low emission ratios for reduced gases) for both fires. It is believed that the consistently low emission ratios were a unique result of graminoid wetlands fires, in which the grasses and rushes burned rapidly down to standing water and were quickly extinguished. Consequently, the efficiency of the combustion was good and the amount and duration of smoldering combustion was greatly deminished.

Rapid prototyping of three-dimensional microstructures from multiwalled carbon nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hung, W.H.; Kumar, Rajay; Bushmaker, Adam

The authors report a method for creating three-dimensional carbon nanotube structures, whereby a focused laser beam is used to selectively burn local regions of a dense forest of multiwalled carbon nanotubes. Raman spectroscopy and scanning electron microscopy are used to quantify the threshold for laser burnout and depth of burnout. The minimum power density for burning carbon nanotubes in air is found to be 244 {mu}W/{mu}m{sup 2}. We create various three-dimensional patterns using this method, illustrating its potential use for the rapid prototyping of carbon nanotube microstructures. Undercut profiles, changes in nanotube density, and nanoparticle formation are observed after lasermore » surface treatment and provide insight into the dynamic process of the burnout mechanism.« less

Dicarboxylic acids, metals and isotopic compositions of C and N in atmospheric aerosols from inland China: implications for dust and coal burning emission and secondary aerosol formation

NASA Astrophysics Data System (ADS)

Wang, G.; Xie, M.; Hu, S.; Tachibana, E.; Kawamura, K.

2010-03-01

Dicarboxylic acids (C2-C10), metals, elemental carbon (EC), organic carbon (OC), and stable isotopic compositions of total carbon (TC) and total nitrogen (TN) were determined for PM10 samples collected at three urban and one suburban sites of Baoji, an inland city of China, during winter and spring 2008. Oxalic acid (C2) was the dominant diacid, followed by succinic (C4) and malonic (C3) acids. Total diacids in the urban and suburban areas are 1546±203 and 1728±495 ng m-3 during winter and 1236±335 and 1028±193 ng m-3 during spring. EC in the urban and the suburban atmospheres are 17±3.8 and 8.0±2.1 μg m-3 during winter and 20±5.9 and 7.1±2.7 μg m-3 during spring whereas OC at the urban and suburban sites are 74±14 and 51±7.9 μg m-3 in winter and 51±20 and 23±6.1 μg m-3 in spring. Secondary organic carbon (SOC) accounted for 38±16% of OC in winter and 28±18% of OC in spring, suggesting an enhanced photochemical production of secondary organic aerosols in winter under an inversion layer development. Total metal elements in winter and spring are 34±10 and 61±27 μg m-3 in the urban air and 18±7 and 32±23 μg m-3 in the suburban air. A linear correlation (r2>0.8 in winter and r2>0.6 in spring) was found between primary organic carbon (POC) and Ca2+/Fe, together with a strong dependence of pH value on water-soluble inorganic carbon, suggesting fugitive dust as a major source of the airborne particles. Polycyclic aromatic hydrocarbons (PAHs), sulfate, and Pb in the samples well correlated each other (r2>0.6) in winter samples, suggesting an importance of emissions from coal burning for house heating. Stable carbon isotope compositions of TC (δ13C) became higher with an increase in the concentration ratios of C2/OC due to aerosol aging. In contrast, nitrogen isotope compositions of TN (δ15N) became lower with an increases in the mass ratios of NH4+/PM10 and NO3-/PM10 due to an enhanced adsorption and/or condensation of NH3 and HNO3 from gas phase onto solid phase.

Dicarboxylic acids, metals and isotopic compositions of C and N in atmospheric aerosols from inland China: implications for dust and coal burning emission and secondary aerosol formation

NASA Astrophysics Data System (ADS)

Wang, G.; Xie, M.; Hu, S.; Gao, S.; Tachibana, E.; Kawamura, K.

2010-07-01

Dicarboxylic acids (C2-C10), metals, elemental carbon (EC), organic carbon (OC), and stable isotopic compositions of total carbon (TC) and total nitrogen (TN) were determined for PM10 samples collected at three urban and one suburban sites of Baoji, an inland city of China, during winter and spring 2008. Oxalic acid (C2) was the dominant diacid, followed by succinic (C4) and malonic (C3) acids. Total diacids in the urban and suburban areas were 1546±203 and 1728±495 ng m-3 during winter and 1236±335 and 1028±193 ng m-3 during spring. EC in the urban and the suburban atmospheres were 17±3.8 and 8.0±2.1 μg m-3 during winter and 20±5.9 and 7.1±2.7 μg m-3 during spring, while OC at the urban and suburban sites were 74±14 and 51±7.9 μg m-3 in winter and 51±20 and 23±6.1 μg m-3 in spring. Secondary organic carbon (SOC) accounted for 38±16% of OC in winter and 28±18% of OC in spring, suggesting an enhanced photochemical production of secondary organic aerosols in winter under an inversion layer development. Total metal elements in winter and spring were 34±10 and 61±27 μg m-3 in the urban air and 18±7 and 32±23 μg m-3 in the suburban air. A linear correlation (r2>0.8 in winter and r2>0.6 in spring) was found between primary organic carbon (POC) and Ca2+/Fe, together with a strong dependence of pH value of sample extracts on water-soluble inorganic carbon, suggesting fugitive dust as an important source of the airborne particles. Polycyclic aromatic hydrocarbons (PAHs), sulfate, and Pb in the samples well correlated each other (r2>0.6) in winter, indicating an importance of emissions from coal burning for house heating. Stable carbon isotope compositions of TC (δ13C) became higher with an increase in the concentration ratios of C2/OC due to aerosol aging. In contrast, nitrogen isotope compositions of TN (δ15N) became lower with an increases in the mass ratios of NH4+/PM10 and NO3-/PM10, which is possibly caused by an enhanced adsorption and/or condensation of gaseous NH3 and HNO3 onto particles.

The Carbon Cycle: Implications for Climate Change and Congress

DTIC Science & Technology

2008-03-13

burning of fossil fuels, deforestation , and other land use activities, have significantly altered the carbon cycle. As a result, atmospheric...80% of human-related CO2 emissions results from fossil fuel combustion, and 20% from land use change (primarily deforestation ). Fossil fuel burning...warming the planet. At present, the oceans and land surface are acting as sinks for CO2 emitted from fossil fuel combustion and deforestation , but

Air Quality Impact from Biomass Burning in Northern Sub-Saharan Africa (NSSA).

NASA Astrophysics Data System (ADS)

Damoah, R.; Ichoku, C. M.; Ellison, L.

2016-12-01

Biomass burning (BB) is one of the major sources of troposheric ozone (O3) precursors such as nitrogen oxides (NOx), carbon monoxides (CO), and non-methane volatile organics compounds (NMVOCs) as well as primary aerosols such as organic carbon (OC) and black carbon (BC). These emissions do not only affect air quality locally, but also on continental to hemispheric scales through long-range transport. It is estimated that about 350 Million hectares of land burn globally every year of which 54 % are in Africa. The northern sub-Saharan African (NSSA) region (0 - 20N, 20W - 55E) is known to show one of the highest biomass burning rates (in terms of per unit land area) among all regions of the world. This is due to the high concentration and frequency of fires in this region. In 2016 a newly installed AERONET ( ) sun photometer at All Nations University College (6.2N, 0.3W) within our study region recorded enhanced aerosol optical depth presume to be triggered by smoke from fires. We will discuss sources of this enhancement as well results obtained from NASA's Global Modeling Initiative Chemistry and Transport Model (GMI-CTM), to quantify the impact on air quality by biomass burning.

Improving Large-scale Biomass Burning Carbon Consumption and Emissions Estimates in the Former Soviet Union based on Fire Weather

NASA Astrophysics Data System (ADS)

Westberg, D. J.; Soja, A. J.; Tchebakova, N.; Parfenova, E. I.; Kukavskaya, E.; de Groot, B.; McRae, D.; Conard, S. G.; Stackhouse, P. W., Jr.

2012-12-01

Estimating the amount of biomass burned during fire events is challenging, particularly in remote and diverse regions, like those of the Former Soviet Union (FSU). Historically, we have typically assumed 25 tons of carbon per hectare (tC/ha) is emitted, however depending on the ecosystem and severity, biomass burning emissions can range from 2 to 75 tC/ha. Ecosystems in the FSU span from the tundra through the taiga to the forest-steppe, steppe and desserts and include the extensive West Siberian lowlands, permafrost-lain forests and agricultural lands. Excluding this landscape disparity results in inaccurate emissions estimates and incorrect assumptions in the transport of these emissions. In this work, we present emissions based on a hybrid ecosystem map and explicit estimates of fuel that consider the depth of burning based on the Canadian Forest Fire Weather Index System. Specifically, the ecosystem map is a fusion of satellite-based data, a detailed ecosystem map and Alexeyev and Birdsey carbon storage data, which is used to build carbon databases that include the forest overstory and understory, litter, peatlands and soil organic material for the FSU. We provide a range of potential carbon consumption estimates for low- to high-severity fires across the FSU that can be used with fire weather indices to more accurately estimate fire emissions. These data can be incorporated at ecoregion and administrative territory scales and are optimized for use in large-scale Chemical Transport Models. Additionally, paired with future climate scenarios and ecoregion cover, these carbon consumption data can be used to estimate potential emissions.

Turbidite carbon distribution by Ramped PyrOx, Astoria Canyon

NASA Astrophysics Data System (ADS)

Childress, L. B.; Galy, V.; McNichol, A. P.

2017-12-01

The magnitude and nature of carbon preserved in marine sediments can be affected by long-term processes such as climate change and tectonic transport; preservation of carbon can also be affected by short-term, episodic disturbances such as storm events, landslides, and earthquakes. In margins with active canyons, these systems can be efficient burial networks for carbon. The downslope displacement and reorganization of sediment and associated organic carbon (OC) during turbidite formation alters oxygen diffusion and the potential for aerobic oxidation, thereby modifying the redox geochemistry of the sediment package. Generally termed as a `burn-down', reactions at the subsurface oxidation front are linked to a loss of OC preservation within turbidite sequences. Still debated is the source of the OC residual within `burn-down' events, primarily whether the preserved material is dominated by terrestrial or marine components. To better understand the significance of canyon systems and turbidite deposits in the transport, preservation, and `burn-down' of organic carbon, samples from these systems can be studied using the Ramped PyrOx (RPO) technique. Whereas bulk radiocarbon measurements are unsuitable within turbidite deposits, RPO is well suited for characterizing the distribution of carbon sources within a turbidite interval. To complement RPO analyses, OC and N content, stable carbon isotope composition, gamma ray attenuation bulk density, computerized tomography, and magnetic susceptibility were determined. The turbidite systems of the Cascadia Subduction Zone have been extensively studied in relation to the Holocene paleoseismic record. Gravity cores collected in 2011 aboard the R/V Wecoma capture turbidite deposits in Astoria Canyon and demonstrate characteristics of `burn down' intervals. RPO data from within a 15 cm turbidite interval indicate minimal variation in reactivity structure, stable carbon isotope values and radiocarbon age, suggesting a shared source of sediment input. Such similarities imply minimal source-selective OC alteration and are consistent with a singular event (e.g. - flood) associated with late Holocene warm interval influence on the Columbia River Basin.

Do Polyethylene Plastic Covers Affect Smoke Emissions from Debris Piles?

NASA Astrophysics Data System (ADS)

Weise, D. R.; Jung, H.; Cocker, D.; Hosseini, E.; Li, Q.; Shrivastava, M.; McCorison, M.

2010-12-01

Shrubs and small diameter trees exist in the understories of many western forests. They are important from an ecological perspective; however, this vegetation also presents a potential hazard as “ladder fuels” or as a heat source to damage the overstory during prescribed burns. Cutting and piling of this material to burn under safe conditions is a common silvicultural practice. To improve ignition success of the piled debris, polyethylene plastic is often used to cover a portion of the pile. While burning of piled forest debris is an acceptable practice in southern California from an air quality perspective, inclusion of plastic in the piles changes these debris piles to rubbish piles which should not be burned. With support from the four National Forests in southern California, we conducted a laboratory experiment to determine if the presence of polyethylene plastic in a pile of burning wood changed the smoke emissions. Debris piles in southern California include wood and foliage from common forest trees such as sugar and ponderosa pines, white fir, incense cedar, and California black oak and shrubs such as ceanothus and manzanita in addition to forest floor material and dirt. Manzanita wood was used to represent the debris pile in order to control the effects of fuel bed composition. The mass of polyethylene plastic incorporated into the pile was 0, 0.25 and 2.5% of the wood mass—a range representative of field conditions. Measured emissions included NOx, CO, CO2, SO2, polycyclic and light hydrocarbons, carbonyls, particulate matter (5 to 560 nm), elemental and organic carbon. The presence of polyethylene did not alter the emissions composition from this experiment.

The formation of light absorbing insoluble organic compounds from the reaction of biomass burning precursors and Fe(III)

NASA Astrophysics Data System (ADS)

Lavi, Avi; Lin, Peng; Bhaduri, Bhaskar; Laskin, Alexander; Rudich, Yinon

2017-04-01

Dust particles and volatile organic compounds from fuel or biomass burning are two major components that affect air quality in urban polluted areas. We characterized the products from the reaction of soluble Fe(III), a reactive transition metal originating from dust particles dissolution processes, with phenolic compounds , namely, guaiacol, syringol, catechol, o- and p- cresol that are known products of incomplete fuel and biomass combustion but also from other natural sources such as humic compounds degradation. We found that under acidic conditions comparable to those expected on a dust particle surface, phenolic compounds readily react with dissolved Fe(III), leading to the formation of insoluble polymeric compounds. We characterized the insoluble products by x-ray photoelectron microscopy, UV-Vis spectroscopy, mass spectrometry, elemental analysis and thermo-gravimetric analysis. We found that the major chromophores formed are oligomers (from dimers to pentamers) of the reaction precursors that efficiently absorb light between 300nm and 500nm. High variability of the mass absorption coefficient of the reaction products was observed with catechol and guaiacol showing high absorption at the 300-500nm range that is comparable to that of brown carbon (BrC) from biomass burning studies. The studied reaction is a potential source for the in-situ production of secondary BrC material under dark conditions. Our results suggest a reaction path for the formation of bio-available iron in coastal polluted areas where dust particles mix with biomass burning pollution plumes. Such mixing can occur, for instance in the coast of West Africa or North Africa during dust and biomass burning seasons

Reliability assessment of MVP-BURN and JENDL-4.0 related to nuclear transmutation of light platinum group elements

NASA Astrophysics Data System (ADS)

Terashima, Atsunori; Nilsson, Mikael; Ozawa, Masaki; Chiba, Satoshi

2017-09-01

The Aprés ORIENT research program, as a concept of advanced nuclear fuel cycle, was initiated in FY2011 aiming at creating stable, highly-valuable elements by nuclear transmutation from ↓ssion products. In order to simulate creation of such elements by (n, γ) reaction succeeded by β- decay in reactors, a continuous-energy Monte Carlo burnup calculation code MVP-BURN was employed. Then, it is one of the most important tasks to con↓rm the reliability of MVP-BURN code and evaluated neutron cross section library. In this study, both an experiment of neutron activation analysis in TRIGA Mark I reactor at University of California, Irvine and the corresponding burnup calculation using MVP-BURN code were performed for validation of the simulation on transmutation of light platinum group elements. Especially, some neutron capture reactions such as 102Ru(n, γ)103Ru, 104Ru(n, γ)105Ru, and 108Pd(n, γ)109Pd were dealt with in this study. From a comparison between the calculation (C) and the experiment (E) about 102Ru(n, γ)103Ru, the deviation (C/E-1) was signi↓cantly large. Then, it is strongly suspected that not MVP-BURN code but the neutron capture cross section of 102Ru belonging to JENDL-4.0 used in this simulation have made the big di↑erence as (C/E-1) >20%.

Relationship between trace gases and aerosols from biomass burning in Southeast Asia using satellite and emission data

NASA Astrophysics Data System (ADS)

Azuma, Yoshimi; Nakamura, Maya; Kuji, Makoto

2012-11-01

Southeast Asia is one of the biggest regions of biomass burning with forest fires and slash-and-burn farming. From the fire events, a large amount of air pollutants are emitted such as carbon monoxide (CO), nitrogen oxide (NOx) and aerosol (black carbon; BC). Biomass burning generally causes not only local, but also transboundary air pollution, and influences the atmospheric environment in the world accordingly. However, impact of air pollutants' emissions from large-scale fire in Southeast Asia is not well investigated compared to other regions such as South America and Africa. In this study, characteristics of the atmospheric environment were investigated with correlative analyses among several satellite data (MOPITT, OMI, and MODIS) and emission inventory (GFEDv3) in Southeast Asia from October 2004 to June 2008 on a monthly basis. As a result, it is suggested that the transboundary air pollution from the biomass burning regions occurred over Southeast Asia, which caused specifically higher air pollutants' concentration at Hanoi, Vietnam in spring dry season.

Levoglucosan indicates high levels of biomass burning aerosols over oceans from the Arctic to Antarctic

PubMed Central

Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; Zhang, Pengfei

2013-01-01

Biomass burning is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we report the molecular tracer levoglucosan concentrations in marine air from the Arctic Ocean through the North and South Pacific Ocean to Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m3 levels with the highest atmospheric loadings present in the mid-latitudes (30°–60° N and S), intermediate loadings in the Arctic, and lowest loadings in the Antarctic and equatorial latitudes. As a whole, levoglucosan concentrations in the Southern Hemisphere were comparable to those in the Northern Hemisphere. Biomass burning has a significant impact on atmospheric Hg and water-soluble organic carbon (WSOC) from pole-to-pole, with more contribution to WSOC in the Northern Hemisphere than in the Southern Hemisphere. PMID:24176935

AmeriFlux US-An3 Anaktuvuk River Unburned

DOE Data Explorer

Hobbie, John [Marine Biological Laboratory; Rocha, Adrian [Marine Biological Laboratory; Shaver, Gaius [Marine Biological Laboratory

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-An3 Anaktuvuk River Unburned. Site Description - The Anaktuvuk River fire on the North Slope of Alaska started on July 16, 2007 by lightning. It continued until the end of September when nearby lakes had already frozen over and burned >256,000 acres, creating a mosaic of patches that differed in burn severity. The Anaktuvuk River Severe Burn, Moderate Burn, and Unburned sites are 40 km to the west of the nearest road and were selected in late May 2008 to determine the effects of the fire on carbon, water, and energy exchanges during the growing season. Because the fire had burned through September of the previous year, initial deployment of flux towers occurred prior to any significant vegetative regrowth, and our sampling campaign captured the full growing season in 2008. The Unburned site was located in a large area of tundra that was unaffected by the fire.

Local biomass burning is a dominant cause of the observed precipitation reduction in southern Africa

PubMed Central

Hodnebrog, Øivind; Myhre, Gunnar; Forster, Piers M.; Sillmann, Jana; Samset, Bjørn H.

2016-01-01

Observations indicate a precipitation decline over large parts of southern Africa since the 1950s. Concurrently, atmospheric concentrations of greenhouse gases and aerosols have increased due to anthropogenic activities. Here we show that local black carbon and organic carbon aerosol emissions from biomass burning activities are a main cause of the observed decline in southern African dry season precipitation over the last century. Near the main biomass burning regions, global and regional modelling indicates precipitation decreases of 20–30%, with large spatial variability. Increasing global CO2 concentrations further contribute to precipitation reductions, somewhat less in magnitude but covering a larger area. Whereas precipitation changes from increased CO2 are driven by large-scale circulation changes, the increase in biomass burning aerosols causes local drying of the atmosphere. This study illustrates that reducing local biomass burning aerosol emissions may be a useful way to mitigate reduced rainfall in the region. PMID:27068129

Levoglucosan indicates high levels of biomass burning aerosols over oceans from the Arctic to Antarctic.

PubMed

Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; Zhang, Pengfei

2013-11-01

Biomass burning is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we report the molecular tracer levoglucosan concentrations in marine air from the Arctic Ocean through the North and South Pacific Ocean to Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m(3) levels with the highest atmospheric loadings present in the mid-latitudes (30°-60° N and S), intermediate loadings in the Arctic, and lowest loadings in the Antarctic and equatorial latitudes. As a whole, levoglucosan concentrations in the Southern Hemisphere were comparable to those in the Northern Hemisphere. Biomass burning has a significant impact on atmospheric Hg and water-soluble organic carbon (WSOC) from pole-to-pole, with more contribution to WSOC in the Northern Hemisphere than in the Southern Hemisphere.

Scheduled Civil Aircraft Emission Inventories for 1976 and 1984: Database Development and Analysis

NASA Technical Reports Server (NTRS)

Baughcum, Steven L.; Henderson, Stephen C.; Tritz, Terrance G.

1996-01-01

This report describes the development of a three-dimensional database of aircraft fuel burn and emissions (fuel burned, NOx, CO, and hydrocarbons) from scheduled commercial aircraft for four months (February, May, August, and November) of 1976 and 1984. Combining this data with earlier published data for 1990 and 1992, trend analyses for fuel burned, NOx, carbon monoxide, and hydrocarbons were calculated for selected regions (global, North America, Europe, North Atlantic, and North Pacific). These emissions inventories are available for use by atmospheric scientists conducting the Atmospheric Effects of Aviation Project (AEAP) modeling studies. Fuel burned and emissions of nitrogen oxides (NOx as NO2), carbon monoxide, and hydrocarbons have been calculated on a 1 degree latitude x 1 degree longitude x 1 kilometer altitude grid and delivered to NASA as electronic files.

Trace gas emissions to the atmosphere by biomass burning in the west African savannas. Final report, 1 October 1991-31 March 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frouin, R.J.; Iacobellis, S.F.; Razafimpanilo, H.

1994-08-01

Savanna fires and atmospheric carbon dioxide (CO2) detection and estimating burned area using Advanced Very High Resolution Radiometer (AVHRR) reflectance data are investigated in this two part research project. The first part involves carbon dioxide flux estimates and a three-dimensional transport model to quantify the effect of North African savanna fires on atmospheric CO2 concentration, including CO2 spatial and temporal variability patterns and their significance to global emissions. The second article describes two methods used to determine burned area from AVHRR data. The article discusses the relationship between the percentage of burned area and AVHRR channel 2 reflectance (the linearmore » method) and Normalized Difference Vegetation Index (NDVI) (the nonlinear method). A comparative performance analysis of each method is described.« less

Morphological study of fluorescent carbon Nanoparticles (F-CNPs) from ground coffee waste soot oxidation by diluted acid

NASA Astrophysics Data System (ADS)

Gea, S.; Tjandra, S.; Joshua, J.; Wirjosentono, B.

2018-02-01

Coffee ground waste utilization for fluorescent carbon nanoparticles (F-CNPs) through soot oxidation with diluted HNO3 has been conducted. Soot was obtained through three different treatments to coffee ground waste; which was burned in furnaceat 550°C and 650°C and directly burned in a heat-proofcontainer. Then they were analyzed morphologically with Scanning Electron Microscope (SEM) instrument. Soot from direct burning indicated the optimum result where it has denser pores compared to other two soots. Soot obtained from direct burning was refluxed in diluted HNO3 for 12 hours to perform the oxidation. Yellowish brown supernatant was later observed which lead to green fluorescent under the UV light. F-CNPs characterization was done in Transmission Electron Microscopy, which showed that 7.4-23.4 nm of particle size were distributed.

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

NASA Astrophysics Data System (ADS)

Schütze, Katharina; Wilson, James Charles; Weinbruch, Stephan; Benker, Nathalie; Ebert, Martin; Günther, Gebhard; Weigel, Ralf; Borrmann, Stephan

2017-10-01

Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM = 3872; SEM = 330) were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were refractory in the electron beams. Carbonaceous particles containing additional elements to C and O comprised from 72 to 100 % of the refractory particles. The rest were internal mixtures of these materials with sulfates. The median number mixing ratio of the refractory particles, expressed in units of particles per milligram of air, was 1.1 (mg air)-1 and varied between 0.65 and 2.3 (mg air)-1. Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation). Carbon and oxygen are the only detected major elements with an atomic O/C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si/C: 0.010 ± 0.011; S/C: 0.0007 ± 0.0015; Fe/C: 0.0052 ± 0.0074; Cr/C: 0.0012 ± 0.0017; Ni/C: 0.0006 ± 0.0011 (all mean values ± standard deviation).High-resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix; i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between particles collected inside and outside the polar vortex. Based on chemistry and nanostructure, aircraft exhaust, volcanic emissions and biomass burning can certainly be excluded as sources. The same is true for the less probable but globally important sources: wood burning, coal burning, diesel engines and ship emissions. Recondensed organic matter and extraterrestrial particles, potentially originating from ablation and fragmentation, remain as possible sources of the refractory carbonaceous particles studied. However, additional work is required in order to identify the sources unequivocally.

Modelling Carbon Emissions in Calluna vulgaris-Dominated Ecosystems when Prescribed Burning and Wildfires Interact.

PubMed

Santana, Victor M; Alday, Josu G; Lee, HyoHyeMi; Allen, Katherine A; Marrs, Rob H

2016-01-01

A present challenge in fire ecology is to optimize management techniques so that ecological services are maximized and C emissions minimized. Here, we modeled the effects of different prescribed-burning rotation intervals and wildfires on carbon emissions (present and future) in British moorlands. Biomass-accumulation curves from four Calluna-dominated ecosystems along a north-south gradient in Great Britain were calculated and used within a matrix-model based on Markov Chains to calculate above-ground biomass-loads and annual C emissions under different prescribed-burning rotation intervals. Additionally, we assessed the interaction of these parameters with a decreasing wildfire return intervals. We observed that litter accumulation patterns varied between sites. Northern sites (colder and wetter) accumulated lower amounts of litter with time than southern sites (hotter and drier). The accumulation patterns of the living vegetation dominated by Calluna were determined by site-specific conditions. The optimal prescribed-burning rotation interval for minimizing annual carbon emissions also differed between sites: the optimal rotation interval for northern sites was between 30 and 50 years, whereas for southern sites a hump-backed relationship was found with the optimal interval either between 8 to 10 years or between 30 to 50 years. Increasing wildfire frequency interacted with prescribed-burning rotation intervals by both increasing C emissions and modifying the optimum prescribed-burning interval for minimum C emission. This highlights the importance of studying site-specific biomass accumulation patterns with respect to environmental conditions for identifying suitable fire-rotation intervals to minimize C emissions.

The influence of black carbon on the sorption and desorption of two model PAHs in natural soils.

PubMed

Chi, Fung-Hwa

2014-01-01

Black carbons (BC) which result from the incomplete combustion of farm waste [man-made (burned) BC] are highly absorbent. In Taiwan, the burning of farm waste known as slash and burn is common. The BCs from the burning may present an environmental challenge. Little is known about the effect of BCs on the transport of hydrophobic organic contaminants (HOC). This study investigates the sorption of anthracene and naphthalene to BCs in soil and efficiency of the surfactants Tween 80 and Triton X-100 in their removal. Both surfactants demonstrated 2-6 times increased solubility in the soils with the addiction of BC. Column experiments were performed to imitate the transportation of these contaminants in groundwater through soils before and after adding BC produced by burning farm waste in the lab. We found significantly increased sorption of anthracene in soil added with BCs produced in the lab, suggesting that fraction of organic carbon (foc) can contribute to sorption of such HOCs. Sorption of naphthalene was increased but not significantly. Comparing the concentrations of contaminants, we found the soil containing BC from burned farm waste absorbed HOC more efficiently than the organic BC (naturally-occurring) in the original soil. Therefore, sorption capacity and influence on the transport of HOC cannot be estimated simply by the foc of the soil because the two BCs differ greatly in their sorption ability. BC from farm waste absorbs more contaminants than naturally occurring BC in the soil.

Carbon monoxide and the burning earth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newell, R.E.; Reichle, H.G. Jr.; Seiler, W.

1989-10-01

Carbon monoxide is one of many gases whose presence in the atmosphere is blamed largely on industrial activity in the Northern Hemisphere. Data collected by the authors show that the gas is also abundant in the Southern Hemisphere, where it comes mainly from the burning of tropical rain forests and savannas. The high levels of carbon monoxide confirm other evidence that the rain forests are being diminished rapidly, which may affect the climates of these regions as well as globally. Increases in carbon monoxide could also encourage the accumulation of pollutant gases such as ozone and methane. The first ismore » highly toxic to plants and the second would add to the greenhouse effect.« less

American Burn Association Practice Guidelines: Burn Shock Resuscitation

DTIC Science & Technology

2008-02-01

Ann Surg 1979;189: 546–52. 39. Jelenko C III, Williams JB, Wheeler ML, et al. Studies in shock and resuscitation, I: use of a hypertonic, albumin...SUMMARY ARTICLE American Burn Association Practice Guidelines Burn Shock Resuscitation Tam N. Pham, MD,* Leopoldo C . Cancio, MD,† Nicole S. Gibran...practice guidelines burn shock resuscitation 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Pham T. N., Cancio L. C

PM10 source apportionment in a Swiss Alpine valley impacted by highway traffic.

PubMed

Ducret-Stich, Regina E; Tsai, Ming-Yi; Thimmaiah, Devraj; Künzli, Nino; Hopke, Philip K; Phuleria, Harish C

2013-09-01

Although trans-Alpine highway traffic exhaust is one of the major sources of air pollution along the highway valleys of the Alpine regions, little is known about its contribution to residential exposure and impact on respiratory health. In this paper, source-specific contributions to particulate matter with an aerodynamic diameter < 10 μm (PM10) and their spatio-temporal distribution were determined for later use in a pediatric asthma panel study in an Alpine village. PM10 sources were identified by positive matrix factorization using chemical trace elements, elemental, and organic carbon from daily PM10 filters collected between November 2007 and June 2009 at seven locations within the village. Of the nine sources identified, four were directly road traffic-related: traffic exhaust, road dust, tire and brake wear, and road salt contributing 16 %, 8 %, 1 %, and 2 % to annual PM10 concentrations, respectively. They showed a clear dependence with distance to highway. Additional contributions were identified from secondary particles (27 %), biomass burning (18 %), railway (11 %), and mineral dust including a local construction site (13 %). Comparing these source contributions with known source-specific biomarkers (e.g., levoglucosan, nitro-polycyclic aromatic hydrocarbons) showed high agreement with biomass burning, moderate with secondary particles (in winter), and lowest agreement with traffic exhaust.

EVALUATION OF CARBON BLACK SLURRIES AS CLEAN BURNING FUELS

EPA Science Inventory

Experiments were performed to examine the pumpability, atomization and combustion characteristics of slurries made of mixtures of carbon black with No. 2 fuel oil and methanol. Carbon black-No. 2 fuel oil and carbon black-methanol slurries, with carbon black contents of up to 50 ...

Anthropogenic disturbance of element cycles at the Earth's surface.

PubMed

Sen, Indra S; Peucker-Ehrenbrink, Bernhard

2012-08-21

The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts (Klee and Graedel, 2004). We quantify anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compare it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions, and for helium, hydrodynamic escape from the Earth's atmosphere. We introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporate uncertainties of element mass fluxes through Monte Carlo simulations. We find that at the Earth's surface anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium currently exceed natural fluxes. For these elements mining is the major factor of anthropogenic influence, whereas petroleum burning strongly influences the surficial cycle of rhenium. Our assessment indicates that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 elements surpass their corresponding natural fluxes.

Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

NASA Technical Reports Server (NTRS)

Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

1981-01-01

A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

Black carbon aerosol properties measured by a single particle soot photometer in emissions from biomass burning in the laboratory and field

Treesearch

G. R. McMeeking; J. W. Taylor; A. P. Sullivan; M. J. Flynn; S. K. Akagi; C. M. Carrico; J. L. Collett; E. Fortner; T. B. Onasch; S. M. Kreidenweis; R. J. Yokelson; C. Hennigan; A. L. Robinson; H. Coe

2010-01-01

We present SP2 observations of BC mass, size distributions and mixing state in emissions from laboratory and field biomass fires in California, USA. Biomass burning is the primary global black carbon (BC) source, but understanding of the amount emitted and its physical properties at and following emission are limited. The single particle soot photometer (SP2) uses a...

Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide.

PubMed

Walker, J C; Kasting, J F

1992-01-01

We develop a numerical simulation of the global biogeochemical cycles of carbon that works over time scales extending from years to millions of years. The ocean is represented by warm and cold shallow water reservoirs, a thermocline reservoir, and deep Atlantic, Indian, and Pacific reservoirs. The atmosphere is characterized by a single carbon reservoir and the global biota by a single biomass reservoir. The simulation includes the rock cycle, distinguishing between shelf carbonate and pelagic carbonate precipitation, with distinct lysocline depths in the three deep ocean reservoirs. Dissolution of pelagic carbonates in response to decrease in lysocline depth is included. The simulation is tuned to reproduce the observed radiocarbon record resulting from atomic weapon testing. It is tuned also to reproduce the distribution of dissolved phosphate and total dissolved carbon between the ocean reservoirs as well as the carbon isotope ratios for both 13C and 14C in ocean and atmosphere. The simulation reproduces reasonably well the historical record of carbon dioxide partial pressure as well as the atmospheric isotope ratios for 13C and 14C over the last 200 yr as these have changed in response to fossil fuel burning and land use changes, principally forest clearance. The agreements between observation and calculation involves the assumption of a carbon dioxide fertilization effect in which the rate of production of biomass increases with increasing carbon dioxide partial pressure. At present the fertilization effect of increased carbon dioxide outweighs the effects of forest clearance, so the biota comprises an overall sink of atmospheric carbon dioxide sufficiently large to bring the budget approximately into balance. This simulation is used to examine the future evolution of carbon dioxide and its sensitivity to assumptions about the rate of fossil fuel burning and of forest clearance. Over times extending up to thousands of years, the results are insensitive to the formulation of the rock cycle and to the dissolution of deep sea carbonate sediments. Atmospheric carbon dioxide continues to increase as long fossil fuel is burned at a significant rate, because the rate of fossil fuel production of carbon dioxide far exceeds the rates at which geochemical processes can remove carbon dioxide from the atmosphere. The maximum concentration of carbon dioxide achieved in the atmosphere depends on the total amount of fossil fuel burned, but only weakly on the rate of burning. The future course of atmospheric carbon dioxide is, however, very sensitive to the fate of the forests in this simulation because of the important role assigned to carbon dioxide fertilization of plant growth rate. Forest clearance drives up atmospheric carbon dioxide not only by converting biomass into atmospheric carbon dioxide but more importantly by reducing the capacity of the biota to sequester fossil fuel carbon dioxide. In this simulation, atmospheric carbon dioxide levels could be sustained indefinitely below 500 parts per million (ppm) if fossil fuel combustion rates were immediately cut from their present value of 5 x 10(14) m/y to 0.2 x 10(14) m/y (a factor of 25 reduction) and if further forest clearance were halted. If neither of these conditions is met and if we consume most of the world's fossil fuel reserves, peak carbon dioxide concentrations of 1000-2000 ppm are probable within the next few centuries.

Seasonal and interannual variations in CO and BC emissions from open biomass burning in Southern Africa during 1998-2005

NASA Astrophysics Data System (ADS)

Ito, Akinori; Ito, Akihiko; Akimoto, Hajime

2007-06-01

We estimate the emissions of carbon monoxide (CO) and black carbon (BC) from open vegetation fires in the Southern Hemisphere Africa from 1998 to 2005 using satellite information in conjunction with a biogeochemical model. Monthly burned areas at a 0.5-degree resolution are estimated from the Visible InfraRed Scanner (VIRS) fire count product and the MODerate resolution Imaging Spectroradiometer (MODIS) burned area data set associated with the MODIS tree cover imagery in grasslands and woodlands. The monthly fuel load distributions are derived from a 0.5-degree terrestrial carbon cycle model in conjunction with satellite data. The monthly maps of combustion factors and emission factors are estimated using empirical models that predict the effects of fuel conditions on these factors in grasslands and woodlands. Our annually averaged effective CO and BC emissions per area burned are 27 g CO m-2 and 0.17 g BC m-2 which are consistent with the products of fuel consumption and emission factors typically measured in southern Africa. The CO and BC emissions from open vegetation burning in southern Africa range from 45 Tg CO yr-1 and 0.26 Tg BC yr-1 for 2002 to 75 Tg CO yr-1 and 0.42 Tg BC yr-1 for 1998. The monthly averaged burned areas from VIRS fire counts peak earlier than modeled CO emissions. This characteristic delay between burned areas and emissions is mainly explained by significant changes in combustion factors for woodlands in our model. Consequently, the peaks in CO and BC emissions from our bottom-up approach are identical to those from previous top-down estimates using the Measurement Of the Pollution In The Troposphere (MOPITT) and the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) data.

Fuel Treatment Effects on Water Use Efficiency in Western Pine Forests Under Fire Suppression Evaluated Using Tree Ring Carbon Isotopes

NASA Astrophysics Data System (ADS)

Taylor, A. H.; Belmecheri, S.; Harris, L. B.

2016-12-01

We identified variation on water use efficiency interpreted from carbon 13 in tree ring cellulose in dense ponderosa pines forests in Washington and Arizona. Historically, these forests burned every decade until fires were suppressed beginning in the early twentieth century. The reduction in fire caused large increases in forest density and forest biomass and potential for intense fire. Forests with hazardous fuels are common in the western United States and these types of forests are treated with mechanical thinning and mechanical thinning and burning to reduce hazardous fuels and fire intensity. At each site we extracted tree ring samples from five trees in each treatment type and a control to identify the effects of fuel treatment of concentration of carbon 13 in tree ring cellulose. Water use efficiency as measured by carbon 13 increased after fuel treatments. Treatment effects were larger for the mechanical plus burn treatment than for the mechanical treatment in each study area compared to the control stands Our results suggest that fuel treatments reduce sensitivity of tree growth to climate and increase water use efficiency. Since tree ring carbon 13 is related to plant productivity, carbon 13 in tree rings can be used as a metric of change in ecosystem function for evaluating fuel treatments.

Emission measurements from a crude oil tanker at sea.

PubMed

Agrawal, Harshit; Welch, William A; Miller, J Wayne; Cockert, David R

2008-10-01

This work presents an all-inclusive set of regulated and nonregulated emission factors for the main propulsion engine (ME), auxiliary engine (AE) and an auxiliary boiler on a Suezmax class tanker while operating at sea. The data include criteria pollutants (carbon monoxide, nitrogen oxides, sulfur oxides, and particulate matter), a greenhouse gas (carbon dioxide), the principal speciated hydrocarbons needed for human health risk assessments, and a detailed analysis of the PM into its primary constituents (ions, elements, organic, and elemental carbon). Measurements followed ISO 8178-1 methods with modifications described in the paper. The vessel burned two fuels: a heavy fuel oil in the ME and boiler and a distillate fuel in the AE. The weighted NO(x) emissions for the ME and AE are 19.87 +/- 0.95 and 13.57 +/- 0.31 g/kWh, respectively. The weighted PM mass emissions factor is 1.60 +/- 0.08 g/kWh for the ME and 0.141 +/- 0.005 g/kWh for the AE, with the sulfate content of the PM being the root cause for the difference. For the ME, sulfate with associated water is about 75% of total PM mass, and the organic carbon ranges from 15 to 25% of the PM mass. A deeper analysis showed that the conversion of fuel sulfur to sulfate in the ME ranged from 1.4to 5%. This article also provides emission factors for selected polycyclic aromatic hydrocarbons, heavy alkanes, carbonyls, light hydrocarbon species, metals, and ions for the ME, AE, and the boiler.

An aerosol climatology for a rapidly growing arid region (southern Arizona): Major aerosol species and remotely sensed aerosol properties

NASA Astrophysics Data System (ADS)

Sorooshian, Armin; Wonaschütz, Anna; Jarjour, Elias G.; Hashimoto, Bryce I.; Schichtel, Bret A.; Betterton, Eric A.

2011-10-01

This study reports a comprehensive characterization of atmospheric aerosol particle properties in relation to meteorological and back trajectory data in the southern Arizona region, which includes two of the fastest growing metropolitan areas in the United States (Phoenix and Tucson). Multiple data sets (MODIS, AERONET, OMI/TOMS, MISR, GOCART, ground-based aerosol measurements) are used to examine monthly trends in aerosol composition, aerosol optical depth (AOD), and aerosol size. Fine soil, sulfate, and organics dominate PM2.5 mass in the region. Dust strongly influences the region between March and July owing to the dry and hot meteorological conditions and back trajectory patterns. Because monsoon precipitation begins typically in July, dust levels decrease, while AOD, sulfate, and organic aerosol reach their maximum levels because of summertime photochemistry and monsoon moisture. Evidence points to biogenic volatile organic compounds being a significant source of secondary organic aerosol in this region. Biomass burning also is shown to be a major contributor to the carbonaceous aerosol budget in the region, leading to enhanced organic and elemental carbon levels aloft at a sky-island site north of Tucson (Mt. Lemmon). Phoenix exhibits different monthly trends for aerosol components in comparison with the other sites owing to the strong influence of fossil carbon and anthropogenic dust. Trend analyses between 1988 and 2009 indicate that the strongest statistically significant trends are reductions in sulfate, elemental carbon, and organic carbon, and increases in fine soil during the spring (March-May) at select sites. These results can be explained by population growth, land-use changes, and improved source controls.

Measurements and Analysis of Chemical Composition of Particulate Matter during High Pollution Events at Guanzhong Plain, China

NASA Astrophysics Data System (ADS)

Junji, C.

2017-12-01

Particulate matter pollution is a serious environmental problem which influencing air quality, regional and global climates, and human health. PM2.5 samples were collected at Guanzhong Plain with six sampling sites atdifferent cities in the year scale from 2012 to 2014. All of the six sites exhibited highest organic carbon (OC)and elemental carbon (EC) values in winter and lowest values in summer. OC correlates well with EC indicating similar emission sources. The contributions of secondary species SO42-, NO3- and NH4+ in total ions were greatest, and the high concentrations in winter were mainly due to emissions from coal combustion and biomass burning.During autumn the haze days were severest in Xi'an city with similar tendency of PM2.5 variations, and it was proved that biomass burning may be the main emission source of the regional pollution. In winter pollution episodes, the pollution patterns in Guanzhong Plain were similar which was resulted from strong secondary reactions and coal burning.Source apportionment using a positive matrix factorizationreceptor model indicates that on average secondary aerosol was the main source of PM2.5 (39.3%), followed by coal burning (17.3%), motor vehicle/industrial emissions (15.7%), fugitive dust (14.9%), and biomass burning (12.8%). The online, in situ measurement airborne species, especially the chemical composition of non-refectory submicron aerosol, during a heavyhaze-fog event, was analyzed in detailed.The formation of secondary sulfate and organic aerosol were observed during the event. The sulfur oxidation ratio (SOR), defined as sulfate/(SO2+sulfate) were mostly over 0.10, with a maximum of 0.30, when relative humidity > 80%. The aging product of organic aerosol (OA) were also observed in the event. The wet scattering coefficient was influenced by secondary sulfate, in the form of (NH4)2SO4, with contribution of 48.9% of wet particulate phase scattering. Thus decreased the visibility dramatically with a minimum of 128m. The current WRF-Chem model study suggested the secondary sulfate formation was essential to the increasing of sulfate concentration. The formation of secondary species was a decisive reason to form severe haze after fog event.

Emissions from fireplace and woodstove combustion of prevalent Portuguese woods

NASA Astrophysics Data System (ADS)

Alves, Célia

2010-05-01

P. Fernandes, C. Gonçalves, C.A. Alves, L. Tarelho, F. Mirante, T. Nunes and C. Pio Centre for Environmental and Marine Studies, Department of Environment, University of Aveiro, 3810-193 Aveiro, Portugal In Portugal, it was estimated that around 390000 ton/year of wood is burned in fireplaces, although the chemical characterisation of emission profiles has not yet been performed. Emission inventories and source apportionment, photochemistry and climate change models use values obtained for American or Alpine wood-fuels, uncommon in South Europe. Previous work has suggested that the species of wood used can have a huge influence on the particle emissions. Since the distribution of compounds emitted differs by species and burning conditions and there are many variations among published profiles, it is desirable to obtain specific data at a regional level on the chemical characterisation of wood smoke. A series of source tests was performed to compare the emission profiles from the woodstove combustion to those of fireplaces. Eight types of biomass were burned in the laboratory: seven species of wood grown in Portugal (Pinus pinaster, Eucalyptus globulus, Quercus suber, Acacia longifolia, Quercus faginea, Olea europea, Quercus ilex rotundifolia), and briquettes of biomass residues. The gas sampling was carried out in the exhaust ducts of both combustion systems. The collection of particles (PM2.5) was conducted in the dilution tunnel that was directly coupled to the chimney. Dilution sampling was used to characterise fine particle emissions from the combustion sources because it simulates the rapid cooling and dilution that occurs as exhaust mixes with the atmosphere. During each burning cycle, the concentrations of O2, CO2 and CO, as well as operational parameters (e.g. temperatures, flows, etc.), were automatically monitored. The PM2.5 samples were analysed by a thermal optical technique in order to obtain their organic carbon (OC) and elemental carbon (EC) content. It has been observed that fireplace emissions are higher than those of stoves. The emission factors were in the ranges 43 - 149 g CO/kg, 326 - 2699 g CO2/kg, 3 - 25 g PM2.5/kg, 1.34 - 12.0 g OC/kg and 0.16 - 1.25 g EC/kg of biomass burned on a dry basis. Very significant differences among emission factors for the different combusted wood species have not been registered.

Toxicity of Urban PM10 and Relation with Tracers of Biomass Burning.

PubMed

Van Den Heuvel, Rosette; Staelens, Jeroen; Koppen, Gudrun; Schoeters, Greet

2018-02-12

The chemical composition of particles varies with space and time and depends on emission sources, atmospheric chemistry and weather conditions. Evidence suggesting that particles differ in toxicity depending on their chemical composition is growing. This in vitro study investigated the biological effects of PM 10 in relation to PM-associated chemicals. PM 10 was sampled in ambient air at an urban traffic site (Borgerhout) and a rural background location (Houtem) in Flanders (Belgium). To characterize the toxic potential of PM 10 , airway epithelial cells (Beas-2B cells) were exposed to particles in vitro. Different endpoints were studied including cell damage and death (cell viability) and the induction of interleukin-8 (IL-8). The mutagenic capacity was assessed using the Ames II Mutagenicity Test. The endotoxin levels in the collected samples were analyzed and the oxidative potential (OP) of PM 10 particles was evaluated by electron paramagnetic resonance (EPR) spectroscopy. Chemical characteristics of PM 10 included tracers for biomass burning (levoglucosan, mannosan and galactosan), elemental and organic carbon (EC/OC) and polycyclic aromatic hydrocarbons (PAHs). Most samples displayed dose-dependent cytotoxicity and IL-8 induction. Spatial and temporal differences in PM 10 toxicity were seen. PM 10 collected at the urban site was characterized by increased pro-inflammatory and mutagenic activity as well as higher OP and elevated endotoxin levels compared to the background area. Reduced cell viability (-0.46 < r s < -0.35, p < 0.01) and IL-8 induction (-0.62 < r s < -0.67, p < 0.01) were associated with all markers for biomass burning, levoglucosan, mannosan and galactosan. Furthermore, direct and indirect mutagenicity were associated with tracers for biomass burning, OC, EC and PAHs. Multiple regression analyses showed levoglucosan to explain 16% and 28% of the variance in direct and indirect mutagenicity, respectively. Markers for biomass burning were associated with altered cellular responses and increased mutagenic activity. These findings may indicate a role of biomass burning in the observed adverse health effect of particulate matter.

Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

NASA Astrophysics Data System (ADS)

Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

2014-05-01

Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in size segregated aerosol particles suggested that combustion processes could strongly affect isotopic fractionation in aerosol particles of different sizes thereby potentially affecting an interpretation of ambient atmospheric observations.

Physicochemical characterization of smoke aerosol during large-scale wildfires: Extreme event of August 2010 in Moscow

NASA Astrophysics Data System (ADS)

Popovicheva, O.; Kistler, M.; Kireeva, E.; Persiantseva, N.; Timofeev, M.; Kopeikin, V.; Kasper-Giebl, A.

2014-10-01

Enhancement of biomass burning-related research is essential for the assessment of large-scale wildfires impact on pollution at regional and global scale. Starting since 6 August 2010 Moscow was covered with thick smoke of unusually high PM10 and BC concentrations, considerably affected by huge forest and peat fires around megacity. This work presents the first comprehensive physico-chemical characterization of aerosols during extreme smoke event in Moscow in August 2010. Sampling was performed in the Moscow center and suburb as well as one year later, in August 2011 during a period when no biomass burning was observed. Small-scale experimental fires of regional biomass were conducted in the Moscow region. Carbon content, functionalities of organic/inorganic compounds, tracers of biomass burning (anhydrosaccharides), ionic composition, and structure of smoke were analyzed by thermal-optical analysis, FTIR spectroscopy, liquid and ion chromatography, and electron microscopy. Carbonaceous aerosol in August 2010 was dominated by organic species with elemental carbon (EC) as minor component. High average OC/EC near 27.4 is found, comparable to smoke of regional biomass smoldering fire, and exceeded 3 times the value observed in August 2011. Organic functionalities of Moscow smoke aerosols were hydroxyl, aliphatic, aromatic, acid and non-acid carbonyl, and nitro compound groups, almost all of them indicate wildfires around city as the source of smoke. The ratio of levoglucosan (LG) to mannosan near 5 confirms the origin of smoke from coniferous forest fires around megacity. Low ratio of LG/OC near 0.8% indicates the degradation of major molecular tracer of biomass burning in urban environment. Total concentration of inorganic ions dominated by sulfates SO4 2 - and ammonium NH4+ was found about 5 times higher during large-scale wildfires than in August 2011. Together with strong sulfate and ammonium absorbance in smoke aerosols, these observations prove the formation of secondary inorganic species associated with wildfire gaseous emissions and their transformation in aged smoke. Accumulation of carbonyl compounds during extreme smoke event in Moscow resulted from photochemical aging and secondary organic aerosol (SOA) formation in the urban atmosphere. The mixture of carbonaceous particles and dust revealed multicomponent structure of Moscow smoke aerosols, pointing the difference with non-smoke ambient aerosols. The abundance of group containing soot and tar balls approached at least a half of total aerosol concentration during extreme event, relating to elevated OC, EC and SOA. Fly ash groups contained calcium sulfates and carbonates from soil entrainment by hot air convection. Small-scale open fire experiments support the identification of specific chemical features of regional biomass burning and demonstrate the strong impact of large-scale wildfires on aerosol chemistry and air quality in highly polluted megacity.

Influence of gas temperature on ignition, burning and extinction of carbon particles-gas suspension

NASA Astrophysics Data System (ADS)

Orlovskaya, S. G.; Zuy, O. N.; Liseanskaia, M. V.

2017-11-01

The ignition and burning of monodisperse and two-fraction suspensions of carbon particles at gas temperature in the range 1100 ÷ 1500 K are modeled. The critical gas temperature of the suspension ignition, the particles ignition delay and burning time, the burning temperature, and the extinction parameters are determined. The data obtained are compared with burning characteristics of single particle of equal size. The ignition temperatures of the fine fraction (the particle diameter 60 μm) and the coarse one (120 μm) are practically the same. The ignition temperatures of the equivalent single particles are much higher and they differ by 100 K and more. The gas temperature is found below which the ignition delay of the fine fraction exceeds the one of the coarse fraction. It is found that, at critical ignition temperatures the burning temperature of the fine fraction is lower than that of the coarse fraction. At gas temperatures above 1250 K, the burning temperature of the fine fraction is higher. It is established that, in contrast to single particles, the temperature difference between the particles and the gas is small during gas-suspension extinction. Further oxidation of the particles occurs in the kinetic regime, so it is possible to estimate the time of their complete conversion.

Reaction rate for carbon burning in massive stars

NASA Astrophysics Data System (ADS)

Jiang, C. L.; Santiago-Gonzalez, D.; Almaraz-Calderon, S.; Rehm, K. E.; Back, B. B.; Auranen, K.; Avila, M. L.; Ayangeakaa, A. D.; Bottoni, S.; Carpenter, M. P.; Dickerson, C.; DiGiovine, B.; Greene, J. P.; Hoffman, C. R.; Janssens, R. V. F.; Kay, B. P.; Kuvin, S. A.; Lauritsen, T.; Pardo, R. C.; Sethi, J.; Seweryniak, D.; Talwar, R.; Ugalde, C.; Zhu, S.; Bourgin, D.; Courtin, S.; Haas, F.; Heine, M.; Fruet, G.; Montanari, D.; Jenkins, D. G.; Morris, L.; Lefebvre-Schuhl, A.; Alcorta, M.; Fang, X.; Tang, X. D.; Bucher, B.; Deibel, C. M.; Marley, S. T.

2018-01-01

Carbon burning is a critical phase for nucleosynthesis in massive stars. The conditions for igniting this burning stage, and the subsequent isotope composition of the resulting ashes, depend strongly on the reaction rate for 12C+12C fusion at very low energies. Results for the cross sections for this reaction are influenced by various backgrounds encountered in measurements at such energies. In this paper, we report on a new measurement of 12C+12C fusion cross sections where these backgrounds have been minimized. It is found that the astrophysical S factor exhibits a maximum around Ecm=3.5 -4.0 MeV, which leads to a reduction of the previously predicted astrophysical reaction rate.

Fire Impact on Phytomass and Carbon Emissions in the Forests of Siberia

NASA Astrophysics Data System (ADS)

Ivanova, Galina A.; Zhila, Sergei V.; Ivanov, Valery A.; Kovaleva, Nataly M.; Kukavskaya, Elena A.; Platonova, Irina A.; Conard, Susan G.

2014-05-01

Siberian boreal forests contribute considerably to the global carbon budget, since they take up vast areas, accumulate large amount of carbon, and are sensitive to climatic changes. Fire is the main forest disturbance factor, covering up to millions of hectares of boreal forests annually, of which the majority is in Siberia. Carbon emissions released from phytomass burning influence atmospheric chemistry and global carbon cycling. Changing climate and land use influence the number and intensity of wildfires, forest state, and productivity, as well as global carbon balance. Fire effects on forest overstory, subcanopy woody layer, and ground vegetation phytomass were estimated on sites in light-conifer forests of the Central Siberia as a part of the project "The Influence of Changing Forestry Practices on the Effects of Wildfire and on Interactions Between Fire and Changing Climate in Central Siberia" supported by NASA (NEESPI). This study focuses on collecting quantitative data and modeling the influence of fires of varying intensity on fire emissions, carbon budget, and ecosystem processes in coniferous stands. Fires have a profound impact on forest-atmospheric carbon exchange and transform forests from carbon sinks to carbon sources lasting long after the time of burning. Our long-term experiments allowed us to identify vegetation succession patterns in taiga Scots pine stands after fires of known behavior. Estimating fire contributions to the carbon budget requires consideration of many factors, including vegetation type and fire type and intensity. Carbon emissions were found to depend on fire intensity and weather. In the first several years after fire, the above-ground phytomass appeared to be strongly controlled by fire intensity. However, the influence of burning intensity on organic matter accumulation was found to decrease with time.

[Soil functioning in foci of Siberian moth population outbreaks in the southern taiga subzone of Central Siberia].

PubMed

Krasnoshchekov, Iu N; Beskorovaĭnaia, I N

2008-01-01

The results of experimental studies on the contribution of zoogenic debris to transformation of soil properties in the southern taiga subzone of Central Siberia are analyzed. They show that water-soluble carbon outflow from the forest litter increases by 21-26% upon a Siberian moth invasion, with this value decreasing to 14% one year later. The burning of forest in an area completely defoliated by the pest leads to changes in the stock, fractional composition, actual acidity, and ash element contents of the litter. The litter-dwelling invertebrate assemblage is almost completely destroyed by fire and begins to recover only after two years.

Equivalent Black Carbon measurements and spectral analysis of absorption coefficient during a biomass burning episode in the city of Bogotá, Colombia.

NASA Astrophysics Data System (ADS)

Quirama, M.; Morales, R.

2016-12-01

Light-absorbing carbonaceous aerosol is recognized as a significant short lived climate pollutant that can contribute to direct and indirect radiative forcing. In urban environments, black carbon is an important contributor to the deterioration of local air quality. In this study, we report measurements of equivalent Black Carbon performed during the months of January, February, and March 2016 in the city of Bogotá, Colombia. During this period, a persistent condition of atmospheric stability lead to high concentrations of particulate matter throughout the city. During the month of February, the city was further impacted by a series of small-scale forest fires that took place on hills neighboring the city center. Equivalent Black Carbon (eBC) concentrations were monitored before, during, and after a mayor forest fire episode with a 7-wavelength Aethalometer. The monitoring instruments were located at a traffic impacted site, 18.3 km from the forest fire. To evaluate the contribution of biomass burning to the light-absorbing aerosol particle concentration, spectral analysis of the absorption coefficient of the sampled aerosol particles was performed. When the biomass burning plume directly impacted the monitoring station during the night of February 4, eBC concentrations of up to 40 µg/m3 were observed at nighttime. This concentration was significantly higher than average nighttime concentrations of eBC, observed to be 4 µg/m3 at the site. However, during the period most intensely affected by the biomass burning plume, the angstrom exponent computed between the 450nm and the 970 nm channel, was found to be close to 1. Angstrom exponent close to 1 is an indication that the contribution from traffic generated black carbon is dominant compared to the contribution of biomass burning. The data set collected during this period suggests that despite the significant contribution of the fresh biomass burning plume to the particulate matter concentration in the city, the spectral analysis of the light-absorption coefficient proved insufficient to detect the presence of UV absorbing carbonaceous material during this episode.

Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sciare, J.; Poulain, L.; Kamili, K.; Merkel, M.; Müller, T.; Wiedensohler, A.; Eckhardt, S.; Stohl, A.; Sarda-Estève, R.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.

2012-02-01

An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150-1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65-0.68 respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data compared with 85% and 15% respectively for BC estimated from the aethalometer model. On average, the mass size distribution for EC particles is bimodal; the smaller mode is attributed to locally emitted, mostly externally mixed EC particles, while the larger mode is dominated by aged, internally mixed ECOCNOx particles associated with continental transport events. Periods of continental influence were identified using the Lagrangian Particle Dispersion Model (LPDM) "FLEXPART". A consistent minimum between the two EC mass size modes was observed at approximately 400 nm for the measurement period. EC particles below this size are attributed to local emissions using chemical mixing state information and contribute 79% of the scaled ATOFMS EC particle mass, while particles above this size are attributed to continental transport events and contribute 21% of the EC particle mass. These results clearly demonstrate the potential benefit of monitoring size-resolved mass concentrations for the separation of local and continental EC emissions. Knowledge of the relative input of these emissions is essential for assessing the effectiveness of local abatement strategies.

Pyrogenic carbon from tropical savanna burning: production and stable isotope composition

NASA Astrophysics Data System (ADS)

Saiz, G.; Wynn, J. G.; Wurster, C. M.; Goodrick, I.; Nelson, P. N.; Bird, M. I.

2014-10-01

Widespread burning of mixed tree-grass ecosystems represents the major natural locus of pyrogenic carbon (PyC) production. PyC is a significant, pervasive, and yet poorly understood "slow-cycling" form of carbon present in the atmosphere, hydrosphere, soils and sediments. We conducted sixteen experimental burns on a rainfall transect in northern Australian savannas with C4 grasses ranging from 35 to 99% of total biomass. Residues from each fire were partitioned into PyC and further into recalcitrant (HyPyC) components, with each of these also partitioned into proximal (> 125 μm) and distal (< 125 μm) fluxes. The median [range] PyC production across all burns was 16.0 [11.5]% of total carbon exposed (TCE), with HyPyC accounting for 2.5 [4.9]% of TCE. Both PyC and HyPyC were dominantly partitioned into the proximal flux, likely to remain (initially) close to the site of production. Production of HyPyC was strongly related to fire residence time, with shorter duration fires resulting in higher HyPyC yields. The carbon isotope (δ13C) compositions of PyC and HyPyC were generally lower by 1-3‰ relative to the original biomass, with marked depletion up to 7 ‰ for grasslands dominated by C4 biomass. δ13C values of CO2 produced by combustion was computed by mass balance and ranged from ~0.4 to 1.3‰. The depletion of 13C in PyC and HyPyC relative to the original biomass has significant implications for the interpretation of δ13C values of savanna soil organic carbon and of ancient PyC preserved in the geologic record, and for global 13C isotopic disequilibria calculations.

Methods to Reduce Forest Residue Volume after Timber Harvesting and Produce Black Carbon.

PubMed

Page-Dumroese, Deborah S; Busse, Matt D; Archuleta, James G; McAvoy, Darren; Roussel, Eric

2017-01-01

Forest restoration often includes thinning to reduce tree density and improve ecosystem processes and function while also reducing the risk of wildfire or insect and disease outbreaks. However, one drawback of these restoration treatments is that slash is often burned in piles that may damage the soil and require further restoration activities. Pile burning is currently used on many forest sites as the preferred method for residue disposal because piles can be burned at various times of the year and are usually more controlled than broadcast burns. In many cases, fire can be beneficial to site conditions and soil properties, but slash piles, with a large concentration of wood, needles, forest floor, and sometimes mineral soil, can cause long-term damage. We describe several alternative methods for reducing nonmerchantable forest residues that will help remove excess woody biomass, minimize detrimental soil impacts, and create charcoal for improving soil organic matter and carbon sequestration.

Theoretical studies of massive stars. II - Evolution of a 15 solar-mass star from carbon shell burning to iron core collapse

NASA Technical Reports Server (NTRS)

Sparks, W. M.; Endal, A. S.

1980-01-01

The evolution of a Population I star of 15 solar masses is described from the carbon shell burning stage to the formation and collapse of an iron core. An unusual aspect of the evolution is that neon ignition occurs off-center and neon burning propagates inward by a series of shell flashes. The extent of the core burning is generally smaller than the Chandrasekhar mass, so that most of the nuclear energy generation occurs in shell sources. Because of degeneracy and the influence of rapid convective mixing, these shell sources are unstable and the core goes through large excursions in temperature and density. The small core also causes the shell sources to converge into a narrow mass region slightly above the Chandrasekhar mass. Thus, the final nucleosynthesis yields are generally small, with silicon being most strongly enhanced with respect to solar system abundances.

Ambient measurements and source apportionment of fossil fuel and biomass burning black carbon in Ontario

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sofowote, U.; Su, Y.; Debosz, J.; Noble, M.; Jeong, C.-H.; Wang, J. M.; Hilker, N.; Evans, G. J.; Doerksen, G.; Jones, K.; Munoz, A.

2017-07-01

Black carbon (BC) is of significant interest from a human exposure perspective but also due to its impacts as a short-lived climate pollutant. In this study, sources of BC influencing air quality in Ontario, Canada were investigated using nine concurrent Aethalometer datasets collected between June 2015 and May 2016. The sampling sites represent a mix of background and near-road locations. An optical model was used to estimate the relative contributions of fossil fuel combustion and biomass burning to ambient concentrations of BC at every site. The highest annual mean BC concentration was observed at a Toronto highway site, where vehicular traffic was found to be the dominant source. Fossil fuel combustion was the dominant contributor to ambient BC at all sites in every season, while the highest seasonal biomass burning mass contribution (35%) was observed in the winter at a background site with minimal traffic contributions. The mass absorption cross-section of BC was also investigated at two sites, where concurrent thermal/optical elemental carbon data were available, and was found to be similar at both locations. These results are expected to be useful for comparing the optical properties of BC at other near-road environments globally. A strong seasonal dependence was observed for fossil fuel BC at every Ontario site, with mean summer mass concentrations higher than their respective mean winter mass concentrations by up to a factor of two. An increased influence from transboundary fossil fuel BC emissions originating in Michigan, Ohio, Pennsylvania and New York was identified for the summer months. The findings reported here indicate that BC should not be considered as an exclusively local pollutant in future air quality policy decisions. The highest seasonal difference was observed at the highway site, however, suggesting that changes in fuel composition may also play an important role in the seasonality of BC mass concentrations in the near-road environment. This finding has implications for future policies aiming to improve air quality in urban environments where fuel composition changes as a function of season.

Carbon-cycle effects of differences in soil moisture and soil extracellular enzyme activity at sites representing different land-use histories in high-elevation Ecuadorian páramo landscapes

NASA Astrophysics Data System (ADS)

McKnight, J.; Harden, C. P.; Schaeffer, S. M.

2016-12-01

Ecuadorian páramo grasslands are important regional soil carbon sinks. In the páramo of the Mazar Wildlife Reserve, differences in soil carbon content among different types of land use may reflect changes in soil carbon-acquisition related microbial enzyme activity after land cover and soil moisture are altered; however, this hypothesis has not been tested explicitly for Ecuadorian páramos. This study used a fluorescence enzyme assay to assess the activities of four different extracellular enzymes representing carbon acquisition: α-glucosidase, β-glucosidase, β-D-cellulobiohydrolase, and β-xylosidase in Andean páramo soils. Acquisition activities were also measured for nitrogen (N-acetyl-β-glucosidase and leucine aminopeptidase) and phosphorus (phosphatase) to assess stoichiometric differences between land-uses, which can affect soil microbial activity related to carbon acquisition. Soils were analyzed from four land uses: native forest, grass páramo, recently burned grass páramo, and non-native pine plantation. Carbon acquisition activity was highest at the pine site (678 nmol h-1 g-1) and lowest at the recently burned páramo site (252 nmol h-1 g-1), indicating the lowest and highest available soil carbon, respectively. Carbon-acquisition EE activity was significantly higher at the grass páramo site (595 nmol h-1 g-1) than at the recently burned páramo and native forest sites. At the grass páramo site, a history of burning as a management strategy and high carbon-acquisition EE activity could indicate the presence of pyrogenic soil organic matter, which is more resistant to microbial decomposition. Soils at the native forest and both grassland sites were phosphorus limited, and soil at the pine site had higher nitrogen-acquisition activity, indicative of a shift to nitrogen-limited soil stoichiometric conditions. To our knowledge these are the first data reported for soil extracellular enzyme activities for Ecuadorian páramos.

Checklist and Decision Support in Nutritional Care for Burned Patients

DTIC Science & Technology

2014-10-01

in Nutritional Care for Burned Patients PRINCIPAL INVESTIGATOR: Steven E. Wolf, MD CONTRACTING ORGANIZATION: REPORT DATE... Nutritional Care for Burned Patients 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Steven E Wolf, MD Betty Diamond...Study/Product Aim(s) were as follows: 1) To determine under what conditions compliance with nutritional goals are not met in severely burned adults, 2

Did enhanced afforestation cause high severity peat burn in the Fort McMurray Horse River wildfire?

NASA Astrophysics Data System (ADS)

Wilkinson, S. L.; Moore, P. A.; Flannigan, M. D.; Wotton, B. M.; Waddington, J. M.

2018-01-01

Climate change mediated drying of boreal peatlands is expected to enhance peatland afforestation and wildfire vulnerability. The water table depth-afforestation feedback represents a positive feedback that can enhance peat drying and consolidation and thereby increase peat burn severity; exacerbating the challenges and costs of wildfire suppression efforts and potentially shifting the peatland to a persistent source of atmospheric carbon. To address this wildfire management challenge, we examined burn severity across a gradient of drying in a black spruce dominated peatland that was partially drained in 1975-1980 and burned in the 2016 Fort McMurray Horse River wildfire. We found that post-drainage black spruce annual ring width increased substantially with intense drainage. Average (±SD) basal diameter was 2.6 ± 1.2 cm, 3.2 ± 2.0 cm and 7.9 ± 4.7 cm in undrained (UD), moderately drained (MD) and heavily drained (HD) treatments, respectively. Depth of burn was significantly different between treatments (p < 0.001) and averaged (±SD) 2.5 ± 3.5 cm, 6.4 ± 5.0 cm and 36.9 ± 29.6 cm for the UD, MD and HD treatments, respectively. The high burn severity in the HD treatment included 38% of the treatment that experienced combustion of the entire peat profile, and we estimate that overall 51% of the HD pre-burn peat carbon stock was lost. We argue that the HD treatment surpassed an ecohydrological tipping point to high severity peat burn that may be identified using black spruce stand characteristics in boreal plains bogs. While further studies are needed, we believe that quantifying this threshold will aid in developing effective adaptive management techniques and protecting boreal peatland carbon stocks.

Nutrient dynamics across a dissolved organic carbon and burn gradient in central Siberia

NASA Astrophysics Data System (ADS)

Rodriguez-Cardona, B.; Coble, A. A.; Prokishkin, A. S.; Kolosov, R.; Spencer, R. G.; Wymore, A.; McDowell, W. H.

2016-12-01

In stream ecosystems, dissolved organic carbon (DOC) and nitrogen (N) processing are tightly linked. In temperate streams, greater DOC concentrations and higher DOC:NO3- ratios promote the greatest nitrate (NO3-) uptake. However, less is known about this relationship in other biomes including the arctic which is undergoing changes due to climate change contributing to thawing of permafrost and alterations in biogeochemical cycles in soils and streams. Headwater streams draining into the N. Tunguska River in the central Siberian plateau are affected by forest fires but little is known about the aquatic biogeochemical implications in both a thawing and burning landscape. There are clear patterns between carbon concentration and fire history where generally DOC concentration in streams decrease after fires and older burn sites have shown greater DOC concentrations and more bioavailable DOC that could promote greater heterotrophic uptake of NO3-. However, the relationship between nutrient dynamics, organic matter composition, and fire history in streams is not very clear. In order to assess the influence of organic matter composition and DOC concentration on nutrient uptake in arctic streams, we conducted a series of short-term nutrient addition experiments following the tracer addition for spiraling curve characterization (TASCC) method, consisting of NO3- and NH4++PO43- additions, across 4 streams that comprise a fire gradient that spans 3- >100 years since the last burn with DOC concentrations ranging between 12-23 mg C/L. We hypothesized that nutrient uptake would be greatest in older burn sites due to greater DOC concentrations and availability. We will specifically examine how nutrient uptake relates to DOC concentration and OM composition (analyzed via FTICR-MS) across the burn gradient. Across the four sites DOC concentration and DOC:NO3- ratios decreased from old burn sites to recently burned sites. Results presented here can elucidate on the potential impacts of permafrost thawing and forest fires on nutrient dynamics in arctic streams.

Post-wildfire erosion in mountainous terrain leads to rapid and major redistribution of soil organic carbon

NASA Astrophysics Data System (ADS)

Abney, Rebecca B.; Sanderman, Jonathan; Johnson, Dale; Fogel, Marilyn L.; Berhe, Asmeret Asefaw

2017-11-01

Catchments impacted by wildfire typically experience elevated rates of post-fire erosion and formation and deposition of pyrogenic carbon (PyC). To better understand the role of erosion in post-fire soil carbon dynamics, we determined distribution of soil organic carbon in different chemical fractions before and after the Gondola fire in South Lake Tahoe, CA. We analyzed soil samples from eroding and depositional landform positions in control and burned plots pre- and post-wildfire (in 2002, 2003, and 10-years post-fire in 2013). We determined elemental concentrations, stable isotope compositions, and biochemical composition of organic matter (OM) using mid-infrared (MIR) spectroscopy for all of the samples. A subset of samples was analyzed by 13C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (CPMAS 13C-NMR). We combined the MIR and CPMAS 13C-NMR data in the Soil Carbon Research Program partial least squares regression model to predict distribution of soil carbon into three different fractions: 1) particulate, humic, and resistant organic matter fractions representing relatively fresh larger pieces of OM, 2) fine, decomposed OM, and 3) pyrogenic C, respectively. Samples from the post-fire eroding landform position showed no major difference in soil organic carbon (SOC) fractions one year post-fire. The depositional samples, however, had increased concentrations of all SOC fractions, particularly the fraction that resembles PyC, one year post-fire (2002), which had a mean of 160 g/kg compared with burned hillslope soils, which had 84 g/kg. The increase in all SOC fractions in the post-fire depositional landform position one year post-fire indicates significant lateral mobilization of the eroded PyC. In addition, our NMR analyses revealed a post-fire increase in both the aryl and O-aryl carbon compounds in the soils from the depositional landform position, indicating increases in soil PyC concentrations post-fire. After 10 years, the C concentration from all three fractions declined in the depositional landform position to below pre-fire levels likely due to further erosion or elevated rates of decomposition. Thus, we found, at this site, that both fire and erosion exert significant influence on the distribution of PyC throughout a landscape and its long-term fate in the soil system.

Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

NASA Astrophysics Data System (ADS)

Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

2016-04-01

The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles < 200 nm are depleted in 13C with respect to larger particles by 1 - 2 ‰Ṫhis shows that OC in small particle arises mainly from fossil fuel sources, whereas OC in larger particles from 200 nm to 1 μm has higher contribution from biomass burning/other sources. Moreover, there is a clear distinction in source contribution between the more volatile OC fraction and the more refractory fraction. The more refractory fraction is enriched in 13C by 1 to 2 ‰ for both small and large particles. These results show that the fossil fuel combustion is associated to a larger degree with more volatile carbon, whereas biomass burning is the main source of the more refractory particles. According to our source apportionment, the more volatile carbon fraction in the smallest particles is almost completely from fossil fuels, whereas the more refractory carbon fraction in the large size range is almost complete from biomass burning. The more refractory small particles and the less refractory large particles are roughly an even mix of these two sources. The detailed chemical speciation of the carbonaceous aerosol will be presented as well. Acknowledgements This study was funded by the Dutch Science Foundation (NWO grants Nr. 820.01.001, and 834.08.002).

Modelling Carbon Emissions in Calluna vulgaris–Dominated Ecosystems when Prescribed Burning and Wildfires Interact

PubMed Central

Santana, Victor M.; Alday, Josu G.; Lee, HyoHyeMi; Allen, Katherine A.; Marrs, Rob H.

2016-01-01

A present challenge in fire ecology is to optimize management techniques so that ecological services are maximized and C emissions minimized. Here, we modeled the effects of different prescribed-burning rotation intervals and wildfires on carbon emissions (present and future) in British moorlands. Biomass-accumulation curves from four Calluna-dominated ecosystems along a north-south gradient in Great Britain were calculated and used within a matrix-model based on Markov Chains to calculate above-ground biomass-loads and annual C emissions under different prescribed-burning rotation intervals. Additionally, we assessed the interaction of these parameters with a decreasing wildfire return intervals. We observed that litter accumulation patterns varied between sites. Northern sites (colder and wetter) accumulated lower amounts of litter with time than southern sites (hotter and drier). The accumulation patterns of the living vegetation dominated by Calluna were determined by site-specific conditions. The optimal prescribed-burning rotation interval for minimizing annual carbon emissions also differed between sites: the optimal rotation interval for northern sites was between 30 and 50 years, whereas for southern sites a hump-backed relationship was found with the optimal interval either between 8 to 10 years or between 30 to 50 years. Increasing wildfire frequency interacted with prescribed-burning rotation intervals by both increasing C emissions and modifying the optimum prescribed-burning interval for minimum C emission. This highlights the importance of studying site-specific biomass accumulation patterns with respect to environmental conditions for identifying suitable fire-rotation intervals to minimize C emissions. PMID:27880840

A two-year study of carbonaceous aerosols in ambient PM2.5 at a regional background site for western Yangtze River Delta, China

NASA Astrophysics Data System (ADS)

Chen, Dong; Cui, Hongfei; Zhao, Yu; Yin, Lina; Lu, Yan; Wang, Qingeng

2017-01-01

To analyze the characteristics of regional background carbonaceous aerosols in western Yangtze River Delta (YRD), hourly organic carbon (OC) and elemental carbon (EC) in fine particular matter (PM2.5) were measured with a semi-continuous carbon analyzer at a suburban site in upwind Nanjing from June 2013 to May 2015. Relatively low OC, EC and OC/EC were observed compared to other studies conducted in Nanjing. The reasons include the limited primary emissions around the observation site, the improved emission controls in recent years, and the use of denuder to reduce positive artifact in OC measurement. Resulting from the stable atmosphere conditions and emission variations, the highest concentrations of carbonaceous aerosols were found in both winters, with average OC and EC observed at 11.8 ± 10.0 and 5.9 ± 3.4 μg/m3 for the first one, and 8.1 ± 5 and 4.5 ± 2.4 μg/m3 for the second one, respectively. Compared to 2013, reduced OC and EC were found in summer and autumn 2014, demonstrating the benefits of emission control polices implemented for the Nanjing Youth Olympic, while elevated OC observed in spring 2015 was attributed probably to the increased biomass burning. For the hazy event in winter 2013, the back trajectories of air masses suggested that heavy pollution were from eastern Jiangsu, northern Anhui and Jiangsu, downtown Nanjing, and Shanghai. Secondary aerosol formation played an important role indicated by the larger mass fraction of OC and increased OC/EC in PM2.5 during the heavy pollution period. In the harvest season, biomass burning was estimated to contribute 51% and 16% of OC and EC concentrations, respectively.

Characterization of carbonaceous materials in PM2.5 and PM10 size fractions in Morogoro, Tanzania, during 2006 wet season campaign

NASA Astrophysics Data System (ADS)

Mkoma, Stelyus L.; Chi, Xuguang; Maenhaut, Willy

2010-05-01

Atmospheric aerosol samples in PM10 and PM2.5 size fractions were collected in parallel at a rural site in Morogoro during wet season in March and April 2006. All samples were analysed for the particulate matter mass, for organic, elemental, and total carbon (OC, EC, and TC), and for water-soluble OC (WSOC). The average PM10 and PM2.5 mass concentrations and associated standard deviations were 14 ± 13 μg/m 3 and 7.3 ± 4 μg/m 3 respectively. On average, TC accounted for 33% of the PM10 mass and 44% of the PM2.5 mass for the campaign. The average OC/PM percentage ratios were 27% and 33% in PM10 and PM2.5 size fractions respectively and a larger fraction of the OC was water-soluble. The observed low EC/TC mean percentage ratios of 10-14% respectively for PM10 and PM2.5 fractions indicate that the carbonaceous aerosol originates mainly from biogenic aerosols and/or biomass burning. A simple source apportionment approach was used to apportion the OC to biofuel and charcoal burning. On average, 93% of the PM10 OC was attributed to biofuel and 7% to charcoal burning in the 2006 wet season campaign. However, it is suggested that a contribution to the OC at Morogoro could also come from other natural biogenic matter, and/or biomass burning aerosols. The results for the sources of OC at Morogoro should therefore be considered with great caution.

Aircraft measurement over the Gulf of Tonkin capturing aloft transport of biomass burning

NASA Astrophysics Data System (ADS)

Yang, Xiaoyang; Xu, Jun; Bi, Fang; Zhang, Zhongzhi; Chen, Yunbo; He, Youjiang; Han, Feng; Zhi, Guorui; Liu, Shijie; Meng, Fan

2018-06-01

A suite of aircraft measurements was conducted over the Gulf of Tonkin, located downwind to the east of Mainland Southeast Asia (MSE), between March 23rd and April 6th, 2015. To the best of our knowledge, this campaign of 11 flights (totaling 34.4 h) was the first in-flight measurement over the region. Measurements of sulfur dioxide, nitrogen oxides, ozone, carbon monoxide, black carbon and the particulate scattering coefficient were recorded at approximately 1 500 m (low level) and 3 000 m (high level). Significantly higher measurements of black carbon, carbon monoxide and ozone in the high level on March 23rd and April 5th and 6th were directly related to biomass burning in the MSE and were comparable to severe pollution events at the surface. Similarly, relatively low pollutant concentrations were observed at both altitudes between March 23rd and April 5th. A combined analysis of the measurements with meteorology and satellite data verified that the plumes captured at 3 000 m were attributed to transport in the high altitude originating from biomass burning in northern MSE. Furthermore, each plume captured by the measurements in the high level corresponded to heavy regional air pollution caused by biomass burning in northern MSE. In addition, relatively low levels of the measured pollutants corresponded to relatively light pollution levels in MSE and its adjacent areas. Taken together, these results indicated that aircraft measurements were accurate in characterizing the variation in transport and pollutant levels. During the most active season of biomass burning in MSE, pollutant emissions and their regional impact could vary on an episodic basis. Nonetheless, such concentrated emissions from biomass burning is likely to lead to particularly high atmospheric-loading of pollutants at a regional level and, depending on weather conditions, has the potential of being transported over considerably longer distances. Further investigation of the short-term impacts of such concentrations therefore appears prudent.

The effects of fire severity on black carbon additions to forest soils - 10 years post fire

NASA Astrophysics Data System (ADS)

Poore, R.; Wessman, C. A.; Buma, B.

2013-12-01

Wildfires play an active role in the global carbon cycle. While large amounts of carbon dioxide are released, a small fraction of the biomass consumed by the fire is only partially combusted, yielding soot and charcoal. These products, also called black carbon (BC) make up only 1-5% of the biomass burnt, yet they can have a disproportionate effect on both the atmosphere and fluxes in long-term carbon pools. This project specifically considers the fraction that is sequestered in forest soils. Black carbon is not a specific compound, and exists along a continuum ranging from partially burned biomass to pure carbon or graphite. Increasing aromaticity as the result of partial combustion means charcoal is highly resistant to oxidation. Although debated, most studies indicate a turnover time on the order of 500-1,000 years in warm, wet, aerobic soils. Charcoal may function as a long-term carbon sink, however its overall significance depends on its rate of formation and loss. At the landscape level, fire characteristics are one of the major factors controlling charcoal production. A few studies suggest that charcoal production increases with cooler, less-severe fires. However, there are many factors to tease apart, partly because of a lack of specificity in how fire severity is defined. Within this greater context, our lab has been working on a landscape-level study within Routt National Forest, north of Steamboat Springs, Colorado. In 2002, a large fire swept through a subalpine spruce, fir and lodgepole pine forest. In 2011-2013 we sampled BC pools in 44 plots across a range of fire severities from unburned to severe crown We hypothesized that charcoal stocks will be higher in areas of low severity fire as compared to high severity because of decreased re-combustion of charcoal in the organic soil and increased overall charcoal production due to lower temperatures. In each of our plots we measured charcoal on snags and coarse woody debris, sampled the entire organic horizon and the top 10cm mineral horizon. The soils were sieved to 2mm and their BC content measured using the Kurth-MacKenzie-DeLuca method of digesting labile carbon using nitric acid and hydrogen peroxide at 95C for 20hrs. We integrated both remotely sensed data and field observations. We used the Relative Difference Normalized Burn Ratio (RdNBR) calculated by Monitoring Trends in Burn Severity (MTBS). This index used Landsat images from July in the years before and after the fire and is based on differences in bands 4 and 7, with the aim of assessing coarse scale changes in soil and vegetation post fire. For each plot we also collected data on tree mortality and organic soil depth. These metrics were chosen from the Composite Burn Index as those that were most reliable even 10 years after the fire. We observed no significant differences in BC totals between high severity fire and unburned plots, although BC increased slightly on burned plots. Early results for low severity sites (analysis still in progress) suggest that BC increased in plots experiencing lower severity fires compared to unburned and high severity plots. Comparing carbon and BC totals on unburned and severely burned plots, and assuming no loss of BC from mineral soil during the fire, we observed a 1.2% conversion of burned biomass to BC, which corresponds with literature estimates of 1-4%.

Acetylenic carbon allotrope

DOEpatents

Lagow, Richard J.

1998-01-01

A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

Acetylenic carbon allotrope

DOEpatents

Lagow, Richard J.

1999-01-01

A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

AmeriFlux US-ARb ARM Southern Great Plains burn site- Lamont

DOE Data Explorer

Torn, Margaret [Lawrence Berkeley National Laboratory

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-ARb ARM Southern Great Plains burn site- Lamont. Site Description - The ARM SGP Burn site is located in the native tallgrass prairies of the USDA Grazinglands Research Laboratory near El Reno, OK. One of two adjacent 35 ha plots, the US-ARb plot was burned on 2005/03/08. The second plot, US-ARc, was left unburned as the control for experimental purposes. Aside from 2005, the region evaded burning activities for at least 15 years. Current disturbances consist of only light grazing activities.

Evaluation of carbon uptake and emissions by forests in Korea during the last thirty years (1973-2002).

PubMed

Choi, Sung-Deuk; Chang, Yoon-Seok

2006-06-01

The contribution of Korean forests to carbon sequestration for anthropogenic carbon emissions was evaluated. In addition, monitoring of carbon species released from forest fires was conducted. Despite a high carbon uptake by Korean forests, a tremendous increase in fossil fuel burning resulted in a small contribution by forests to carbon removal. The removal efficiency had a 5-31% range with an average of 12% during the period 1973-2002. In 2000, the amount of carbon released from burned trees corresponded to 1.6% of carbon uptake by forests. The distribution of surface CO concentration (ppb) derived from MOPITT (Measurement of Pollution in the Troposphere) showed high CO levels over the East/Japan Sea on April 10, 2000 when the largest forest fires occurred along the east coast of Korea. Trajectory analysis and ground CO measurements also indicated that CO levels over the East/Japan Sea were influenced by forest fires. This study suggests that continuous monitoring of carbon emissions from forest fires is needed for a more reliable estimate of carbon flux in the environment.

Constraints on natural global atmospheric CO2 fluxes from 1860 to 2010 using a simplified explicit forward model

PubMed Central

Hellevang, Helge; Aagaard, Per

2015-01-01

Land-use changes until the beginning of the 20th century made the terrestrial biosphere a net source of atmospheric carbon. Later, burning of fossil fuel surpassed land use changes as the major anthropogenic source of carbon. The terrestrial biosphere is at present suggested to be a carbon sink, but the distribution of excess anthropogenic carbon to the ocean and biosphere sinks is highly uncertain. Our modeling suggest that land-use changes can be tracked quite well by the carbon isotopes until mid-20th century, whereas burning of fossil fuel dominates the present-day observed changes in the isotope signature. The modeling indicates that the global carbon isotope fractionation has not changed significantly during the last 150 years. Furthermore, increased uptake of carbon by the ocean and increasing temperatures does not yet appear to have resulted in increasing the global gross ocean-to-atmosphere carbon fluxes. This may however change in the future when the excess carbon will emerge in the ocean upwelling zones, possibly reducing the net-uptake of carbon compared to the present-day ocean. PMID:26611741

Moss and soil contributions to the annual net carbon flux of a maturing boreal forest

USGS Publications Warehouse

Harden, J.W.; O'Neill, K. P.; Trumbore, S.E.; Veldhuis, H.; Stocks, B.J.

1997-01-01

We used input and decomposition data from 14C studies of soils to determine rates of vertical accumulation of moss combined with carbon storage inventories on a sequence of burns to model how carbon accumulates in soils and moss after a stand-killing fire. We used soil drainage - moss associations and soil drainage maps of the old black spruce (OBS) site at the BOREAS northern study area (NSA) to areally weight the contributions of each moderately well drained, feathermoss areas; poorly drained sphagnum - feathermoss areas; and very poorly drained brown moss areas to the carbon storage and flux at the OBS NSA site. On this very old (117 years) complex of black spruce, sphagnum bog veneer, and fen systems we conclude that these systems are likely sequestering 0.01-0.03 kg C m-2 yr-' at OBS-NSA today. Soil drainage in boreal forests near Thompson, Manitoba, controls carbon storage and flux by controlling moss input and decomposition rates and by controlling through fire the amount and quality of carbon left after burning. On poorly drained soils rich in sphagnum moss, net accumulation and long-term storage of carbon is higher than on better drained soils colonized by feathermosses. The carbon flux of these contrasting ecosystems is best characterized by soil drainage class and stand age, where stands recently burned are net sources of CO2, and maturing stands become increasingly stronger sinks of atmospheric CO2. This approach to measuring carbon storage and flux presents a method of scaling to larger areas using soil drainage, moss cover, and stand age information.

Satellite Remote Sensing of Atmospheric Pollution: the Far-Reaching Impact of Burning in Southern Africa

NASA Technical Reports Server (NTRS)

Fishman, Jack; Al-Saadi, Jassim A.; Neil, Doreen O.; Creilson, John K.; Severance, Kurt; Thomason, Larry W.; Edwards, David R.

2008-01-01

When the first observations of a tropospheric trace gas were obtained in the 1980s, carbon monoxide enhancements from tropical biomass burning dominated the observed features. In 2005, an active remote-sensing system to provide detailed information on the vertical distribution of aerosols and clouds was launched, and again, one of the most imposing features observed was the presence of emissions from tropical biomass burning. This paper presents a brief overview of space-borne observations of the distribution of trace gases and aerosols and how tropical biomass burning, primarily in the Southern Hemisphere, has provided an initially surprising picture of the distribution of these species and how they have evolved from prevailing transport patterns in that hemisphere. We also show how interpretation of these observations has improved significantly as a result of the improved capability of trajectory modeling in recent years and how information from this capability has provided additional insight into previous measurements form satellites. Key words: pollution; biomass burning; aerosols; tropical trace gas emissions; Southern Hemisphere; carbon monoxide.

Impact of a low severity fire on soil organic carbon and nitrogen characteristics in Japanese cedar soil Yamagata Prefecture, Japan

NASA Astrophysics Data System (ADS)

Seidel, Felix

2017-04-01

Slash and burn practices are widely used around the globe with different degrees of success which are mostly related to the impact of fire on the soil properties. In Japan slash and burn practises, known as Yakihata, have a long history and are still used in Yamagata Prefecture today. The purpose of this study was to determine the impact of a low severity controlled fire on Japanese cedar (Cryptomeria japonica) forest soil (Cambisol) which is the dominant species among plantations in Japan. We measured organic carbon and nitrogen content as well as changes in carbon (δ13C) and nitrogen (δ15N) stable isotope composition in a steep west facing slope under heavy precipitation ( 2600 mm/a) and heavy snowfall ( 3-4 m/a). The results show that Ctotal and Ntotal values as well as the isotopes ratios of C and N change with decreasing elevation in the forest as well as in the burned site being consistent with leaching and erosion. The accumulation of Ctotal and Ntotal at the bottom of the slopes was remarkably higher at the slash and burned site than in the control forest site. After slash and burn δ15N isotopes in the slope in general became significantly lighter than in the control forest while the δ13C did not show any significant difference between the two sites except at the bottom of the slopes where δ13C was heavier in the forest. The reason for these changes in nitrogen and carbon isotopes appears to be related to the physical changes in soil horizon sequence of the original forest soil layer. Keywords: high precipitation, Japanese cedar forest soil, low severity fire, stable isotopes, steep slopes

Persistent Influences of the 2002 Hayman Fire on Stream Nitrate and Dissolved Organic Carbon

NASA Astrophysics Data System (ADS)

Rhoades, C.; Pierson, D. N.; Fegel, T. S., II; Chow, A. T.; Covino, T. P.

2016-12-01

Large, high severity wildfires alter the physical and biological conditions that determine how watersheds retain and release nutrients and regulate stream water quality. For five years after the 2002 Hayman Fire burned in Colorado conifer forests, stream nitrate concentrations and export increased steadily in watersheds with extensive high-severity burning. Stream temperature and turbidity also increased in relation to the extent of high-severity burning and remained elevated above background levels throughout the initial five year post-fire period. Our recent sampling documents that 14 years after the Hayman Fire stream nitrate remains an order of magnitude higher in extensively-burned (35-90%) compared to unburned watersheds (0.2 vs 2.8 mg L-1). Nitrate represents 83% of the total dissolved N in extensively-burned watersheds compared to 29% in unburned watersheds. In contrast, dissolved organic carbon (DOC), was highest in watersheds that burned to a moderate extent (10-20%) and lowest in those with extensive burning. Catchments with a moderate extent burned had DOC concentrations 2.5 and 1.7 times more than those with extensive burning and unburned catchments, respectively. Peak concentrations of DOC and nitrate track the rising limb of the streamflow hydrograph and reach a maximum in May, but patterns among burn extent categories were seasonally consistent. Current riparian conditions are linked to stream nitrate in burned watersheds. For example, stream nitrate increases proportionally to the extent of riparian zones with low shrub cover (R2 = 0.76). We found signs of watershed recovery compared to the initial post-fire period; stream temperature and turbidity remained elevated in extensively burned catchments, but increases were only significant during the spring season. The persistent stream nitrate concentrations as well as the relation between riparian cover and post-fire stream nitrate may help prioritize restoration planting efforts and mitigate chronic, elevated nitrate export from burned watersheds.

Sensitivity of glomalin-related soil protein to wildfires: Immediate and medium-term changes.

PubMed

Lozano, Elena; Jiménez-Pinilla, Patricia; Mataix-Solera, Jorge; Arcenegui, Victoria; Mataix-Beneyto, Jorge

2016-12-01

Forest fires are part of many ecosystems, especially in the Mediterranean Basin. Depending on the fire severity, they can be a great disturbance, so it is of special importance to know their impact on the ecosystem elements. In this study, we measured the sensitivity of glomalin related soil protein (GRSP), a glycoprotein produced by arbuscular mycorrhizal fungi (AMF), to fire perturbation. Two wildfire-affected areas in the SE Spain (Gata and Gorga) were studied. Soil organic carbon (SOC) was also measured. Effects on GRSP immediately after fire were analyzed in both areas, while in Gorga a monitoring of GRSP stocks over a year period after the fire was also carried out. Soil samplings were carried out every 4months. Plots (1×2m 2 ) were installed beneath pines and shrubs in burned and an adjacent control area. Results of GRSP content immediately after a fire only showed significant differences for shrub plots (burned vs control) (p<0.01) in the Gorga site. However, a year of monitoring showed significant fire effect on GRSP content in both plot types (pines and shrubs). Control plots varied considerably over time, while in burned plots GRSP content remained constant during the whole studied period. This research provides evidence of the sensitivity of GRSP to a wildfire perturbation. Copyright © 2015 Elsevier B.V. All rights reserved.

Emissions, energy return and economics from utilizing forest residues for thermal energy compared to onsite pile burning

Treesearch

Greg Jones; Dan Loeffler; Edward Butler; Woodam Chung; Susan Hummel

2010-01-01

The emissions from delivering and burning forest treatment residue biomass in a boiler for thermal energy were compared with onsite disposal by pile-burning and using fossil fuels for the equivalent energy. Using biomass for thermal energy reduced carbon dioxide emissions on average by 39 percent and particulate matter emissions by 89 percent for boilers with emission...

Uncertainty analysis of moderate- versus coarse-scale satellite fire products for quantifying agricultural burning: Implications for Air Quality in European Russia, Belarus, and Lithuania

NASA Astrophysics Data System (ADS)

McCarty, J. L.; Krylov, A.; Prishchepov, A. V.; Banach, D. M.; Potapov, P.; Tyukavina, A.; Rukhovitch, D.; Koroleva, P.; Turubanova, S.; Romanenkov, V.

2015-12-01

Cropland and pasture burning are common agricultural management practices that negatively impact air quality at a local and regional scale, including contributing to short-lived climate pollutants (SLCPs). This research focuses on both cropland and pasture burning in European Russia, Lithuania, and Belarus. Burned area and fire detections were derived from 500 m and 1 km Moderate Resolution Imaging Spectroradiometer (MODIS), 30 m Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Operational Land Imager (OLI) data. Carbon, particulate matter, volatile organic carbon (VOCs), and harmful air pollutants (HAPs) emissions were then calculated using MODIS and Landsat-based estimates of fire and land-cover and land-use. Agricultural burning in Belarus, Lithuania, and European Russia showed a strong and consistent seasonal geographic pattern from 2002 to 2012, with the majority of fire detections occurring in March - June and smaller peak in July and August. Over this 11-year period, there was a decrease in both cropland and pasture burning throughout this region. For Smolensk Oblast, a Russian administrative region with comparable agro-environmental conditions to Belarus and Lithuania, a detailed analysis of Landsat-based burned area estimations for croplands and pastures and field data collected in summer 2014 showed that the agricultural burning area can be up to 10 times higher than the 1 km MODIS active fire estimates. In general, European Russia is the main source of agricultural burning emissions compared to Lithuania and Belarus. On average, all cropland burning in European Russia as detected by the MCD45A1 MODIS Burned Area Product emitted 17.66 Gg of PM10 while annual burning of pasture in Smolensk Oblast, Russia as detected by Landsat burn scars emitted 494.85 Gg of PM10, a 96% difference. This highlights that quantifying the contribution of pasture burning and burned area versus cropland burning in agricultural regions is important for accurately calculating carbonaceous emissions and emissions that negatively impact air quality.

Chemical composition and source apportionment of PM10 and PM2.5 in different functional areas of Lanzhou, China.

PubMed

Qiu, Xionghui; Duan, Lei; Gao, Jian; Wang, Shulan; Chai, Fahe; Hu, Jun; Zhang, Jingqiao; Yun, Yaru

2016-02-01

To elucidate the air pollution characteristics of northern China, airborne PM10 (atmospheric dynamic equivalent diameter ≤ 10 μm) and PM2.5 (atmospheric dynamic equivalent diameter ≤ 2.5 μm) were sampled in three different functional areas (Yuzhong County, Xigu District and Chengguan District) of Lanzhou, and their chemical composition (elements, ions, carbonaceous species) was analyzed. The results demonstrated that the highest seasonal mean concentrations of PM10 (369.48 μg/m(3)) and PM2.5 (295.42 μg/m(3)) were detected in Xigu District in the winter, the lowest concentration of PM2.5 (53.15 μg/m(3)) was observed in Yuzhong District in the fall and PM10 (89.60 μg/m(3)) in Xigu District in the fall. The overall average OC/EC (organic carbon/elemental carbon) value was close to the representative OC/EC ratio for coal consumption, implying that the pollution of Lanzhou could be attributed to the burning of coal. The content of SNA (the sum of sulfate, nitrate, ammonium, SNA) in PM2.5 in Yuzhong County was generally lower than that at other sites in all seasons. The content of SNA in PM2.5 and PM10 in Yuzhong County was generally lower than that at other sites in all seasons (0.24-0.38), indicating that the conversion ratios from precursors to secondary aerosols in the low concentration area was slower than in the area with high and intense pollutants. Six primary particulate matter sources were chosen based on positive matrix factorization (PMF) analysis, and emissions from dust, secondary aerosols, and coal burning were identified to be the primary sources responsible for the particle pollution in Lanzhou. Copyright © 2015. Published by Elsevier B.V.

Reaction rate for carbon burning in massive stars

DOE PAGES

Jiang, C. L.; Santiago-Gonzalez, D.; Almaraz-Calderon, S.; ...

2018-01-10

Carbon burning is a critical phase for nucleosynthesis in massive stars. The conditions for igniting this burning stage, and the subsequent isotope composition of the resulting ashes, depend strongly on the reaction rate for 12C+ 12C fusion at very low energies. Results for the cross sections for this reaction are influenced by various backgrounds encountered in measurements at such energies. In this paper, we report on a new measurement of 12C+ 12C fusion cross sections where these backgrounds have been minimized. In conclusion, it is found that the astrophysical S factor exhibits a maximum around E cm=3.5–4.0 MeV, which leadsmore » to a reduction of the previously predicted astrophysical reaction rate.« less

Determining contributions of biomass burning and other sources to fine particle contemporary carbon in the western United States

NASA Astrophysics Data System (ADS)

Holden, Amanda S.; Sullivan, Amy P.; Munchak, Leigh A.; Kreidenweis, Sonia M.; Schichtel, Bret A.; Malm, William C.; Collett, Jeffrey L., Jr.

2011-02-01

Six-day integrated fine particle samples were collected at urban and rural sampling sites using Hi-Volume samplers during winter and summer 2004-2005 as part of the IMPROVE (Interagency Monitoring of PROtected Visual Environments) Radiocarbon Study. Filter samples from six sites (Grand Canyon, Mount Rainier, Phoenix, Puget Sound, Rocky Mountain National Park, and Tonto National Monument) were analyzed for levoglucosan, a tracer for biomass combustion, and other species by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD). Contemporary carbon concentrations were available from previous carbon isotope measurements at Lawrence Livermore National Laboratory. Primary contributions of biomass burning to measured fine particle contemporary carbon were estimated for residential wood burning (winter) and wild/prescribed fires (summer). Calculated contributions ranged from below detection limit to more than 100% and were typically higher at rural sites and during winter. Mannitol, a sugar alcohol emitted by fungal spores, was analyzed and used to determine contributions of fungal spores to fine particle contemporary carbon. Contributions reached up to 13% in summer samples, with higher contributions at rural sites. Concentrations of methyltetrols, oxidation products of isoprene, were also measured by HPAEC-PAD. Secondary organic aerosol (SOA) from isoprene oxidation was estimated to contribute up to 22% of measured contemporary carbon. For each sampling site, a substantial portion of the contemporary carbon was unexplained by primary biomass combustion, fungal spores, or SOA from isoprene oxidation. This unexplained fraction likely contains contributions from other SOA sources, including oxidation products of primary smoke emissions and plant emissions other than isoprene, as well as other primary particle emissions from meat cooking, plant debris, other biological aerosol particles, bio-diesel combustion, and other sources. Loss of levoglucosan during atmospheric aging of biomass burning emissions likely also results in an underestimate of apportioned primary smoke contributions.

Could managed burning of peatlands lead to carbon storage?

NASA Astrophysics Data System (ADS)

Clay, G.; Worrall, F.

2007-12-01

Peatlands are the UK's largest single terrestrial carbon store with carbon stored in UK peatlands than in forests of Britain and France combined. Unlike most northern peatlands in the peat soils of the UK are heavily managed for recreation and agriculture and due to their proximity to major centres of population are under more anthropogenic pressure than most peatlands. A typical management strategy on UK upland peats is the use of managed fire to restrict vegetation. Fires are used upon a 10-25 year rotation and are described as "cool" as they remove the crown of the vegetation without scorching the litter layer or the underlying soil. In this case the fire destroys primary productivity and limits litter production but produces char. Char is a low volume, highly refractory, high carbon content product while litter is a high volume, decomposable, lower carbon content product. Therefore, the question is if there are fire conditions underwhich the production of char causes more carbon to be stored in the peat than would have been stored if no fire management had been employed. This study uses detailed vegetation studies from a long term monitoring site in order to assess litter and biomass production; in laboratory experimental burns were undertaken in order to assess the amount and controls upon char production and the carbon content of that char. Results of field and laboratory observations are used to model carbon accumulation under s aseries of fire management scenarios and the modelling shows that cools burns at long rotations could lead to higher carbon storage than if no fire had occurred, further than in several cases more carbon accumulation occurred even if less depth of peat was generated.

Chemical characterization of the fine particle emissions from commercial aircraft engines during the Aircraft Particle Emissions eXperiment (APEX) 1 to 3.

PubMed

Kinsey, J S; Hays, M D; Dong, Y; Williams, D C; Logan, R

2011-04-15

This paper addresses the need for detailed chemical information on the fine particulate matter (PM) generated by commercial aviation engines. The exhaust plumes of seven turbofan engine models were sampled as part of the three test campaigns of the Aircraft Particle Emissions eXperiment (APEX). In these experiments, continuous measurements of black carbon (BC) and particle surface-bound polycyclic aromatic compounds (PAHs) were conducted. In addition, time-integrated sampling was performed for bulk elemental composition, water-soluble ions, organic and elemental carbon (OC and EC), and trace semivolatile organic compounds (SVOCs). The continuous BC and PAH monitoring showed a characteristic U-shaped curve of the emission index (EI or mass of pollutant/mass of fuel burned) vs fuel flow for the turbofan engines tested. The time-integrated EIs for both elemental composition and water-soluble ions were heavily dominated by sulfur and SO(4)(2-), respectively, with a ∼2.4% median conversion of fuel S(IV) to particle S(VI). The corrected OC and EC emission indices obtained in this study ranged from 37 to 83 mg/kg and 21 to 275 mg/kg, respectively, with the EC/OC ratio ranging from ∼0.3 to 7 depending on engine type and test conditions. Finally, the particle SVOC EIs varied by as much as 2 orders of magnitude with distinct variations in chemical composition observed for different engine types and operating conditions.

Mercury removal from coal combustion flue gas by modified fly ash.

PubMed

Xu, Wenqing; Wang, Hairui; Zhu, Tingyu; Kuang, Junyan; Jing, Pengfei

2013-02-01

Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2, CuCl2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg0) into its oxidized form (Hg2+). Cu2+ and Fe3+ can also promote Hg0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2, CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.

Exposure to PM2.5 and PAHs from the Tong Liang, China epidemiological study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, J.C.; Watson, J.G.; Chen, L.W.A.

2006-07-01

Chemically speciated PM2.5 and particle-bound polycyclic aromatic hydrocarbon (PAH) measurements were made at three sites near urban Tong Liang, Chongqing, a Chinese inland city where coal combustion is used for electricity generation and residential purposes outside of the central city. Ambient sampling was based on 72-hr averages between 3/2/2002 and 2/26/2003. Elevated PM2.5 and PAH concentrations were observed at all three sites, with the highest concentrations found in winter and the lowest in summer. This reflects a coupling effect of source variability and meteorological conditions. The PM2.5 mass estimated from sulfate, nitrate, ammonium, organics, elemental carbon, crustal material, and saltmore » corresponded with the annual average gravimetric mass within 10%. Carbonaceous aerosol was the dominant species, while positive correlations between organic carbon and trace elements (e.g., As, Se, Br, Pb, and Zn) were consistent with coal-burning and motor vehicle contributions. Ambient particle-bound PAHs of molecular weight 168-266 were enriched by 1.5 to 3.5 times during the coal-fired power plant operational period. However, further investigation is needed to determine the relative contribution from residential and utility coal combustion and vehicular activities.« less

CARBON MONOXIDE AND THE NERVOUS SYSTEM

EPA Science Inventory

Carbon monoxide (CO) is a colorless, tasteless, odorless, and non-irritating gas formed when carbon in fuel is not burned completely. It enters the bloodstream through the lungs and attaches to hemoglobin (Hb), the body's oxygen carrier, forming carboxyhemoglobin (COHb) and there...

CARBON MONOOXIDE AND THE NERVOUS SYSTEM

EPA Science Inventory

Carbon monoxide (CO) is a colorless, tasteless, odorless, and non-irriating gas formed when carbon fuel is not burned completely. It enter the bloodstream through the lungs and attaches to hemoglobin (Hb), the body's oxygen carrier, forming carboxyhemoglobin (COHb) and thereby r...

[Distribution characteristics of soil organic carbon of burned area under different restorations.

PubMed

Li, Hong Yun; Xin, Ying; Zhao, Yu Sen

2016-09-01

The distribution characteristics of soil organic carbon (SOC), soil dissolved organic carbon (DOC) and soil microbial biomass carbon (MBC) under different restorations were studied in Larix gmelinii plantation, Pinus sylvestris var. mongolica plantation, artificial promotion poplar-birch forest and the natural secondary poplar-birch forest restored from burned area after the severe fire of Greater Xing' an Mountains in 1987. The results showed that the variations in SOC, DOC and MBC ranged from 9.63 to 79.72 g·kg -1 , from 33.21 to 186.30 mg·kg -1 and from 200.85 to 1755.63 mg·kg -1 , respectively, which decreased with soil depth increasing. There was significant diffe-rence in SOC, DOC and MBC among different restorations, with the maximum carbon contents for artificial promotion poplar-birch forest, followed by L. gmelinii plantation, natural secondary poplar-birch forest and P. sylvestris var. mongolica plantation successively. The soil microbial quotient va-ried from 1.1% under P. sylvestris var. mongolica plantation to 2.3% under artificial promotion poplar-birch forest, and its vertical distributions were different in the four restoration forests. Correlation analysis indicated that MBC had a significant positive correlation with SOC and DOC, respectively. The activity of soil organic carbon in artificial promotion poplar-birch forest was higher than in other forest stands, suggesting a stronger capacity of the soil carbon cycle through natural regeneration with artificial promotion on burned area in Greater Xing'an Mountains.

The Characteristics of Peats and Co2 Emission Due to Fire in Industrial Plant Forests

NASA Astrophysics Data System (ADS)

Ratnaningsih, Ambar Tri; Rayahu Prasytaningsih, Sri

2017-12-01

Riau Province has a high threat to forest fire in peat soils, especially in industrial forest areas. The impact of fires will produce carbon (CO2) emissions in the atmosphere. The magnitude of carbon losses from the burning of peatlands can be estimated by knowing the characteristics of the fire peat and estimating CO2 emissions produced. The objectives of the study are to find out the characteristics of fire-burning peat, and to estimate carbon storage and CO2 emissions. The location of the research is in the area of industrial forest plantations located in Bengkalis Regency, Riau Province. The method used to measure peat carbon is the method of lost in ignation. The results showed that the research location has a peat depth of 600-800 cm which is considered very deep. The Peat fiber content ranges from 38 to 75, classified as hemic peat. The average bulk density was 0.253 gram cm-3 (0.087-0,896 gram cm-3). The soil ash content is 2.24% and the stored peat carbon stock with 8 meter peat thickness is 10723,69 ton ha-1. Forest fire was predicted to burn peat to a depth of 100 cm and produced CO2 emissions of 6,355,809 tons ha-1.

[Characteristics of atmospheric CO2 concentration and variation of carbon source & sink at Lin'an regional background station].

PubMed

Pu, Jing-Jiao; Xu, Hong-Hui; Kang, Li-Li; Ma, Qian-Li

2011-08-01

Characteristics of Atmospheric CO2 concentration obtained by Flask measurements were analyzed at Lin'an regional background station from August 2006 to July 2009. According to the simulation results of carbon tracking model, the impact of carbon sources and sinks on CO2 concentration was evaluated in Yangtze River Delta. The results revealed that atmospheric CO2 concentrations at Lin'an regional background station were between 368.3 x 10(-6) and 414.8 x 10(-6). The CO2 concentration varied as seasons change, with maximum in winter and minimum in summer; the annual difference was about 20.5 x 10(-6). The long-term trend of CO2 concentration showed rapid growth year by year; the average growth rate was about 3.2 x 10(-6)/a. CO2 flux of Yangtze River Delta was mainly contributed by fossil fuel burning, terrestrial biosphere exchange and ocean exchange, while the contribution of fire emission was small. CO2 flux from fossil fuel burning played an important role in carbon source; terrestrial biosphere and ocean were important carbon sinks in this area. Seasonal variations of CO2 concentration at Lin'an regional background station were consistent with CO2 fluxes from fossil fuel burning and terrestrial biosphere exchange.

Fine particles at a background site in Central France: Chemical compositions, seasonal variations and pollution events.

PubMed

He, Lin; Chen, Hui; Rangognio, Jérôme; Yahyaoui, Abderrazak; Colin, Patrice; Wang, Jinhe; Daële, Véronique; Mellouki, Abdelwahid

2018-01-15

To expand our knowledge of regional fine particles in Central France (Centre-Val de Loire region), a field observation study of PM 2.5 was carried out at Verneuil site (46.81467N, 2.61012E, 180m.a.s.l.) from 2011 to 2014. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC), elemental carbon (EC) and biomass burning tracer (Levoglucosan) in PM 2.5 were measured. Annual average PM 2.5 mass concentrations were 11.8, 9.5, 12.6 and 10.2μg·m -3 in 2011, 2012, 2013 and 2014, respectively, three of four higher than the WHO guideline of 10μg·m -3 . Secondary inorganic aerosol (SIA) and organic matter (OM) appeared to be the major components in PM 2.5 in Verneuil, contributing 30.1-41.8% and 36.9-46.3%, respectively. Main chemical species were observed in the following order: winter≥spring>autumn>summer. Backward atmospheric trajectories were performed using Hysplit model and suggested that the PM 2.5 pollutants caused by atmospheric transport were mainly originated from European inland, mainly east to north-east areas. During the observation period, five pollution events were reported and indicated that not only the polluted air masses from central Europe but also the biomass burning from East Europe significantly influenced the air quality in Verneuil site. Copyright © 2017 Elsevier B.V. All rights reserved.

Secondary organic aerosol: a comparison between foggy and nonfoggy days.

PubMed

Kaul, D S; Gupta, Tarun; Tripathi, S N; Tare, V; Collett, J L

2011-09-01

Carbonaceous species, meteorological parameters, trace gases, and fogwater chemistry were measured during winter in the Indian city of Kanpur to study secondary organic aerosol (SOA) during foggy and clear (nonfoggy) days. Enhanced SOA production was observed during fog episodes. It is hypothesized that aqueous phase chemistry in fog drops is responsible for increasing SOA production. SOA concentrations on foggy days exceeded those on clear days at all times of day; peak foggy day SOA concentrations were observed in the evening vs peak clear day SOA concentrations which occurred in the afternoon. Changes in biomass burning emissions on foggy days were examined because of their potential to confound estimates of SOA production based on analysis of organic to elemental carbon (OC/EC) ratios. No evidence of biomass burning influence on SOA during foggy days was found. Enhanced oxidation of SO(2) to sulfate during foggy days was observed, possibly causing the regional aerosol to become more acidic. No evidence was found in this study, either, for effects of temperature or relative humidity on SOA production. In addition to SOA production, fogs can also play an important role in cleaning the atmosphere of carbonaceous aerosols. Preferential scavenging of water-soluble organic carbon (WSOC) by fog droplets was observed. OC was found to be enriched in smaller droplets, limiting the rate of OC deposition by droplet sedimentation. Lower EC concentrations were observed on foggy days, despite greater stagnation and lower mixing heights, suggesting fog scavenging and removal of EC was active as well.

Acetylenic carbon allotrope

DOEpatents

Lagow, R.J.

1998-02-10

A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein. 17 figs.

Theoretical studies of massive stars. I - Evolution of a 15-solar-mass star from the zero-age main sequence to neon ignition

NASA Technical Reports Server (NTRS)

Endal, A. S.

1975-01-01

The evolution of a star with mass 15 times that of the sun from the zero-age main sequence to neon ignition has been computed by the Henyey method. The hydrogen-rich envelope and all shell sources were explicitly included in the models. An algorithm has been developed for approximating the results of carbon burning, including the branching ratio for the C-12 + C-12 reaction and taking some secondary reactions into account. Penetration of the convective envelope into the core is found to be unimportant during the stages covered by the models. Energy transfer from the carbon-burning shell to the core by degenerate electron conduction becomes important after the core carbon-burning stage. Neon ignition will occur in a semidegenerate core and will lead to a mild 'flash.' Detailed numerical results are given in an appendix. Continuation of the calculations into later stages and variations with the total mass of the star will be discussed in later papers.

Three Orbital Burns to Molniya Orbit Via Shuttle_Centaur G Upper Stage

NASA Technical Reports Server (NTRS)

Williams, Craig H.

2015-01-01

An unclassified analytical trajectory design, performance, and mission study was done for the 1982 to 1986 joint National Aeronautics and Space Administration (NASA)-United States Air Force (USAF) Shuttle/Centaur G upper stage development program to send performance-demanding payloads to high orbits such as Molniya using an unconventional orbit transfer. This optimized three orbital burn transfer to Molniya orbit was compared to the then-baselined two burn transfer. The results of the three dimensional trajectory optimization performed include powered phase steering data and coast phase orbital element data. Time derivatives of the orbital elements as functions of thrust components were evaluated and used to explain the optimization's solution. Vehicle performance as a function of parking orbit inclination was given. Performance and orbital element data was provided for launch windows as functions of launch time. Ground track data was given for all burns and coasts including variation within the launch window. It was found that a Centaur with fully loaded propellant tanks could be flown from a 37 deg inclination low Earth parking orbit and achieve Molniya orbit with comparable performance to the baselined transfer which started from a 57 deg inclined orbit: 9,545 versus 9,552 lb of separated spacecraft weight, respectively. There was a significant reduction in the need for propellant launch time reserve for a 1 hr window: only 78 lb for the three burn transfer versus 320 lb for the two burn transfer. Conversely, this also meant that longer launch windows over more orbital revolutions could be done for the same amount of propellant reserve. There was no practical difference in ground tracking station or airborne assets needed to secure telemetric data, even though the geometric locations of the burns varied considerably. There was a significant adverse increase in total mission elapsed time for the three versus two burn transfer (12 vs. 1-1/4 hr), but could be accommodated by modest modifications to Centaur systems. Future applications were discussed. The three burn transfer was found to be a viable, arguably preferable, alternative to the two burn transfer.

Three Orbital Burns to Molniya Orbit via Shuttle Centaur G Upper Stage

NASA Technical Reports Server (NTRS)

Williams, Craig H.

2014-01-01

An unclassified analytical trajectory design, performance, and mission study was done for the 1982-86 joint NASA-USAF Shuttle/Centaur G upper stage development program to send performance-demanding payloads to high orbits such as Molniya using an unconventional orbit transfer. This optimized three orbital burn transfer to Molniya orbit was compared to the then-baselined two burn transfer. The results of the three dimensional trajectory optimization performed include powered phase steering data and coast phase orbital element data. Time derivatives of the orbital elements as functions of thrust components were evaluated and used to explain the optimization's solution. Vehicle performance as a function of parking orbit inclination was given. Performance and orbital element data was provided for launch windows as functions of launch time. Ground track data was given for all burns and coasts including variation within the launch window. It was found that a Centaur with fully loaded propellant tanks could be flown from a 37deg inclination low Earth parking orbit and achieve Molniya orbit with comparable performance to the baselined transfer which started from a 57deg inclined orbit: 9,545 lb vs. 9,552 lb of separated spacecraft weight respectively. There was a significant reduction in the need for propellant launch time reserve for a one hour window: only 78 lb for the three burn transfer vs. 320 lb for the two burn transfer. Conversely, this also meant that longer launch windows over more orbital revolutions could be done for the same amount of propellant reserve. There was no practical difference in ground tracking station or airborne assets needed to secure telemetric data, even though the geometric locations of the burns varied considerably. There was a significant adverse increase in total mission elapsed time for the three vs. two burn transfer (12 vs. 11/4 hrs), but could be accommodated by modest modifications to Centaur systems. Future applications were discussed. The three burn transfer was found to be a viable, arguably preferable, alternative to the two burn transfer.

Checklist and Decision Support in Nutritional Care for Burned Patients

DTIC Science & Technology

2016-10-01

AD______________ AWARD NUMBER: W81XWH-12-2-0074 TITLE: Checklist and Decision Support in Nutritional Care for Burned Patients PRINCIPAL...in Nutritional Care for Burned Patients 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-2-0074 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Steven E... nutritional goals are not met in severely burned adults, 2) To find strategies to address identified gaps in feeding to incorporate into a checklist with easy

TRIAL BURN RESULTS AND FUTURE ACTIVITES OF THE EPA MOBILE INCINERATOR

EPA Science Inventory

The EPA Mobile Incinerator has demonstrated its ability to successfully destroy dioxin. A trial burn conducted in 1987 demonstrated the incinerator's ability to destroy a wide variety of compounds. The destruction and removal efficiency (DRE) of carbon tetrachloride, hexachloro...

The influence of burn severity on postfire vegetation recovery and albedo change during early succession in North American boreal forests

NASA Astrophysics Data System (ADS)

Jin, Yufang; Randerson, James T.; Goetz, Scott J.; Beck, Pieter S. A.; Loranty, Michael M.; Goulden, Michael L.

2012-03-01

Severity of burning can influence multiple aspects of forest composition, carbon cycling, and climate forcing. We quantified how burn severity affected vegetation recovery and albedo change during early succession in Canadian boreal regions by combining satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Canadian Large Fire Database. We used the MODIS-derived difference Normalized Burn Ratio (dNBR) and initial changes in spring albedo as measures of burn severity. We found that the most severe burns had the greatest reduction in summer MODIS Enhanced Vegetation Index (EVI) in the first year after fire, indicating greater loss of vegetation cover. By 5-8 years after fire, summer EVI for all severity classes had recovered to within 90%-108% of prefire levels. Spring and summer albedo progressively increased during the first 7 years after fire, with more severely burned areas showing considerably larger postfire albedo increases during spring and more rapid increases during summer as compared with moderate- and low-severity burns. After 5-7 years, increases in spring albedo above prefire levels were considerably larger in high-severity burns (0.20 ± 0.06; defined by dNBR percentiles greater than 75%) as compared to changes observed in moderate- (0.16 ± 0.06; for dNBR percentiles between 45% and 75%) or low-severity burns (0.13 ± 0.06; for dNBR percentiles between 20% and 45%). The sensitivity of spring albedo to dNBR was similar in all ecozones and for all vegetation types along gradients of burn severity. These results suggest carbon losses associated with increases in burn severity observed in some areas of boreal forests may be at least partly offset, in terms of climate impacts, by increases in negative forcing associated with changes in surface albedo.

[An analysis of nutritional and harmful components of vegetables grown in plastic greenhouses].

PubMed

Yao, H; Yan, W; Li, G; Chen, Y; Guo, W; Wang, G; Xu, Z; Feng, C; Liu, K; Jin, D

1999-09-01

To study the changes in nutritional and harmful components of vegetables grown in plastic greenhouses. In plastic greenhouses, microclimate and air concentrations of carbon monoxide, carbon dioxide, fluoride and respirable particulate were measured, and chlorophyll, total sugar, crude fiber, nitrite, fluoride, arsenic and some mineral elements in vegetables were determined as compared with those grown in the open-air fields. Greenhouse appeared a lower wind speed and darker illumination. Contents of chlorophyll a an b, total chlorophyll, reduced vitamin C, crude fiber in vegetables grown in greenhouse all were lower than those grown in open-air fields. Contents of potassium, calcium, magnesium, iron, zinc, copper and phosphorous were all lower in the vegetables grown in greenhouse than those grown in open-air fields. The contents of chlorophyll reducing Vitamin C. Lower wind speed and inadequate illumination in greenhouse affected photosynthesis and uptake of water in vegetables causing changes in their nutritional components. But, no contamination of burning coal was found in vegetables grown in greenhouse.

Factors affecting the behavior of unburned carbon upon steam activation

NASA Astrophysics Data System (ADS)

Lu, Zhe

The main objective of this study is to investigate the factors that could affect the behavior of unburned carbon samples upon steam activation. Through this work, the relationships among the factors that could influence the carbon-steam reaction with the surface area of the produced activated carbon were explored. Statistical analysis was used to relate the chemical and physical properties of the unburned carbon to the surface area of the activated carbon. Six unburned carbons were selected as feedstocks for activated carbon, and marked as UCA through UCF. The unburned carbons were activated using steam at 850°C for 90 minutes, and the surface areas of their activated counterparts were measured using N2 adsorption isotherms at 77K. The activated carbons produced from different unburned carbon precursors presented different surface areas at similar carbon burn-off levels. Moreover, in different carbon burn-off regions, the sequences for surface area of activated carbons from different unburned carbon samples were different. The factors that may affect the carbon-steam gasification reactions, including the concentration of carbon active sites, the crystallite size of the carbon, the intrinsic porous structure of carbon, and the inorganic impurities, were investigated. All unburned carbons investigated in this study were similar in that they showed the very broad (002) and (10 ) carbon peaks, which are characteristic of highly disordered carbonaceous materials. In this study, the unburned carbon samples contained about 17--48% of inorganic impurities. Compared to coals, the unburned carbon samples contain a larger amount of inorganic impurities as a result of the burn-off, or at lease part, of the carbon during the combustion process. These inorganic particles were divided into two groups in terms of the way they are associated with carbon particles: free single particles, and particles combined with carbon particles. As indicated from the present work, unburned carbons with one of the following properties will produce activated carbons with high surface areas. These properties include: (a) large amount of O2 chemisorption capacity; (b) high concentration of surface C-O complex; and (c) small crystallite diameter; (d) high concentration of Na+K particles that are combined with carbon; (e) high concentration of isotropic carbon. (Abstract shortened by UMI.)

Modeling carbon-nutrient interactions during the early recovery of tundra after fire.

PubMed

Jiang, Yueyang; Rastetter, Edward B; Rocha, Adrian V; Pearce, Andrea R; Kwiatkowski, Bonnie L; Shaver, Gaius R

2015-09-01

Fire frequency has dramatically increased in the tundra of northern Alaska, USA, which has major implications for the carbon budget of the region and the functioning of these ecosystems, which support important wildlife species. We investigated the postfire succession of plant and soil carbon (C), nitrogen (N), and phosphorus (P) fluxes and stocks along a burn severity gradient in the 2007 Anaktuvuk River fire scar in northern Alaska. Modeling results indicated that the early regrowth of postfire tundra vegetation was limited primarily by its canopy photosynthetic potential, rather than nutrient availability, because of the initially low leaf area and relatively high inorganic N and P concentrations in soil. Our simulations indicated that the postfire recovery of tundra vegetation was sustained predominantly by the uptake of residual inorganic N (i.e., in the remaining ash), and the redistribution of N and P from soil organic matter to vegetation. Although residual nutrients in ash were higher in the severe burn than the moderate burn, the moderate burn recovered faster because of the higher remaining biomass and consequent photosynthetic potential. Residual nutrients in ash allowed both burn sites to recover and exceed the unburned site in both aboveground biomass and production five years after the fire. The investigation of interactions among postfire C, N, and P cycles has contributed to a mechanistic understanding of the response of tundra ecosystems to fire disturbance. Our study provided insight on how the trajectory of recovery of tundra from wildfire is regulated during early succession.

Nuclear fusion and carbon flashes on neutron stars

NASA Technical Reports Server (NTRS)

Taam, R. E.; Picklum, R. E.

1978-01-01

This paper reports on detailed calculations of the thermal evolution of the carbon-burning shells in the envelopes of accreting neutron stars for mass-accretion rates of 1 hundred-billionth to 2 billionths of a solar mass per yr and neutron-star masses of 0.56 and 1.41 solar masses. The work of Hansen and Van Horn (1975) is extended to higher densities, and a more detailed treatment of nuclear processing in the hydrogen- and helium-burning regions is included. Results of steady-state calculations are presented, and results of time-dependent computations are examined for accretion rates of 3 ten-billionths and 1 billionth of solar mass per yr. It is found that two evolutionary sequences lead to carbon flashes and that the carbon abundance at the base of the helium shell is a strong function of accretion rate. Upper limits are placed on the accretion rates at which carbon flashes will be important.

Inert matrix fuel in dispersion type fuel elements

NASA Astrophysics Data System (ADS)

Savchenko, A. M.; Vatulin, A. V.; Morozov, A. V.; Sirotin, V. L.; Dobrikova, I. V.; Kulakov, G. V.; Ershov, S. A.; Kostomarov, V. P.; Stelyuk, Y. I.

2006-06-01

The advantages of using inert matrix fuel (IMF) as a dispersion fuel in an aluminium alloy matrix are considered, in particular, low temperatures in the fuel centre, achievable high burn-ups, serviceability in transients and an environmentally friendly process of fuel rod fabrication. Two main versions of IMF are under development at A.A. Bochvar Institute, i.e. heterogeneous or isolated distribution of plutonium. The out-of-pile results on IMF loaded with uranium dioxide as plutonium simulator are presented. Fuel elements with uranium dioxide composition fabricated at A.A. Bochvar Institute are currently under MIR tests (RIAR, Dimitrovgrad). The fuel elements reached a burn-up of 88 MW d kg-1 (equivalent to the burn up of the standard uranium dioxide pelletized fuel) without loss of leak-tightness of the cladding. The feasibility of fabricating IMF of these particular types with plutonium dioxide is considered with a view to in-pile irradiation.

Effect of repeated burning on plant and soil carbon and nitrogen in cheatgrass (Bromus tectorum) dominated ecosystems

Treesearch

Rachel Jones; Jeanne C. Chambers; Dale W. Johnson; Robert R. Blank; David I. Board

2015-01-01

Fire has profound effects on ecosystem properties, but few studies have addressed the effect of repeated burns on soil nutrients, and none have been conducted in cold desert ecosystems where invasion by exotic annual grasses is resulting in greater fire frequency. In a 5 year study, we examined effects of repeated burning, litter removal, and post-fire seeding on...

Fire impacts on the cryosphere

NASA Astrophysics Data System (ADS)

Kehrwald, N. M.; Zennaro, P.; Skiles, M.; Barbante, C.

2015-12-01

Continental-scale smog clouds and massive boreal smoke plumes deposit dark particles on glaciers, darkening their surfaces and altering surface albedo. These atmospheric brown clouds are primarily comprised of both fossil fuel and biomass burning combustion products. Here, we examine the biomass burning contribution to aerosols trapped in the cryosphere through investigating the specific molecular marker levoglucosan (1,6-anhydro-β-D-glucopyranose) in ice cores. Levoglucosan is only produced by cellulose combustion, and therefore is an ideal comparison for multi-proxy investigations incorporating other markers with multiple sources. Wildfire combustion products are a major component of dark aerosols deposited on the Greenland ice sheet during the 2012 melt event. Levoglucosan concentrations that demonstrate the biomass burning contribution are similar to black carbon concentrations that record both fossil fuel and biomass burning during this same event. This similarity is especially important as levoglucosan and black carbon trends differ during the industrial era in the NEEM, Greenland ice core, demonstrating different contributions of fossil fuel and biomass burning to the Greenland ice sheet. These differences are also present in the EPICA Dome C Antarctic ice core. Low-latitude ice cores such as Kilimanjaro, Tanzania and Muztag, Tibet demonstrate that climate is still the primary control over fire activity in these regions, even with increased modern biomass burning and the possible impacts of atmospheric brown clouds.

Emissions of volatile organic compounds and particulate matter from small-scale peat fires

NASA Astrophysics Data System (ADS)

George, I. J.; Black, R.; Walker, J. T.; Hays, M. D.; Tabor, D.; Gullett, B.

2013-12-01

Air pollution emitted from peat fires can negatively impact regional air quality, visibility, climate, and human health. Peat fires can smolder over long periods of time and, therefore, can release significantly greater amounts of carbon into the atmosphere per unit area compared to burning of other types of biomass. However, few studies have characterized the gas and particulate emissions from peat burning. To assess the atmospheric impact of peat fires, particulate matter (PM) and volatile organic compounds (VOCs) were quantified from controlled small-scale peat fire experiments. Major carbon emissions (i.e. CO2, CO, methane and total hydrocarbons) were measured during the peat burn experiments. Speciated PM mass was also determined from the peat burns from filter and polyurethane foam samples. Whole air samples were taken in SUMMA canisters and analyzed by gas chromatography-mass spectrometry to measure 82 trace VOCs. Additional gaseous carbonyl species were measured by sampling with dinitrophenylhydrazine-coated cartridges and analyzed with high performance liquid chromatography. VOCs with highest observed concentrations measured from the peat burns were propylene, benzene, chloromethane and toluene. Gas-phase carbonyls with highest observed concentrations included acetaldehyde, formaldehyde and acetone. Emission factors of major pollutants will be compared with recommended values for peat and other biomass burning.

Trace gas emissions from burning Florida wetlands

NASA Astrophysics Data System (ADS)

Cofer, Wesley R.; Levine, Joel S.; Winstead, Edward L.; Lebel, Peter J.; Koller, Albert M.; Hinkle, C. Ross

1990-02-01

Measurements of biomass burn-produced trace gases are presented that were obtained using a helicopter at low altitudes above burning Florida wetlands on November 9, 1987, and from both helicopter and light-aircraft samplings on November 7, 1988. Carbon dioxide (CO2) normalized emission ratios (ΔX/ΔCO2; V/V; where X is trace gas) for carbon monoxide (CO), hydrogen (H2), methane (CH4), total nonmethane hydrocarbons (TNMHC), and nitrous oxide (N2O) were obtained over burning graminoid wetlands consisting primarily of Spartina bakeri and Juncus roemerianus. Some interspersed scrub oak (Quercus spp) and saw palmetto (Screnoa repens) were also burned. No significant differences were observed in the emission ratios determined for these gases from samples collected over flaming, mixed, and smoldering phases of combustion during the 1987 fire. Combustion-categorized differences in emission ratios were small for the 1988 fire. Combustion efficiency was relatively good (low emission ratios for reduced gases) for both fires. We believe that the consistently low emission ratios were a unique result of graminoid wetlands fires, in which the grasses and rushes (both small-size fuels) burned rapidly down to standing water and were quickly extinguished. Consequently, the efficiency of the combustion was good and the amount and duration of smoldering combustion was greatly diminished.

Measuring the effect of fuel treatments on forest carbon using landscape risk analysis

NASA Astrophysics Data System (ADS)

Ager, A. A.; Finney, M. A.; McMahan, A.; Cathcart, J.

2010-12-01

Wildfire simulation modelling was used to examine whether fuel reduction treatments can potentially reduce future wildfire emissions and provide carbon benefits. In contrast to previous reports, the current study modelled landscape scale effects of fuel treatments on fire spread and intensity, and used a probabilistic framework to quantify wildfire effects on carbon pools to account for stochastic wildfire occurrence. The study area was a 68 474 ha watershed located on the Fremont-Winema National Forest in southeastern Oregon, USA. Fuel reduction treatments were simulated on 10% of the watershed (19% of federal forestland). We simulated 30 000 wildfires with random ignition locations under both treated and untreated landscapes to estimate the change in burn probability by flame length class resulting from the treatments. Carbon loss functions were then calculated with the Forest Vegetation Simulator for each stand in the study area to quantify change in carbon as a function of flame length. We then calculated the expected change in carbon from a random ignition and wildfire as the sum of the product of the carbon loss and the burn probabilities by flame length class. The expected carbon difference between the non-treatment and treatment scenarios was then calculated to quantify the effect of fuel treatments. Overall, the results show that the carbon loss from implementing fuel reduction treatments exceeded the expected carbon benefit associated with lowered burn probabilities and reduced fire severity on the treated landscape. Thus, fuel management activities resulted in an expected net loss of carbon immediately after treatment. However, the findings represent a point in time estimate (wildfire immediately after treatments), and a temporal analysis with a probabilistic framework used here is needed to model carbon dynamics over the life cycle of the fuel treatments. Of particular importance is the long-term balance between emissions from the decay of dead trees killed by fire and carbon sequestration by forest regeneration following wildfire.

Mass closure and source apportionment of PM2.5 by Positive Matrix Factorization analysis in urban Mediterranean environment

NASA Astrophysics Data System (ADS)

Mantas, E.; Remoundaki, E.; Halari, I.; Kassomenos, P.; Theodosi, C.; Hatzikioseyian, A.; Mihalopoulos, N.

2014-09-01

A systematic monitoring of PM2.5 was carried out during a period of three years (from February 2010 to April 2013) at an urban site, at the National Technical University of Athens campus. Two types of 24-h PM2.5 samples have been collected: 271 samples on PTFE and 116 samples on quartz filters. Daily PM2.5 concentrations were determined for both types of samples. Total sulfur, crustal origin elements and elements of a major crustal component (Al, Si, Fe, Ca, K, Mg, Ti) trace elements (Zn, Pb, Cu, Ni, P, V, Cr, Mn) and water soluble ions (Cl-, NO3-, SO42-, Na+, K+, NH4+, Ca2+, Mg2+) were determined on the PTFE samples. Organic carbon (OC), elemental carbon (EC) and water soluble ions were determined on the quartz samples. For the mass closure six components were considered: Secondary Inorganic Aerosol (SIA), Organic Matter (OM), Elemental Carbon (EC), Dust, Mineral anthropogenic component (MIN) and Sea Salt (SS). SIA and OM contributed in the mass of PM2.5 almost equally: 30-36% and 30% respectively. EC, SS and MIN accounted for 5, 4 and 3% respectively of the total PM2.5 mass. Dust accounted for about 3-5% in absence of dust transport event and reached a much higher percentage in case of dust transport event. These contributions justify at least 80% of the PM2.5 mass. Source apportionment analysis has been performed by Positive Matrix Factorization. The combination of the PMF results obtained by both data sets lead to the definition of six factors: 1. SO42-, NH4+, OC (industrial/regional sources, secondary aerosol) 2. EC, OC, K and trace metals (traffic and heating by biomass burning, locally emitted aerosol). 3. Ca, EC, OC and trace metals (urban-resuspended road dust reflecting exhaust emissions), 4. Secondary nitrates 5. Na, Cl (marine source) 6. Si, Al, Ti, Ca, Fe (Dust transported from Sahara). These factors reflect not only main sources contributions but also underline the key role of atmospheric dynamics and aerosol ageing processes in this Mediterranean environment.

Fast and Luminous Transients from the Explosions of Long-lived Massive White Dwarf Merger Remnants

NASA Astrophysics Data System (ADS)

Brooks, Jared; Schwab, Josiah; Bildsten, Lars; Quataert, Eliot; Paxton, Bill; Blinnikov, Sergei; Sorokina, Elena

2017-12-01

We study the evolution and final outcome of long-lived (≈ {10}5 years) remnants from the merger of an He white dwarf (WD) with a more massive C/O or O/Ne WD. Using Modules for Experiments in Stellar Astrophysics ({\\mathtt{MESA}}), we show that these remnants have a red giant configuration supported by steady helium burning, adding mass to the WD core until it reaches {M}{core}≈ 1.12{--}1.20 {M}⊙ . At that point, the base of the surface convection zone extends into the burning layer, mixing the helium-burning products (primarily carbon and magnesium) throughout the convective envelope. Further evolution depletes the convective envelope of helium and dramatically slows the mass increase of the underlying WD core. The WD core mass growth re-initiates after helium depletion, as then an uncoupled carbon-burning shell is ignited and proceeds to burn the fuel from the remaining metal-rich extended envelope. For large enough initial total merger masses, O/Ne WD cores would experience electron-capture triggered collapse to neutron stars (NSs) after growing to near Chandrasekhar mass ({M}{Ch}). Massive C/O WD cores could suffer the same fate after a carbon-burning flame converts them to ONe. The NS formation would release ≈ {10}50 erg into the remaining extended low mass envelope. Using the STELLA radiative transfer code, we predict the resulting optical light curves from these exploded envelopes. Reaching absolute magnitudes of {M}V≈ -17, these transients are bright for about one week and have many features of the class of luminous, rapidly evolving transients studied by Drout and collaborators.

Terrestrial cycling of 13CO2 by photosynthesis, respiration, and biomass burning in SiBCASA

NASA Astrophysics Data System (ADS)

van der Velde, I. R.; Miller, J. B.; Schaefer, K.; van der Werf, G. R.; Krol, M. C.; Peters, W.

2014-12-01

We present an enhanced version of the SiBCASA terrestrial biosphere model that is extended with (a) biomass burning emissions from the SiBCASA carbon pools using remotely sensed burned area from the Global Fire Emissions Database (GFED), (b) an isotopic discrimination scheme that calculates 13C signatures of photosynthesis and autotrophic respiration, and (c) a separate set of 13C pools to carry isotope ratios into heterotrophic respiration. We quantify in this study the terrestrial exchange of CO2 and 13CO2 as a function of environmental changes in humidity and biomass burning. The implementation of biomass burning yields similar fluxes as CASA-GFED both in magnitude and spatial patterns. The implementation of isotope exchange gives a global mean discrimination value of 15.2‰, ranges between 4 and 20‰ depending on the photosynthetic pathway in the plant, and compares favorably (annually and seasonally) with other published values. Similarly, the isotopic disequilibrium is similar to other studies that include a small effect of biomass burning as it shortens the turnover of carbon. In comparison to measurements, a newly modified starch/sugar storage pool propagates the isotopic discrimination anomalies to respiration much better. In addition, the amplitude of the drought response by SiBCASA is lower than suggested by the measured isotope ratios. We show that a slight increase in the stomatal closure for large vapor pressure deficit would amplify the respired isotope ratio variability. Our study highlights the importance of isotope ratio observations of 13C to assess and improve biochemical models like SiBCASA, especially with regard to the allocation and turnover of carbon and the responses to drought.

The role of fire in the pan-tropical carbon budget

NASA Astrophysics Data System (ADS)

van der Werf, G.; Randerson, J. T.; Giglio, L.; Baccini, A.; Morton, D. C.; DeFries, R. S.

2012-12-01

Fires are an important management tool in the tropics and subtropics, and are used in the deforestation process, to manage savanna areas, and burn agricultural waste. Satellite-derived datasets of precipitation, aboveground tree biomass, and burned area are now available with over a decade worth of data for precipitation and burned area. Here we used these datasets to assess fire carbon emissions, to better understand relations between interannual variability in precipitation rates and fire activity, and to test ecological hypotheses centered on the role of fire and climate in governing biomass loads in the tropics and subtropics. We show that while most fire carbon emissions are from savanna fires, fires in deforestation regions are crucial from a net carbon emissions perspective and for emissions of reduced trace gases. These tropical fires burning in the dry season increase the amplitude of the CO2 exchange seasonality, in contrast to fires in the boreal region. We then show the large interannual variability of fires and highlight the difference in response of fires to changes in precipitation rates between dry and wet regions. Finally, by studying relations between fire, climate, and biomass, we show that savanna areas that saw fires over the past decade had lower tree biomass than those that did not, but only in medium or high rainfall areas. In areas up to about a meter of rain annually, tree biomass increased monotonically whether there were fires or not. In higher rainfall areas, precipitation seasonality appeared to be a crucial factor in explaining potential biomass. These results show that a world without fires may change the savanna carbon landscape less dramatically than often thought.

Role of Fire and Landscape Position on Dissolved Organic Carbon Composition and Reactivity in the Yukon-Kuskokwim Delta, Alaska

NASA Astrophysics Data System (ADS)

Bristol, E. M.; Dabrowski, J. S.; Jimmie, J. A.; Peter, D. L.; Holmes, R. M.; Mann, P. J.; Natali, S.; Schade, J. D.

2017-12-01

The Yukon-Kuskokwim Delta in southwest, Alaska is characterized by discontinuous permafrost, which is vulnerable to thaw induced by climate change. Recent fires in the delta have caused dramatic changes in the landscape, likely changing carbon dynamics, and potentially altering dissolved organic carbon (DOC) composition and DOC concentrations in aquatic ecosystems. These changes, in turn, likely affect microbial respiration and hydrologic C export from watersheds in the delta. In this study, we investigated how landscape position and fire history drive changes in DOC composition and reactivity in aquatic ecosystems. We surveyed soil pore waters, ponds, fens, and streams at varying landscape positions in burned and unburned landscapes. We also conducted a laboratory experiment to compare the role of photooxidation, photodegradation, and microbial respiration in altering DOC composition and concentration. Surface waters in burned regions were higher in temperature and inorganic nitrogen concentrations. Higher conductivity in burned areas suggests that fire is deepening the water table, causing water to flow through a more mineral soil horizon. While DOC concentrations did not vary significantly by landscape position or fire history, optical properties of DOC suggest that DOC molecular weight is lower in burned regions and decreases along flow paths. Similarly, our incubation experiment indicated that changes in DOC composition are driven by exposure to light more than bacterial respiration, and that photochemical reactivity declines along flow paths. Percent DOC loss was greatest in waters exposed to both light and bacterial, and percent DOC loss from burned watershed waters was correlated with optical properties. Based on our findings, we predict that the combination of increased surface water temperatures, increased inorganic nitrogen concentrations, and lower molecular weight DOC will increase bacterial respiration of DOC in watersheds burned by wildfire. Further research is needed to better understand the changing hydrology in burned tundra, and the relationship between photooxidation and biological mineralization of DOC.

Molecular Diversity of Brown Carbon Chromophores in Biomass Burning Aerosol

NASA Astrophysics Data System (ADS)

Lin, P.; Laskin, A.; Laskin, J.; Fleming, L.; Nizkorodov, S.

2017-12-01

Brown carbon (BrC) is ubiquitous in the atmosphere and significant contributor to climate forcing. Understanding the environmental effects of BrC, its sources, formation, and atmospheric transformation mechanisms requires identification of BrC chromophores and characterization of their light-absorption properties. In this study, we investigate the chemical composition, molecular identity and optical properties of BrC chromophores associated with biomass burning aerosols emitted from burns of different biofuels during the NOAA FIREX/FireLab experiment. The results show that BrC in the biomass burning smoke contains organic compounds of various molecular structures, polarities, and volatilities. The relative contributions to light absorption from different classes of chromophores such as nitro-phenols, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and heterocyclic PAHs are quantified and are shown to be diverse among aerosol samples from different biofuel sources. Despite complexity of BrC, grouping its chromophores according to their polarity and volatility may simplify the parameters for modelling input.

Methods to Reduce Forest Residue Volume after Timber Harvesting and Produce Black Carbon

PubMed Central

Busse, Matt D.; Archuleta, James G.; McAvoy, Darren; Roussel, Eric

2017-01-01

Forest restoration often includes thinning to reduce tree density and improve ecosystem processes and function while also reducing the risk of wildfire or insect and disease outbreaks. However, one drawback of these restoration treatments is that slash is often burned in piles that may damage the soil and require further restoration activities. Pile burning is currently used on many forest sites as the preferred method for residue disposal because piles can be burned at various times of the year and are usually more controlled than broadcast burns. In many cases, fire can be beneficial to site conditions and soil properties, but slash piles, with a large concentration of wood, needles, forest floor, and sometimes mineral soil, can cause long-term damage. We describe several alternative methods for reducing nonmerchantable forest residues that will help remove excess woody biomass, minimize detrimental soil impacts, and create charcoal for improving soil organic matter and carbon sequestration. PMID:28377830

Comparison of the physical and chemical characteristics of fine road dust at different urban sites.

PubMed

Lee, Kwang Yul; Batmunkh, Tsatsral; Joo, Hung Soo; Park, Kihong

2018-04-18

The size distribution and chemical components of a fine fraction (<2.5 μm) of road dust collected at urban sites in Korea (Gwangju) and Mongolia (Ulaanbaatar) where distinct urban characteristics exist were measured. A clear bimodal size distribution was observed for the resuspended fine road dust at the urban sites in Korea. The first mode peaked at 100-110 nm, and the second peak was observed at 435-570 nm. Ultrafine mode (~30 nm) was found for the fine road dust at the Mongolia site, which was significantly affected by residential coal/biomass burning. The contribution of the water-soluble ions to the fine road dust was higher at the sites in Mongolia (15.8-16.8%) than at those in Korea (1.2-4.8%). Sulfate and chloride were the most dominant ionic species for the fine road dust in Mongolia. As (arsenic) was also much higher for the Mongolian road dust than the others. The sulfate, chloride, and As mainly come from coal burning activity, suggesting that coal and biomass combustion in Mongolia during the heating season should affect the size and chemical components of the fine road dust. Cu (copper) and Zn (zinc), carbonaceous particles (organic carbon [OC] and elemental carbon [EC]) increased at sites in Korea, suggesting that the fine road dust at these sites was significantly affected by the high volume of traffic (engine emission and brake/tire wear). Our results suggest that chemical profiles for road dust specific to certain sites should be applied to more accurately apportion road dust source contributing to the ambient particulate matter. Size and chemical characteristics of fine road dust at sites having distinct urban characteristics were examined. Residential coal and biomass burning and traffic affected physiochemical properties of the fine road dust. Different road dust profiles at different sites should be needed to determine the ambient PM2.5 sources more accurately.

Biomass burning influences determination based on PM2.5 chemical composition combined with fire counts at southeastern Tibetan Plateau during pre-monsoon period

NASA Astrophysics Data System (ADS)

Zhang, Ningning; Cao, Junji; Wang, Qiyuan; Huang, Rujin; Zhu, Chongshu; Xiao, Shun; Wang, Linlin

2018-07-01

Influences of biomass burning (BB) on a high altitude site were investigated by collecting fine particulate matter (PM2.5) samples from 29 March to 27 April of 2012 at Mt. Yulong (4500 m above sea level), and analyzing them for selected chemical species including water soluble ions (WSIs), organic carbon (OC), elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The mean PM2.5 mass loading for the study was 6.30 ± 4.90 μg m-3, and 15.48 ± 2.82 μg m-3 and 1.75 ± 0.41 μg m-3 for a high and a low PM episode, respectively. WSIs accounted for 62% of the total mass, and SO42- was the dominant anion and NH4+ was the main cation. PAHs were mainly 3 ring compounds, fluorene (Flo) and phenanthrene (Phe) together accounted for 54% of the total PAHs. For n-alkanes, n-Nonacosane (C29) concentration was the highest with the value of 1.09 ± 1.18 ng m-3, following is n-Hentriacontane (C31) and n-Heptacosane (C27) suggested that n-alkane in our samples were mainly contributed by biogenic sources. BB emission was confirmed by the diagnostic ratios, and it also had a significant influence on aerosol optical depth (AOD) distribution and enhances the concentration of most species, especially for OC, K+ and EC. Significant relationships were found between daily fire counts and BB species, and correlation coefficients (r) for mass, K+, OC, and EC were 0.58, 0.57, 0.53 and 0.60 (n = 29, P < 0.01), respectively. It indicated that daily fire counts can advance our understanding of how biomass burning affect aerosols and air quality at a high-altitude site.

Dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls in fine aerosols over central Alaska: Implications for sources and atmospheric processes

NASA Astrophysics Data System (ADS)

Deshmukh, Dhananjay K.; Mozammel Haque, Md.; Kawamura, Kimitaka; Kim, Yongwon

2018-04-01

The presence of water-soluble dicarboxylic acids in atmospheric aerosols has a significant influence on the regional radiative forcing through direct aerosol effect and cloud formation process. Fine aerosol (PM2.5) samples collected in central Alaska (Fairbanks: 64.51°N and 147.51°W) during summer of 2009 were measured for water-soluble diacids (C2-C12), oxoacids (C2-C9) and α-dicarbonyls (C2-C3) as well as elemental carbon (EC), organic carbon (OC) and water-soluble OC (WSOC) to assess their sources and formation processes. We found the predominance of oxalic acid (C2) followed by malonic (C3) and succinic acid (C4) in Alaskan aerosols. Higher C3/C4 diacid ratios (ave. 1.2) in Alaskan aerosols than those reported for fresh aerosols emitted from fossil fuel combustion (ave. 0.35) and biomass burning (0.51-0.66) suggest that organic aerosols in central Alaska were photochemically processed. The relatively high correlations of major diacids and related compounds with levoglucosan (r = 0.80-0.99) than those with 2-methylglyceric acid (r = 0.59-0.98) suggest that they were significantly produced from biomass burning emission. Strong correlations of C2 with normal-chain saturated diacids (C3-C9: r = 0.80-0.98), glyoxylic acid (ωC2: r = 0.95) and methylglyoxal (MeGly: r = 0.88), together with strong correlations of solar radiation with ratio of C2 to C2-C12 diacids (r = 0.83), ωC2 (r = 0.80) and MeGly (r = 0.82) suggest that oxalic acid in PM2.5 aerosol was produced by the photooxidation of higher homologous diacids, glyoxylic acid and methylglyoxal in the atmosphere of central Alaska. These results reveal that photochemical processing of organic precursors mainly produced from biomass burning control the water-soluble organic chemical composition of fine aerosols in central Alaska.

Chemical composition, source, and process of urban aerosols during winter haze formation in Northeast China.

PubMed

Zhang, Jian; Liu, Lei; Wang, Yuanyuan; Ren, Yong; Wang, Xin; Shi, Zongbo; Zhang, Daizhou; Che, Huizheng; Zhao, Hujia; Liu, Yanfei; Niu, Hongya; Chen, Jianmin; Zhang, Xiaoye; Lingaswamy, A P; Wang, Zifa; Li, Weijun

2017-12-01

The characteristics of aerosol particles have been poorly evaluated even though haze episodes frequently occur in winter in Northeast China. OC/EC analysis, ion chromatography, and transmission electron microscopy (TEM) were used to investigate the organic carbon (OC) and elemental carbon (EC), and soluble ions in PM 2.5 and the mixing state of individual particles during a severe wintertime haze episode in Northeast China. The organic matter (OM), NH 4 + , SO 4 2- , and NO 3 - concentrations in PM 2.5 were 89.5 μg/m 3 , 24.2 μg/m 3 , 28.1 μg/m 3 , and 32.8 μg/m 3 on the haze days, respectively. TEM observations further showed that over 80% of the haze particles contained primary organic aerosols (POAs). Based on a comparison of the data obtained during the haze formation, we generate the following synthetic model of the process: (1) Stable synoptic meteorological conditions drove the haze formation. (2) The early stage of haze formation (light or moderate haze) was mainly caused by the enrichment of POAs from coal burning for household heating and cooking. (3) High levels of secondary organic aerosols (SOAs), sulfates, and nitrates formation via heterogeneous reactions together with POAs accumulation promoted to the evolution from light or moderate to severe haze. Compared to the severe haze episodes over the North China Plain, the PM 2.5 in Northeast China analyzed in the present study contained similar sulfate, higher SOA, and lower nitrate contents. Our results suggest that most of the POAs and secondary particles were likely related to emissions from coal-burning residential stoves in rural outskirts and small boilers in urban areas. The inefficient burning of coal for household heating and cooking should be monitored during wintertime in Northeast China. Copyright © 2017 Elsevier Ltd. All rights reserved.

A modification of the U.S. Geological Survey one-sixth order semiquantitative spectrographic method for the analysis of geologic materials that improves limits of determination of some volatile to moderately volatile elements

USGS Publications Warehouse

Detra, D.E.; Cooley, Elmo F.

1988-01-01

A modification of the one-sixth order semi-quantitative emission spectrographic method for the analysis of 30 elements in geologic materials (Grimes and Marranzino 1968) improves the limits of determination of some volatile to moderately volatile elements. The modification uses a compound-pendulum-mounted filter to regulate the amount of emitted light passing into the spectrograph. One hundred percent transmission of emitted light is allowed during the initial 20 seconds of the burn, then continually reduced to 40 percent over the next 32 seconds using the pendulum-mounted filter, and followed by an additional 68 seconds of burn time. The reduction of light transmission during the latter part of the burn decreases spectral background and the line emission of less volatile elements commonly responsible for problem-causing interferences. The sensitivity of the method for some geochemically important trace elements commonly determined in mineral exploration (Ag, As, Au, Be, Bi, Cd, Cr, Cu, Pb, Sb, Sn, and Zn) is improved up to five-fold under ideal conditions without compromising precision or accuracy

Emission factors of air pollutants from CNG-gasoline bi-fuel vehicles: Part I. Black carbon.

PubMed

Wang, Yang; Xing, Zhenyu; Xu, Hui; Du, Ke

2016-12-01

Compressed natural gas (CNG) is considered to be a "cleaner" fuel compared to other fossil fuels. Therefore, it is used as an alternative fuel in motor vehicles to reduce emissions of air pollutants in transportation. To quantify "how clean" burning CNG is compared to burning gasoline, quantification of pollutant emissions under the same driving conditions for motor vehicles with different fuels is needed. In this study, a fleet of bi-fuel vehicles was selected to measure the emissions of black carbon (BC), carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NO x ) for driving in CNG mode and gasoline mode respectively under the same set of constant speeds and accelerations. Comparison of emission factors (EFs) for the vehicles burning CNG and gasoline are discussed. This part of the paper series reports BC EFs for bi-fuel vehicles driving on the real road, which were measured using an in situ method. Our results show that burning CNG will lead to 54%-83% reduction in BC emissions per kilometer, depending on actual driving conditions. These comparisons show that CNG is a cleaner fuel than gasoline for motor vehicles in terms of BC emissions and provide a viable option for reducing BC emissions cause by transportation. Copyright © 2016 Elsevier B.V. All rights reserved.

Impacts of Brown Carbon from Biomass Burning on Surface UV and Ozone Photochemistry in the Amazon Basin

NASA Technical Reports Server (NTRS)

Mok, Jungbin; Krotkov, Nickolay A.; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F.; Li, Zhangqing; Dickerson, Russell R.;

Impacts of brown carbon from biomass burning on surface UV and ozone photochemistry in the Amazon Basin.

PubMed

Mok, Jungbin; Krotkov, Nickolay A; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F; Li, Zhanqing; Dickerson, Russell R; Stenchikov, Georgiy L; Osipov, Sergey; Ren, Xinrong

2016-11-11

The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or "brown" carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305-368 nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18% and lead to reduced concentrations of radicals OH, HO 2 , and RO 2 by up to 17%, 15%, and 14%, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

Small global effect on terrestrial net primary production due to increased fossil fuel aerosol emissions from East Asia since the turn of the century.

PubMed

O'Sullivan, M; Rap, A; Reddington, C L; Spracklen, D V; Gloor, M; Buermann, W

2016-08-16

The global terrestrial carbon sink has increased since the start of this century at a time of growing carbon emissions from fossil fuel burning. Here we test the hypothesis that increases in atmospheric aerosols from fossil fuel burning enhanced the diffuse light fraction and the efficiency of plant carbon uptake. Using a combination of models, we estimate that at global scale changes in light regimes from fossil fuel aerosol emissions had only a small negative effect on the increase in terrestrial net primary production over the period 1998-2010. Hereby, the substantial increases in fossil fuel aerosol emissions and plant carbon uptake over East Asia were effectively canceled by opposing trends across Europe and North America. This suggests that if the recent increase in the land carbon sink would be causally linked to fossil fuel emissions, it is unlikely via the effect of aerosols but due to other factors such as nitrogen deposition or nitrogen-carbon interactions.

Fuel moisture influences on fire-altered carbon in masticated fuels: An experimental study

Treesearch

Nolan W. Brewer; Alistair M.S. Smith; Jeffery A. Hatten; Philip E. Higuera; Andrew T. Hudak; Roger D. Ottmar; Wade T. Tinkham

2013-01-01

Biomass burning is a significant contributor to atmospheric carbon emissions but may also provide an avenue in which fire-affected ecosystems can accumulate carbon over time, through the generation of highly resistant fire-altered carbon. Identifying how fuel moisture, and subsequent changes in the fire behavior, relates to the production of fire-altered carbon is...

PM2.5 levels, chemical composition and health risk assessment in Xinxiang, a seriously air-polluted city in North China.

PubMed

Feng, Jinglan; Yu, Hao; Liu, Shuhui; Su, Xianfa; Li, Yi; Pan, Yuepeng; Sun, Jianhui

2017-10-01

Seventeen PM 2.5 samples were collected at Xinxiang during winter in 2014. Nine water-soluble ions, 19 trace elements and eight fractions of carbonaceous species in PM 2.5 were analyzed. PM 2.5 concentrations and elements species during different periods with different pollution situations were compared. The threat of heavy metals in PM 2.5 was assessed using incremental lifetime cancer risk. During the whole period, serious regional haze pollution persisted, and the averaged concentration of PM 2.5 was 168.5 μg m -3 , with 88.2 % of the daily samples exhibiting higher PM 2.5 concentrations than the national air quality standard II. The high NO 3 - /SO 4 2- ratio suggested that vehicular exhaust made an important contribution to atmospheric pollution. All of organic carbon and elemental carbon ratios in this study were above 2.0 for PM 2.5 , which might reflect the combined contributions from coal combustion, motor vehicle exhaust and biomass burning. Mean 96-h backward trajectory clusters indicated that more serious air pollution occurred when air masses transported from the Hebei, Shanxi and Zhengzhou. The concentrations of the water-soluble ions and trace elements on haze days were 2 and 1.8 times of those on clear days. The heavy metals in PM 2.5 might not cause non-cancerous health issues by exposure through the human respiratory system. However, lifetime cancer risks of heavy metals obviously exceeded the threshold (10 -6 ) and might have a cancer risk for residents in Xinxiang. This study provided detailed composition data and comprehensive analysis of PM 2.5 during the serious haze pollution period and their potential impact on human health in Xinxiang.

Carbon monoxide poisoning

MedlinePlus

... a chemical produced from the incomplete burning of natural gas or other products containing carbon. This includes exhaust, ... indoor and camp stoves) Water heaters that use natural gas Note: This list may not be all-inclusive.

Flammability Parameters of Candles

NASA Astrophysics Data System (ADS)

Balog, Karol; Kobetičová, Hana; Štefko, Tomáš

2017-06-01

The paper deals with the assessment of selected fire safety characteristics of candles. Weight loss of a candle during the burning process, candle burning rate, soot index, heat release rate and yield of carbon oxides were determined. Soot index was determined according to EN 15426: 2007 - Candles - Specification for Sooting Behavior. All samples met the prescribed amount of produced soot. Weight loss, heat release rate and the yield of carbon oxides were determined for one selected sample. While yield of CO increased during the measurement, the yield of CO2 decreased by half in 40 minutes.

40 CFR Table 13 to Subpart Ddddd... - Alternative Emission Limits for New or Reconstructed Boilers and Process Heaters That Commenced...

Code of Federal Regulations, 2014 CFR

2014-07-01

... coal boilers designed to burn coal/solid fossil fuel a. Carbon monoxide (CO) (or CEMS) 130 ppm by... dscm per run. 3. Stokers designed to burn coal/solid fossil fuel a. CO (or CEMS) 130 ppm by volume on a... per run. 4. Fluidized bed units designed to burn coal/solid fossil fuel a. CO (or CEMS) 130 ppm by...

Forest Fires Darken Snow for Years following Disturbance: Magnitude, Duration, and Composition of Light Absorbing Impurities in Seasonal Snow across a Chronosequence of Burned Forests in the Colorado River Headwaters

NASA Astrophysics Data System (ADS)

Gleason, K. E.; Arienzo, M. M.; Chellman, N.; McConnell, J.

2017-12-01

Charred forests shed black carbon and burned debris, which accumulates and concentrates on winter snowpack, reducing snow surface albedo, and subsequently increasing snowmelt rates, and advancing the date of snow disappearance. Forest fires have occurred across vast areas of the seasonal snow zone in recent decades, however we do not understand the long-term implications of burned forests in montane headwaters to snow hydrology and downstream water resources. Across a chronosequence of nine burned forests in the Colorado River Headwaters, we sampled snow throughout the complete snowpack profile to conserve the composition, properties, and vertical stratigraphy of impurities in the snowpack during maximum snow accumulation. Using state-of-the-art geochemical analyses, we determined the magnitude, composition, and particle size distribution of black carbon, dust, and other impurities in the snowpack relative to years-since fire. Forest fires continue to darken snow for many years following fire, however the magnitude, composition, and particle size distribution of impurities change through time, altering the post-fire radiative forcing on snow as a burned forest ages.

Light-absorbing carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

EPA Science Inventory

Carbonaceous aerosols are ubiquitous in the atmosphere and can directly affect Earth’s climate by absorbing and scattering incoming solar radiation. Both field and laboratory measurements have confirmed that biomass burning (BB) is an important primary source of light absorbing o...

The conductive propagation of nuclear flames. 2: Convectively bounded flames in C + O and O + Ne + Mg cores

NASA Technical Reports Server (NTRS)

Timmes, F. X.; Woosley, S. E.; Taam, Ronald E.

1994-01-01

We determine the speeds, and many other physical properties, of flame fronts that propagate inward into degenerate and semidegenerate cores of carbon and oxygen (CO) and neon and oxygen (NeOMg) white dwarfs when such flames are bounded on their exterior by a convective region. Combustion in such fronts, per se, is incomplete, with only a small part of the initial mass function burned. A condition of balanced power is set up in the star where the rate of energy emitted as neutrinos from the convective region equals the power available from the unburned fuel that crosses the burning front. The propagation of the burning front itself is in turn limited by the temperature at the base of the convective shell, while cannot greatly exceed the adiabatic value. Solving for consistency between these two conditions gives a unique speed for the flame. Typical values for CO white dwarfs are a few hundredths of a centimeter per second. Flames in NeOMg mixtures are slower. Tables are presented in a form that can easily be implemented in stellar evolution codes and yield the rate at which the convective shell advances into the interior. Combining these velocities with the local equations for stellar structure, we find a minimum density for each gravitational potential below with the local equations for stellar structure, we find a minimum density for each gravitational potential below which the flame cannot propagate, and must die. Although detailed stellar models will have to be constructed to reslove some issues conclusively, our results that a CO white dwarf inginted at its edge will not burn carbon all the way to its center unless the mass of the white dwarf exceeds 0.8 solar mass. On the other hand, it is difficult to ignite carbon burning by compression alone anywhere in a white dwarf whose mass does not exceed 1.0 solar mass. Thus, compressionally ignited shell carbon burning in an accerting CO dwarf almost certainly propagates all the way to the center of the star. Implications for neutron star formation, and Type Ia supernova models, are briefly discussed. These are also applicable to massive stars in the about 10-12 solar mass range which ignite neon burning off center.

Evaluation of biomass burning aerosols in the HadGEM3 climate model with observations from the SAMBBA field campaign

NASA Astrophysics Data System (ADS)

Johnson, Ben T.; Haywood, James M.; Langridge, Justin M.; Darbyshire, Eoghan; Morgan, William T.; Szpek, Kate; Brooke, Jennifer K.; Marenco, Franco; Coe, Hugh; Artaxo, Paulo; Longo, Karla M.; Mulcahy, Jane P.; Mann, Graham W.; Dalvi, Mohit; Bellouin, Nicolas

2016-11-01

We present observations of biomass burning aerosol from the South American Biomass Burning Analysis (SAMBBA) and other measurement campaigns, and use these to evaluate the representation of biomass burning aerosol properties and processes in a state-of-the-art climate model. The evaluation includes detailed comparisons with aircraft and ground data, along with remote sensing observations from MODIS and AERONET. We demonstrate several improvements to aerosol properties following the implementation of the Global Model for Aerosol Processes (GLOMAP-mode) modal aerosol scheme in the HadGEM3 climate model. This predicts the particle size distribution, composition, and optical properties, giving increased accuracy in the representation of aerosol properties and physical-chemical processes over the Coupled Large-scale Aerosol Scheme for Simulations in Climate Models (CLASSIC) bulk aerosol scheme previously used in HadGEM2. Although both models give similar regional distributions of carbonaceous aerosol mass and aerosol optical depth (AOD), GLOMAP-mode is better able to capture the observed size distribution, single scattering albedo, and Ångström exponent across different tropical biomass burning source regions. Both aerosol schemes overestimate the uptake of water compared to recent observations, CLASSIC more so than GLOMAP-mode, leading to a likely overestimation of aerosol scattering, AOD, and single scattering albedo at high relative humidity. Observed aerosol vertical distributions were well captured when biomass burning aerosol emissions were injected uniformly from the surface to 3 km. Finally, good agreement between observed and modelled AOD was gained only after scaling up GFED3 emissions by a factor of 1.6 for CLASSIC and 2.0 for GLOMAP-mode. We attribute this difference in scaling factor mainly to different assumptions for the water uptake and growth of aerosol mass during ageing via oxidation and condensation of organics. We also note that similar agreement with observed AOD could have been achieved with lower scaling factors if the ratio of organic carbon to primary organic matter was increased in the models toward the upper range of observed values. Improved knowledge from measurements is required to reduce uncertainties in emission ratios for black carbon and organic carbon, and the ratio of organic carbon to primary organic matter for primary emissions from biomass burning.

Effects of experimental fuel additions on fire intensity and severity: unexpected carbon resilience of a neotropical forest.

PubMed

Brando, Paulo M; Oliveria-Santos, Claudinei; Rocha, Wanderley; Cury, Roberta; Coe, Michael T

2016-07-01

Global changes and associated droughts, heat waves, logging activities, and forest fragmentation may intensify fires in Amazonia by altering forest microclimate and fuel dynamics. To isolate the effects of fuel loads on fire behavior and fire-induced changes in forest carbon cycling, we manipulated fine fuel loads in a fire experiment located in southeast Amazonia. We predicted that a 50% increase in fine fuel loads would disproportionally increase fire intensity and severity (i.e., tree mortality and losses in carbon stocks) due to multiplicative effects of fine fuel loads on the rate of fire spread, fuel consumption, and burned area. The experiment followed a fully replicated randomized block design (N = 6) comprised of unburned control plots and burned plots that were treated with and without fine fuel additions. The fuel addition treatment significantly increased burned area (+22%) and consequently canopy openness (+10%), fine fuel combustion (+5%), and mortality of individuals ≥5 cm in diameter at breast height (dbh; +37%). Surprisingly, we observed nonsignificant effects of the fuel addition treatment on fireline intensity, and no significant differences among the three treatments for (i) mortality of large trees (≥30 cm dbh), (ii) aboveground forest carbon stocks, and (iii) soil respiration. It was also surprising that postfire tree growth and wood increment were higher in the burned plots treated with fuels than in the unburned control. These results suggest that (i) fine fuel load accumulation increases the likelihood of larger understory fires and (ii) single, low-intensity fires weakly influence carbon cycling of this primary neotropical forest, although delayed postfire mortality of large trees may lower carbon stocks over the long term. Overall, our findings indicate that increased fine fuel loads alone are unlikely to create threshold conditions for high-intensity, catastrophic fires during nondrought years. © 2016 John Wiley & Sons Ltd.

Fire effects on temperate forest soil C and N storage.

PubMed

Nave, Lucas E; Vance, Eric D; Swanston, Christopher W; Curtis, Peter S

2011-06-01

Temperate forest soils store globally significant amounts of carbon (C) and nitrogen (N). Understanding how soil pools of these two elements change in response to disturbance and management is critical to maintaining ecosystem services such as forest productivity, greenhouse gas mitigation, and water resource protection. Fire is one of the principal disturbances acting on forest soil C and N storage and is also the subject of enormous management efforts. In the present article, we use meta-analysis to quantify fire effects on temperate forest soil C and N storage. Across a combined total of 468 soil C and N response ratios from 57 publications (concentrations and pool sizes), fire had significant overall effects on soil C (-26%) and soil N (-22%). The impacts of fire on forest floors were significantly different from its effects on mineral soils. Fires reduced forest floor C and N storage (pool sizes only) by an average of 59% and 50%, respectively, but the concentrations of these two elements did not change. Prescribed fires caused smaller reductions in forest floor C and N storage (-46% and -35%) than wildfires (-67% and -69%), and the presence of hardwoods also mitigated fire impacts. Burned forest floors recovered their C and N pools in an average of 128 and 103 years, respectively. Among mineral soils, there were no significant changes in C or N storage, but C and N concentrations declined significantly (-11% and -12%, respectively). Mineral soil C and N concentrations were significantly affected by fire type, with no change following prescribed burns, but significant reductions in response to wildfires. Geographic variation in fire effects on mineral soil C and N storage underscores the need for region-specific fire management plans, and the role of fire type in mediating C and N shifts (especially in the forest floor) indicates that averting wildfires through prescribed burning is desirable from a soils perspective.

Derivation of burn scar depths and estimation of carbon emissions with LIDAR in Indonesian peatlands

PubMed Central

Ballhorn, Uwe; Siegert, Florian; Mason, Mike; Limin, Suwido

2009-01-01

During the 1997/98 El Niño-induced drought peatland fires in Indonesia may have released 13–40% of the mean annual global carbon emissions from fossil fuels. One major unknown in current peatland emission estimations is how much peat is combusted by fire. Using a light detection and ranging data set acquired in Central Kalimantan, Borneo, in 2007, one year after the severe peatland fires of 2006, we determined an average burn scar depth of 0.33 ± 0.18 m. Based on this result and the burned area determined from satellite imagery, we estimate that within the 2.79 million hectare study area 49.15 ± 26.81 megatons of carbon were released during the 2006 El Niño episode. This represents 10–33% of all carbon emissions from transport for the European Community in the year 2006. These emissions, originating from a comparatively small area (approximately 13% of the Indonesian peatland area), underline the importance of peat fires in the context of green house gas emissions and global warming. In the past decade severe peat fires occurred during El Niño-induced droughts in 1997, 2002, 2004, 2006, and 2009. Currently, this important source of carbon emissions is not included in IPCC carbon accounting or in regional and global carbon emission models. Precise spatial measurements of peat combusted and potential avoided emissions in tropical peat swamp forests will also be required for future emission trading schemes in the framework of Reduced Emissions from Deforestation and Degradation in developing countries. PMID:19940252

40 CFR 63.1573 - What are my monitoring alternatives?

Code of Federal Regulations, 2013 CFR

2013-07-01

... continuous gas analyzer to measure and record the concentration of carbon dioxide, carbon monoxide, and... instrumentations, dscm/min (dscf/min); %CO2 = Carbon dioxide concentration in regenerator exhaust, percent by... regenerator atmospheric exhaust gas flow rate for your catalytic reforming unit during the coke burn and...

Intermediate time scale response of atmospheric CO 2 following prescribed fire in a longleaf pine forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viner, Brian; Parker, M.; Maze, G.

Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO 2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements ofmore » the CO 2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO 2 concentration and CO 2 flux during the fire and increases in atmospheric CO 2 concentration and reduced CO 2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO 2 measurements and NEE were found to return to their preburn states within 60–90 days following the burn when no statistical significance was found between preburn and postburn NEE. Furthermore, this study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO 2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO 2 concentration and fluxes.« less

The contribution of charcoal burning to the rise and decline of suicides in Hong Kong from 1997-2007.

PubMed

Law, C K; Yip, Paul S F; Caine, Eric D

2011-09-01

There has been scant research exploring the relationship between choice of method (means) of self-inflicted death, and broader social or contextual factors. The recent emergence and growth of suicide using carbon monoxide poisoning resulting from burning charcoal in an enclosed space (hereafter, "charcoal burning") was related to an increase in the overall suicide rate in Hong Kong. The growth of this method coincided with changing economic conditions. This paper expands upon previous work to explore possible relationships further. This study aims to discern the role of charcoal burning in overall suicide rate transition during times of both economic recession and expansion, as captured in the unemployment rate of Hong Kong, and to examine whether there was evidence of an effect from means-substitution. Age and gender specific suicide rates in Hong Kong by suicide methods from 1997 to 2007 were calculated. To model the transition of suicide rate by different methods, Poisson regression analyses were employed. Charcoal burning constituted 18.3% of all suicides, 88% of which involved individuals drawn from the middle years (25-59) of life. During both periods of rising and declining unemployment, charcoal burning played an important role in the changing suicide rates, and this effect was most prominent among for those in their middle years. Means-substitution was found among the married women during the period of rate advancement (1997-2003). Compared to others, working-age adults preferentially selected carbon monoxide poisoning from charcoal burning.

Quantifying the effects of wildfire on changes in soil properties by surface burning of soils from the Boulder Creek Critical Zone Observatory

USGS Publications Warehouse

Wieting, Celeste; Ebel, Brian A.; Singha, Kamini

2017-01-01

Study regionThis study used intact soil cores collected at the Boulder Creek Critical Zone Observatory near Boulder, Colorado, USA to explore fire impacts on soil properties.Study focusThree soil scenarios were considered: unburned control soils, and low- and high-temperature burned soils. We explored simulated fire impacts on field-saturated hydraulic conductivity, dry bulk density, total organic carbon, and infiltration processes during rainfall simulations.New hydrological insights for the regionSoils burned to high temperatures became more homogeneous with depth with respect to total organic carbon and bulk density, suggesting reductions in near-surface porosity. Organic matter decreased significantly with increasing soil temperature. Tension infiltration experiments suggested a decrease in infiltration rates from unburned to low-temperature burned soils, and an increase in infiltration rates in high-temperature burned soils. Non-parametric statistical tests showed that field-saturated hydraulic conductivity similarly decreased from unburned to low-temperature burned soils, and then increased with high-temperature burned soils. We interpret these changes result from the combustion of surface and near-surface organic materials, enabling water to infiltrate directly into soil instead of being stored in the litter and duff layer at the surface. Together, these results indicate that fire-induced changes in soil properties from low temperatures were not as drastic as high temperatures, but that reductions in surface soil water repellency in high temperatures may increase infiltration relative to low temperatures.

Intermediate time scale response of atmospheric CO 2 following prescribed fire in a longleaf pine forest

DOE PAGES

Viner, Brian; Parker, M.; Maze, G.; ...

2016-10-12

Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO 2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements ofmore » the CO 2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO 2 concentration and CO 2 flux during the fire and increases in atmospheric CO 2 concentration and reduced CO 2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO 2 measurements and NEE were found to return to their preburn states within 60–90 days following the burn when no statistical significance was found between preburn and postburn NEE. Furthermore, this study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO 2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO 2 concentration and fluxes.« less

Intermediate time scale response of atmospheric CO2 following prescribed fire in a longleaf pine forest

NASA Astrophysics Data System (ADS)

Viner, B.; Parker, M.; Maze, G.; Varnedoe, P.; Leclerc, M.; Starr, G.; Aubrey, D.; Zhang, G.; Duarte, H.

2016-10-01

Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements of the CO2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO2 concentration and CO2 flux during the fire and increases in atmospheric CO2 concentration and reduced CO2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO2 measurements and NEE were found to return to their preburn states within 60-90 days following the burn when no statistical significance was found between preburn and postburn NEE. This study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO2 concentration and fluxes.

Fires and Thick Smoke Across Southeast Asia

NASA Technical Reports Server (NTRS)

2007-01-01

Vehicles and power plants are not the only sources of air pollution and greenhouses gases: fires contribute, too. In the Northern Hemisphere spring, which is the end of dry season across much of Southeast Asia, thousands of fires burn each year as people clear cropland and pasture in anticipation of the upcoming wet (growing) season. Intentional fires also escape people's control and burn into adjacent forest. The smoke from these fires crosses the Pacific Ocean, affecting climate far away. This dramatic photo-like image of fires and smoke in Southeast Asia was captured on April 2, 2007, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite. MODIS detected hundreds, possibly thousands of fires (marked in red), burning in Thailand, Laos, Vietnam, and China. Thick smoke hides nearly all of Laos, where the highest concentration of fires is located. In southern China and northern Vietnam, the smoke has sunk into the valleys that crisscross the mountainous terrain; only the highest ridgelines, which appear dark green, emerge from the blanket of smoke. The smoke sails above a bank of clouds at upper right as a dingy, yellowish haze. Fires have been burning in the region for more than month, as shown by the high carbon monoxide levels observed by NASA's MOPITT sensor during March 2007. In addition to carbon dioxide and other greenhouse gases, fires produce tiny particles of incompletely burned, or charred, carbon. According to research published in mid-March 2007 in the Journal of Geophysical Research, significant amounts of this black carbon travel across the Pacific Ocean to North America at altitudes above 2 kilometers. In spring 2004, between 25-35 gigatons (roughly 55 to 77 million pounds) of black carbon crossed the Pacific and entered skies over western North America between March 26 and April 25; nearly 75 percent of it came from Asia. (Smoke and other pollution have no respect for borders; for example, scientists have also documented smoke pollution from fires in Alaska and Canada crossing the Atlantic and entering skies over Europe.) Black carbon influences the climate. Like any dark-colored material, it absorbs incoming sunlight, dimming and cooling the Earth's surface. But while the surface cools, the atmosphere where the black carbon is located heats up. Which effect is stronger? When scientists looked at the overall effect for an entire column of the atmosphere, black carbon's warming effects outweighed its cooling effects. They concluded that trans-Pacific transport of black carbon, such as the soot released from the fires shown in this image, may amplify greenhouse-gas warming over the western United States and the Pacific Ocean. The analysis was based on a variety of information, including weather models, observations collected from airplanes, and aerosol data from MODIS.

Chemistry of burning the forest floor during the FROSTFIRE experimental burn, interior Alaska, 1999.

Treesearch

J.W. Harden; J.C. Neff; D.V. Sandberg; M.R. Turetsky; R. Ottmar; G. Gleixner; T.L. Fries; K.L. Manies

2004-01-01

Wildfires represent one of the most common disturbances in boreal regions, and have the potential to reduce C, N, and Hg stocks in soils while contributing to atmospheric emissions. Organic soil layers of the forest floor were sampled before and after the FROSTFIRE experimental burn in interior Alaska, and were analyzed for bulk density, major and trace elements, and...

Potency of bio-charcoal briquette from leather cassava tubers and industrial sludge

NASA Astrophysics Data System (ADS)

Citrasari, Nita; Pinatih, Tety A.; Kuncoro, Eko P.; Soegianto, Agoes; Salamun, Irawan, Bambang

2017-06-01

The purpose of this study was to determine the quality of the bio-charcoal briquette with materials from leather cassava tubers and sludge of wastewater treatment plant. The first, bio-charcoal briquette analized stability test and compressive strength. Then, bio-charcoal briquette with best value analyzed for parameter including moisture content, ash content, calorific content, and burned test. The result briquette quality based on compressive strength for bio-charcoal briquettes carbonated water content between 3.8%-4.5% and non-carbonated bio-charcoal briquettes between 5.2%-7.6%. Bio-charcoal carbonation briquette ash content was between 5.30%-7.40% and non-carbonated bio-charcoal briquettes was between 6.86%-7.46%. Bio-charcoal carbonation levels briquettes heated between 578.2 calories/g-1837.7 calories/g and non carbonatedbio-charcoal briquettes between 858.1 calories/g-891.1 calories/g. Carbonated bio-charcoal burned test was between 48-63 minutes and non-carbonated bio-charcoal was between 22-42 minutes. Emissions resulted from the bio-charcoal briquettes for carbonated and non carbonated composition according to the government regulations ESDM No. 047 of 2006 which, at 128 mg/Nm3 and 139 mg/Nm3.

Standardization of the carbon-phenolic materials and processes. Vol. 2: Test methods and specifications

NASA Technical Reports Server (NTRS)

Hall, William B.

1988-01-01

Carbon-phenolic composite materials are used in the ablation process in the nozzles of the Space Shuttle Main Engine. The nozzle is lined with carbon cloth-phenolic resin composites. The extreme heat and erosion of the burning propellant are controlled by the carbon-phenolic composite by means of ablation, a heat and mass transfer process in which a large amount of heat is dissipated by sacrificailly removing material from a surface. Phenolic materials ablate with the initial formation of a char. The depth of the char is a function of the heat conduction coefficient of the composite. The char layer is a poor conductor so it protects the underlying phenolic composite from the high heat of the burning propellant. The nozzle component ablative liners (carbon cloth-phenolic resin composites) are tape wrapped, hydroclave and/or autoclave cured, machined and assembled. The tape consists of prepreg broadcloth. The materials flow sheet for the nozzle ablative liners is given. The prepreg is a three component system: phenolic resin, carbon cloth, and carbon filler. This is Volume 2 of the report, Test Methods and Specifications.

Coal and cremation at the Tschudi burn, Chan Chan, Northern Peru

USGS Publications Warehouse

Brooks, W.E.; Galvez, Mora C.; Jackson, J.C.; McGeehin, J.P.; Hood, D.G.

2008-01-01

Analyses of a 20-30 cm thick, completely combusted ash at the 25 ?? 70 m Tschudi burn at Chan Chan, northern Peru??, contain 52-55 wt% SiO2, 180-210 ppm zirconium and are consistent with coal ash. Soil geochemistry across the burn showed elevated calcium and phosphorus content, possible evidence for reported human cremation. A calcined, 5 g, 4.5 cm skull fragment recovered from the burn was confirmed as human by protein radioimmunoassay (pRIA). X-ray diffraction showed that the bone had been heated to 520??C. The burn took place c. ad 1312-1438 based on interpretation of a 14C date on carbonized plant tinder. ?? 2008 University of Oxford.

Dissolved black carbon in grassland streams: is there an effect of recent fire history?

PubMed

Ding, Yan; Yamashita, Youhei; Dodds, Walter K; Jaffé, Rudolf

2013-03-01

While the existence of black carbon as part of dissolved organic matter (DOM) has been confirmed, quantitative determinations of dissolved black carbon (DBC) in freshwater ecosystem and information on factors controlling its concentration are scarce. In this study, stream surface water samples from a series of watersheds subject to different burn frequencies in Konza Prairie (Kansas, USA) were collected in order to determine if recent fire history has a noticeable effect on DBC concentration. The DBC levels detected ranged from 0.04 to 0.11 mg L(-1), accounting for ca. 3.32±0.51% of dissolved organic carbon (DOC). No correlation was found between DBC concentration and neither fire frequency nor time since last burn. We suggest that limited DBC flux is related to high burning efficiency, possibly greater export during periods of high discharge and/or the continuous export of DBC over long time scales. A linear correlation between DOC and DBC concentrations was observed, suggesting the export mechanisms determining DOC and DBC concentrations are likely coupled. The potential influence of fire history was less than the influence of other factors controlling the DOC and DBC dynamics in this ecosystem. Assuming similar conditions and processes apply in grasslands elsewhere, extrapolation to a global scale would suggest a global grasslands flux of DBC on the order of 0.14 Mt carbon year(-1). Copyright © 2012 Elsevier Ltd. All rights reserved.

Estimating the consequences of fire exclusion for food crop production, soil fertility, and fallow recovery in shifting cultivation landscapes in the humid tropics.

PubMed

Norgrove, Lindsey; Hauser, Stefan

2015-03-01

In the Congo Basin, smallholder farmers practice slash-and-burn shifting cultivation. Yet, deliberate burning might no longer be sustainable under reduced fallow scenarios. We synthesized data from the Forest Margins Benchmark Area (FMBA), comprising 1.54 million hectares (ha), in southern Cameroon and assessed the impact of fire exclusion on yield, labor inputs, soil fertility, ecosystem carbon stocks, and fallow recovery indicators in two common field types (plantain and maize) under both current and reduced fallow scenarios. While we could not distinguish between impacts of standard farmer burning practice and fire exclusion treatments for the current fallow scenario, we concluded that fire exclusion would lead to higher yields, higher ecosystem carbon stocks as well as potentially faster fallow recovery under the reduced fallow scenario. While its implementation would increase labor requirements, we estimated increased revenues of 421 and 388 US$ ha(-1) for plantain and maize, respectively. Applied to the FMBA, and assuming a 6-year reduced fallow scenario, fire exclusion in plantain fields would potentially retain 240,464 Mg more ecosystem carbon, comprising topsoil carbon plus tree biomass carbon, than standard farmer practice. Results demonstrate a potential "win-win scenario" where yield benefits, albeit modest, and conservation benefits can be obtained simultaneously. This could be considered as a transitional phase towards higher input use and thus higher yielding systems.

Estimating the Consequences of Fire Exclusion for Food Crop Production, Soil Fertility, and Fallow Recovery in Shifting Cultivation Landscapes in the Humid Tropics

NASA Astrophysics Data System (ADS)

Norgrove, Lindsey; Hauser, Stefan

2015-03-01

In the Congo Basin, smallholder farmers practice slash-and-burn shifting cultivation. Yet, deliberate burning might no longer be sustainable under reduced fallow scenarios. We synthesized data from the Forest Margins Benchmark Area (FMBA), comprising 1.54 million hectares (ha), in southern Cameroon and assessed the impact of fire exclusion on yield, labor inputs, soil fertility, ecosystem carbon stocks, and fallow recovery indicators in two common field types (plantain and maize) under both current and reduced fallow scenarios. While we could not distinguish between impacts of standard farmer burning practice and fire exclusion treatments for the current fallow scenario, we concluded that fire exclusion would lead to higher yields, higher ecosystem carbon stocks as well as potentially faster fallow recovery under the reduced fallow scenario. While its implementation would increase labor requirements, we estimated increased revenues of 421 and 388 US ha-1 for plantain and maize, respectively. Applied to the FMBA, and assuming a 6-year reduced fallow scenario, fire exclusion in plantain fields would potentially retain 240,464 Mg more ecosystem carbon, comprising topsoil carbon plus tree biomass carbon, than standard farmer practice. Results demonstrate a potential "win-win scenario" where yield benefits, albeit modest, and conservation benefits can be obtained simultaneously. This could be considered as a transitional phase towards higher input use and thus higher yielding systems.

Prescribed burning and mechanical thinning effects on belowground conditions and soil respiration in a mixed-conifer forest, California

Treesearch

Soung-Ryoul Ryu; Amy Concilio; Jiquan Chen; Malcolm North; Siyan Ma

2009-01-01

Soil respiration (RS) is a major carbon pathway from terrestrial ecosystems to the atmosphere and is sensitive to environmental changes. Although commonly used mechanical thinning and prescribed burning can significantly alter the soil environment, the effect of these practices on RS...

[Severe burns of lower limb due to association of hot water and citrullus colocynthis].

PubMed

Fejjal, N; Gharib, N E; El Mazouz, S; Abbassi, A; Belmahi, A

2011-06-30

The case is reported of a patient suffering from severe burns through having used Citrullus colocynthis as a medicinal plant together with hot water. This led to carbonization of the foot and to its amputation. A description of the plant and its toxicity is given.

Sodium and sulfur release and recapture during black liquor burning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frederick, W.J.; Iisa, K.; Wag, K.

1995-08-01

The objective of this study was to provide data on sulfur and sodium volatilization during black liquor burning, and on SO2 capture by solid sodium carbonate and sodium chloride. This data was interpreted and modeled into rate equations suitable for use in computational models for recovery boilers.

Distribution, Transport, and Accumulation of Pyrogenic Black Carbon in Post-Wildfire Watersheds

NASA Astrophysics Data System (ADS)

Galanter, A.; Cadol, D. D.; Frey, B.; Lohse, K. A.

2014-12-01

Large, high severity wildfires greatly alter forest structure, water quality, and soil development/erosion. With increased frequency of such wildfires also follows heavy post-wildfire debris flows and flooding which deliver high loads of sediment and pyrogenic black carbon (PyC) to downstream waterways. The accumulation of PyC is a multi-faceted and dynamic issue in the critical zone. Generated by incomplete combustion of organic matter, PyC (in the form of soot and char) impacts turbidity, biological and chemical oxygen demand, and pH. In addition, PyC has the potential to sequester contaminants and can store carbon over short and long timescales. The impacts of two recent wildfires in Northern New Mexico are studied with the goal of understanding the fluxes and residence times of PyC in post-wildfire, mountainous watersheds. Employing burn severity maps and geospatial data, we selected three sites to collect soil and water samples to characterize PyC: a control, an area impacted by a large, severe burn (2011), and an area impacted by a smaller, less severe burn (2013). By collaborating with researchers at the Jemez Critical Zone Observatory, soil samples are being analyzed and will provide pre-wildfire PyC concentrations for the 2013 burn area. In this study, PyC is treated as both a particulate and a solute that is transported throughout the watershed as well as degraded in soils, surface water and groundwater. We used two black carbon quantification methods: the chemo-thermal oxidation (CTO-375) method to distinguish between soil soot and char, and the benzene polycarboxylic acids (BPCA) method to quantify the total concentrations of PyC in soil and water samples. Preliminary soil data from the CTO-375 method show comparable soot concentrations in the control, 2011, and 2013 burn indicating that the soot is more recalcitrant than char and remains in the watershed long after a wildfire. This data also suggests that the fluxes of black carbon over short time scales are composed mainly of char.

Carbon fluxes in ecosystems of Yellowstone National Park predicted from remote sensing data and simulation modeling

PubMed Central

2011-01-01

Background A simulation model based on remote sensing data for spatial vegetation properties has been used to estimate ecosystem carbon fluxes across Yellowstone National Park (YNP). The CASA (Carnegie Ames Stanford Approach) model was applied at a regional scale to estimate seasonal and annual carbon fluxes as net primary production (NPP) and soil respiration components. Predicted net ecosystem production (NEP) flux of CO2 is estimated from the model for carbon sinks and sources over multi-year periods that varied in climate and (wildfire) disturbance histories. Monthly Enhanced Vegetation Index (EVI) image coverages from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) instrument (from 2000 to 2006) were direct inputs to the model. New map products have been added to CASA from airborne remote sensing of coarse woody debris (CWD) in areas burned by wildfires over the past two decades. Results Model results indicated that relatively cooler and wetter summer growing seasons were the most favorable for annual plant production and net ecosystem carbon gains in representative landscapes of YNP. When summed across vegetation class areas, the predominance of evergreen forest and shrubland (sagebrush) cover was evident, with these two classes together accounting for 88% of the total annual NPP flux of 2.5 Tg C yr-1 (1 Tg = 1012 g) for the entire Yellowstone study area from 2000-2006. Most vegetation classes were estimated as net ecosystem sinks of atmospheric CO2 on annual basis, making the entire study area a moderate net sink of about +0.13 Tg C yr-1. This average sink value for forested lands nonetheless masks the contribution of areas burned during the 1988 wildfires, which were estimated as net sources of CO2 to the atmosphere, totaling to a NEP flux of -0.04 Tg C yr-1 for the entire burned area. Several areas burned in the 1988 wildfires were estimated to be among the lowest in overall yearly NPP, namely the Hellroaring Fire, Mink Fire, and Falls Fire areas. Conclusions Rates of recovery for burned forest areas to pre-1988 biomass levels were estimated from a unique combination of remote sensing and CASA model predictions. Ecosystem production and carbon fluxes in the Greater Yellowstone Ecosystem (GYE) result from complex interactions between climate, forest age structure, and disturbance-recovery patterns of the landscape. PMID:21835025

Carbon fluxes in ecosystems of Yellowstone National Park predicted from remote sensing data and simulation modeling.

PubMed

Potter, Christopher; Klooster, Steven; Crabtree, Robert; Huang, Shengli; Gross, Peggy; Genovese, Vanessa

2011-08-11

A simulation model based on remote sensing data for spatial vegetation properties has been used to estimate ecosystem carbon fluxes across Yellowstone National Park (YNP). The CASA (Carnegie Ames Stanford Approach) model was applied at a regional scale to estimate seasonal and annual carbon fluxes as net primary production (NPP) and soil respiration components. Predicted net ecosystem production (NEP) flux of CO2 is estimated from the model for carbon sinks and sources over multi-year periods that varied in climate and (wildfire) disturbance histories. Monthly Enhanced Vegetation Index (EVI) image coverages from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) instrument (from 2000 to 2006) were direct inputs to the model. New map products have been added to CASA from airborne remote sensing of coarse woody debris (CWD) in areas burned by wildfires over the past two decades. Model results indicated that relatively cooler and wetter summer growing seasons were the most favorable for annual plant production and net ecosystem carbon gains in representative landscapes of YNP. When summed across vegetation class areas, the predominance of evergreen forest and shrubland (sagebrush) cover was evident, with these two classes together accounting for 88% of the total annual NPP flux of 2.5 Tg C yr-1 (1 Tg = 1012 g) for the entire Yellowstone study area from 2000-2006. Most vegetation classes were estimated as net ecosystem sinks of atmospheric CO2 on annual basis, making the entire study area a moderate net sink of about +0.13 Tg C yr-1. This average sink value for forested lands nonetheless masks the contribution of areas burned during the 1988 wildfires, which were estimated as net sources of CO2 to the atmosphere, totaling to a NEP flux of -0.04 Tg C yr-1 for the entire burned area. Several areas burned in the 1988 wildfires were estimated to be among the lowest in overall yearly NPP, namely the Hellroaring Fire, Mink Fire, and Falls Fire areas. Rates of recovery for burned forest areas to pre-1988 biomass levels were estimated from a unique combination of remote sensing and CASA model predictions. Ecosystem production and carbon fluxes in the Greater Yellowstone Ecosystem (GYE) result from complex interactions between climate, forest age structure, and disturbance-recovery patterns of the landscape.

Determining nucleosynthesis yields in supernovae with spectral modelling

NASA Astrophysics Data System (ADS)

Jerkstrand, Anders

2018-04-01

The methodology to estimate element masses in supernova ejecta from nebular spectroscopy is discussed. Results using the SUMO spectral synthesis code are reviewed with regard to two key elements; oxygen (a hydrostatic burning ash) and nickel (an explosive burning ash). The typical oxygen mass in both Type IIP and IIb supernovae is found to be ˜0.5 M⊙, and points to progenitor stars in the 8 - 17 M⊙ range. For nickel, a new diagnostic method has been developed that shows Ni/Fe production close to solar in most cases, but sometimes larger by a factor of a few. It is shown that the larger values require the burning of silicon shell layers in the progenitor, a unique constraint on explosion theory.

40 CFR 610.42 - Fuel economy measurement.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Fuel economy measurement. (a) Fuel consumption will be measured by: (1) The carbon balance method, or... in addition to the emissions measuring equipment. (b) The carbon balance procedure for measuring fuel consumption relates the carbon products in the exhaust to the amount of fuel burned during the test. This...

40 CFR 610.42 - Fuel economy measurement.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Fuel economy measurement. (a) Fuel consumption will be measured by: (1) The carbon balance method, or... in addition to the emissions measuring equipment. (b) The carbon balance procedure for measuring fuel consumption relates the carbon products in the exhaust to the amount of fuel burned during the test. This...

40 CFR 610.42 - Fuel economy measurement.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Fuel economy measurement. (a) Fuel consumption will be measured by: (1) The carbon balance method, or... in addition to the emissions measuring equipment. (b) The carbon balance procedure for measuring fuel consumption relates the carbon products in the exhaust to the amount of fuel burned during the test. This...

40 CFR 610.42 - Fuel economy measurement.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Fuel economy measurement. (a) Fuel consumption will be measured by: (1) The carbon balance method, or... in addition to the emissions measuring equipment. (b) The carbon balance procedure for measuring fuel consumption relates the carbon products in the exhaust to the amount of fuel burned during the test. This...

40 CFR 60.2265 - What definitions must I know?

Code of Federal Regulations, 2013 CFR

2013-07-01

... hydrogen, carbon monoxide, synthesis gas, or other gases for use in other manufacturing processes. (7... liquids or solids to produce hydrogen, carbon monoxide, synthesis gas, or other gases for use in other...) Units burning only coke to produce purified carbon monoxide that is used as an intermediate in the...

40 CFR 60.2875 - What definitions must I know?

Code of Federal Regulations, 2013 CFR

2013-07-01

... purified carbon monoxide that is used as an intermediate in the production of other chemical compounds. (6) Units burning only hydrocarbon liquids or solids to produce hydrogen, carbon monoxide, synthesis gas, or... hydrogen, carbon monoxide, synthesis gas, or other gases for use in other manufacturing processes. (7...

40 CFR 60.2265 - What definitions must I know?

Code of Federal Regulations, 2014 CFR

2014-07-01

... hydrogen, carbon monoxide, synthesis gas, or other gases for use in other manufacturing processes. (7... liquids or solids to produce hydrogen, carbon monoxide, synthesis gas, or other gases for use in other...) Units burning only coke to produce purified carbon monoxide that is used as an intermediate in the...

40 CFR 60.2875 - What definitions must I know?

Code of Federal Regulations, 2014 CFR

2014-07-01

... purified carbon monoxide that is used as an intermediate in the production of other chemical compounds. (6) Units burning only hydrocarbon liquids or solids to produce hydrogen, carbon monoxide, synthesis gas, or... hydrogen, carbon monoxide, synthesis gas, or other gases for use in other manufacturing processes. (7...

Carbon benefits from fuel treatments

Treesearch

Jim Cathcart; Alan A. Ager; Andrew McMahan; Mark Finney; Brian Watt

2010-01-01

Landscape simulation modeling is used to examine whether fuel treatments result in a carbon offset from avoided wildfire emissions. The study landscape was a 169,200-acre watershed located in south-central Oregon. Burn probability modeling was employed under extreme weather and fuel moisture conditions. Expected carbon stocks post-treatment, post-wildfire were...

Trace gas emissions from biomass burning in tropical Australian savannas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurst, D.F.; Griffith, D.W.T.; Cook, G.D.

1994-08-20

The trace gas emissions of biomass burning was measured during the 1991 and 1992 dry seasons (April through October) at the Kapalga Research Station in Kakadu National Park, Northern Territory, Australia. Over 100 smoke samples from savannah fires were collected, from the ground and from aircraft flying at 50 to 700 meters above the fires. The samples were analyzed for carbon dioxide, carbon monoxide, nitrous oxides, and other carbon and nitrogen compounds using gas phase Fourier transform infrared (FTIR) spectroscopy, matrix isolation FTIR spectroscopy, and chemiluminescence techniques. This paper describes the results of the gas analyses and discusses the potentialmore » impacts of these gases on regional atmospheric chemistry.49 refs., 4 figs., 7 tabs.« less

Pre Conference Hazardous Materials Workshop, West/East Coast Safety Conference, held 3-4 October/31 October - 1 November 1981,

DTIC Science & Technology

1981-01-01

itation and ulceration of skin Blacher,. picklers (nicals). refiners (metals). tinners. c,".:mical manufactur- ing Hydrofluoric X Severe burning of skin...strong solutions are used) DNc,.g, felt hat industry Nitric X Severe skin burns and ulcers Nitric acid worker%, electroplaters. met- al refincr, acid...Fertilije, makers, gr:cultural workers. Calcium cyanamide alkali salt makers Calcium oxide, carbon- X Dermatitis,. burns , or ulcers Lime %orkers

Toxicity of Urban PM10 and Relation with Tracers of Biomass Burning

PubMed Central

Staelens, Jeroen; Koppen, Gudrun; Schoeters, Greet

2018-01-01

The chemical composition of particles varies with space and time and depends on emission sources, atmospheric chemistry and weather conditions. Evidence suggesting that particles differ in toxicity depending on their chemical composition is growing. This in vitro study investigated the biological effects of PM10 in relation to PM-associated chemicals. PM10 was sampled in ambient air at an urban traffic site (Borgerhout) and a rural background location (Houtem) in Flanders (Belgium). To characterize the toxic potential of PM10, airway epithelial cells (Beas-2B cells) were exposed to particles in vitro. Different endpoints were studied including cell damage and death (cell viability) and the induction of interleukin-8 (IL-8). The mutagenic capacity was assessed using the Ames II Mutagenicity Test. The endotoxin levels in the collected samples were analyzed and the oxidative potential (OP) of PM10 particles was evaluated by electron paramagnetic resonance (EPR) spectroscopy. Chemical characteristics of PM10 included tracers for biomass burning (levoglucosan, mannosan and galactosan), elemental and organic carbon (EC/OC) and polycyclic aromatic hydrocarbons (PAHs). Most samples displayed dose-dependent cytotoxicity and IL-8 induction. Spatial and temporal differences in PM10 toxicity were seen. PM10 collected at the urban site was characterized by increased pro-inflammatory and mutagenic activity as well as higher OP and elevated endotoxin levels compared to the background area. Reduced cell viability (−0.46 < rs < −0.35, p < 0.01) and IL-8 induction (−0.62 < rs < −0.67, p < 0.01) were associated with all markers for biomass burning, levoglucosan, mannosan and galactosan. Furthermore, direct and indirect mutagenicity were associated with tracers for biomass burning, OC, EC and PAHs. Multiple regression analyses showed levoglucosan to explain 16% and 28% of the variance in direct and indirect mutagenicity, respectively. Markers for biomass burning were associated with altered cellular responses and increased mutagenic activity. These findings may indicate a role of biomass burning in the observed adverse health effect of particulate matter. PMID:29439546

Characterization of biomass burning aerosols from forest fire in Indonesia

NASA Astrophysics Data System (ADS)

Fujii, Y.; Iriana, W.; Okumura, M.; Lestari, P.; Tohno, S.; Akira, M.; Okuda, T.

2012-12-01

Biomass burning (forest fire, wild fire) is a major source of pollutants, generating an estimate of 104 Tg per year of aerosol particles worldwide. These particles have adverse human health effects and can affect the radiation budget and climate directly and indirectly. Eighty percent of biomass burning aerosols are generated in the tropics and about thirty percent of them originate in the tropical regions of Asia (Andreae, 1991). Several recent studies have reported on the organic compositions of biomass burning aerosols in the tropical regions of South America and Africa, however, there is little data about forest fire aerosols in the tropical regions of Asia. It is important to characterize biomass burning aerosols in the tropical regions of Asia because the aerosol properties vary between fires depending on type and moisture of wood, combustion phase, wind conditions, and several other variables (Reid et al., 2005). We have characterized PM2.5 fractions of biomass burning aerosols emitted from forest fire in Indonesia. During the dry season in 2012, PM2.5 aerosols from several forest fires occurring in Riau, Sumatra, Indonesia were collected on quartz and teflon filters with two mini-volume samplers. Background aerosols in forest were sampled during transition period of rainy season to dry season (baseline period). Samples were analyzed with several analytical instruments. The carbonaceous content (organic and elemental carbon, OC and EC) of the aerosols was analyzed by a thermal optical reflectance technique using IMPROVE protocol. The metal, inorganic ion and organic components of the aerosols were analyzed by X-ray Fluorescence (XRF), ion chromatography and gas chromatography-mass spectrometry, respectively. There was a great difference of chemical composition between forest fire and non-forest fire samples. Smoke aerosols for forest fires events were composed of ~ 45 % OC and ~ 2.5 % EC. On the other hand, background aerosols for baseline periods were composed of ~ 18 % OC and ~ 10 % EC. OC/EC ratio was consistently lower (~ 2) for baseline periods than that for forest fire events (~ 20). OC and EC concentrations for forest fire events were more than 150 times and 10 times higher than those for baseline periods.

Predictors of sustaining burn injury: does the use of common prevention strategies matter?

PubMed

Taira, Breena R; Cassara, Guy; Meng, Hongdao; Salama, Michael N; Chohan, Jasmine; Sandoval, Steven; Singer, Adam J

2011-01-01

The incidence of burn injury has decreased over the past several decades. Although this has been largely attributed to increased prevention awareness, few studies evaluate the effectiveness of implementing standard burn prevention strategies in preventing burn injury. The authors hypothesized that patients who sustain burns use burn prevention strategies less frequently than those who do not. This was a case-control study composed of a prospective survey questionnaire and retrospective burn registry query, which was performed in a suburban academic medical center with a burn unit. All burn patients seen by the burn service in the year 2008 and a nonrandom sample of nonburned emergency department patients and visitors during the same time period were enrolled. Demographics included age, gender, income, education, house type, insurance status, and prevention strategy usage including smoke alarms, carbon monoxide detectors, fire extinguishers, and escape plans. The primary outcome of interest in this study was burn injury. Chi-square tests were used to compare rates, Student's t-tests were used to compare mean values of continuous variables between burn patients and others, and multivariate logistic regression was used to determine the strongest predictors of sustaining burn injury. One hundred ninety-four burn patients and 348 nonburned emergency department patients and visitors were surveyed. Burn patients reported the same rates of smoke alarm usage (96.9 vs 96.3%, P = .692), carbon monoxide detectors (75.3 vs 67.2%, P = .05), and higher rates of fire extinguisher ownership (80.4 vs 72.7%, P = .045) when compared with others. In multivariable analysis, the strongest predictor of sustaining burn injury was less than high school education (odds ratio [OR] 3.61, 95% confidence interval [CI] 1.27-10.27), whereas English as a primary language (OR 0.48, 95% CI 0.26-0.89), a graduate degree (OR 0.10, 95% CI 0.02-0.42), income >$50,000 (OR 0.46, 95% CI 0.29-0.72), and keeping flammable liquids in a locked place (OR 0.59, 95% CI 0.44-0.80) were protective against burn injury. Smoke alarms (OR 0.75, 95% CI 0.22-2.61), fire extinguishers (OR 1.34, 95% CI 0.80-2.32), and having an escape plan (OR 0.85, 95% CI 0.56-1.29) were not protective. Patients who sustain burn injury use burn prevention strategies at similar rates when compared with those who do not. When holding demographic characteristics constant, utilization of most burn prevention strategies is not protective of sustaining burn injury. Those with lower levels of education and income remain more susceptible to burn injury.

Snow Impurities on Central Asian Glaciers: Mineral Dust, Organic & Elemental Carbon

NASA Astrophysics Data System (ADS)

Schmale, J.; Kang, S.; Peltier, R.; Sprenger, M.; Guo, J.; Li, Y.; Zhang, Q.

2014-12-01

In Central Asia, 90 % of the population depend on water stored in glaciers and mountain snow cover. Accelerated melting can be induced by the deposition of e.g., mineral dust and black carbon that reduce the surface albedo. Data on source regions and chemical characteristics of snow impurities are however scarce in Central Asia. We studied aerosol deposited between summers of 2012 and 2013on three different glaciers in the Kyrgyz Republic. Samples were taken from two snow pits on the glacier Abramov in the northern Pamir and from one snow pit on Ak-Shiirak and Suek in the central Tien Shan. The snow was analyzed for elemental and total organic carbon, major ions and mineral dust. In addition, dissolved organic carbon was speciated by using the Aerodyne high-resolution time-of-flight aerosol spectrometer. Elevated mineral dust concentrations were found on all glaciers during summer and winter with lower annual average concentrations (20 mg l-1)in the northern Pamir (factor 5 to 6). Correlations between dust tracers varied, indicating different source regions. Average EC concentrations showed seasonal variation in the northern Pamir (> 100 μg l-1 in summer, < 30 μg l-1 in winter) while there was little variation throughout the year in the central Tien Shan (~ 200 μg l-1). Similarly, OC:EC ratios showed no seasonal cycle in that region averaging around 3. On Abramov, the ratio was significantly higher in winter (> 12) than in summer (< 4). The average O:C ratios across all glaciers ranged between 0.65 and 1.09, indicating a high degree of oxygenation which suggests long-range transport of the organic snow impurities. Marker substances such as potassium and mercury and their correlations suggest contribution from biomass burning emissions. Atmospheric measurements in August 2013 were conducted to obtain information on background aerosol characteristics in the remote high mountain areas. The average black carbon concentration was 0.26 μg/m³ (± 0.24 μg/m³).

Turbulent Nuclear Burning of Carbon Fuel in Double-Degenerate White Dwarfs

NASA Astrophysics Data System (ADS)

Mozumdar, Pritom; Fisher, Robert

2018-01-01

Type Ia supernovae (SNe Ia) are of interest as standardizable cosmological candles, though their stellar progenitors are still poorly understood. The double-degenerate (DD) channel is promising, but the mechanism for the explosion remains a matter of active investigation. A long-standing problem in modeling SNe Ia is the fact that 3D simulations leave the length scales crucial for a possible detonation unresolved. In this work, we have performed local 3D hydrodynamical adaptive mesh refinement simulations of driven turbulence for various initial conditions characteristic of the DD scenario, which are capable of capturing length scales relevant to the Zel’dovich gradient mechanism. Because the carbon burning rate is highly sensitive to temperature in this regime, we demonstrate that turbulence can dramatically enhance the nuclear burning rate, and we investigate the connection to a possible detonation.

Anthropogenic, biomass burning, and volcanic emissions of black carbon, organic carbon, and SO2 from 1980 to 2010 for hindcast model experiments

NASA Astrophysics Data System (ADS)

Diehl, T.; Heil, A.; Chin, M.; Pan, X.; Streets, D.; Schultz, M.; Kinne, S.

2012-09-01

Two historical emission inventories of black carbon (BC), primary organic carbon (OC), and SO2 emissions from land-based anthropogenic sources, ocean-going vessels, air traffic, biomass burning, and volcanoes are presented and discussed for the period 1980-2010. These gridded inventories are provided to the internationally coordinated AeroCom Phase II multi-model hindcast experiments. The horizontal resolution is 0.5°×0.5° and 1.0°×1.0°, while the temporal resolution varies from daily for volcanoes to monthly for biomass burning and aircraft emissions, and annual averages for land-based and ship emissions. One inventory is based on inter-annually varying activity rates of land-based anthropogenic emissions and shows strong variability within a decade, while the other one is derived from interpolation between decadal endpoints and thus exhibits linear trends within a decade. Both datasets capture the major trends of decreasing anthropogenic emissions over the USA and Western Europe since 1980, a sharp decrease around 1990 over Eastern Europe and the former USSR, and a steep increase after 2000 over East and South Asia. The inventory differences for the combined anthropogenic and biomass burning emissions in the year 2005 are 34% for BC, 46% for OC, and 13% for SO2. They vary strongly depending on species, year and region, from about 10% to 40% in most cases, but in some cases the inventories differ by 100% or more. Differences in emissions from wild-land fires are caused only by different choices of the emission factors for years after 1996 which vary by a factor of about 1 to 2 for OC depending on region, and by a combination of emission factors and the amount of dry mass burned for years up to 1996. Volcanic SO2 emissions, which are only provided in one inventory, include emissions from explosive, effusive, and quiescent degassing events for 1167 volcanoes.

Not carbon neutral: Assessing the net emissions impact of residues burned for bioenergy

NASA Astrophysics Data System (ADS)

Booth, Mary S.

2018-03-01

Climate mitigation requires emissions to peak then decline within two decades, but many mitigation models include 100 EJ or more of bioenergy, ignoring emissions from biomass oxidation. Treatment of bioenergy as ‘low carbon’ or carbon neutral often assumes fuels are agricultural or forestry residues that will decompose and emit CO2 if not burned for energy. However, for ‘low carbon’ assumptions about residues to be reasonable, two conditions must be met: biomass must genuinely be material left over from some other process; and cumulative net emissions, the additional CO2 emitted by burning biomass compared to its alternative fate, must be low or negligible in a timeframe meaningful for climate mitigation. This study assesses biomass use and net emissions from the US bioenergy and wood pellet manufacturing sectors. It defines the ratio of cumulative net emissions to combustion, manufacturing and transport emissions as the net emissions impact (NEI), and evaluates the NEI at year 10 and beyond for a variety of scenarios. The analysis indicates the US industrial bioenergy sector mostly burns black liquor and has an NEI of 20% at year 10, while the NEI for plants burning forest residues ranges from 41%-95%. Wood pellets have a NEI of 55%-79% at year 10, with net CO2 emissions of 14-20 tonnes for every tonne of pellets; by year 40, the NEI is 26%-54%. Net emissions may be ten times higher at year 40 if whole trees are harvested for feedstock. Projected global pellet use would generate around 1% of world bioenergy with cumulative net emissions of 2 Gt of CO2 by 2050. Using the NEI to weight biogenic CO2 for inclusion in carbon trading programs and to qualify bioenergy for renewable energy subsidies would reduce emissions more effectively than the current assumption of carbon neutrality.