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.

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.

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.

Aerial Sampling of Emissions from Biomass Pile Burns in ...

EPA Pesticide Factsheets

Abstract (already cleared). 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), black carbon, ultraviolet absorbing PM, elemental/organic carbon, semi-volatile organics (polycyclic aromatic hydrocarbons and polychlorinated dibenzodioxins/dibenzofurans), filter-based metals, and volatile organics were sampled for determination of emission factors. The effect on emissions from covering or not covering piles with polyethylene sheets to prevent fuel wetting was determined. Results showed that the uncovered (“wet”) piles burned with lower combustion efficiency and higher emissions of volatile organic compounds. Results for other pollutants will also be discussed. This work determines the first known in-field emission factors for burning of timber slash piles. The results also document the effect on emissions of covering the piles with polyethylene covers to reduce the moisture content of the biomass.

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.

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.

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.

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...

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.

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 .

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.

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.

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.

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.

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

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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).

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.

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.

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

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.

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.

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.

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.

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.

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).

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.

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.

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.

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 %).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment

EPA Science Inventory

Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental Hg (Hg0(g)). However, ...

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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 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.

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

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.

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.

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.

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.

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.

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.

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 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.

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.

Optical properties and possible sources of brown carbon in PM2.5 over Xi'an, China

NASA Astrophysics Data System (ADS)

Shen, Zhenxing; Zhang, Qian; Cao, Junji; Zhang, Leiming; Lei, Yali; Huang, Yu; Huang, R.-J.; Gao, Jinjin; Zhao, Zhuzi; Zhu, Chongshu; Yin, Xiuli; Zheng, Chunli; Xu, Hongmei; Liu, Suixin

2017-02-01

To quantify optical and chemical properties of PM2.5 brown carbon (BrC) in Xi'an, 58 high-volume ambient PM2.5 samples were collected during 2 November 2009 to 13 October 2010. Mass concentrations of chemical components were determined, including water-soluble ions, water-soluble organic carbon, levoglucosan, organic carbon (OC), and element carbon (EC). BrC, as an unidentified and wavelength-dependent organic compound, was also measured from water-soluble carbon (WSOC) at 340 nm using UV-vis spectrometer. The wavelength-dependent absorption coefficient (babs) and mass absorption coefficient (MAC) were much abundant at 340 nm, and the high Absorption Ångström coefficient (AAC) values were observed around 5.4, corresponding to the existence of BrC in ambient PM2.5, especially in winter. Good correlations (R > 0.60) between babs and biomass burning markers, such as levoglucosan and K+, in winter indicated significant amounts of primary BrC from biomass burning emissions. Secondary organic carbon BrC (SOCsbnd BrC) was more abundant in winter than in summer. SOCsbnd BrC in winter was mainly fresh SOC formed from aqueous phase reactions while in summer, aged SOC from photo-chemical formation. Source profiles of BrC optical parameters were detected, which verified sources of BrC from biomass burning and coal burning emissions in areas surrounding Xi'an. The rapidly decreasing babs-340nm values from biomass burning smoldering to straw pellet burning suggested that burning straw pellet instead of burning straw directly is an effective measure for reducing BrC emissions.

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.

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.

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.

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.

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

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.

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.

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...

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.

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.

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.

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.

Source Contributions to Wintertime Elemental and Organic Carbon in the Western Arctic Based on Radiocarbon and Tracer Apportionment.

PubMed

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

2015-10-06

To quantify the contributions of fossil and biomass sources to the wintertime Arctic aerosol burden source apportionment is reported for elemental (EC) and organic carbon (OC) fractions of six PM10 samples collected during a wintertime (2012-2013) campaign in Barrow, AK. Radiocarbon apportionment of EC indicates that fossil sources contribute an average of 68 ± 9% (0.01-0.07 μg m(-3)) in midwinter decreasing to 49 ± 6% (0.02 μg m(-3)) in late winter. The mean contribution of fossil sources to OC for the campaign was stable at 38 ± 8% (0.04-0.32 μg m(-3)). Samples were also analyzed for organic tracers, including levoglucosan, for use in a chemical mass balance (CMB) source apportionment model. The CMB model was able to apportion 24-53% and 99% of the OC and EC burdens, respectively, during the campaign, with fossil OC contributions ranging from 25 to 74% (0.02-0.09 μg m(-3)) and fossil EC contributions ranging from 73 to 94% (0.03-0.07 μg m(-3)). Back trajectories identified two major wintertime source regions to Barrow: the Russian and North American Arctic. Atmospheric lifetimes of levoglucosan, ranging from 50 to 320 h, revealed variability in wintertime atmospheric processing of this biomass burning tracer. This study allows for unambiguous apportionment of EC to fossil fuel and biomass combustion sources and intercomparison with CMB modeling.

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.

Characterization of Emissions from Heaters Burning Leaded Diesel Fuel in Unvented Tents

DTIC Science & Technology

1999-06-01

ultrafine particles . On the other hand, emissions from burning liquid fuels can be substantial in terms of both gas pollutants and particles. For...2.5) and the distribution of ultrafine particles can be estimated. The real-time particle and gas concentration can also be monitored. The...heaters produced fine and ultrafine particles . 19 Chemical Elemental Analysis Twenty-seven test runs were made under the various conditions. The air

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.

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.

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.

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

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.

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...

Fossil and contemporary sources of organic and elemental carbon at a rural and an urban site in the Netherlands

NASA Astrophysics Data System (ADS)

Dusek, U.; Monaco, M.; Weijers, E.; Röckmann, T.

2012-04-01

Measurement of the radioactive carbon isotope 14C in aerosols can provide a direct estimate of the contribution of fossil fuel sources to aerosol carbon. In aerosol science, measurements of 14C/12C ratios are usually reported as fraction modern (fm), relative to an oxalic acid standard that, by definition, has fm=1. The radiocarbon signature gives a clear distinction between 'modern' carbon sources (fm around 1.1-1.2 for biomass burning and around 1.05 for biogenic secondary organic aerosol) and 'fossil' carbon sources (fm =0 for primary and secondary formation from fossil fuel combustion). High volume filter samples have been collected since February 2011 at Cabauw, a rural location in the Netherlands, and additionally in May and June at two suburban locations around Rotterdam. We report measurements of fm for total carbon (TC), organic carbon (OC), water insoluble OC (WIOC) and thermally refractory carbon (RC) as a proxy for elemental carbon. The carbon fractions are isolated by combusting TC at 650 °C, OC and WIOC at 360 °C. Refractory carbon is defined as the carbon remaining on the filter after water extraction, combustion at 360 °C for 15 min and at 450 °C for 2 minutes. The method has been tested with test substances and real aerosol filters and shows little charring for water-extracted filters. First results of 7 filter samples taken from February - Mai 2011 show fm(OC) generally larger than 0.86 at the rural site, except for one case, when a strongly polluted air mass originating in Eastern Europe reached the site. This indicates a strong contribution of natural sources to OC, even in the Netherlands, a very densely populated country with one of the highest levels of aerosol pollution in Western Europe. In particular, WSOC in the rural springtime aerosol seems to originate almost entirely from contemporary sources. Refractory carbon also showed relatively high fm, generally between 0.3-0.5, except in two cases, when marine air masses reached the site from the West and fm(RC) dropped to around 0.1. This could mean that biomass combustion plays a significant role around the Netherlands even in springtime. It is also possible that there exists a biogenic, organic component of the aerosol that evolves at such high temperatures that it is virtually inseparable from elemental carbon. Both hypotheses are consistent with low fM(RC) in marine aerosol. One urban sample was taken concurrently with one of the samples analyzed so far from the rural site. For both OC and RC, fM values were roughly 10-15% lower in the urban area than at the rural sites, which shows only a moderate influence of the urban fossil emissions on fm. A more detailed comparison between the rural and urban location as well as fm values in other seasons will be presented, as more samples from the rural site become available.

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.

Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis

EPA Science Inventory

Thermal-optical analysis (TOA) is typically used to measure the OC/EC (organic carbon/elemental carbon) and EC/TC (elemental carbon/total carbon) ratios in source and atmospheric aerosols. The present study utilizes a dual-optical carbon aerosol analyzer to examine the effects of...

Isotopic anomalies from neutron reactions during explosive carbon burning

NASA Technical Reports Server (NTRS)

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

1978-01-01

The possibility that the newly discovered correlated isotopic anomalies for heavy elements in the Allende meteorite were synthesized in the secondary neutron capture episode during the explosive carbon burning, the possible source of the O-16 and Al-26 anomalies, is examined. Explosive carbon burning calculations under typical conditions were first performed to generate time profiles of temperature, density, and free particle concentrations. These quantities were inputted into a general neutron capture code which calculates the resulting isotopic pattern from exposing the preexisting heavy seed nuclei to these free particles during the explosive carbon burning conditions. The interpretation avoids the problem of the Sr isotopic data and may resolve the conflict between the time scales inferred from 1-129, Pu-244, and Al-26.

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).

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 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.

CHEMICAL CHARACTERIZATION OF AMBIENT PARTICULATE MATTER NEAR THE WORLD TRADE CENTER: ELEMENTAL CARBON, ORGANIC CARBON, AND MASS RECONSTRUCTION

EPA Science Inventory

Concentrations of elemental carbon (EC), organic carbon matter (OM), particulate matter less than 2.5 um (PM2.5), and reconstructed soil, trace element oxides, and sulfate are reported from four locations near the World Trade Center (WTC) complex for airborne particulate matter (...

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.

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.

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.

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.

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.

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.

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..

Particle Morphology From Wood-Burning Cook Stoves Emissions

NASA Astrophysics Data System (ADS)

Peralta, O.; Carabali, G.; Castro, T.; Torres, R.; Ruiz, L. G.; Molina, L. T.; Saavedra, I.

2013-12-01

Emissions from three wood-burning cook stoves were sampled to collect particles. Transmission electron microscope (TEM) copper grids were placed on the last two stages of an 8-stage MOUDI cascade impactor (d50= 0.32, and 0.18 μm). Samples were obtained on two heating stages of cooking, the first is a quick heating process to boil 1 liter of water, and the second is to keep the water at 90 C. Absorption coefficient, scattering coefficients, and particles concentration (0.01 - 2.5 μm aerodynamic diameter) were measured simultaneously using an absorption photometer (operated at 550 nm), a portable integrating nephelometer (at 530 nm), and a condensation particle counter connected to a chamber to dilute the wood stoves emissions. Transmission electron micrographic images of soot particles were acquired at different magnifications using a High Resolution Transmission Electron Microscope (HRTEM) JEOL HRTEM 4000EX operating at 200 kV, equipped with a GATAN digital micrograph system for image acquisition. The morphology of soot particles was analyzed calculating the border-based fractal dimension (Df). Particles sampled on the first heating stage exhibit complex shapes with high values of Df, which are present as aggregates formed by carbon ceno-spheres. The presence of high numbers of carbon ceno-spheres can be attributed to pyrolysis, thermal degradation, and others processes prior to combustion. Energy dispersive X-ray spectroscopy (EDS) was used to determine the elemental composition of particles. EDS analysis in particles with d50= 0.18 μm showed a higher content of carbonaceous material and relevant amounts of Si, S and K.

Valorisation of chicken feathers: Characterisation of chemical properties.

PubMed

Tesfaye, Tamrat; Sithole, Bruce; Ramjugernath, Deresh; Chunilall, Viren

2017-10-01

The characterisation of the chemical properties of the whole chicken feather and its fractions (barb and rachis), was undertaken to identify opportunities for valorizing this waste product. The authors have described the physical, morphological, mechanical, electrical and thermal properties of the chicken feathers and related them to potential valorisation routes of the waste. However, identification of their chemical properties is necessary to complete a comprehensive description of chicken feather fractions. Hence, the chicken feathers were thoroughly characterised by proximate and ultimate analyses, elemental composition, spectroscopic analyses, durability in different solvents, burning test, and hydrophobicity. The proximate analysis of chicken feathers revealed the following compositions: crude lipid (0.83%), crude fibre (2.15%), crude protein (82.36%), ash (1.49%), NFE (1.02%) and moisture content (12.33%) whereas the ultimate analyses showed: carbon (64.47%), nitrogen (10.41%), oxygen (22.34%), and sulphur (2.64%). FTIR analysis revealed that the chicken feather fractions contain amide and carboxylic groups indicative of proteinious functional groups; XRD showed a crystallinity index of 22. Durability and burning tests confirmed that feathers behaved similarly to animal fibre. This reveals that chicken feather can be a valuable raw material in textile, plastic, cosmetics, pharmaceuticals, biomedical and bioenergy industries. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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 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.

Method 440.0 Determination of Carbon and Nitrogen in Sediments and Particulatesof Estuarine/Coastal Waters Using Elemental Analysis

EPA Science Inventory

Elemental analysis is used to determine particulate carbon (PC) and particulate nitrogen (PN) in estuarine and coastal waters and sediment. The method measures the total carbon and nitrogen irrespective of source (inorganic or organic).

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

Particulate matter in Southwestern Africa cities of Cotonou (Benin) and Abidjan (Côte d'Ivoire).

NASA Astrophysics Data System (ADS)

Leon, J. F.; Djossou, J.; Liousse, C.; Akpo, A.; Veronique, Y.; Gardrat, E.; Bedou, M.; Bodjrenou, M.

2017-12-01

Air quality observations in the major cities of South-Western Africa still remains few with regards to economic growth and the large increase in the urban population. The main cities lying on the Gulf of Guinea experiences low air quality because of the contribution of local emissions and advection of pollutants from the African continent. We present in this paper new observations acquired from February 2015 to March 2017 in the major cities of Cotonou (Bénin) and Abidjan (Côte d'Ivoire). The PM2.5 mass concentration and carbon composition (elemental and organic carbon) were recorded on a weekly basis at 4 different locations representative of major emission sources, i.e. traffic emission, domestic fire and waste burning. Additionally, the aerosol optical depth (AOD) was also recorded daily inside and outside the cities. We observe large similarly between both cities. The mean PM2.5 concentration of around 30 µg.m-3 is coherent with previous studies for sub-Saharan western Africa and is 3 times higher than the concentrations recommended by the World Health Organization. The sampled collected at the domestic fire site shows a large pollution by smoking activity with an average concentration of 145 µg.m-3, nearly 5 times the traffic background. The seasonality of PM2.5 is affected by the contribution of desert dust and biomass burning emissions that is clearly observed from the AOD time series. We observe that dust events contribute sporadically to large amount of PM2.5, above 100 µg.m-3, during the dry seasons. Moreover, the biomass burning activity is also maximum before and during the dry season and contributes to increase the PM2.5 concentration. Low PM2.5 observed during the minor dry season can be explain by an enhancement of the atmospheric dispersion due to the increase in the wind intensity and the absence of biomass burning activity. We observe a significant difference in the carbonaceous aerosols between the traffic site in Abidjan and Cotonou. The mean OC/EC ratio is on average 4.0 for Cotonou and 2.0 for Abidjan, clearly indicating the larger contribution emission by the 2-wheel motorcycles in Cotonou compared to Abidjan

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.

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

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.

Simply scan--optical methods for elemental carbon measurement in diesel exhaust particulate.

PubMed

Forder, James A

2014-08-01

This article describes a performance assessment of three optical methods, a Magee Scientific OT21 Transmissometer, a Hach-Lange Microcolor II difference gloss meter, and a combination of an office scanner with Adobe Photoshop software. The optical methods measure filter staining as a proxy for elemental carbon in diesel exhaust particulate (DEP) exposure assessment and the suitability of each as a replacement for the existing Bosch meter optical method. Filters loaded with DEP were produced from air in a non-coal mine and the exhaust gases from a mobile crane. These were measured with each apparatus and then by combustion to obtain a reference elemental carbon value. The results from each apparatus were then plotted against both the Bosch number and reference elemental carbon values. The equations of the best fit lines for these plots were derived, and these gave functions for elemental carbon and Bosch number from the output of each new optical method. For each optical method, the range of DEP loadings which can be measured has been determined, and conversion equations for elemental carbon and Bosch number have been obtained. All three optical methods studied will effectively quantify blackness as a measure of elemental carbon. Of these the Magee Scientific OT21 transmissometer has the best performance. The Microcolor II and scanner/photoshop methods will in addition allow conversion to Bosch number which may be useful if historical Bosch data are available and functions for this are described. The scanner/photoshop method demonstrates a technique to obtain measurements of DEP exposure without the need to purchase specialized instrumentation. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

EPA Science Inventory

The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

1999-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate-solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

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.

Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

NASA Technical Reports Server (NTRS)

Hung, Ching-Chen (Inventor)

1999-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a percursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

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.

Impacts of controlling biomass burning emissions on wintertime carbonaceous aerosol in Europe

NASA Astrophysics Data System (ADS)

Fountoukis, C.; Butler, T.; Lawrence, M. G.; Denier van der Gon, H. A. C.; Visschedijk, A. J. H.; Charalampidis, P.; Pilinis, C.; Pandis, S. N.

2014-04-01

We use a 3-D regional chemical transport model, with the latest advancements in the organic aerosol (OA) treatment, and an updated emission inventory for wood combustion to study the organic aerosol change in response to the replacement of current residential wood combustion technologies with pellet stoves. Simulations show a large decrease of fine organic aerosol (more than 60%) in urban and suburban areas during winter and decreases of 30-50% in elemental carbon levels in large parts of Europe. There is also a considerable decrease (around 40%) of oxidized OA, mostly in rural and remote regions. Total PM2.5 mass is predicted to decrease by 15-40% on average during the winter in continental Europe. Accurate representation of the intermediate volatility precursors of organic aerosol in the emission inventory is crucial in assessing the efficiency of such abatement strategies.

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.

Elemental and Organic Carbon Measurements at the Kosetice Observatory, Czech Republic within EU Projects in 2009-2014

NASA Astrophysics Data System (ADS)

Vana, M.; Holubova, A.; Cech, J.

2016-12-01

Carbonaceous aerosol (TC) is a complex mixture of many organics (OC fraction) and elemental carbon (EC). EC is a product of anthropogenic activities, especially incomplete combustion of fossil fuels by transport, heating, power plants, wood and biomass burning and agriculture activities. EC could have larger health impact than other PM constituents (Cassee et al., 2013). Carbonaceous aerosols also play an important role in climate change (Boucher et al., 2013). Kosetice Observatory, operated by the Czech Hydrometeorological Institute has been carrying out long-term air quality monitoring at the background scale the Czech Republic since 1988. Regular EC-OC measurement has been implementing within EU-projects EUSAAR and ACTRIS since 2009. Sampling frequency is every 6th day in fraction PM2,5 on 2 quartz-fibre filters. Since October 2011 the sampling on filters has been implementing behind the denuder catching the organic vapor. Amount of OC on back quartz fiber filter represents positive artifact by measurement without denuder and negative artifact by measurements with denuder. The analytical method is thermal-optical analysis. The samples are analyzed in CHMI Central Laboratories in Prague-Libuš using EC-OC Sunset Lab Dual Analyzer. Charring correction is made by laser transmission monitoring. Slightly decreasing tendency of EC-OC was found in the period under review (2009-2014). The mean annual concentration of total carbon (TC) in PM2,5 was 3,73 µg.m-3. The figure for elemental carbon (0,5 µg.m-3) represents the mean annual ratio of 13% on TC. EC-OC concentrations follow an annual course that reflects their emission levels, i.e. with maximums in winter and minimums in summer. The seasonal variation of EC/TC ratio ranges between 9,6 (summer) - 14,2% (winter). Mean TC ratio on PM2,5 total mass in the period under review was 29%, the highest ratios reached 50%. EC participated on PM2,5 total mass by 3,5% in average. 3D trajectories were used for sector analysis of measured EC-OC data (NILU, 2016). The highest concentrations are recorded in situations when air masses reach the territory of the Czech Republic from the north-eastern directions or the local air masses prevailing. The differences between sectors are much larger in the cold period of the year.

ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR

EPA Science Inventory

The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

Soot on snow in Iceland: First results on black carbon and organic carbon in Iceland 2016 snow and ice samples, including the glacier Solheimajökull

NASA Astrophysics Data System (ADS)

Meinander, Outi; Dagsson-Waldhauserova, Pavla; Gritsevich, Maria; Aurela, Minna; Arnalds, Olafur; Dragosics, Monika; Virkkula, Aki; Svensson, Jonas; Peltoniemi, Jouni; Kontu, Anna; Kivekäs, Niku; Leppäranta, Matti; de Leeuw, Gerrit; Laaksonen, Ari; Lihavainen, Heikki; Arslan, Ali N.; Paatero, Jussi

2017-04-01

New results on black carbon (BC) and organic carbon (OC) on snow and ice in Iceland in 2016 will be presented in connection to our earlier results on BC and OC on Arctic seasonal snow surface, and in connection to our 2013 and 2016 experiments on effects of light absorbing impurities, including Icelandic dust, on snow albedo, melt and density. Our sampling included the glacier Solheimajökull in Iceland. The mass balance of this glacier is negative and it has been shrinking during the last 20 years by 900 meters from its southwestern corner. Icelandic snow and ice samples were not expected to contain high concentrations of BC, as power generation with domestic renewable water and geothermal power energy sources cover 80 % of the total energy consumption in Iceland. Our BC results on filters analyzed with a Thermal/Optical Carbon Aerosol Analyzer (OC/EC) confirm this assumption. Other potential soot sources in Iceland include agricultural burning, industry (aluminum and ferroalloy production and fishing industry), open burning, residential heating and transport (shipping, road traffic, aviation). On the contrary to low BC, we have found high concentrations of organic carbon in our Iceland 2016 samples. Some of the possible reasons for those will be discussed in this presentation. Earlier, we have measured and reported unexpectedly low snow albedo values of Arctic seasonally melting snow in Sodankylä, north of Arctic Circle. Our low albedo results of melting snow have been confirmed by three independent data sets. We have explained these low values to be due to: (i) large snow grain sizes up to 3 mm in diameter (seasonally melting snow); (ii) meltwater surrounding the grains and increasing the effective grain size; (iii) absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon) in snow of 87 ppb, and organic carbon 2894 ppb. The high concentrations of carbon were due to air masses originating from the Kola Peninsula, Russia, where mining and refining industries are located. SNICAR-model showed that the impurities absorb irradiance the more the shorter the wavelength. We have also presented a hypothesis that soot can decrease the liquid-water retention capacity of melting snow. There we also presented data, where both the snow density and elemental carbon content were measured. In our snow density related experiments, artificially added light-absorbing impurities decreased the density of seasonally melting natural snow. No relationship was found in case of natural non-melting snow. Our experimental results on Icelandic volcanic ash have showed that Eyjafjällajökull ash with grain size smaller than 500 μm insulated the ice below at a thickness of 9-15 mm (called as 'critical thickness'). For the 90 μm grain size, the insulation thickness was 13 mm. The maximum melt occurred at thickness of 1mm for the larger particles, and at the thickness of < 1-2 mm for the smaller particles (called as 'effective thickness'). Earlier, similar threshold dust layer thickness values have been given for Mt St Helens (1980) ash, and Hekla (1947) tephra, but our results were the first ones reported for the Eyjafjällajökull ash. In Iceland, the dust layers in the nature can be from mm scale up to tens of meters. Our results clearly demonstrate how important it is in the Arctic to perform measurements of BC, OC, and dust in the snow to fully understand the effects of light absorbing impurities on the cryosphere.

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.

SAMPLING ARTIFACTS IN MEASUREMENT OF ELEMENTAL AND ORGANIC CARBON: LOW VOLUME SAMPLING IN INDOOR AND OUTDOOR ENVIRONMENTS

EPA Science Inventory

Experiments were completed to determine the extent of artifacts from sampling elemental carbon (EC) and organic carbon (OC) under sample conditions consistent with personal sampling. Two different types of experiments were completed; the first examined possible artifacts from oil...

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.

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.

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.

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...

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

Persistence of organic carbon in heated aerosol residuals measured during Tropical Composition Cloud and Climate Coupling (TC4)

NASA Astrophysics Data System (ADS)

Thornberry, T.; Froyd, K. D.; Murphy, D. M.; Thomson, D. S.; Anderson, B. E.; Thornhill, K. L.; Winstead, E. L.

2010-05-01

The Particle Analysis by Laser Mass Spectrometry (PALMS) single particle mass spectrometer was used to analyze the composition of the nonvolatile fraction of atmospheric aerosol in a number of different environments. The mass spectra of individual particles sampled through an inlet section heated to 300°C were compared to unheated particles during flights of the NASA DC-8 aircraft during the Tropical Composition Cloud and Climate Coupling (TC4) mission. Comparisons are presented of measurements made in the marine boundary layer, the free troposphere, and the continental boundary layer over the Colombian jungle. The heated section completely removed sulfate from the aerosols except for sodium sulfate and related compounds in sea salt particles. Organic material in sea salt particles was observed to be less volatile than chlorine. Biomass burning particles were more likely to survive heating than other mixed sulfate-organic particles. For all particle types, there was a significant contribution to the residues from carbonaceous material other than elemental carbon. These results demonstrate the remaining compositional complexity of aerosol residuals that survive heating in a thermal denuder.

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.

Radiative response of biomass-burning aerosols over an urban atmosphere in northern peninsular Southeast Asia.

PubMed

Pani, Shantanu Kumar; Lin, Neng-Huei; Chantara, Somporn; Wang, Sheng-Hsiang; Khamkaew, Chanakarn; Prapamontol, Tippawan; Janjai, Serm

2018-08-15

A large concentration of finer particulate matter (PM 2.5 ), the primary air-quality concern in northern peninsular Southeast Asia (PSEA), is believed to be closely related to large amounts of biomass burning (BB) particularly in the dry season. In order to quantitatively estimate the contributions of BB to aerosol radiative effects, we thoroughly investigated the physical, chemical, and optical properties of BB aerosols through the integration of ground-based measurements, satellite retrievals, and modelling tools during the Seven South East Asian Studies/Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles & Interactions Experiment (7-SEAS/BASELInE) campaign in 2014. Clusters were made on the basis of measured BB tracers (Levoglucosan, nss-K + , and NO 3 - ) to classify the degree of influence from BB over an urban atmosphere, viz., Chiang Mai (18.795°N, 98.957°E, 354m.s.l.), Thailand in northern PSEA. Cluster-wise contributions of BB to PM 2.5 , organic carbon, and elemental carbon were found to be 54-79%, 42-79%, and 39-77%, respectively. Moreover, the cluster-wise aerosol optical index (aerosol optical depth at 500nm≈0.98-2.45), absorption (single scattering albedo ≈0.87-0.85; absorption aerosol optical depth ≈0.15-0.38 at 440nm; absorption Ångström exponent ≈1.43-1.57), and radiative impacts (atmospheric heating rate ≈1.4-3.6Kd -1 ) displayed consistency with the degree of BB. PM 2.5 during Extreme BB (EBB) was ≈4 times higher than during Low BB (LBB), whereas this factor was ≈2.5 for the magnitude of radiative effects. Severe haze (visibility≈4km) due to substantial BB loadings (BB to PM 2.5 ≈79%) with favorable meteorology can significantly impact the local-to-regional air quality and the, daily life of local inhabitants as well as become a respiratory health threat. Additionally, such enhancements in atmospheric heating could potentially influence the regional hydrological cycle and crop productivity over Chiang Mai in northern PSEA. Copyright © 2018 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.

A Critical Review of the Impacts of Leaking CO 2 Gas and Brine on Groundwater Quality

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

Qafoku, Nikolla; Zheng, Liange; Bacon, Diana H.

2015-09-30

Geological carbon sequestration (GCS) is a global carbon emission reduction strategy involving the capture of CO 2 emitted from fossil fuel burning power plants, as well as the subsequent injection of the captured CO 2 gas into deep saline aquifers or depleted oil and gas reservoirs. A critical question that arises from the proposed GCS is the potential impacts of CO 2 injection on the quality of drinking-water systems overlying CO 2 sequestration storage sites. Although storage reservoirs are evaluated and selected based on their ability to safely and securely store emplaced fluids, leakage of CO 2 from storage reservoirsmore » is a primary risk factor and potential barrier to the widespread acceptance of geologic CO 2 sequestration (OR Harvey et al. 2013; Y-S Jun et al. 2013; DOE 2007). Therefore, a systematic understanding of how CO 2 leakage would affect the geochemistry of potable aquifers, and subsequently control or affect elemental and contaminant release via sequential and/or simultaneous abiotic and biotic processes and reactions is vital.« less

Photochemical properties and source of pollutants during continuous pollution episodes in Beijing, October, 2011.

PubMed

Gao, Jian; Zhang, Yuechong; Zhang, Meng; Zhang, Jingqiao; Wang, Shulan; Tao, Jun; Wang, Han; Luo, Datong; Chai, Fahe; Ren, Chun

2014-01-01

Beijing suffered from serious air pollution in October, 2011 with the occurrence of three continuous episodes. Here we analyze the pollution status of particulate matter, the relationship between the gaseous pollutants, physical and chemical properties of single particles, and the profile of water-soluble ions in PM2.5 during the three episodes. Regional and photochemically aged air masses, which were characterized as having high values of O3 and SO2, were hypothesized to have played a dominant role in the first episode. After mixing local air masses with freshly-emitted primary pollutants, the concentration of NO(x) continued to increase and the size of SO4(2-), NO3(-) and NH4(+) in the particle population continued to become smaller. The amount of elemental carbon-rich and organic carbon-rich particles in the scaled single particles (0.2-2 microm) and water-soluble K(+) in PM2.5 also increased in the episodes. All the available information suggests that the biomass or fuel burning sources in or around Beijing may have had a huge impact on the last two episodes.

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.

IMPROVING SOURCE PROFILES AND APPORTIONMENT OF COMBUSTION SOURCES USING THERMAL CARBON FRACTIONS IN MULTIVARIATE RECEPTOR MODELS

EPA Science Inventory

The purpose of this study was to improve combustion source profiles and apportionment of a PM2.5 urban aerosol by using 7 individual organic and elemental carbon thermal fractions in place of total organic and elemental carbon. This study used 3 years (96-99) of speciated data...

Symposium on the Tropospheric Chemistry of the Antarctic Region: Pre- Conference Abstracts

DTIC Science & Technology

1991-06-01

and composition); elemental carbon particles can scatter and absorb solar radiation. In addition, molecular species present as organic carbon aerosol ...elemental carbon to organic carbon aerosol particles are measured. This accounting pro- vides useful information needed to describe the ambient levels... Particle Analysis of Five Years of Aerosol Sampling in the Antarctic Peninsula P. Artaxo, W. M aenhaut and Rend Van Grieken

PRIMARY AND SECONDARY ORGANIC AEROSOLS OVER THE UNITED STATES: ESTIMATES ON THE BASIS OF OBSERVED ORGANIC CARBON (OC) AND ELEMENTAL CARBON (EC), AND AIR QUALITY MODELED PRIMARY (OC/EC) RATIOS

EPA Science Inventory

The temporal and spatial distributions of primary and secondary organic carbon aerosols (OC) over the continental US during June 15 to August 31, 1999, were estimated by using observational OC and elemental carbon (EC) data from Interagency Monitoring of Protected Visual Environm...

On diamond, graphitic and amorphous carbons in primitive extraterrestrial solar system materials

NASA Technical Reports Server (NTRS)

Rietmeijer, Frans J. M.

1990-01-01

Carbon is among the most abundant elements in the universe and carbon chemistry in meteorites and comets is an important key to understanding many Solar System and interstellar processes. Yet, the mineralogical properties and interrelations between various structural forms of elemental carbon remain ambiguous. Crystalline elemental carbons include rhombohedral graphite, hexagonal graphite, cubic diamond, hexagonal diamond (i.e., lonsdaleite or carbon-2H) and chaoite. Elemental carbon also occurs as amorphous carbon and poorly graphitized (or turbostratic) carbon but of all the forms of elemental carbon only graphite is stable under physical conditions that prevail in small Solar System bodies and in the interstellar medium. The recent discovery of cubic diamond in carbonaceous chondrites and hexagonal diamond in chondritic interplanetary dust particles (IDPs) have created a renewed interest in the crystalline elemental carbons that were not formed by shock processes on a parent body. Another technique, Raman spectroscopy, confirms a widespread occurrence of disordered graphite in the Allende carbonaceous chondrite and in chondritic IDPs. Elemental carbons have also been identified by their characteristic K-edge features in electron energy loss spectra (EELS). However, the spectroscopic data do not necessarily coincide with those obtained by selected area electron diffraction (SAED). In order to interpret these data in terms of rational crystalline structures, it may be useful to consider the principles underlying electron diffraction and spectroscopic analyses. Electron diffraction depends on electron scattering, on the type of atom and the distance between atoms in a crystal lattice. Spectroscopic data are a function of the type of atom and the energy of bonds between atoms. Also, SAED is a bulk sampling technique when compared to techniques such as Raman spectroscopy or EELS. Thus, it appears that combined analyses provide contradictory results and that amorphous, or short-range ordered, carbon identified by conventional TEM imaging and SAED may show evidence for sp(3) bonds in EELS spectra. It is suggested that complex, nanometer-scale, mineralogical interrelations are common to all elemental carbons irrespective of their origin. The subsequent thermal history, or energy balance, will determine the ultimate microstructure.

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...

What predictions can be made on the nature of carbon and carbon-bearing compounds (hydrocarbons) in the interstellar medium based on studies of interplanetary dust particles?

NASA Technical Reports Server (NTRS)

Rietmeijer, F. J. M.

1986-01-01

The nature of hydrocarbons and properties of elemental carbon in circumstellar, interstellar, and interplanetary dust is a long standing problem in astronomy and meteorite research. The textures and crystallographical properties of poorly graphitized carbon (PGC) from carbonaceous chondrites and Chondritic Porous Aggregates (CPAs) are comparable with PGCs formed by dehydrogenation and carbonization of hydrocarbon precursors under natural terrestrial and experimental conditions. A multistage model of hydrocarbon diagenesis in CPA and carbonaceous chondrite (proto-) planetary parent bodies was proposed in which hydrocarbons are subjected to low temperature hydrous pyrolysis. Continued efforts to recognize hydrocarbons and elemental phases in CPAs may allow understanding of the multistage hydrocarbon/elemental carbon model.

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...

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.

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.

Carbide and carbonitride surface treatment method for refractory metals

DOEpatents

Meyer, G.A.; Schildbach, M.A.

1996-12-03

A carbide and carbonitride surface treatment method for refractory metals is provided, in steps including, heating a part formed of boron, chromium, hafnium, molybdenum, niobium, tantalum, titanium, tungsten or zirconium, or alloys thereof, in an evacuated chamber and then introducing reaction gases including nitrogen and hydrogen, either in elemental or water vapor form, which react with a source of elemental carbon to form carbon-containing gaseous reactants which then react with the metal part to form the desired surface layer. Apparatus for practicing the method is also provided, in the form of a carbide and carbonitride surface treatment system including a reaction chamber, a source of elemental carbon, a heating subassembly and a source of reaction gases. Alternative methods of providing the elemental carbon and the reaction gases are provided, as well as methods of supporting the metal part, evacuating the chamber with a vacuum subassembly and heating all of the components to the desired temperature. 5 figs.

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...

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

Non-polar organic compounds in marine aerosols over the northern South China Sea: Influence of continental outflow.

PubMed

Zhao, Yan; Zhang, Yingyi; Fu, Pingqing; Ho, Steven Sai Hang; Ho, Kin Fai; Liu, Fobang; Zou, Shichun; Wang, Shan; Lai, Senchao

2016-06-01

Filter samples of total suspended particle (TSP) collected during a cruise campaign over the northern South China Sea (SCS) from September to October 2013 were analyzed for non-polar organic compounds (NPOCs) as well as organic carbon (OC), elemental carbon (EC) and water-soluble ions. A total of 115 NPOCs species in groups of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), iso-/antiso-alkanes, hopanes, steranes, methylalkanes, branched alkanes, cycloalkanes, alkenes and phthalates were detected. The characteristics of NPOCs in marine TSP samples were investigated to understand the sources from the Asian continent and other regions. The concentrations of total NPOCs ranged from 19.8 to 288.2 ng/m(3) with an average of 87.9 ng/m(3), which accounted for 0.8-1.7% (average 1.0%) of organic matter (OM). n-Alkanes was the predominant group, accounting for 43.1-79.5%, followed by PAHs (5.5-44.4%) and hopanes (1.6-11.4%). We found that primary combustion (biomass burning/fossil fuel combustion) was the dominant source for the majority of NPOCs (89.1%). Biomass burning in southern/southeastern China via long-range transport was proposed to be a major contributor of NPOCs in marine aerosols over the northern SCS, suggested by the significant correlations between nss-K(+) and NPOCs groups as well as the analysis of air mass back-trajectory and fire spots. For the samples with strong continental influence, the strong enhancement in concentrations of n-alkanes, PAHs, hopanes and steranes were attributed to fossil fuel (coal/petroleum) combustion. In addition, terrestrial plants waxes were another contributor to NPOCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Simulating the transport and chemical evolution of biomass burning pollutants originating from Southeast Asia during 7-SEAS/2010 Dongsha experiment

NASA Astrophysics Data System (ADS)

Chuang, Ming-Tung; Fu, Joshua S.; Lin, Neng-Huei; Lee, Chung-Te; Gao, Yang; Wang, Sheng-Hsiang; Sheu, Guey-Rong; Hsiao, Ta-Chih; Wang, Jia-Lin; Yen, Ming-Cheng; Lin, Tang-Huang; Thongboonchoo, Narisara; Chen, Wei-Chen

2015-07-01

This study aimed to simulate the transport of biomass burning (BB) aerosol originating from Southeast Asia (SEA) during the Dongsha Experiment conducted from March 2010 to April 2010. Transport pathways were reanalyzed and steering flow in the mid-latitude areas and anticyclones in low-latitude areas were found to control the transport of BB plume after it was injected to a high atmosphere. For the 12 simulated and observed events at Mt. Lulin (2862 m MSL; 23°28‧07″ N, 120°52‧25″ E), the 72 h backward trajectories were all tracked back to southern China and northern Indochina, which were the locations of the largest BB fire activities in SEA. Chemical evolutions of BB pollutants along the moving trajectories showed that organic matter was always the dominant component in PM2.5, consistent with the observations at both near-source regions and Mt. Lulin. For nitrogen species, nearly all NOx molecules oxidized into HNO3, NO3-, PAN, and PANX in fires or near fires. The synchronic consumption of NOx, SO2, and NH3 explained the production of the major components of inorganic salts. In the moving BB plume, sulfate concentration increased with decreased nitrate concentration. Ratios of ammonium to PM2.5 and elemental carbon to PM2.5 remained nearly constant because additional sources were lacking.

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.

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...

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.

Quantifying black carbon light absorption enhancement with a novel statistical approach

NASA Astrophysics Data System (ADS)

Wu, Cheng; Wu, Dui; Zhen Yu, Jian

2018-01-01

Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, Eabs, was quantified using a 1-year measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAEp), the key for Eabs estimation, is demonstrated using the minimum R squared (MRS) method, exploring the inherent source independency between BC and its coating materials. A unique feature of Eabs estimation with the MRS approach is its insensitivity to systematic biases in elemental carbon (EC) and σabs measurements. The annual average Eabs550 is found to be 1.50 ± 0.48 (±1 SD) in the PRD region, exhibiting a clear seasonal pattern with higher values in summer and lower in winter. Elevated Eabs in the summertime is likely associated with aged air masses, predominantly of marine origin, along with long-range transport of biomass-burning-influenced air masses from Southeast Asia. Core-shell Mie simulations along with measured Eabs and absorption Ångström exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than in the dry season.

Reducing mortality risk by targeting specific air pollution sources: Suva, Fiji.

PubMed

Isley, C F; Nelson, P F; Taylor, M P; Stelcer, E; Atanacio, A J; Cohen, D D; Mani, F S; Maata, M

2018-01-15

Health implications of air pollution vary dependent upon pollutant sources. This work determines the value, in terms of reduced mortality, of reducing ambient particulate matter (PM 2.5 : effective aerodynamic diameter 2.5μm or less) concentration due to different emission sources. Suva, a Pacific Island city with substantial input from combustion sources, is used as a case-study. Elemental concentration was determined, by ion beam analysis, for PM 2.5 samples from Suva, spanning one year. Sources of PM 2.5 have been quantified by positive matrix factorisation. A review of recent literature has been carried out to delineate the mortality risk associated with these sources. Risk factors have then been applied for Suva, to calculate the possible mortality reduction that may be achieved through reduction in pollutant levels. Higher risk ratios for black carbon and sulphur resulted in mortality predictions for PM 2.5 from fossil fuel combustion, road vehicle emissions and waste burning that surpass predictions for these sources based on health risk of PM 2.5 mass alone. Predicted mortality for Suva from fossil fuel smoke exceeds the national toll from road accidents in Fiji. The greatest benefit for Suva, in terms of reduced mortality, is likely to be accomplished by reducing emissions from fossil fuel combustion (diesel), vehicles and waste burning. Copyright © 2017. Published by Elsevier B.V.

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.

AN ELECTROCHEMICAL SYSTEM FOR REMOVING AND RECOVERING ELEMENTAL MERCURY FROM FLUE-STACK GASES

EPA Science Inventory

the impending EPA regulations on the control of mercury emissions from the flue stacks of coal-burning electric utilities has resulted in heightened interest in the development of advanced mercury control technologies such as sorbent injection and in-situ mercury oxidation. Altho...

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.

Diagnostic air quality model evaluation of source-specific primary and secondary fine particulate carbon.

PubMed

Napelenok, Sergey L; Simon, Heather; Bhave, Prakash V; Pye, Havala O T; Pouliot, George A; Sheesley, Rebecca J; Schauer, James J

2014-01-01

Ambient measurements of 78 source-specific tracers of primary and secondary carbonaceous fine particulate matter collected at four midwestern United States locations over a full year (March 2004-February 2005) provided an unprecedented opportunity to diagnostically evaluate the results of a numerical air quality model. Previous analyses of these measurements demonstrated excellent mass closure for the variety of contributing sources. In this study, a carbon-apportionment version of the Community Multiscale Air Quality (CMAQ) model was used to track primary organic and elemental carbon emissions from 15 independent sources such as mobile sources and biomass burning in addition to four precursor-specific classes of secondary organic aerosol (SOA) originating from isoprene, terpenes, aromatics, and sesquiterpenes. Conversion of the source-resolved model output into organic tracer concentrations yielded a total of 2416 data pairs for comparison with observations. While emission source contributions to the total model bias varied by season and measurement location, the largest absolute bias of -0.55 μgC/m(3) was attributed to insufficient isoprene SOA in the summertime CMAQ simulation. Biomass combustion was responsible for the second largest summertime model bias (-0.46 μgC/m(3) on average). Several instances of compensating errors were also evident; model underpredictions in some sectors were masked by overpredictions in others.

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).

The application of carbon-14 analyses to the source apportionment of atmospheric carbonaceous particulate matter: a review.

PubMed

Heal, Mathew R

2014-01-01

Organic carbon (OC) and elemental carbon (EC) together constitute a substantial proportion of airborne particulate matter (PM). Insight into the sources of this major contributor to PM is important for policies to mitigate the impact of PM on human health and climate change. In recent years measurement of the abundance of the radioisotope of carbon ((14)C) in samples of PM by accelerator mass spectrometry has been used to help quantify the relative contributions from sources of fossil carbon and contemporary carbon. This review provides an introduction to the different sources of carbon within PM and the role of (14)C measurements, a description of the preparation of PM samples and of the instrumentation used to quantify (14)C, and a summary of the results and source apportionment methods reported in published studies since 2004. All studies report a sizable fraction of the carbonaceous PM as of non-fossil origin. Even for PM collected in urban locations, the proportions of non-fossil carbon generally exceed 30%; typically the proportion in urban background locations is around 40-60% depending on the local influence of biomass burning. Where values have been measured directly, proportions of non-fossil carbon in EC are lower than in OC, reflecting the greater contribution of fossil-fuel combustion to EC and the generally small sources of contemporary EC. Detailed source apportionment studies point to important contributions from biogenic-derived secondary OC, consistent with other evidence of a ubiquitous presence of heavily oxidized background secondary OC. The review concludes with some comments on current issues and future prospects, including progress towards compound-class and individual-compound-specific (14)C analyses.

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.

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.

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.

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).

Carbide and carbonitride surface treatment method for refractory metals

DOEpatents

Meyer, Glenn A.; Schildbach, Marcus A.

1996-01-01

A carbide and carbonitride surface treatment method for refractory metals is provided, in steps including, heating a part formed of boron, chromium, hafnium, molybdenum, niobium, tantalum, titanium, tungsten or zirconium, or alloys thereof, in an evacuated chamber and then introducing reaction gases including nitrogen and hydrogen, either in elemental or water vapor form, which react with a source of elemental carbon to form carbon-containing gaseous reactants which then react with the metal part to form the desired surface layer. Apparatus for practicing the method is also provided, in the form of a carbide and carbonitride surface treatment system (10) including a reaction chamber (14), a source of elemental carbon (17), a heating subassembly (20) and a source of reaction gases (23). Alternative methods of providing the elemental carbon (17) and the reaction gases (23) are provided, as well as methods of supporting the metal part (12), evacuating the chamber (14) with a vacuum subassembly (18) and heating all of the components to the desired temperature.

Difference in production routes of water-soluble organic carbon in PM2.5 observed during non-biomass and biomass burning periods in Gwangju, Korea.

PubMed

Yu, Geun-Hye; Cho, Sung-Yong; Bae, Min-Suk; Park, Seung-Shik

2014-07-01

4 h integrated PM2.5 samples were collected from an urban site of Gwangju, Korea, for five days and analyzed for organic carbon and elemental carbon (OC and EC), total water-soluble OC (WSOC), hydrophilic and hydrophobic WSOC fractions (WSOCHPI and WSOCHPO), oxalate, and inorganic ionic species (sodium (Na(+)), ammonium (NH4(+)), potassium (K(+)), calcium (Ca(2+)), magnesium (Mg(2+)), chloride (Cl(-)), nitrate (NO3(-)), and sulfate (SO4(2-))) to investigate the possible sources of water-soluble organic aerosols. Two types of sampling periods were classified according to the regression relationship between black carbon (BC) concentrations measured at wavelengths of 370 nm (BC370nm) and 880 nm (BC880nm) using an aethalometer; the first period was traffic emission influence ("non-biomass burning (BB) period") and the second was biomass burning influence ("BB period"). The slope of the regression equation (BC370nm/BC880nm) was 0.95 for the non-BB period and 1.29 for the BB period. However, no noticeable difference in the WSOC/OC ratio, which can be used to infer the extent of secondary organic aerosol (SOA) formation, was found between the non-BB (0.61, range = 0.43-0.75) and BB (0.61, range = 0.52-0.68) periods, due to significant contribution of primary BB emissions to the WSOC. The concentrations of OC, WSOC and K(+), which were used as the BB emission markers, were 15.7 μg C m(-3) (11.5-24.3), 9.4 μg C m(-3) (7.0-12.7), and 1.2 μg m(-3) (0.6-2.7), respectively, during the BB period, and these results were approximately 1.7, 1.7, and 3.9 times higher than those during the non-BB period. During the non-BB period, good correlations among WSOC, SO4(2-) and oxalate, and poor correlations among WSOC, EC, and K(+) suggest that SOA is probably an important source of WSOC (and WSOCHPI) concentration. For the WSOC fractions, better correlations among WSOCHPI, oxalate (R(2) = 0.52), and SO4(2-) (R(2) = 0.57) were found than among WSOCHPO, oxalate (R(2) = 0.23), and SO4(2-) (R(2) = 0.20), suggesting that a significant proportion of the WSOCHPI fraction of OC could be produced through processes (gas-phase and heterogeneous oxidations) such as SOA formation. However, during the BB period, the BB emission source accounted for the high correlations between total WSOC (and WSOC fractions) and other relevant atmospheric parameters (EC, Na(+), Cl(-), K(+), and oxalate), with higher correlations in WSOCHPI than in WSOCHPO. These results suggest a significant contribution of BB emissions to WSOC.

IN-FLIGHT CAPTURE OF ELEMENTAL MERCURY BY A CHLORINE-IMPREGNATED ACTIVATED CARBON

EPA Science Inventory

The paper discusses the in-flight capture of elemental mercury (Hgo) by a chlorine (C1)-impregnated activated carbon. Efforts to develop sorbents for the control of Hg emissions have demonstrated that C1-impregnation of virgin activated carbons using dilute solutions of hydrogen ...

Observations and analysis of organic aerosol evolution in some prescribed fire smoke plumes

NASA Astrophysics Data System (ADS)

May, A. A.; Lee, T.; McMeeking, G. R.; Akagi, S.; Sullivan, A. P.; Urbanski, S.; Yokelson, R. J.; Kreidenweis, S. M.

2015-06-01

Open biomass burning is a significant source of primary air pollutants such as particulate matter (PM) and non-methane organic gases (NMOG). However, the physical and chemical atmospheric processing of these emissions during transport is poorly understood. Atmospheric transformations of biomass burning emissions have been investigated in environmental chambers, but there have been limited opportunities to investigate these transformations in the atmosphere. In this study, we deployed a suite of real-time instrumentation on a Twin Otter aircraft to sample smoke from prescribed fires in South Carolina, conducting measurements at both the source and downwind to characterize smoke evolution with atmospheric aging. Organic aerosol (OA) within the smoke plumes was quantified using an aerosol mass spectrometer (AMS); refractory black carbon (rBC) was quantified using a single-particle soot photometer, and carbon monoxide (CO) and carbon dioxide (CO2) were measured using a cavity ring-down spectrometer. During the two fires for which we were able to obtain aerosol aging data, normalized excess mixing ratios and "export factors" of conserved species (rBC, CO, CO2) suggested that changes in emissions at the source did not account for most of the differences observed in samples of increasing age. An investigation of AMS mass fragments indicated that the in-plume fractional contribution (fm/z) to OA of the primary fragment (m/z 60) decreased downwind, while the fractional contribution of the secondary fragment (m/z 44) increased. Increases in f44 are typically interpreted as indicating chemical aging of OA. Likewise, we observed an increase in the O : C elemental ratio downwind, which is usually associated with aerosol aging. However, the rapid mixing of these plumes into the background air suggests that these chemical transformations may be attributable to the different volatilities of the compounds that fragment to these m/z in the AMS. The gas-particle partitioning behavior of the bulk OA observed during the study was consistent with the predictions from a parameterization developed for open biomass burning emissions in the laboratory. Furthermore, we observed no statistically significant increase in total organic mass with atmospheric transport. Hence, our results suggest that dilution-driven evaporation likely dominated over the chemical production of secondary organic aerosol (SOA) within our smoke plumes, presumably due to the fast dilution and limited aging times (< ~ 5 h) that we could sample.

PERSONAL, INDOOR, AND OUTDOOR CONCENTRATIONS OF PM2.5, PARTICULATE NITRATE, AND ELEMENTAL CARBON FOR INDIVIDUALS WITH COPD IN LOS ANGELES, CA

EPA Science Inventory

This study characterizes the personal, indoor, and outdoor concentrations of PM2.5 and the major components of PM2.5, including nitrate (NO3-), elemental carbon (EC), and the elements for individuals with chronic obstructive pulmonary disease (COPD) living in Los Angeles, CA. ...

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.

Mass absorption efficiency of elemental carbon over Van Vihar National Park, Bhopal, India: Temporal variability and implications to estimates of black carbon radiative forcing

NASA Astrophysics Data System (ADS)

Samiksha, S.; Raman, R. S.; Singh, A.

2016-12-01

It is now well recognized that black carbon (a component of aerosols that is similar but not identical to elemental carbon) is an important contributor to global warming, second only to CO2.However, the most popular methods for estimation of black carbon rely on accurate estimates of its mass absorption efficiency (MAE) to convert optical attenuation measurements to black carbon concentrations. Often a constant manufacturer specified MAE is used for this purposes. Recent literature has unequivocally established that MAE shows large spatio-temporal heterogeneities. This is so because MAE depends on emission sources, chemical composition, and mixing state of aerosols. In this study, ambient PM2.5 samples were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected on Teflon, Nylon, and Tissue quartz filter substrates. Punches of quartz fibre filter were analysed for organic and elemental carbon (OC/EC) by a thermal-optical-transmittance/reflectance (TOT-TOR) analyser operating with a 632 nm laser diode. Teflon filters were also used to interdependently measure PM2.5 attenuation (at 370 nm and 800 nm) by transmissometry. Site-specific mass absorption efficiency (MAE) for elemental carbon over the study site will be derived using a combination of measurements from the TOT/TOR analyser and transmissometer. An assessment of site-specific MAE values, its temporal variability and implications to black carbon radiative forcing will be discussed. It is now well recognized that black carbon (a component of aerosols that is similar but not identical to elemental carbon) is an important contributor to global warming, second only to CO2. However, the most popular methods for estimation of black carbon rely on accurate estimates of its mass absorption efficiency (MAE) to convert optical attenuation measurements to black carbon concentrations. Often a constant manufacturer specified MAE is used for this purposes. Recent literature has unequivocally established that MAE shows large spatio-temporal heterogeneities. This is so because MAE depends on emission sources, chemical composition, and mixing state of aerosols. In this study, ambient PM2.5 samples were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected on Teflon, Nylon, and Tissue quartz filter substrates. Punches of quartz fibre filter were analysed for organic and elemental carbon (OC/EC) by a thermal-optical-transmittance/reflectance (TOT-TOR) analyser operating with a 632 nm laser diode. Teflon filters were also used to interdependently measure PM2.5 attenuation (at 370 nm and 800 nm) by transmissometry. Site-specific mass absorption efficiency (MAE) for elemental carbon over the study site will be derived using a combination of measurements from the TOT/TOR analyser and transmissometer. An assessment of site-specific MAE values, its temporal variability and implications to black carbon radiative forcing will be discussed.

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.

Composition and Morphology of Individual Combustion, Biomass Burning, and Secondary Organic Particle Types Obtained Using ATOFMS and STXM-NEXAFS Measurements (Invited)

NASA Astrophysics Data System (ADS)

Russell, L. M.; Bahadur, R.; Liu, S.; Takahama, S.; Prather, K. A.

2010-12-01

Complementary single particle measurements of organic aerosols using aerosol time-of-flight mass spectrometry (ATOFMS) and Scanning Transmission X-ray Microscopy—Near Edge X-ray Absorption Fine Structure (STXM-NEXAFS) are compared to examine the relationships between particle morphologies and chemical composition of particles having similar sources. ATOFMS measurements from field campaigns in polluted or urban (Riverside/SOAR 2005; Mexico City/MILAGRO 2006; Port of Long Beach 2007) and clean or marine (Arabian Sea/INDOEX 1999; Sea of Japan/ACE-Asia 2001; Trinidad Head/CIFEX 2004) locations illustrate regional differences in the amount and types of organic particles. The majority (≥ 85%) of the number of submicron particles are carbonaceous (including elemental and organic carbon), but represent less than 10% of the number of supermicron particles. Organic carbon (OC) particles are classified into three meta-classes corresponding to (1) combustion-generated OC/EC internalmixtures, (2) biomass burning generated K/OC mixtures, and (3) OC/High MassOC (HMOC) mixtures containing secondary markers of atmospheric processing. Normalized dot products are used to quantify similarity among fragment spectra and indicate that OC particle types are consistent across (and within) platforms. Single particle carbon STXM-NEXAFS measurements during ACE-Asia 2001 and MILAGRO 2006 yield similar source categories based on relative abundances of aromatic, alkane, and carboxylic acid functional groups. All three organic particle types correspond to a variety of very heterogeneous particle morphologies, although the highly oxygenated OC particles with likely secondary organic contributions frequently are nearly spherical, liquid-like particles. Similar particle types are observed at many other locations, including recent measurements at Bakersfield, Tijuana, and the R/V Atlantis as part of CalNex and CalMex. Size-resolved number fractions of the major ATOFMS organic particle types show qualitative agreement with OC particle types from STXM NEXAFS analysis, indicating a correspondence of the OC/EC type with the presence of strong aromatic groups, of the OC/HMOC type with high carboxylic acid groups, and of the biomass burning OC type with aromatic and carbonyl groups. The comparison shows that ATOFMS measurements can be used to establish robust statistics for offline single particle techniques, providing the atmospheric context for the functional group and morphological information obtained from STXM-NEXAFS for an improved understanding of the climate impact of organic aerosols.

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.

DEVELOPMENT OF A CL-IMPREGNATED ACTIVATED CARBON FOR ENTRAINED-FLOW CAPTURE OF ELEMENTAL MERCURY

EPA Science Inventory

Efforts to discern the role of an activated carbon's surface functional groups on the adsorption of elemental mercury [Hg(0)] and mercuric chloride demonstrated that chlorine (Cl) impregnation of a virgin activated carbon using dilute solutions of hydrogen chloride leads to incre...

MODELING REFLECTANCE AND TRANSMITTANCE OF QUARTZ-FIBER FILTER SAMPLES CONTAINING ELEMENTAL CARBON PARTICLES: IMPLICATIONS FOR THERMAL/OPTICAL ANALYSIS. (R831086)

EPA Science Inventory

A radiative transfer scheme that considers absorption, scattering, and distribution of light-absorbing elemental carbon (EC) particles collected on a quartz-fiber filter was developed to explain simultaneous filter reflectance and transmittance observations prior to and during...

Sources of primary and secondary organic aerosol and their diurnal variations.

PubMed

Zheng, Mei; Zhao, Xiuying; Cheng, Yuan; Yan, Caiqing; Shi, Wenyan; Zhang, Xiaolu; Weber, Rodney J; Schauer, James J; Wang, Xinming; Edgerton, Eric S

2014-01-15

PM(2.5), as one of the criteria pollutants regulated in the U.S. and other countries due to its adverse health impacts, contains more than hundreds of organic pollutants with different sources and formation mechanisms. Daytime and nighttime PM2.5 samples from the August Mini-Intensive Gas and Aerosol Campaign (AMIGAS) in the southeastern U.S. were collected during summer 2008 at one urban site and one rural site, and were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), and various individual organic compounds including some important tracers for carbonaceous aerosol sources by gas chromatography-mass spectrometry. Most samples exhibited higher daytime OC concentration, while higher nighttime OC was found in a few events at the urban site. Sources, formation mechanisms and composition of organic aerosol are complicated and results of this study showed that it exhibited distinct diurnal variations. With detailed organic tracer information, sources contributing to particulate OC were identified: higher nighttime OC concentration occurring in several occasions was mainly contributed by the increasing primary emissions at night, especially diesel exhaust and biomass burning; whereas sources responsible for higher daytime OC concentration included secondary organic aerosol (SOA) formation (e.g., cis-pinonic acid and non-biomass burning WSOC) together with traffic emissions especially gasoline engine exhaust. Primary tracers from combustion related sources such as EC, polycyclic aromatic hydrocarbons, and hopanes and steranes were significantly higher at the urban site with an urban to rural ratio between 5 and 8. However, this urban-rural difference for secondary components was less significant, indicating a relatively homogeneous distribution of SOA spatially. We found cholesterol concentrations, a typical tracer for meat cooking, were consistently higher at the rural site especially during the daytime, suggesting the likely additional sources for this tracer at rural site and that it should be used with caution as meat cooking tracer in rural areas in the future. Copyright © 2013 Elsevier B.V. All rights reserved.

Chemical composition of fine particles in fresh smoke plumes from boreal wild-land fires in Europe.

PubMed

Saarnio, Karri; Aurela, Minna; Timonen, Hilkka; Saarikoski, Sanna; Teinilä, Kimmo; Mäkelä, Timo; Sofiev, Mikhail; Koskinen, Jarkko; Aalto, Pasi P; Kulmala, Markku; Kukkonen, Jaakko; Hillamo, Risto

2010-05-15

A series of smoke plumes was detected in Helsinki, Finland, during a one-month-lasting period in August 2006. The smoke plumes originated from wildfires close to Finland, and they were short-term and had a high particulate matter (PM) concentration. Physical and chemical properties of fine particles in those smokes were characterised by a wide range of real-time measurements that enabled the examination of individual plume events. Concurrently PM(1) filter samples were collected and analysed off-line. Satellite observations employing MODIS sensor on board of NASA EOS Terra satellite with the dispersion model SILAM and the Fire Assimilation System were used for evaluation of the emission fluxes from wildfires. The model predicted well the timing of the plumes but the predicted PM concentrations differed from the observed. The measurements showed that the major growth in PM concentration was caused by submicrometer particles consisting mainly of particulate organic matter (POM). POM had not totally oxidised during the transport based on the low WSOC-to-OC ratio. The fresh plumes were compared to another major smoke episode that was observed in Helsinki during April-May 2006. The duration and the source areas of the two episode periods differed. The episode in April-May was a period of nearly constantly upraised level of long-range transported PM and it was composed of aged particles when arriving in Helsinki. The two episodes had differences also in the chemical composition of PM. The mass concentrations of biomass burning tracers (levoglucosan, potassium, and oxalate) increased during both the episodes but different concentration levels of elemental carbon and potassium indicated that the episodes differed in the form of burning as well as in the burning material. In spring dry crop residue and hay from the previous season were burnt whereas in August smokes from smouldering and incomplete burning of fresh vegetation were detected. Copyright 2010 Elsevier B.V. All rights reserved.

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.

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.

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.

Spatial variation of chemical constituents from the burning of commonly used biomass fuels in rural areas of the Indo-Gangetic Plain (IGP), India

NASA Astrophysics Data System (ADS)

Saud, T.; Saxena, M.; Singh, D. P.; Saraswati; Dahiya, Manisha; Sharma, S. K.; Datta, A.; Gadi, Ranu; Mandal, T. K.

2013-06-01

In the present paper, we have determined emission factor of chemical composition of the emission from the burning of biomass (e.g. Dung cake, Acacia, Neem, Mulberry, Indian Rosewood, Pigeon pea etc.) commonly used as a residential fuel in the rural sector of Indo-Gangetic Plain (IGP) (Delhi, Punjab, Haryana, Uttar Pradesh, Bihar and West Bengal), India. For comparison, we have selected only those biomass fuels, which are used in at least three of the above mentioned states. Dung cake from all the states reports highest emission of particulate matter (PM) (15.68 g kg-1), Organic Carbon (OC) (4.32 g kg-1) and Elemental Carbon (EC) (0.51 g kg-1). Among all biomass fuels studied, agricultural residue reports substantial amount of emission of Na+ (104 mg kg-1), K+ (331 mg kg-1) and Cl- (447 mg kg-1) particularly in Pigeon pea and Mustard stem. Eucalyptus (fuel wood) emits large amounts of Ca2+ (21.47 mg kg-1) and NO3- (614 mg kg-1). The emission of PM from dung cake is higher in Delhi (19.31 g kg-1) and followed by Uttar Pradesh (17.58 g kg-1) > Haryana (15.46 g kg-1) > Bihar (14.99 g kg-1) > Punjab (12.06 g kg-1) > West Bengal (5.90 g kg-1). Carbonaceous aerosols (OC and EC) and dominant Ionic species (Cl-, K+, SO42-, NO3- and PO43-) are altogether contributing 40-70% of total emissions. Characteristics and ratios of chemical species of emissions may help to develop a methodology of discriminating the sources of ambient particulate matter. Using a laboratory determined emission factor of chemical species, we have determined the emission budget over IGP, India.

Absorbing and scattering aerosols over the source region of biomass burning emissions: Implications in the assessment of optical and radiative properties

NASA Astrophysics Data System (ADS)

Singh, Atinderpal; Srivastava, Rohit; Rastogi, Neeraj; Singh, Darshan

2016-02-01

The current study focuses on the assessment of model simulated optical and radiative properties of aerosols incorporating the measured chemical composition of aerosol samples collected at Patiala during October, 2011-February, 2012. Monthly average mass concentration of PM2.5, elemental carbon (EC), primary organic carbon (POC), water-soluble (WS) and insoluble (INS) aerosols ranged from 120 to 192, 6.2 to 7.2, 20 to 39, 59 to 111 and 35 to 90 μg m-3, respectively. Mass concentration of different components of aerosols was further used for the assessment of optical properties derived from Optical Properties of Aerosols and Clouds (OPAC) model simulations. Microtops based measured aerosol optical depth (AOD500) ranged from 0.47 to 0.62 showing maximum value during November and December, and minimum during February. Ångström exponent (α380-870) remained high (>0.90) throughout the study period except in February (0.74), suggesting predominance of fine mode particles over the study region. The observed ratio of scattering to absorbing aerosols was incorporated in OPAC model simulations and single scattering albedo (SSA at 500 nm) so obtained ranged between 0.80 and 0.92 with relatively low values during the period of extensive biomass burning. In the present study, SBDART based estimated values of aerosol radiative forcing (ARF) at the surface (SRF) and top of the atmosphere (TOA) ranged from -31 to -66 Wm-2 and -2 to -18 W m-2 respectively. The atmospheric ARF, ranged between + 18 and + 58 Wm-2 resulting in the atmospheric heating rate between 0.5 and 1.6 K day-1. These results signify the role of scattering and absorbing aerosols in affecting the magnitude of aerosol forcing.

Chemical characteristics and source apportionment of indoor and outdoor fine particles observed in an urban environment in Korea

NASA Astrophysics Data System (ADS)

Heo, J.; Yi, S. M.

2016-12-01

Paired indoor-outdoor fine particulate matter (PM2.5) samples were collected at subway stations, underground shopping centers, and schools in Seoul metropolitan over a 4-year period between 2004 and 2007. Relationships between indoor and outdoor PM2.5 chemical species were determined and source contributions to indoor and outdoor PM2.5 mass were estimated using a positive matrix factorization (PMF) model. The PM2.5 samples were analyzed for major chemical components including organic carbon and elemental carbon, ions, and metals, and the results were used in the PMF model. The levels of the PM2.5 mass and its chemical components observed at the indoor sites were higher than those at the outdoor sites. Indoor levels of ions (i.e. sulfate, nitrate, ammonium), elemental carbon, and several metals (i.e. Fe, Zn, and Cu) were found to be significantly affected by outdoor sources. Very high indoor-to-outdoor mass ratio of these chemical components, in particular, were observed, representing the significant impacts of outdoor sources on indoor levels of them. Seven sources (secondary sulfate, secondary nitrate, mobile, biomass burning, roadway emissions, dust, and sea salt) were resolved by the PMF model at both of the indoor and outdoor sites. The secondary inorganic aerosol (i.e. secondary sulfate and nitrate) and the mobile sources were major contributors to the indoor and outdoor PM2.5, accounting for 47% and 27% of the outdoor PM2.5 and 40% and 25% of the indoor PM2.5, respectively. Furthermore, the contributions of the secondary inorganic aerosol and the mobile sources to the indoor PM2.5 were very comparable to its corresponding contributions to the outdoor PM2.5 levels. The spatial and temporal characteristics of each of sources resolved by the PMF model across the sites were examined using summary statistics, correlation analysis, and coefficient of variation and divergence analysis and the detailed results will be discussed in the presentation.

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...

Morphology and Chemical Composition of soot particles emitted by Wood-burning Cook-Stoves: a HRTEM, XPS and Elastic backscattering Studies.

NASA Astrophysics Data System (ADS)

Carabali-Sandoval, G. A., Sr.; Castro, T.; Peralta, O.; De la Cruz, W.; Días, J.; Amelines, O.; Rivera-Hernández, M.; Varela, A.; Muñoz-Muñoz, F.; Policroniades, R.; Murillo, G.; Moreno, E.

2014-12-01

The morphology, microstructure and the chemical composition on surface of soot particles were studied by using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and elastic backscattering spectrometry. In order to obtain freshly soot particles emitted by home-made wood-burning cook stoves, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot particles. The XPS survey spectra show a large carbon peak around 285 eV and the oxygen signal at 533 eV. Some differences observed in the carbon/oxygen (C/O) ratio of the particles probably depend on the combustion process efficiency of each cook-stove analyzed. The C-1s XPS spectra show an asymmetric broad peak and other with low intensity that corresponds to sp2 and sp3hybridization, which were fitted with a convolution using Gaussian functions. Elastic backscattering technique allows a chemical elemental analysis of samples and confirms the presence of C, O and Si observed by XPS. Additionally, the morphological properties of soot aggregates were analyzed calculating the border-based fractal dimension (Df). Particles exhibit complex shapes with high values of Df. Also, real-time absorption (σabs) and scattering (σsct) coefficients of fine (with aerodynamic diameter < 2.5 µm) soot particles were measured. The trend in σabs and σsct indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

Seasonal variability of carbonaceous aerosols in an urban background area in Southern Italy

NASA Astrophysics Data System (ADS)

Cesari, D.; Merico, E.; Dinoi, A.; Marinoni, A.; Bonasoni, P.; Contini, D.

2018-02-01

Organic (OC) and Elemental Carbon (EC) are important components of atmospheric aerosol particles, playing a key role in climate system and potentially affecting human health. There is a lack of data reported for Southern Italy and this work aims to fill this gap, focusing the attention on the long-term trends of OC and EC concentrations in PM2.5 and PM10, and on atmospheric processes and sources influencing seasonal variability. Measurements were taken at the Environmental-Climate Observatory of Lecce (SE Italy, 40°20‧8″N-18°07‧28″E, 37 m a.s.l.), regional station of the Global Atmosphere Watch program (GAW-WMO). Daily PM10 and PM2.5 samples were collected between July 2013 and July 2016. In addition, starting in December 2014, simultaneous equivalent Black Carbon (eBC) concentrations in PM10 were measured using a Multi Angle Absorption Photometer. A subset of 722 PM samples (361 for each size fraction) was analysed by using a thermo-optical method with a Sunset Laboratory OC/EC analyser, to determine elemental and organic carbon concentrations. The average PM10 and PM2.5 concentrations were 28.8 μg/m3 and 17.5 μg/m3. The average OC and EC concentrations in PM10 were 5.4 μg/m3 and 0.8 μg/m3, in PM2.5 these were 4.7 μg/m3 and 0.6 μg/m3. Carbonaceous content was larger during cold season with respect to warm season as well as secondary organic carbon (SOC) that was evaluated using the OC/EC minimum ratio method. SOC was mainly segregated in PM2.5 and represented 53% - 75% of the total OC. A subset of EC data was compared with eBC measurements, showing a good correlation (R2 = 0.80), however, eBC concentrations were higher than EC concentrations of an average factor of 1.95 (+/- 0.55 standard deviation). This could be explained by the presence of a contribution of Brown Carbon (BrC), for example from biomass burning, in eBC measurements. Weekly patterns showed a slight decrease of carbon content during weekends with respect to weekdays especially visible on eBC concentration due to the decrease of road traffic emissions. The daily patterns of hourly eBC concentrations showed a decrease in central diurnal hours, due to the cycle of planetary boundary-layer height, and concentrations peaks during rush hours due to road traffic emissions.

Characterization of PM(2.5) collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona.

PubMed

Robinson, Marin S; Zhao, Min; Zack, Lindsay; Brindley, Christine; Portz, Lillian; Quarterman, Matthew; Long, Xiufen; Herckes, Pierre

2011-04-01

Prescribed burning, in combination with mechanical thinning, is a successful method for reducing heavy fuel loads from forest floors and thereby lowering the risk of catastrophic wildfire. However, an undesirable consequence of managed fire is the production of fine particulate matter or PM(2.5) (particles ≤2.5 µm in aerodynamic diameter). Wood-smoke particulate data from 21 prescribed burns are described, including results from broadcast and slash-pile burns. All PM(2.5) samples were collected in situ on day 1 (ignition) or day 2. Samples were analyzed for mass, polycyclic aromatic hydrocarbons (PAHs), inorganic elements, organic carbon (OC), and elemental carbon (EC). Results were characteristic of low intensity, smoldering fires. PM(2.5) concentrations varied from 523 to 8357 µg m(-3) and were higher on day 1. PAH weight percents (19 PAHs) were higher in slash-pile burns (0.21 ± 0.08% OC) than broadcast burns (0.07 ± 0.03% OC). The major elements were K, Cl, S, and Si. OC and EC values averaged 66 ± 7 and 2.8 ± 1.4% PM(2.5), respectively, for all burns studied, in good agreement with literature values for smoldering fires.

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

PubMed Central

Zhao, Min; Zack, Lindsay; Brindley, Christine; Portz, Lillian; Quarterman, Matthew; Long, Xiufen; Herckes, Pierre

2011-01-01

Prescribed burning, in combination with mechanical thinning, is a successful method for reducing heavy fuel loads from forest floors and thereby lowering the risk of catastrophic wildfire. However, an undesirable consequence of managed fire is the production of fine particulate matter or PM2.5 (particles ≤2.5 µm in aerodynamic diameter). Wood-smoke particulate data from 21 prescribed burns are described, including results from broadcast and slash-pile burns. All PM2.5 samples were collected in situ on day 1 (ignition) or day 2. Samples were analyzed for mass, polycyclic aromatic hydrocarbons (PAHs), inorganic elements, organic carbon (OC), and elemental carbon (EC). Results were characteristic of low intensity, smoldering fires. PM2.5 concentrations varied from 523 to 8357 µg m−3 and were higher on day 1. PAH weight percents (19 PAHs) were higher in slash-pile burns (0.21 ± 0.08% OC) than broadcast burns (0.07 ± 0.03% OC). The major elements were K, Cl, S, and Si. OC and EC values averaged 66 ± 7 and 2.8 ± 1.4% PM2.5, respectively, for all burns studied, in good agreement with literature values for smoldering fires. PMID:21625396

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.

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.

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...

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.

Emission Factors, Size Distributions and Emission Inventories of Carbonaceous Particulate Matter from Residential Wood Combustion in Rural China

PubMed Central

Shen, Guofeng; Wei, Siye; Wei, Wen; Zhang, Yanyan; Min, Yujia; Wang, Bin; Wang, Rong; Li, Wei; Shen, Huizhong; Huang, Ye; Huang, Ye; Yang, Yifeng; Wang, Wei; Wang, Xilong; Wang, Xuejun; Tao, Shu

2012-01-01

Published emission factors (EFs) often vary significantly, leading to high uncertainties in emission estimations. There are few reliable EFs from field measurements of residential wood combustion in China. In this study, 17 wood fuels and one bamboo were combusted in a typical residential stove in rural China to measure realistic EFs of particulate matter (PM), organic carbon (OC) and elemental carbon (EC), as well as to investigate the influence of fuel properties and combustion conditions on the EFs. Measured EFs of PM, OC, and EC (EFPM, EFOC, and EFEC, respectively) were in the range of 0.38~6.4, 0.024~3.0 and 0.039~3.9 g/kg (dry basis), with means and standard derivation of 2.2±1.2, 0.62±0.64 and 0.83±0.69 g/kg, respectively. Shrubby biomass combustion produced higher EFs than tree woods, and both species had lower EFs than those of indoor crop residue burning (p<0.05). Significant correlations between EFPM, EFOC and EFEC were expected. By using a nine-stage cascade impactor, it was shown that size distributions of PM emitted from tree biomass combustions were unimodal with peaks at a diameter less than 0.4 µm (PM0.4), much finer than the PM from indoor crop residue burning. Approximately 79.4% of the total PM from tree wood combustion was PM with a diameter less than 2.1µm (PM2.1). PM size distributions for shrubby biomasses were slightly different from those for tree fuels. Based on the measured EFs, total emissions of PM, OC, and EC from residential wood combustion in rural China in 2007 were estimated at about 303, 75.7, and 92.0 Gg. PMID:22380753

77 FR 18987 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Nonattainment New...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-29

... sulfate (SO 4 ); nitrate (NO 3 ); ammonium; elemental carbon; a great variety of organic compounds; and inorganic material (including metals, dust, sea salt, and other trace elements) generally referred to as... the air as a solid or liquid particle (e.g., elemental carbon from diesel engines or fire 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.

Comparison of structural features of water-soluble organic matter from atmospheric aerosols with those of aquatic humic substances

NASA Astrophysics Data System (ADS)

Duarte, Regina M. B. O.; Santos, Eduarda B. H.; Pio, Casimiro A.; Duarte, Armando C.

Elemental analysis, Fourier transform infrared coupled to attenuated total reflectance (FTIR-ATR) and solid-state cross polarization with magic angle spinning- 13C-nuclear magnetic resonance (CPMAS 13C NMR) spectroscopies were used to compare the chemical features of water-soluble organic compounds (WSOC) from atmospheric aerosols with those of aquatic humic and fulvic acids. The influence of different meteorological conditions on the structural composition of aerosol WSOC was also evaluated. Prior to the structural characterisation, the WSOC samples were separated into hydrophobic acids and hydrophilic acids fractions by using a XAD-8/XAD-4 isolation procedure. Results showed that WSOC hydrophobic acids are mostly aliphatic (40-62% of total NMR peak area), followed by oxygenated alkyls (15-21%) and carboxylic acid (5.4-13.4%) functional groups. Moreover, the aromatic content of aerosol WSOC samples collected between autumn and winter seasons is higher (˜18-19%) than that of samples collected during warmer periods (˜6-10%). The presence of aromatic signals typical of lignin-derived structures in samples collected during low-temperature conditions highlights the major contribution of wood burning processes in domestic fireplaces into the bulk chemical properties of WSOC from aerosols. According to our investigations, aerosol WSOC hydrophobic acids and aquatic fulvic and humic acids hold similar carbon functional groups; however, they differ in terms of the relative carbon distribution. Elemental analysis indicates that H and N contents of WSOC hydrophobic acids samples surpass those of aquatic fulvic and humic acids. In general, the obtained results suggest that WSOC hydrophobic acids have a higher aliphatic character and a lower degree of oxidation than those of standard fulvic and humic acids. The study here reported suggests that aquatic fulvic and humic acids may not be good models for WSOC from airborne particulate matter.

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.

Characterization of PM 2.5 collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona

NASA Astrophysics Data System (ADS)

Robinson, Marin S.; Zhao, Min; Zack, Lindsay; Brindley, Christine; Portz, Lillian; Quarterman, Matthew; Long, Xiufen; Herckes, Pierre

2011-04-01

Prescribed burning, in combination with mechanical thinning, is a successful method for reducing heavy fuel loads from forest floors and thereby lowering the risk of catastrophic wildfire. However, an undesirable consequence of managed fire is the production of fine particulate matter or PM 2.5 (particles ≤2.5 μm in aerodynamic diameter). Wood-smoke particulate data from 21 prescribed burns are described, including results from broadcast and slash-pile burns. All PM 2.5 samples were collected in situ on day 1 (ignition) or day 2. Samples were analyzed for mass, polycyclic aromatic hydrocarbons (PAHs), inorganic elements, organic carbon (OC), and elemental carbon (EC). Results were characteristic of low-intensity, smoldering fires. PM 2.5 concentrations varied from 523 to 8357 μg m -3 and were higher on day 1. PAH weight percents (19 PAHs) were higher in slash-pile burns (0.21 ± 0.08% OC) than broadcast burns (0.07 ± 0.03% OC). The major elements were K, Cl, S, and Si. OC and EC values averaged 66 ± 7 and 2.8 ± 1.4% PM 2.5, respectively, for all burns studied, in good agreement with literature values for smoldering fires.

Fine particulate pollution in the Nanjing northern suburb during summer: composition and sources.

PubMed

An, Junlin; Duan, Qing; Wang, Honglei; Miao, Qing; Shao, Ping; Wang, Jian; Zou, Jianan

2015-09-01

To understand the chemical composition characteristic of pollution in a northern suburb of Nanjing, particle samples were collected by two Andersen cascade impactors from May to July 2013. The positive matrix factorization version 3 (EPA-PMF 3.0) was applied to identify the source contribution of PM2.1 concentrations in the study area. Source categories were determined based on the chemical component abundances in the source profiles. Overall, results indicated that seven factors were obtained. The factors are identified as follows: (I) secondary aerosol, characterized by high concentrations of NH4 (+), NO3 (-), and SO4 (2-), accounting for 20.22 %; (II) metallurgical aerosol, characterized by high concentrations of Pb, Cd, and Zn, accounting for 6.71 %; (III) road dust, characterized by high concentrations of Mg, Ca, Na, Al, and Ba, accounting for 11.85 %; (IV) biomass burning, characterized by high concentrations of K(+), Na(+), Cl(-), and K, accounting for 10.17 %; (V) residual oil, characterized by high concentrations of V and Cr, accounting for 16.63 %; (VI) iron and steel industry, characterized by high concentrations of Mn and Fe, accounting for 9.48 %; and (VII) vehicle exhaust, characterized by high concentrations of organic carbon (OC), Mo, elemental carbon (EC) and K, accounting for 24.94 %.

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

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.

Seasonal variations in size distribution, water-soluble ions, and carbon content of size-segregated aerosols over New Delhi.

PubMed

Kumar, Pawan; Kumar, Sushil; Yadav, Sudesh

2018-02-01

Size distribution, water-soluble inorganic ions (WSII), and organic carbon (OC) and elemental carbon (EC) in size-segregated aerosols were investigated during a year-long sampling in 2010 over New Delhi. Among different size fractions of PM 10 , PM 0.95 was the dominant fraction (45%) followed by PM 3-7.2 (20%), PM 7.2-10 (15%), PM 0.95-1.5 (10%), and PM 1.5-3 (10%). All size fractions exceeded the ambient air quality standards of India for PM 2.5 . Annual average mass size distributions of ions were specific to size and ion(s); Ca 2+ , Mg 2+ , K + , NO 3 - , and Cl - followed bimodal distribution while SO 4 2- and NH 4 + ions showed one mode in PM 0.95 . The concentrations of secondary WSII (NO 3 - , SO 4 2- , and NH 4 + ) increased in winters due to closed and moist atmosphere whereas open atmospheric conditions in summers lead to dispersal of pollutants. NH 4 + and Ca 2+ were dominant neutralization ions but in different size fractions. The summer-time dust transport from upwind region by S SW winds resulted in significantly high concentrations of PM 0.95 and PM 3-7.2 and PM 7.2-10 . This indicted influence of dust generation in Thar Desert and its transport is size selective in nature in downwind direction. The mixing of different sources (geogenic, coal combustions, biomass burning, plastic burning, incinerators, and vehicular emissions sources) for soluble ions in different size fractions was noticed in principle component analysis. Total carbon (TC = EC + OC) constituted 8-31% of the total PM 0.95 mass, and OC dominated over EC. Among EC, char (EC1) dominated over soot (EC2 + EC3). High SOC contribution (82%) to OC and OC/EC ratio of 2.7 suggested possible role of mineral dust and high photochemical activity in SOC production. Mass concentrations of aerosols and WSII and their contributions to each size fraction of PM 10 are governed by nature of sources, emission strength of source(s), and seasonality in meteorological parameters.

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

Quantitative assessment of elemental carbon in the lungs of never smokers, cigarette smokers and coal miners

EPA Science Inventory

Inhalation exposure to particulates such as cigarette smoke and coal dust is known to contribute to the development of chronic lung disease. The purpose of this study was to estimate the amount of elemental carbon (EC) deposits from autopsied lung samples from cigarette smokers, ...

Sensitivity of Inverse Estimation of 2004 Elemental Carbon Emissions Inventory in the United States to the Choice of Observational Networks

EPA Science Inventory

Choice of observational networks used for inverse re-estimation of elemental (or black) carbon (EC) emissions in the United States impacts results. We convert the Thermal Optical Transmittance (TOT) EC measurements to the Thermal Optical Reflectance (TOR) equivalent to make full...

Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing

NASA Astrophysics Data System (ADS)

Aggarwal, S. G.; Kawamura, K.; Umarji, G. S.; Tachibana, E.; Patil, R. S.; Gupta, P. K.

2012-08-01

To better understand the sources of PM10 samples from Mumbai, India, aerosol chemical compositions, i.e. total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied together with specific markers such as methanesulfonate (MSA), oxalic acid (C2), azelaic acid (C9), and levoglucosan. The results revealed that biofuel/biomass burning and fossil fuel combustion are the major sources of the Mumbai aerosols. Nitrogen-isotopic (δ15N) composition of aerosol total nitrogen, which ranged from 18.1 to 25.4‰, also suggest that biofuel/biomass burning is the dominant source in both summer and winter seasons. Aerosol mass concentrations of major species increased 3-4 times in winter compared to summer, indicating an enhanced emission from these sources in winter season. Photochemical production tracers, C2 diacid and nssSO42- do not show diurnal changes. Concentrations of C2 diacid and WSOC show a strong correlation (r2 = 0.95). In addition, WSOC to OC (or TC) ratios remain almost constant for day- (0.37 ± 0.06 (0.28 ± 0.04)) and nighttime (0.38 ± 0.07 (0.28 ± 0.06)), suggesting that mixing of fresh secondary organic aerosols is not significant rather the Mumbai aerosols are photochemically well processed. Concentrations of MSA and C9 diacid present a positive correlation (r2 = 0.75), indicating a marine influence on Mumbai aerosols in addition to local/regional influence. Backward air mass trajectory analyses further suggested that the Mumbai aerosols are largely influenced by long-range continental and regional transport. Stable C-isotopic ratios (δ13C) of TC ranged from -27.0 to -25.4‰ with slightly lower average (-26.5 ± 0.3‰) in summer than in winter (-25.9 ± 0.3‰). Positive correlation between WSOC/TC ratios and δ13C values suggested that the increment in δ13C of wintertime TC may be caused by prolonged photochemical processing of organic aerosols in this season. This study suggests that in winter, the tropical aerosols are more aged due to longer residence time in the atmosphere than in the summer aerosols.

Catalytic transformations of biomass substrates using mixed metal oxides derived from substituted hydrotalcites

NASA Astrophysics Data System (ADS)

Macala, Gerald Stephen, II

Fueled by seemingly endless reserves of cheap and easily accessible fossil energy, the industrial age has brought to the developed world tremendous advances in human health and well being. Unfortunately the burning of fossil fuels has also been implicated in increasing atmospheric CO2 concentrations and global climate change. Concerns about short-term and long-term supply further build a case for the need for alternative energy sources. Biomass derived materials are a tantalizing source of fuels and fine chemicals. Unlike petroleum derived hydrocarbons, biomass can be both renewable and carbon neutral. Crops can be regenerated annually or even more often in tropical climates, and since the captured carbon originates as atmospheric CO2, the overall cycle has the potential to be nearly carbon neutral regardless of the final fate of the carbon. In contrast to petroleum derived hydrocarbons, which can often be made more valuable by adding functionality, biomass derived materials are already highly functionalized and can usually be made more valuable by selective removal of functionality. The development of robust catalysts capable of selective defuntionalization of biomass derived substrates remains an important challenge with potentially enormous economic and societal impact. In addition to being robust and selective, catalysts should preferably be heterogeneous to allow for easier removal and regeneration after the reaction is complete. New materials consisting of Mg-Al hydrotalcite-like structures, with a limiting percentage of Mg or Al substituted with other M2+ or M3+ cations, were synthesized by a co-precipitation process in basic aqueous solution with carbonate as counterion. Calcination of these materials at 460 °C resulted in evolution of CO2 and water and yielded high surface area mixed metal oxides with enhanced reactivity. Materials were characterized by ICP for elemental analysis, XRD for structural information, XPS for surface elemental analysis and TEM for morphology. Substituting some of the Al for ferric ion resulted in enhanced basicity and enhanced reactivity towards transesterification of seed oil and the model compound triacetin. Substituting some of the Mg for cupric ion resulted in a transfer hydrogenation catalyst capable of single pot dehydrogenation of methanol and hydrogenation of the model compound dihydrobenzofuran.

Comparing the NIOSH Method 5040 to a Diesel Particulate Matter Meter for Elemental Carbon

NASA Astrophysics Data System (ADS)

Ayers, David Matthew

Introduction: The sampling of elemental carbon has been associated with monitoring exposures in the trucking and mining industries. Recently, in the field of engineered nanomaterials, single wall and muti-wall carbon nanotubes (MWCNTs) are being produced in ever increasing quantities. The only approved atmospheric sampling for multi-wall carbon nanotubes in NIOSH Method 5040. These results are accurate but can take up to 30 days for sample results to be received. Objectives: Compare the results of elemental carbon sampling from the NIOSH Method 5040 to a Diesel Particulate Matter (DPM) Meter. Methods: MWCNTs were transferred and weighed between several trays placed on a scale. The NIOSH Method 5040 and DPM sampling train was hung 6 inches above the receiving tray. The transferring and weighing of the MWCNTs created an aerosol containing elemental carbon. Twenty-one total samples using both meters type were collected. Results: The assumptions for a Two-Way ANOVA were violated therefore, Mann-Whitney U Tests and a Kruskal-Wallis Test were performed. The hypotheses for both research questions were rejected. There was a significant difference in the EC concentrations obtained by the NIOSH Method 5040 and the DPM meter. There were also significant differences in elemental carbon level concentrations when sampled using a DPM meter versus a sampling pump based upon the three concentration levels (low, medium and high). Conclusions: The differences in the EC concentrations were statistically significant therefore, the two methods (NIOSH Method 5040 and DPM) are not the same. The NIOSH Method 5040 should continue to be the only authorized method of establishing an EC concentration for MWCNTs until a MWCNT specific method or an instantaneous meter is invented.

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.

New approaches for the chemical and physical characterization of aerosols using a single particle mass spectrometry based technique

NASA Astrophysics Data System (ADS)

Spencer, Matthew Todd

Aerosols affect the lives of people every day. They can decrease visibility, alter cloud formation and cloud lifetimes, change the energy balance of the earth and are implicated in causing numerous health problems. Measuring the physical and chemical properties of aerosols is essential to understand and mitigate any negative impacts that aerosols might have on climate and human health. Aerosol time-of-flight mass spectrometry (ATOFMS) is a technique that measures the size and chemical composition of individual particles in real time. The goal of this dissertation is to develop new and useful approaches for measuring the physical and/or chemical properties of particles using ATOFMS. This has been accomplished using laboratory experiments, ambient field measurements and sometimes comparisons between them. A comparison of mass spectra generated from petrochemical particles was made to light duty vehicle (LDV) and heavy duty diesel vehicle (HDDV) particle mass spectra. This comparison has given us new insight into how to differentiate between particles from these two sources. A method for coating elemental carbon (EC) particles with organic carbon (OC) was used to generate a calibration curve for quantifying the fraction of organic carbon and elemental carbon on particles using ATOFMS. This work demonstrates that it is possible to obtain quantitative chemical information with regards to EC and OC using ATOFMS. The relationship between electrical mobility diameter and aerodynamic diameter is used to develop a tandem differential mobility analyzer-ATOFMS technique to measure the effective density, size and chemical composition of particles. The method is applied in the field and gives new insight into the physical/chemical properties of particles. The size resolved chemical composition of aerosols was measured in the Indian Ocean during the monsoonal transition period. This field work shows that a significant fraction of aerosol transported from India was from biomass burning and appeared to be internally mixed with sulfate which suggests it was cloud processed during transport. Lastly, noble metal nanoparticles are explored as potential matrices for visible wavelength single particle matrix assisted laser desorption/ionization mass spectrometry (VIS-MALDI). This work demonstrates that noble metal nanoparticle matrices can be used for VIS-MALDI analysis.

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.

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

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)...

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.

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 ...

What matters for the radiative properties of biomass burning smoke?

NASA Astrophysics Data System (ADS)

Murphy, D. M.

2017-12-01

Biomass burning smoke is one of the largest and most diverse sources of aerosol in the atmosphere. I will try to provide an overview of some of the radiative consequences of well-known properties of smoke. Smoke is neither purely scattering nor black, it has multiple light-absorbing species, is often injected above the surface, and every wild fire is different. Each of these properties of smoke can have important implications for the radiative impacts. For example, the altitude of a smoke layer affects the radiative forcing of black aerosol much more than it does a purely scattering aerosol. Therefore, an intermediate aerosol like smoke can have a variety of behaviors depending on its albedo and altitude. The light absorption in smoke comes from a complicated mixture of species. These species are often operationally defined by the measurement methods rather than being fundamental properties of the aerosol. There are already several papers in the literature highlighting the importance of using proper definitions of black or elemental carbon when comparing data with other data or models. New results show that care in definitions is even more important than previously thought. There are several ways that factors of two or more can arise between definitions of light-absorbing aerosol. The same holds true for radiative forcing from light-absorbing aerosols: the distinctions between concepts like instantaneous and adjusted forcings are not just esoteric definitions but may differ by large factors. Future progress will require careful attention to what is being measured and modeled, as well as obtaining data to refine the assumptions in the remote sensing retrievals that define the global scale of biomass burning aerosol.

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

Apportionment of polycyclic aromatic hydrocarbon sources in lower Fox River, USA, sediments by a chemical mass balance model

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

Su, M.C.; Christensen, E.R.; Karls, J.F.

Four sediment cores were collected from the lower Fox River, Wisconsin, USA, to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) using a chemical mass balance model. The cores, which were obtained in 1995 from areas close to Green Bay, Wisconsin, USA, had total PAH concentrations between 19.3 and 0.34 ppm. To determine historical trends of PAH inputs, {sup 210}Pb and {sup 137}Cs dating was used, and elemental carbon particle analysis was done to characterize particles from the combustion of coal, wood, and petroleum. Source fingerprints were taken from the literature. Their results indicate that coke oven emissions, highway dust,more » coal gasification, and wood burning are likely sources of PAHs in the lower Fox River. Coke oven emissions are in the range of 40 to 90% of total PAHs, and this fraction decreases from 1930 to 1990, except in core Fox River-A (FR-A). The overall highway dust (HWY) contribution is between 10 and 75%, and this fraction increases from 1930 to present, except in core FR-A. The wood burning (WB) contribution is less than 7% in cores FR-B, FR-C, and FR-D. In core FR-A, a maximum ({approximately}23%) is found around 1960. The contribution of wood burning has changed from less than 6% in 1950 to between 3 and 10% in 1995. Evidence of aerobic biodegradation or photolysis in the sediment of phenanthrene, with a half-life of approximately 0.5 years has been found at the site of core FR-D, which is the shallowest (1.1 m) of the four core sites.« less

Source characterization of urban particles from meat smoking activities in Chongqing, China using single particle aerosol mass spectrometry.

PubMed

Chen, Yang; Wenger, John C; Yang, Fumo; Cao, Junji; Huang, Rujin; Shi, Guangming; Zhang, Shumin; Tian, Mi; Wang, Huanbo

2017-09-01

A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed in the urban area of Chongqing to characterize the particles present during a severe particulate pollution event that occurred in winter 2014-2015. The measurements were made at a time when residents engaged in traditional outdoor meat smoking activities to preserve meat before the Chinese Spring Festival. The measurement period was predominantly characterized by stagnant weather conditions, highly elevated levels of PM 2.5 , and low visibility. Eleven major single particle types were identified, with over 92.5% of the particles attributed to biomass burning emissions. Most of the particle types showed appreciable signs of aging in the stagnant air conditions. To simulate the meat smoking activities, a series of controlled smoldering experiments was conducted using freshly cut pine and cypress branches, both with and without wood logs. SPAMS data obtained from these experiments revealed a number of biomass burning particle types, including an elemental and organic carbon (ECOC) type that proved to be the most suitable marker for meat smoking activities. The traditional activity of making preserved meat in southwestern China is shown here to be a major source of particulate pollution. Improved measures to reduce emissions from the smoking of meat should be introduced to improve air quality in regions where smoking meat activity prevails. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Attributing risk burden of PM2.5-bound polycyclic aromatic hydrocarbons to major emission sources: Case study in Guangzhou, south China

NASA Astrophysics Data System (ADS)

Yu, Qingqing; Gao, Bo; Li, Guanghui; Zhang, Yanli; He, Quanfu; Deng, Wei; Huang, Zhonghui; Ding, Xiang; Hu, Qihou; Huang, Zuzhao; Wang, Yujun; Bi, Xinhui; Wang, Xinming

2016-10-01

Polycyclic aromatic hydrocarbons (PAHs) have attracted an increasing concern in China's megacities. However, rare information is available on the spatial and seasonal variations of inhalation cancer risk (ICR) due to PAH exposure and their relations to specific sources. In this study, year-round PM2.5 samples were collected from 2013 to 2014 by high-volume samplers at four sites (one urban, two rural and one roadside station) in Guangzhou in the highly industrialized and densely populated Pearl River Delta (PRD) region and analyzed for 26 polycyclic aromatic hydrocarbons (PAHs) together with molecular tracers including levoglucosan, hopanes and elemental carbon. Higher molecular weight PAHs (5-ring or above) accounted for 64.3-87.5% of total PAHs. Estimated annual averages of benzo(a)pyrene-equivalent carcinogenic potency (BaPeq) were 1.37, 2.31 and 1.56 ng/m3 at urban SZ, rural JL and rural WQS, respectively, much higher than that at the roadside station YJ in an urban street canyon. ICR of PAHs in wintertime reached 2.2 × 10-4, nearly 3 times that in summer; and cancer risk of PAHs was surprisingly higher at the rural site than at other sites. Source contributions by positive matrix factorization (PMF) in the aid of molecular tracers revealed that overall coal combustion and biomass burning altogether contributed 73.8% of total PAHs and 85.2% of BaPeq, and particularly in winter biomass burning became the most significant source of total PAHs and BaPeq (51.8% and 52.5%), followed by coal combustion (32.0% and 39.1%) and vehicle emission (16.2% and 8.4%). The findings of this work suggest that even in China's megacities like Guangzhou, limiting biomass burning may benefit PAHs pollution control and cancer risk reduction.

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...

PROCESS FOR PRODUCTION OF URANIUM HEXAFLUORIDE

DOEpatents

Fowler, R.D.

1958-11-01

A process is described for the manufacture of uranium bexafluoride which consists in contacting an oxide of uranium simultaneously with elemental carbon and elemental fluorine at an elevated temperature, using a proportion of the carbon to the oxide about 50% in excess of that theoretically required to combine with f the oxygen as C0/.sub 2/. The process has the advantage that the uranium oxide is reduced by tbe carbon aad converted to the hexafluoride in a single operation.

ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

EPA Science Inventory

The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

RELATING PERSONAL PM AND PM-ASSOCIATED ELEMENTAL CARBON EXPOSURES TO CARDIOVASCULAR AND PULMONARY SYMPTOMS IN A HIGH-RISK SUBPOLULATION

EPA Science Inventory

Sensitive subpopulations such as COPD patients have been shown to be especially susceptible to the effects of PM exposure. Proximity to traffic has been shown to be a predictor of PM effects in susceptible populations. Elemental carbon (EC) has been demonstrated to be a good ...

Morphologies and elemental compositions of local biomass burning particles at urban and glacier sites in southeastern Tibetan Plateau: Results from an expedition in 2010.

PubMed

Hu, Tafeng; Cao, Junji; Zhu, Chongshu; Zhao, Zhuzi; Liu, Suixin; Zhang, Daizhou

2018-07-01

Many studies indicate that the atmospheric environment over the southern part of the Tibetan Plateau is influenced by aged biomass burning particles that are transported over long distances from South Asia. However, our knowledge of the particles emitted locally (within the plateau region) is poor. We collected aerosol particles at four urban sites and one remote glacier site during a scientific expedition to the southeastern Tibetan Plateau in spring 2010. Weather and backward trajectory analyses indicated that the particles we collected were more likely dominated by particles emitted within the plateau. The particles were examined using an electron microscope and identified according to their sizes, shapes and elemental compositions. At three urban sites where the anthropogenic particles were produced mainly by the burning of firewood, soot aggregates were in the majority and made up >40% of the particles by number. At Lhasa, the largest city on the Tibetan Plateau, tar balls and mineral particles were also frequently observed because of the use of coal and natural gas, in addition to biofuel. In contrast, at the glacier site, large numbers of chain-like soot aggregates (~25% by number) were noted. The morphologies of these aggregates were similar to those of freshly emitted ones at the urban sites; moreover, physically or chemically processed ageing was rarely confirmed. These limited observations suggest that the biomass burning particles age slowly in the cold, dry plateau air. Anthropogenic particles emitted locally within the elevated plateau region may thus affect the environment within glaciated areas in Tibet differently than anthropogenic particles transported from South Asia. Copyright © 2018 Elsevier B.V. All rights reserved.

Seasonal and spatial trends in the sources of fine particle organic carbon in Israel, Jordan, and Palestine

NASA Astrophysics Data System (ADS)

von Schneidemesser, Erika; Zhou, Jiabin; Stone, Elizabeth A.; Schauer, James J.; Qasrawi, Radwan; Abdeen, Ziad; Shpund, Jacob; Vanger, Arye; Sharf, Geula; Moise, Tamar; Brenner, Shmuel; Nassar, Khaled; Saleh, Rami; Al-Mahasneh, Qusai M.; Sarnat, Jeremy A.

2010-09-01

A study of carbonaceous particulate matter (PM) was conducted in the Middle East at sites in Israel, Jordan, and Palestine. The sources and seasonal variation of organic carbon, as well as the contribution to fine aerosol (PM 2.5) mass, were determined. Of the 11 sites studied, Nablus had the highest contribution of organic carbon (OC), 29%, and elemental carbon (EC), 19%, to total PM 2.5 mass. The lowest concentrations of PM 2.5 mass, OC, and EC were measured at southern desert sites, located in Aqaba, Eilat, and Rachma. The OC contribution to PM 2.5 mass at these sites ranged between 9.4% and 16%, with mean annual PM 2.5 mass concentrations ranging from 21 to 25 ug m -3. These sites were also observed to have the highest OC to EC ratios (4.1-5.0), indicative of smaller contributions from primary combustion sources and/or a higher contribution of secondary organic aerosol. Biomass burning and vehicular emissions were found to be important sources of carbonaceous PM in this region at the non-southern desert sites, which together accounted for 30%-55% of the fine particle organic carbon at these sites. The fraction of measured OC unapportioned to primary sources (1.4 μgC m -3 to 4.9 μgC m -3; 30%-74%), which has been shown to be largely from secondary organic aerosol, is relatively constant at the sites examined in this study. This suggests that secondary organic aerosol is important in the Middle East during all seasons of the year.

Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization.

PubMed

Duarte, Regina M B O; Matos, João T V; Paula, Andreia S; Lopes, Sónia P; Ribeiro, Sara; Santos, José Francisco; Patinha, Carla; da Silva, Eduardo Ferreira; Soares, Rosário; Duarte, Armando C

2017-04-01

In the framework of two national research projects (ORGANOSOL and CN-linkAIR), fine particulate matter (PM 2.5 ) was sampled for 17 months at an urban location in the Western European Coast. The PM 2.5 samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), major water-soluble inorganic ions, mineralogical, and for the first time in this region, strontium isotope ( 87 Sr/ 86 Sr) composition. Organic matter dominates the identifiable urban PM 2.5 mass, followed by secondary inorganic aerosols. The acquired data resulted also in a seasonal overview of the carbonaceous and inorganic aerosol composition, with an important contribution from primary biomass burning and secondary formation processes in colder and warmer periods, respectively. The fossil-related primary EC seems to be continually present throughout the sampling period. The 87 Sr/ 86 Sr ratios were measured on both the labile and residual PM 2.5 fractions as well as on the bulk PM 2.5 samples. Regardless of the air mass origin, the residual fractions are more radiogenic (representative of a natural crustal dust source) than the labile fractions, whose 87 Sr/ 86 Sr ratios are comparable to that of seawater. The 87 Sr/ 86 Sr ratios and the mineralogical composition data further suggest that sea salt and mineral dust are important primary natural sources of fine aerosols throughout the sampling period.

THE EFFECT OF WATER (VAPOR-PHASE) AND CARBON ON ELEMENTAL MERCURY REMOVAL IN A FLOW REACTOR

EPA Science Inventory

The paper gives results of studying the effect of vapor-phase moisture on elemental mercury (Hgo) removal by activated carbon (AC) in a flow reactor. tests involved injecting AC into both a dry and a 4% moisture nitrogen (N2) /Hgo gas stream. A bituminous-coal-based AC (Calgon WP...

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.

Aerosol elemental concentrations in the tropopause region from intercontinental flights with the Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) platform

NASA Astrophysics Data System (ADS)

Papaspiropoulos, Giorgos; Martinsson, Bengt G.; Zahn, Andreas; Brenninkmeijer, Carl A. M.; Hermann, Markus; Heintzenberg, Jost; Fischer, Herbert; van Velthoven, Peter F. J.

2002-12-01

This study with the Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) platform investigates the aerosol elemental concentrations at 9-11 km altitude in the northern hemisphere. Measurements from 31 intercontinental flights over a 2-year period between Germany and Sri Lanka/Maldives in the Indian Ocean are presented. Aerosol samples were collected with an impaction technique and were analyzed for the concentration of 18 elements using particle-induced X-ray emission (PIXE). Additional measurements of particle number concentrations, ozone and carbon monoxide concentrations, and meteorological modeling were included in the interpretation of the aerosol elemental concentrations. Particulate sulphur was found to be by far the most abundant element. Its upper tropospheric concentration increased, on average, by a factor of 2 from the tropics to midlatitudes, with another factor 2 higher concentrations in the lowermost stratosphere over midlatitudes. Correlation patterns and source profiles suggest contributions from crustal sources and biomass burning, but not from meteor ablation. Coinciding latitudinal gradients in particulate sulphur concentrations and emissions suggest that fossil fuel combustion is an important source of the aerosol in the upper troposphere and lowermost stratosphere. The measurements indicate aerosol transport along isentropic surfaces across the tropopause into the lowermost stratosphere. As a result of the prolonged residence time, ageing via oxidation of sulphur dioxide in the lowermost stratosphere was found to be a likely high-altitude, strong source that, along with downward transport of stratospheric air, could explain the vertical gradient of particulate sulphur mass concentration around the extratropical tropopause.

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.

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.

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.

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.

Process for producing metal compounds from graphite oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Process for Producing Metal Compounds from Graphite Oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon. metal. chloride. and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide: b) in an inert environment to produce metal oxide on carbon substrate: c) in a reducing environment. to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Technical note: Aerosol light absorption measurements with a carbon analyser - Calibration and precision estimates

NASA Astrophysics Data System (ADS)

Ammerlaan, B. A. J.; Holzinger, R.; Jedynska, A. D.; Henzing, J. S.

2017-09-01

Equivalent Black Carbon (EBC) and Elemental Carbon (EC) are different mass metrics to quantify the amount of combustion aerosol. Both metrics have their own measurement technique. In state-of-the-art carbon analysers, optical measurements are used to correct for organic carbon that is not evolving because of pyrolysis. These optical measurements are sometimes used to apply the technique of absorption photometers. Here, we use the transmission measurements of our carbon analyser for simultaneous determination of the elemental carbon concentration and the absorption coefficient. We use MAAP data from the CESAR observatory, the Netherlands, to correct for aerosol-filter interactions by linking the attenuation coefficient from the carbon analyser to the absorption coefficient measured by the MAAP. Application of the calibration to an independent data set of MAAP and OC/EC observations for the same location shows that the calibration is applicable to other observation periods. Because of simultaneous measurements of light absorption properties of the aerosol and elemental carbon, variation in the mass absorption efficiency (MAE) can be studied. We further show that the absorption coefficients and MAE in this set-up are determined within a precision of 10% and 12%, respectively. The precisions could be improved to 4% and 8% when the light transmission signal in the carbon analyser is very stable.

Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk.

PubMed

Johari, Khairiraihanna; Alias, Afidatul Shazwani; Saman, Norasikin; Song, Shiow Tien; Mat, Hanapi

2015-01-01

The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature. © The Author(s) 2014.

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.

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.

Inter-comparison of NIOSH and IMPROVE protocols for OC and EC determination: implications for inter-protocol data conversion

NASA Astrophysics Data System (ADS)

Wu, Cheng; Huang, X. H. Hilda; Ng, Wai Man; Griffith, Stephen M.; Zhen Yu, Jian

2016-09-01

Organic carbon (OC) and elemental carbon (EC) are operationally defined by analytical methods. As a result, OC and EC measurements are protocol dependent, leading to uncertainties in their quantification. In this study, more than 1300 Hong Kong samples were analyzed using both National Institute for Occupational Safety and Health (NIOSH) thermal optical transmittance (TOT) and Interagency Monitoring of Protected Visual Environment (IMPROVE) thermal optical reflectance (TOR) protocols to explore the cause of EC disagreement between the two protocols. EC discrepancy mainly (83 %) arises from a difference in peak inert mode temperature, which determines the allocation of OC4NSH, while the rest (17 %) is attributed to a difference in the optical method (transmittance vs. reflectance) applied for the charring correction. Evidence shows that the magnitude of the EC discrepancy is positively correlated with the intensity of the biomass burning signal, whereby biomass burning increases the fraction of OC4NSH and widens the disagreement in the inter-protocol EC determination. It is also found that the EC discrepancy is positively correlated with the abundance of metal oxide in the samples. Two approaches (M1 and M2) that translate NIOSH TOT OC and EC data into IMPROVE TOR OC and EC data are proposed. M1 uses direct relationship between ECNSH_TOT and ECIMP_TOR for reconstruction: M1 : ECIMP_TOR = a × ECNSH_TOT + b; while M2 deconstructs ECIMP_TOR into several terms based on analysis principles and applies regression only on the unknown terms: M2 : ECIMP_TOR = AECNSH + OC4NSH - (a × PCNSH_TOR + b), where AECNSH, apparent EC by the NIOSH protocol, is the carbon that evolves in the He-O2 analysis stage, OC4NSH is the carbon that evolves at the fourth temperature step of the pure helium analysis stage of NIOSH, and PCNSH_TOR is the pyrolyzed carbon as determined by the NIOSH protocol. The implementation of M1 to all urban site data (without considering seasonal specificity) yields the following equation: M1(urban data) : ECIMP_TOR = 2.20 × ECNSH_TOT - 0.05. While both M1 and M2 are acceptable, M2 with site-specific parameters provides the best reconstruction performance. Secondary OC (SOC) estimation using OC and EC by the two protocols is compared. An analysis of the usability of reconstructed ECIMP_TOR and OCIMP_TOR suggests that the reconstructed values are not suitable for SOC estimation due to the poor reconstruction of the OC / EC ratio.

Environmental controls on the elemental composition of a Southern Hemisphere strain of the coccolithophore Emiliania huxleyi

NASA Astrophysics Data System (ADS)

Feng, Yuanyuan; Roleda, Michael Y.; Armstrong, Evelyn; Law, Cliff S.; Boyd, Philip W.; Hurd, Catriona L.

2018-01-01

A series of semi-continuous incubation experiments were conducted with the coccolithophore Emiliania huxleyi strain NIWA1108 (Southern Ocean isolate) to examine the effects of five environmental drivers (nitrate and phosphate concentrations, irradiance, temperature, and partial pressure of CO2 (pCO2)) on both the physiological rates and elemental composition of the coccolithophore. Here, we report the alteration of the elemental composition of E. huxleyi in response to the changes in these environmental drivers. A series of dose-response curves for the cellular elemental composition of E. huxleyi were fitted for each of the five drivers across an environmentally representative gradient. The importance of each driver in regulating the elemental composition of E. huxleyi was ranked using a semi-quantitative approach. The percentage variations in elemental composition arising from the change in each driver between present-day and model-projected conditions for the year 2100 were calculated. Temperature was the most important driver controlling both cellular particulate organic and inorganic carbon content, whereas nutrient concentrations were the most important regulator of cellular particulate nitrogen and phosphorus of E. huxleyi. In contrast, elevated pCO2 had the greatest influence on cellular particulate inorganic carbon to organic carbon ratio, resulting in a decrease in the ratio. Our results indicate that the different environmental drivers play specific roles in regulating the elemental composition of E. huxleyi with wide-reaching implications for coccolithophore-related marine biogeochemical cycles, as a consequence of the regulation of E. huxleyi physiological processes.

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

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.

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

Hopkins, Rebecca J.; Lewis, K.; Desyaterik, Yury

Aerosols generated from burning different plant fuels were characterized to determine relationships between chemical, optical and physical properties. Single scattering albedo ({omega}) and Angstrom absorption coefficients ({alpha}{sub ap}) were measured using a photoacoustic technique combined with a reciprocal nephelometer. Carbon-to-oxygen atomic ratios, sp{sup 2} hybridization, elemental composition and morphology of individual particles were measured using scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) and scanning electron microscopy with energy dispersion of X-rays (SEM/EDX). Particles were grouped into three categories based on sp2 hybridization and chemical composition. Measured {omega} (0.4-1.0 at 405 nm) and {alpha}{sub ap}more » (1.0-3.5) values displayed a fuel dependence. The category with sp{sup 2} hybridization >80% had values of {omega} (<0.5) and {alpha}{sub ap} ({approx}1.25) characteristic of light absorbing soot. Other categories with lower sp2 hybridization (20 to 60%) exhibited higher {omega} (>0.8) and {alpha}{sub ap} (1.0 to 3.5) values, indicating increased absorption spectral selectivity.« less

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.

Exposure of miners to diesel exhaust particulates in underground nonmetal mines.

PubMed

Cohen, H J; Borak, J; Hall, T; Sirianni, G; Chemerynski, S

2002-01-01

A study was initiated to examine worker exposures in seven underground nonmetal mines and to examine the precision of the National Institute for Occupational Safety and Health (NIOSH) 5040 sampling and analytical method for diesel exhaust that has recently been adopted for compliance monitoring by the Mine Safety and Health Administration (MSHA). Approximately 1000 air samples using cyclones were taken on workers and in areas throughout the mines. Results indicated that worker exposures were consistently above the MSHA final limit of 160 micrograms/m3 (time-weighted average; TWA) for total carbon as determined by the NIOSH 5040 method and greater than the proposed American Conference of Governmental Industrial Hygienists TLV limit of 20 micrograms/m3 (TWA) for elemental carbon. A number of difficulties were documented when sampling for diesel exhaust using organic carbon: high and variable blank values from filters, a high variability (+/- 20%) from duplicate punches from the same sampling filter, a consistent positive interference (+26%) when open-faced monitors were sampled side-by-side with cyclones, poor correlation (r 2 = 0.38) to elemental carbon levels, and an interference from limestone that could not be adequately corrected by acid-washing of filters. The sampling and analytical precision (relative standard deviation) was approximately 11% for elemental carbon, 17% for organic carbon, and 11% for total carbon. An hypothesis is presented and supported with data that gaseous organic carbon constituents of diesel exhaust adsorb onto not only the submicron elemental carbon particles found in diesel exhaust, but also mining ore dusts. Such mining dusts are mostly nonrespirable and should not be considered equivalent to submicron diesel particulates in their potential for adverse pulmonary effects. It is recommended that size-selective sampling be employed, rather than open-faced monitoring, when using the NIOSH 5040 method.

Carbon-oxygen reaction efficiency in air gap switch with graphite electrodes under high current pulse discharge

NASA Astrophysics Data System (ADS)

Dai, Hongyu; Li, Lee; Peng, Ming-yang; Xiong, Jiaming; Wu, Haibo; Yu, Bin

2017-12-01

In order to reduce the effect of residual carbon on the insulation performance, after the GW-hundreds kiloampere graphite-electrode switch turning on, the chemical kinetics of the carbon-oxygen reaction is analyzed. The capacitive pulsed experimental circuit is used to reconstruct the actual condition of high power and high current discharge. The carbon-oxygen reaction efficiency is analyzed using a Fourier transform infrared spectrometer and a flue gas analyzer. The research shows that the gas products include NOX, O3, CH4, and COX. Through the quantitative analysis, the conversion efficiency of COX increases with the augment of the accumulated transferred charge, and the change law of the CO generation efficiency has an extreme value. With the corresponding calculation and the observation of the scanning electron microscope, it is found that most of the carbon consumed from the graphite electrodes is converted to amorphous elemental carbon, and the insufficiency of the carbon-oxygen reaction leads to the problem of carbon residue, for 20%-45% of elemental carbon is not oxidized. The size of amorphous elemental carbon is about several micrometers to tens micrometers by the analysis of metallographic microscope. In the condition of compressed air, changing the amount of transferred charge is helpful to improve the carbon-oxygen reaction efficiency and inhibit the problem of carbon residue.

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.

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.

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.

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.

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

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...

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.

Wet scavenging of organic and elemental carbon during summer monsoon and winter monsoon seasons

NASA Astrophysics Data System (ADS)

Sonwani, S.; Kulshrestha, U. C.

2017-12-01

In the era of rapid industrialization and urbanization, atmospheric abundance of carbonaceous aerosols is increasing due to more and more fossil fuel consumption. Increasing levels of carbonaceous content have significant adverse effects on air quality, human health and climate. The present study was carried out at Delhi covering summer monsoon (July -Sept) and winter monsoon (Dec-Jan) seasons as wind and other meteorological factors affect chemical composition of precipitation in different manner. During the study, the rainwater and PM10 aerosols were collected in order to understand the scavenging process of elemental and organic carbon. The Rain water samples were collected on event basis. PM10 samples were collected before rain (PR), during rain (DR) and after rain (AR) during 2016-2017. The collected samples were analysed by the thermal-optical reflectance method using IMPROVE-A protocol. In PM10, the levels of organic carbon (OC) and its fractions (OC1, OC2, OC3 and OC4) were found significantly lower in the AR samples as compared to PR and DR samples. A significant positive correlation was noticed between scavenging ratios of organic carbon and rain intensity indicating an efficient wet removal of OC. In contrast to OCs, the levels of elemental carbon and its fractions (EC1, EC2, and EC3) in AR were not distinct during PR and DR. The elemental carbon showed very week correlation with rain intensity in Delhi region which could be explained on the basis of hydrophobic nature of freshly emitted carbon soot. The detailed results will be discussed during the conference.

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.

Effects of emission reductions on organic aerosol in the southeastern United States

NASA Astrophysics Data System (ADS)

Blanchard, C. L.; Hidy, G. M.; Shaw, S.; Baumann, K.; Edgerton, E. S.

2015-06-01

Long-term (1999 to 2013) data from the Southeastern Aerosol Research and Characterization (SEARCH) network are used to characterize the effects of anthropogenic emission reductions on fine particle organic aerosol (OA) concentrations in the southeastern US. On average, 45 % (range 25 to 63 %) of the 1999 to 2013 mean organic carbon (OC) concentrations are attributed to combustion processes, including fossil-fuel use and biomass burning, through associations of measured OC with combustion products such as elemental carbon (EC), carbon monoxide (CO), and nitrogen oxides (NOx). The 2013 mean combustion-derived OC concentrations were 0.5 to 1.4 μg m-3 at the five sites operating in that year. Mean annual combustion-derived OC concentrations declined from 3.8 ± 0.2 μg m-3 (68 % of total OC) to 1.4 ± 0.1 μg m-3 (60 % of total OC) between 1999 and 2013 at the urban Atlanta, Georgia, site (JST) and from 2.9 ± 0.4 μg m-3 (39 % of total OC) to 0.7 ± 0.1 μg m-3 (30 % of total OC) between 2001 and 2013 at the urban Birmingham, Alabama, site (BHM). The urban OC declines coincide with reductions of motor-vehicle emissions between 2006 and 2010, which may have decreased mean OC concentrations at the urban SEARCH sites by > 2 μg m-3. BHM additionally exhibits a decline in OC associated with SO2 from 0.4 ± 0.04 μg m-3 in 2001 to 0.2 ± 0.03 μg m-3 in 2013, interpreted as the result of reduced emissions from industrial sources within the city. Analyses using non-soil potassium as a biomass-burning tracer indicate that biomass-burning OC occurs throughout the year at all sites. All eight SEARCH sites show an association of OC with sulfate (SO4) ranging from 0.3 to 1.0 μg m-3 on average, representing ~ 25 % of the 1999 to 2013 mean OC concentrations. Because the mass of OC associated with SO4 averages 20 to 30 % of the SO4 concentrations, the mean SO4-associated OC declined by ~ 0.5 to 1 μg m-3 as SO4 decreased throughout the SEARCH region. The 2013 mean SO4 concentrations of 1.7 to 2.0 μg m-3 imply that future decreases in mean SO4-associated OC concentrations would not exceed ~ 0.3 to 0.5 μg m-3. Seasonal OC concentrations, largely associated with ozone (O3), vary from 0.3 to 1.4 μg m-3 (~ 20 % of the total OC concentrations).

Effects of emission reductions on organic aerosol in the southeastern United States

NASA Astrophysics Data System (ADS)

Blanchard, C. L.; Hidy, G. M.; Shaw, S.; Baumann, K.; Edgerton, E. S.

2016-01-01

Long-term (1999 to 2013) data from the Southeastern Aerosol Research and Characterization (SEARCH) network are used to show that anthropogenic emission reductions led to important decreases in fine-particle organic aerosol (OA) concentrations in the southeastern US On average, 45 % (range 25 to 63 %) of the 1999 to 2013 mean organic carbon (OC) concentrations are attributed to combustion processes, including fossil fuel use and biomass burning, through associations of measured OC with combustion products such as elemental carbon (EC), carbon monoxide (CO), and nitrogen oxides (NOx). The 2013 mean combustion-derived OC concentrations were 0.5 to 1.4 µg m-3 at the five sites operating in that year. Mean annual combustion-derived OC concentrations declined from 3.8 ± 0.2 µg m-3 (68 % of total OC) to 1.4 ± 0.1 µg m-3 (60 % of total OC) between 1999 and 2013 at the urban Atlanta, Georgia, site (JST) and from 2.9 ± 0.4 µg m-3 (39 % of total OC) to 0.7 ± 0.1 µg m-3 (30 % of total OC) between 2001 and 2013 at the urban Birmingham, Alabama (BHM), site. The urban OC declines coincide with reductions of motor vehicle emissions between 2006 and 2010, which may have decreased mean OC concentrations at the urban SEARCH sites by > 2 µg m-3. BHM additionally exhibits a decline in OC associated with SO2 from 0.4 ± 0.04 µg m-3 in 2001 to 0.2 ± 0.03 µg m-3 in 2013, interpreted as the result of reduced emissions from industrial sources within the city. Analyses using non-soil potassium as a biomass burning tracer indicate that biomass burning OC occurs throughout the year at all sites. All eight SEARCH sites show an association of OC with sulfate (SO4) ranging from 0.3 to 1.0 µg m-3 on average, representing ˜ 25 % of the 1999 to 2013 mean OC concentrations. Because the mass of OC identified with SO4 averages 20 to 30 % of the SO4 concentrations, the mean SO4-associated OC declined by ˜ 0.5 to 1 µg m-3 as SO4 concentrations decreased throughout the SEARCH region. The 2013 mean SO4 concentrations of 1.7 to 2.0 µg m-3 imply that future decreases in mean SO4-associated OC concentrations would not exceed ˜ 0.3 to 0.5 µg m-3. Seasonal OC concentrations, largely identified with ozone (O3), vary from 0.3 to 1.4 µg m-3 ( ˜ 20 % of the total OC concentrations).

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.

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.

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.

Seasonal variations, molecular distributions, and stable carbon isotopic compositions of dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls in PM2.5 from Beijing, China

NASA Astrophysics Data System (ADS)

Zhao, W.; Kawamura, K.; Fu, P.

2016-12-01

Low molecular weight (LMW) dicarboxylic acids and related polar compounds comprise a significant fraction of atmospheric aerosols. Seasonal variations, molecular distributions, and stable carbon isotopic compositions of dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls, as well as organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) and inorganic ionic species, were determined to better understand the sources and photochemical aging processes of carbonaceous aerosols in urban Beijing from Sept. 2013 to Jul. 2014 (n=65). Concentrations of total diacids ranged from 110-2580 ng m-3, while ketoacids (9.5-353 ng m-3) and dicarbonyls (1.5-85.9 ng m-3) were less abundant. Higher ambient concentrations of phthalic (Ph) (37.9±27.3 ng m-3), terephthalic (tPh) (48.7±51.1 ng m-3), and glyoxylic (ωC2) (44.3±69 ng m-3) acids were found in winter than other seasons. The temporal variations of malonic acid to succinic acid (C3/C4) ratios were relatively low throughout the whole year, most of which were less than or equal to unity, even in summer, implying more contributions of dicarboxylic acids from primary emissions, rather than aging processes during long-range atmospheric transport. The δ13C mean values of malonic acid (-18.7% to -17.3%) and succinic acid (-28.6% to -17.1%) were larger than those of oxalic acid (-22.9% to -20.1%) in both seasons, except for δ13C of succinic acid in summer. Lower δ13C values of these compounds in Beijing than those in marine areas may be mainly associated with primary emissions, such as biomass burning, vehicular exhaust, incomplete fossil fuel combustion and plastic wastes.

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

Diagnostic Air Quality Model Evaluation of Source-Specific ...

EPA Pesticide Factsheets

Ambient measurements of 78 source-specific tracers of primary and secondary carbonaceous fine particulate matter collected at four midwestern United States locations over a full year (March 2004–February 2005) provided an unprecedented opportunity to diagnostically evaluate the results of a numerical air quality model. Previous analyses of these measurements demonstrated excellent mass closure for the variety of contributing sources. In this study, a carbon-apportionment version of the Community Multiscale Air Quality (CMAQ) model was used to track primary organic and elemental carbon emissions from 15 independent sources such as mobile sources and biomass burning in addition to four precursor-specific classes of secondary organic aerosol (SOA) originating from isoprene, terpenes, aromatics, and sesquiterpenes. Conversion of the source-resolved model output into organic tracer concentrations yielded a total of 2416 data pairs for comparison with observations. While emission source contributions to the total model bias varied by season and measurement location, the largest absolute bias of −0.55 μgC/m3 was attributed to insufficient isoprene SOA in the summertime CMAQ simulation. Biomass combustion was responsible for the second largest summertime model bias (−0.46 μgC/m3 on average). Several instances of compensating errors were also evident; model underpredictions in some sectors were masked by overpredictions in others. The National Exposure Research L

Characterizing the composition and evolution of and urban particles in Chongqing (China) during summertime

NASA Astrophysics Data System (ADS)

Chen, Yang; Yang, Fumo; Mi, Tian; Cao, Junji; Shi, Guangming; Huang, Rujin; Wang, Huanbo; Chen, Jun; Lou, Shengrong; Wang, Qiyuan

2017-05-01

Urban particles were investigated using a single particle aerosol mass spectrometer (SPAMS) in Chongqing during the summertime (from 07/05/2014 to 08/06/2014). Chemical composition, mixing state, and atmospheric behavior of urban particles were studied. The major particle types include ECOC (Elemental-Carbon-Organic-Carbon 20.6%), OC (20.1%), KSec (K-Secondary) (13.3%), BB (Biomass burning, 11.9%), NaK (sodium-potassium-rich, 7.3%), Al-rich (4.0%), Fe-rich (3.2%), Ca-rich (1.4%), Ca-EC (1.6%), and NaKPb (0.5%). EC, ECOC, OC, and Ca-EC were prevalent in the condensation mode (< 0.7 μm), while KSec, EC, NaK were significant in both the droplet mode (0.7-1.1 μm) and coarse mode. Increases in aged groups such as EC, KSec, and NaK were observed in the afternoon. Case studies suggested that wet scavenging (rain) rates of different single particle types followed an order of NaKPb > Fe-rich > EC > Ca-EC > Ca-rich > KSec > OC > NaK > ECOC > Al-rich > BB. Increased number fraction of EC and KSec were correlated with the increase of odd oxygen (Ox = O3 + NO2). EC, OC, and ECOC were enriched at higher relative humidity. The findings of this study on the mixing state, temporal variation, processing, and evolution of single particles provide new insight into the atmospheric behavior and impacts of urban particles.

Riverine Carbon and the Sedimentary Record on the Continental Shelves

DTIC Science & Technology

2005-09-30

focused on the Gulf of Lions: collecting sediment samples and carrying out elemental and stable carbon isotopic analysis . The field work was carried...organisms. For example, the predominance of nitrogen-free biomacromolecules (e.g. tannin , lignin, cellulose, cutin and suberin) over proteins (C:N ≈ 3-4...are cooperating with J. Fabres and A. Calafat (CRG Marine Geosciences) in carrying out elemental and isotopic analysis on suspended material

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 ...

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.

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.

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

Elemental carbon exposure at residence and survival after acute myocardial infarction.

PubMed

von Klot, Stephanie; Gryparis, Alexandros; Tonne, Cathryn; Yanosky, Jeffrey; Coull, Brent A; Goldberg, Robert J; Lessard, Darleen; Melly, Steven J; Suh, Helen H; Schwartz, Joel

2009-07-01

Particulate air pollution has been consistently related to cardiovascular mortality. Some evidence suggests that particulate matter may accelerate the atherosclerotic process. Effects of within-city variations of particulate air pollution on survival after an acute cardiovascular event have been little explored. We conducted a cohort study of hospital survivors of acute myocardial infarction (MI) from the Worcester, MA, metropolitan area to investigate the long-term effects of within-city variation in traffic-related air pollution on mortality. The study builds on an ongoing community-wide investigation examining changes over time in MI incidence and case-fatality rates. We included confirmed cases of MI in 1995, 1997, 1999, 2001, and 2003. Long-term survival status was ascertained through 2005. A validated spatiotemporal land use regression model for traffic-related air pollution was developed and annual averages of elemental carbon at residence estimated. The effect of estimated elemental carbon on the long-term mortality of patients discharged after MI was analyzed using a Cox proportional hazards model, controlling for a variety of demographic, medical history, and clinical variables. Of the 3895 patients with validated MI, 44% died during follow-up. Exposure to estimated elemental carbon in the year of entry into the study was 0.44 microg/m on average. All-cause mortality increased by 15% (95% confidence interval = 0.03%-29%) per interquartile range increase in estimated yearly elemental carbon (0.24 microg/m) after the second year of survival. No association between traffic-related pollution and all-cause mortality was observed during the first 2 years of follow-up. Chronic traffic-related particulate air pollution is associated with increased mortality in hospital survivors of acute MI after the second year of survival.

Uncontrolled combustion of shredded tires in a landfill – Part 1: Characterization of gaseous and particulate emissions

PubMed Central

Downard, Jared; Singh, Ashish; Bullard, Robert; Jayarathne, Thilina; Rathnayake, Chathurika; Simmons, Donald L.; Wels, Brian R.; Spak, Scott N.; Peters, Thomas; Beardsley, Douglas; Stanier, Charles; Stone, Elizabeth A.

2014-01-01

In summer 2012, a landfill liner comprising an estimated 1.3 million shredded tires burned in Iowa City, Iowa. During the fire, continuous monitoring and laboratory measurements were used to characterize the gaseous and particulate emissions and to provide new insights into the qualitative nature of the smoke and the quantity of pollutants emitted. Significant enrichments in ambient concentrations of CO, CO2, SO2, particle number (PN), fine particulate (PM2.5) mass, elemental carbon (EC), and polycyclic aromatic hydrocarbons (PAH) were observed. For the first time, PM2.5 from tire combustion was shown to contain PAH with nitrogen heteroatoms (a.k.a. azaarenes) and picene, a compound previously suggested to be unique to coal-burning. Despite prior laboratory studies’ findings, metals used in manufacturing tires (i.e. Zn, Pb, Fe) were not detected in coarse particulate matter (PM10) at a distance of 4.2 km downwind. Ambient measurements were used to derive the first in situ fuel-based emission factors (EF) for the uncontrolled open burning of tires, revealing substantial emissions of SO2 (7.1 g kg−1), particle number (3.5×1016 kg−1), PM2.5 (5.3 g kg−1), EC (2.37 g kg−1), and 19 individual PAH (totaling 56 mg kg−1). A large degree of variability was observed in day-to-day EF, reflecting a range of flaming and smoldering conditions of the large-scale fire, for which the modified combustion efficiency ranged from 0.85-0.98. Recommendations for future research on this under-characterized source are also provided. PMID:25663800

Optical Properties of Aerosols and Implications for Radiative Effects in Beijing During the Asia-Pacific Economic Cooperation Summit 2014

NASA Astrophysics Data System (ADS)

Zhou, Yaqing; Wang, Qiyuan; Huang, Rujin; Liu, Suixin; Tie, Xuexi; Su, Xiaoli; Niu, Xinyi; Zhao, Zhuzi; Ni, Haiyan; Wang, Meng; Zhang, Yonggang; Cao, Junji

2017-09-01

An intensive measurement campaign was conducted in Beijing during the Asia-Pacific Economic Cooperation (APEC) Summit 2014 to investigate the effectiveness of stringent emission controls on aerosol optical properties and direct radiative forcing (DRF). Average values of PM2.5, light scattering (bscat), and light absorption (babs) coefficients decreased by 40, 64, and 56%, respectively, during the APEC control period compared with noncontrol periods. For the APEC control period, the PM2.5 mass scattering and absorption efficiencies were both smaller than the noncontrol period by a factor of 2. Calculations based on a revised IMPROVE method and linear regression showed that sulfate, nitrate, organic matter, elemental carbon, and fine soil contributed comparably to the light extinction coefficient (bext) in both periods, but the bext values were 27-64% lower during the APEC period. A positive matrix factorization receptor model showed that bext from two secondary aerosol sources, biomass burning, traffic-related emissions, and coal burning decreased by 26-87% during the APEC control period. The average DRF calculated from the Tropospheric Ultraviolet and Visible radiation model was -11.9 and -4.6 W m-2 at the surface during the noncontrol and APEC control periods, respectively, suggesting an overall cooling effect. The reduction of DRF from each emission source ranged from 30-80% during the APEC control period. The results suggest that the pollution control measures implemented for APEC substantially reduced air pollution and could help mitigate the cooling effects of aerosols at the surface in Beijing.

[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.

Uncontrolled combustion of shredded tires in a landfill - Part 1: Characterization of gaseous and particulate emissions

NASA Astrophysics Data System (ADS)

Downard, Jared; Singh, Ashish; Bullard, Robert; Jayarathne, Thilina; Rathnayake, Chathurika M.; Simmons, Donald L.; Wels, Brian R.; Spak, Scott N.; Peters, Thomas; Beardsley, Douglas; Stanier, Charles O.; Stone, Elizabeth A.

2015-03-01

In summer 2012, a landfill liner comprising an estimated 1.3 million shredded tires burned in Iowa City, Iowa. During the fire, continuous monitoring and laboratory measurements were used to characterize the gaseous and particulate emissions and to provide new insights into the qualitative nature of the smoke and the quantity of pollutants emitted. Significant enrichments in ambient concentrations of CO, CO2, SO2, particle number (PN), fine particulate (PM2.5) mass, elemental carbon (EC), and polycyclic aromatic hydrocarbons (PAH) were observed. For the first time, PM2.5 from tire combustion was shown to contain PAH with nitrogen heteroatoms (a.k.a. azaarenes) and picene, a compound previously suggested to be unique to coal-burning. Despite prior laboratory studies' findings, metals used in manufacturing tires (i.e. Zn, Pb, Fe) were not detected in coarse particulate matter (PM10) at a distance of 4.2 km downwind. Ambient measurements were used to derive the first in situ fuel-based emission factors (EF) for the uncontrolled open burning of tires, revealing substantial emissions of SO2 (7.1 g kg-1), particle number (3.5 × 1016 kg-1), PM2.5 (5.3 g kg-1), EC (2.37 g kg-1), and 19 individual PAH (totaling 56 mg kg-1). A large degree of variability was observed in day-to-day EF, reflecting a range of flaming and smoldering conditions of the large-scale fire, for which the modified combustion efficiency ranged from 0.85 to 0.98. Recommendations for future research on this under-characterized source are also provided.

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.

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.

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

Size and composition distribution of fine particulate matter emitted from wood burning, meat charbroiling, and cigarettes

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

Kleeman, M.J.; Schauer, J.J.; Cass, G.R.

A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from air pollution sources. Measurements are made using a laser optical particle counter (OPC), a differential mobility analyzer/condensation nucleus counter (DMA/CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include wood smoke (pine, oak, eucalyptus), meat charbroiling, and cigarettes. The particle mass distributions from all wood smoke sources have a single mode that peaks at approximately 0.1--0.2 {micro}m particle diameter. The smoke from meat charbroiling shows a major peak in the particle mass distribution atmore » 0.1--0.2 {micro}m particle diameter, with some material present at larger particle sizes. Particle mass distributions from cigarettes peak between 0.3 and 0.4 {micro}m particle diameter. Chemical composition analysis reveals that particles emitted from the sources tested here are largely composed of organic compounds. Noticeable concentrations of elemental carbon are found in the particles emitted from wood burning. The size distributions of the trace species emissions from these sources also are presented, including data for Na, K, Ti, Fe, Br, Ru, Cl, Al, Zn, Ba, Sr, V, Mn, Sb, La, Ce, as well as sulfate, nitrate, and ammonium ion when present in statistically significant amounts. These data are intended for use with air quality models that seek to predict the size distribution of the chemical composition of atmospheric fine particles.« less

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...

Biogenic contribution to PM-2.5 ambient aerosol from radiocarbon measurements

NASA Astrophysics Data System (ADS)

Lewis, C.; Klouda, G.; Ellenson, W.

2003-04-01

Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (14C) measurements provide a means to quantify the biogenic fraction of any carbon-containing sample of ambient aerosol. In the absence of an impact from biomass burning (e.g., during summertime) such measurements can provide an estimate of the contribution of biogenic secondary organic aerosol, from biogenic volatile organic compound precursors. Radiocarbon results for 11.5-h PM-2.5 samples collected near Nashville, Tennessee, USA, during summer 1999 will be presented. On average the measured biogenic fraction was surprisingly large (more than half), with the average biogenic fraction for night samples being only slightly smaller than for day samples. Discussion will include (a) description of the radiocarbon methodology, (b) use of radiocarbon measurements on local vegetation and fuel samples as calibration data, (c) concurrent measurements of organic carbon and elemental carbon ambient concentrations, (d) assessment of organic aerosol sampling artifact through use of organic vapor denuders, variable face velocities, and filter extraction, and (e) comparison with published radiocarbon results obtained in Houston, Texas in a similar study. Disclaimer: This work has been funded wholly or in part by the United States Environmental Protection Agency under Interagency Agreement No. 13937923 to the National Institute of Standards and Technology, and Contract No. 68-D5-0049 to ManTech Environmental Tecnology, Inc. It has been subjected to Agency review and approved for publication.

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.

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.

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.

Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

NASA Astrophysics Data System (ADS)

Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Teinilä, K.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

2012-03-01

The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM:OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their origin to be mostly regional. That resulted in much more oxidized OA in the daytime mixing layer than in the nocturnal surface layer. In this study, the high mass resolution and source-related aerosol chemistry from the HR-ToF-AMS was combined with the filter measurements in a total new extent elucidating novel features and sources of organic aerosol in the Po Valley region.

Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing

NASA Astrophysics Data System (ADS)

Aggarwal, S. G.; Kawamura, K.; Umarji, G. S.; Tachibana, E.; Patil, R. S.; Gupta, P. K.

2013-05-01

To better understand the sources of PM10 samples in Mumbai, India, aerosol chemical composition, i.e., total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied together with specific markers such as methanesulfonate (MSA), oxalic acid (C2), azelaic acid (C9), and levoglucosan. The results revealed that biofuel/biomass burning and fossil fuel combustion are the major sources of the Mumbai aerosols. Nitrogen-isotopic (δ15N) composition of aerosol total nitrogen, which ranged from 18.1 to 25.4‰, also suggests that biofuel/biomass burning is a predominate source in both the summer and winter seasons. Aerosol mass concentrations of major species increased 3-4 times in winter compared to summer, indicating enhanced emission from these sources in the winter season. Photochemical production tracers, C2 diacid and nssSO42-, do not show diurnal changes. Concentrations of C2 diacid and WSOC show a strong correlation (r2 = 0.95). In addition, WSOC to OC (or TC) ratios remain almost constant for daytime (0.37 ± 0.06 (0.28 ± 0.04)) and nighttime (0.38 ± 0.07 (0.28 ± 0.06)), suggesting that mixing of fresh secondary organic aerosols is not significant and the Mumbai aerosols are photochemically well processed. Concentrations of MSA and C9 diacid present a positive correlation (r2 = 0.75), indicating a marine influence on Mumbai aerosols in addition to local/regional influence. Backward air mass trajectory analyses further suggested that the Mumbai aerosols are largely influenced by long-range continental and regional transport. Stable C-isotopic ratios (δ13C) of TC ranged from -27.0 to -25.4‰, with slightly lower average (-26.5 ± 0.3‰) in summer than in winter (-25.9 ± 0.3‰). Positive correlation between WSOC/TC ratios and δ13C values suggested that the relative increment in 13C of wintertime TC may be caused by prolonged photochemical processing of organic aerosols in this season. This study suggests that in winter, the tropical aerosols are more aged due to longer residence time in the atmosphere than in summer aerosols. However, these conclusions are based on the analysis of a limited number of samples (n=25) and more information on this topic may be needed from other similar coastal sites in future.

Emission of trace gases and organic components in smoke particles from a wildfire in a mixed-evergreen forest in Portugal.

PubMed

Alves, Célia A; Vicente, Ana; Monteiro, Cristina; Gonçalves, Cátia; Evtyugina, Margarita; Pio, Casimiro

2011-03-15

On May 2009, both the gas and particulate fractions of smoke from a wildfire in Sever do Vouga, central Portugal, were sampled. Total hydrocarbons and carbon oxides (CO(2) and CO) were measured using automatic analysers with flame ionisation and non-dispersive infrared detectors, respectively. Fine (PM(2.5)) and coarse (PM(2.5-10)) particles from the smoke plume were analysed by a thermal-optical transmission technique to determine the elemental and organic carbon (EC and OC) content. Subsequently, the particle samples were solvent extracted and fractionated by vacuum flash chromatography into different classes of organic compounds. The detailed organic speciation was performed by gas chromatography-mass spectrometry. The CO, CO(2) and total hydrocarbon emission factors (g kg(-1) dry fuel) were 170 ± 83, 1485 ± 147, and 9.8 ± 0.90, respectively. It was observed that the particulate matter and OC emissions are significantly enhanced under smouldering fire conditions. The aerosol emissions were dominated by fine particles whose mass was mainly composed of organic constituents, such as degradation products from biopolymers (e.g. levoglucosan from cellulose, methoxyphenols from lignin). The compound classes also included homologous series (n-alkanes, n-alkenes, n-alkanoic acids and n-alkanols), monosaccharide derivatives from cellulose, steroid and terpenoid biomarkers, and polycyclic aromatic hydrocarbons (PAHs). The most abundant PAH was retene. Even carbon number homologs of monoglycerides were identified for the first time as biomarkers in biomass burning aerosols. Copyright © 2010 Elsevier B.V. All rights reserved.

Springtime variations of organic and inorganic constituents in submicron aerosols (PM1.0) from Cape Hedo, Okinawa

NASA Astrophysics Data System (ADS)

Kunwar, Bhagawati; Torii, K.; Zhu, Chunmao; Fu, Pingqing; Kawamura, Kimitaka

2016-04-01

During the spring season with enhanced Asian outflow, we collected submicron aerosol (PM1.0) samples at Cape Hedo, Okinawa Island in the western North Pacific Rim. We analyzed the filter samples for diacids, oxoacids, pyruvic acid, α-dicarbonyls and fatty acids to better understand the sources and atmospheric processes in the outflow regions of Asian pollutants. Molecular distributions of diacids show a predominance of oxalic acid (C2) followed by malonic (C3) and succinic (C4) acids. Total diacids strongly correlated with secondary source tracers such as SO42- (r = 0.87), NH4+ (0.90) and methanesulfonate (MSA-) (0.84), suggesting that diacids are secondarily formed from their precursor compounds. We also found good correlations among C2, organic carbon (OC) and elemental carbon (EC) in the Okinawa aerosols, suggesting that diacids are mainly derived from anthropogenic sources. However, a weak correlation of diacids with levoglucosan, a biomass burning tracer, suggests that biomass buring is not the main source of diacids, rather diacids are secondarily formed by photochemical oxidation of organic precursors derived from fossil fuel combustion. We found a strong correlation (r = 0.98) between inorganic nitrogen (NO3-N + NH4-N) and total nitrogen (TN), to which organic nitrogen (ON) contributed 23%. Fatty acids were characterized by even carbon number predominance, suggesting that they are derived from biogenic sources. The higher abundances of short chain fatty acids (C20) further suggest that fatty acids are largely derived from marine phytoplankton during spring bloom.

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

Chemical characterization and mass closure of PM10 and PM2.5 at an urban site in Karachi - Pakistan

NASA Astrophysics Data System (ADS)

Shahid, Imran; Kistler, Magdalena; Mukhtar, Azam; Ghauri, Badar M.; Ramirez-Santa Cruz, Carlos; Bauer, Heidi; Puxbaum, Hans

2016-03-01

A mass balance method is applied to assess main source contributions to PM2.5 and PM10 levels in Karachi. Carbonaceous species (elemental carbon, organic carbon, carbonate carbon), soluble ions (Ca++, Mg++, Na+, K+, NH4+, Cl-, NO3-, SO4-), saccharides (levoglucosan, galactosan, mannosan, sucrose, fructose, glucose, arabitol and mannitol) were determined in atmospheric fine (PM2.5) and coarse (PM10) aerosol samples collected under pre-monsoon conditions (March-April 2009) at an urban site in Karachi (Pakistan). The concentrations of PM2.5 and PM10 were found to be 75 μg/m3 and 437 μg/m3 respectively. The large difference between PM10 and PM2.5 originated predominantly from mineral dust. "Calcareous dust" and "siliceous dust" were the over all dominating material in PM, with 46% contribution to PM2.5 and 78% to PM10-2.5. Combustion particles and secondary organics (EC + OM) comprised 23% of PM2.5 and 6% of PM10-2.5. EC, as well as OC ambient levels were higher (59% and 56%) in PM10-2.5 than in PM2.5. Biomass burning contributed about 3% to PM2.5, and had a share of about 13% of ;EC + OM; in PM2.5. The impact of bioaerosol (fungal spores) was minor and had a share of 1 and 2% of the OC in the PM2.5 and PM10-2.5 size fractions. In case of secondary inorganic aerosols, ammonium sulphate (NH4)2SO4 contributes 4.4% to PM2.5 and no detectable quantity were found in fraction PM10-2.5. The sea salt contribution is about 2% both to PM2.5 and PM10-2.5.

Seasonal variations of diacids, ketoacids, and α-dicarbonyls in aerosols at Gosan, Jeju Island, South Korea: Implications for sources, formation, and degradation during long-range transport

NASA Astrophysics Data System (ADS)

Kundu, Shuvashish; Kawamura, Kimitaka; Lee, Meehye

2010-10-01

Aerosol samples (n = 84) were collected continuously from April 2003 to April 2004 at Gosan site in Jeju Island, South Korea. The samples were analyzed for diacids, ketoacids, and α-dicarbonyls, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and water-soluble inorganic ions. Oxalic acid (C2) was the most abundant followed by malonic acid (C3) in all the seasons. The mean concentration (784 ng m-3) of total diacids (C2-C12) and their relative abundances in total organic species detected, OC and WSOC were found to be the highest in summer, whereas those of ketoacids and dicarbonyls were the highest in winter. The annual mean contributions of diacids, ketoacids, and dicarbonyls to WSOC are 12, 1, and 0.4%, respectively. They are several times higher than those reported in East Asia from which air masses are transported to Gosan, indicating an importance of photochemical processing of aerosols during a long-range transport. Diacids and related compounds show different seasonal variations, suggesting their season-specific sources and photochemical processing. This study demonstrates an enhanced photochemical production and degradation of water-soluble organics in summer. In contrast, higher positive correlations between combustion tracers (non-sea-salt K+ and EC) and diacids and related compounds were observed in the winter, pointing out higher emission of diacids and related compounds or their precursors from fossil fuel/biomass burning.

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.

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.

Synthesis of Tetraphenylstannacyclopentadienes (Stannoles). II. Derivatives and Adducts of 1,1-Dihalo-2,3,4,5-tetraphenylstannoles.

DTIC Science & Technology

1981-04-15

products (4-bromo-l,2,3,4-tetraphenylbutadienyl)tin tribromide o (4-iodo-l,2,3,4-tetraphenylbutadienyl)tin triiodide. Even gentle chlorination of...hexaphenyistannole by elemental chlorine cleaves the ring tin-carbon bonds to form cis-cis-l ,4-dichloro-l ,2 ,3 ,4-tetraphenylbutadiene-l, 3 and diphenyltin... chlorination of hexaphenylstannole by elemental chlorine cleaves the ring tin-carbon bonds to form cis- cis-l,4-dichloro-l,2,3,4-tetraphenylbutadiene-1,3

Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

NASA Astrophysics Data System (ADS)

Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

2012-09-01

The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using a Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM : OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their origin to be mostly regional. That resulted in much more oxidized OA in the daytime mixing layer than in the nocturnal surface layer. In this study, the high mass resolution and source-related aerosol chemistry from the HR-ToF-AMS was combined with the filter measurements in a total new extent elucidating novel features and sources of organic aerosol in the Po Valley region.

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.

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.

Biomass Burning: Energy and Emissions Performance of Traditional and Improved Cookstoves Under Controlled Laboratory Conditions

NASA Astrophysics Data System (ADS)

Arora, Pooja

Indoor air pollution (IAP) from solid biomass fuel burning in traditional cookstoves is a leading problem all the world which is responsible for health and climate related impacts. The immediate solution in order to combat this threat has been introduction of improved cookstoves among rural populations who doesn't have access clean energy. The extent of improvement in new cookstove designs, in terms of higher energy efficiency and lower emissions is in turn dependent on the customary behaviour of the users on field. The field based cookstove testing conducted in various studies show a disagreement between performance measures in the lab and real world conditions. Some of the important variables which reflect the actual user behaviour on field depending on geographical location include fuel characteristics and cooking cycle. In this thesis, the research approach focused on user-centred testing methodology for cookstoves. The variation in cookstove performance in terms of energy and emission parameters was assessed by isolating the impact of individual variables i.e. types of fuel and cooking cycles. The energy parameters which served as indicators of cookstove performance included SEC and power input, and EFs for CO and PM were used as emission parameters. PM emissions were further analysed with the help of physical and chemical characterization studies. The physical characterization focused on size distribution of the particulate using optical and electron microscopy techniques. While chemical characterization was conducted using quantification methods for organic and elemental carbon content of PM using TOR and CBMS techniques. The test variables were identified through field survey and literature review and were replicated under controlled laboratory conditions where emissions were sampled using hood method. The research resulted in six research papers addressing specific hypothesis related the problem identified through literature survey. The results showed that the difference in cooking cycles and fuel usage pattern has a significant impact on the overall performance of cookstoves. The study provided an in depth analysis of the difference in combustion conditions during the simulated and actual cookstove cooking conditions. The cooking cycle of two different regions of India indicated a significant change in cookstove performance in terms of CO and PM emissions in addition to energy consumption. It was also observed that among the different mix fuel conditions (combinations of wood, crop residue and cow dung), wood when used as a single fuel resulted in lowest CO and PM emissions. This was again a misrepresentation of field performance (specifically for regions with wood scarcity) where use of mix fuels is a prevalent practice followed while cooking. The impact of these variables was also significant on chemical characteristics of PM in terms of elemental carbon (EC)/black carbon (BC) and organic carbon (BC). Similar deviations were also found in physical characteristics of PM where PM size taken as test parameter. Therefore, relying on simulated test protocols might not represent the actual cookstove performance that might exist on field. This calls for an immediate attention towards the development of comprehensive test guidelines for cookstoves which not only highlights the technical aspects but also the social preferences of the targeted rural populations.

Laboratory simulation of meteoritic noble gases. III - Sorption of neon, argon, krypton, and xenon on carbon - Elemental fractionation

NASA Technical Reports Server (NTRS)

Wacker, John F.

1989-01-01

The sorption of Ne, Ar, Kr, and Xe was studied in carbon black, acridine carbon, and diamond in an attempt to understand the origin of trapped noble gases in meteorites. The results support a model in which gases are physically adsorbed on interior surfaces formed by a pore labyrinth within amorphous carbons. The data show that: (1) the adsorption/desorption times are controlled by choke points that restrict the movement of noble gas atoms within the pore labyrinth, and (2) the physical adsorption controls the temperature behavior and elemental fractionation patterns.

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.

Evaluation of the SKC DPM cassette for monitoring diesel particulate matter in coal mines.

PubMed

Noll, James D; Birch, Eileen

2004-12-01

In a previous study, the efficacy of commercial and prototype impactors for sampling diesel particulate matter (DPM) in coal mines was investigated. Laboratory and field samples were collected on quartz-fiber filters and analyzed for organic and elemental carbon. Coal dust contributed a minimal amount of elemental carbon when commercial cascade impactors and prototype impactors, designed by the University of Minnesota (UMN) and the US Bureau of Mines (BOM), were used to collect submicrometer dust fractions. Other impactors were not as effective at excluding coal dust. The impactors evaluated in that study were either not commercially available or were multi-stage, expensive, and difficult to use for personal measurements. A commercial version of the BOM impactor, called the DPM Cassette, was recently introduced by SKC. Tests were conducted to evaluate the performance of the DPM Cassette for measuring diesel-source elemental carbon in the presence of coal dust. Bituminous coals from three mines in two different coal provinces were examined. The dust particle diameters were small and the coal dust contained a high percentage of carbon, thereby giving a worst-case condition for non-anthracite coal mines. Results for the DPM Cassette were essentially identical to those obtained by the BOM impactors in a previous study. At a respirable coal dust concentration of 5.46 mg m(-3), which is 3.8 times the regulatory limit, the DPM Cassette collected only 34 microg m(-3) of coal-source elemental carbon.

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.

Apportionment of urban aerosol sources in Cork (Ireland) by synergistic measurement techniques.

PubMed

Dall'Osto, Manuel; Hellebust, Stig; Healy, Robert M; O'Connor, Ian P; Kourtchev, Ivan; Sodeau, John R; Ovadnevaite, Jurgita; Ceburnis, Darius; O'Dowd, Colin D; Wenger, John C

2014-09-15

The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Cork city (Ireland) have been determined. Aerosol chemical analyses were performed by multiple techniques including on-line high resolution aerosol time-of-flight mass spectrometry (Aerodyne HR-ToF-AMS), on-line single particle aerosol time-of-flight mass spectrometry (TSI ATOFMS), on-line elemental carbon-organic carbon analysis (Sunset_EC-OC), and off-line gas chromatography/mass spectrometry and ion chromatography analysis of filter samples collected at 6-h resolution. Positive matrix factorization (PMF) has been carried out to better elucidate aerosol sources not clearly identified when analyzing results from individual aerosol techniques on their own. Two datasets have been considered: on-line measurements averaged over 2-h periods, and both on-line and off-line measurements averaged over 6-h periods. Five aerosol sources were identified by PMF in both datasets, with excellent agreement between the two solutions: (1) regional domestic solid fuel burning--"DSF_Regional," 24-27%; (2) local urban domestic solid fuel burning--"DSF_Urban," 22-23%; (3) road vehicle emissions--"Traffic," 15-20%; (4) secondary aerosols from regional anthropogenic sources--"SA_Regional" 9-13%; and (5) secondary aged/processed aerosols related to urban anthropogenic sources--"SA_Urban," 21-26%. The results indicate that, despite regulations for restricting the use of smoky fuels, solid fuel burning is the major source (46-50%) of PM2.5 in wintertime in Cork, and also likely other areas of Ireland. Whilst wood combustion is strongly associated with OC and EC, it was found that peat and coal combustion is linked mainly with OC and the aerosol from these latter sources appears to be more volatile than that produced by wood combustion. Ship emissions from the nearby port were found to be mixed with the SA_Regional factor. The PMF analysis allowed us to link the AMS cooking organic aerosol factor (AMS_PMF_COA) to oxidized organic aerosol, chloride and locally produced nitrate, indicating that AMS_PMF_COA cannot be attributed to primary cooking emissions only. Overall, there are clear benefits from factor analysis applied to results obtained from multiple techniques, which allows better association of aerosols with sources and atmospheric processes. Copyright © 2014 Elsevier B.V. All rights reserved.

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

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): emissions of particulate matter from wood- and dung-fueled cooking fires, garbage and crop residue burning, brick kilns, and other sources

NASA Astrophysics Data System (ADS)

Jayarathne, Thilina; Stockwell, Chelsea E.; Bhave, Prakash V.; Praveen, Puppala S.; Rathnayake, Chathurika M.; Robiul Islam, Md.; Panday, Arnico K.; Adhikari, Sagar; Maharjan, Rashmi; Goetz, J. Douglas; DeCarlo, Peter F.; Saikawa, Eri; Yokelson, Robert J.; Stone, Elizabeth A.

2018-02-01

The Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) characterized widespread and under-sampled combustion sources common to South Asia, including brick kilns, garbage burning, diesel and gasoline generators, diesel groundwater pumps, idling motorcycles, traditional and modern cooking stoves and fires, crop residue burning, and heating fire. Fuel-based emission factors (EFs; with units of pollutant mass emitted per kilogram of fuel combusted) were determined for fine particulate matter (PM2.5), organic carbon (OC), elemental carbon (EC), inorganic ions, trace metals, and organic species. For the forced-draft zigzag brick kiln, EFPM2.5 ranged from 12 to 19 g kg-1 with major contributions from OC (7 %), sulfate expected to be in the form of sulfuric acid (31.9 %), and other chemicals not measured (e.g., particle-bound water). For the clamp kiln, EFPM2.5 ranged from 8 to 13 g kg-1, with major contributions from OC (63.2 %), sulfate (23.4 %), and ammonium (16 %). Our brick kiln EFPM2.5 values may exceed those previously reported, partly because we sampled emissions at ambient temperature after emission from the stack or kiln allowing some particle-phase OC and sulfate to form from gaseous precursors. The combustion of mixed household garbage under dry conditions had an EFPM2.5 of 7.4 ± 1.2 g kg-1, whereas damp conditions generated the highest EFPM2.5 of all combustion sources in this study, reaching up to 125 ± 23 g kg-1. Garbage burning emissions contained triphenylbenzene and relatively high concentrations of heavy metals (Cu, Pb, Sb), making these useful markers of this source. A variety of cooking stoves and fires fueled with dung, hardwood, twigs, and/or other biofuels were studied. The use of dung for cooking and heating produced higher EFPM2.5 than other biofuel sources and consistently emitted more PM2.5 and OC than burning hardwood and/or twigs; this trend was consistent across traditional mud stoves, chimney stoves, and three-stone cooking fires. The comparisons of different cooking stoves and cooking fires revealed the highest PM emissions from three-stone cooking fires (7.6-73 g kg-1), followed by traditional mud stoves (5.3-19.7 g kg-1), mud stoves with a chimney for exhaust (3.0-6.8 g kg-1), rocket stoves (1.5-7.2 g kg-1), induced-draft stoves (1.2-5.7 g kg-1), and the bhuse chulo stove (3.2 g kg-1), while biogas had no detectable PM emissions. Idling motorcycle emissions were evaluated before and after routine servicing at a local shop, which decreased EFPM2.5 from 8.8 ± 1.3 to 0.71 ± 0.45 g kg-1 when averaged across five motorcycles. Organic species analysis indicated that this reduction in PM2.5 was largely due to a decrease in emission of motor oil, probably from the crankcase. The EF and chemical emissions profiles developed in this study may be used for source apportionment and to update regional emission inventories.

Aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing in Guangzhou during the 2006 Pearl River Delta campaign.

PubMed

Jung, Jinsang; Lee, Hanlim; Kim, Young J; Liu, Xingang; Zhang, Yuanhang; Gu, Jianwei; Fan, Shaojia

2009-08-01

Optical and chemical aerosol measurements were obtained from 2 to 31 July 2006 at an urban site in the metropolitan area of Guangzhou (China) as part of the Program of Regional Integrated Experiment of Air Quality over Pearl River Delta (PRIDE-PRD2006) to investigate aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing. During the PRIDE-PRD2006 campaign, the average contributions of ammonium sulfate, organic mass by carbon (OMC), elemental carbon (EC), and sea salt (SS) to total PM(2.5) mass were measured to be 36.5%, 5.7%, 27.1%, 7.8%, and 3.7%, respectively. Compared with the clean marine period, (NH(4))(2)SO(4), NH(4)NO(3), and OMC were all greatly enhanced (by up to 430%) during local haze periods via the accumulation of a secondary aerosol component. The OMC dominance increased when high levels of biomass burning influenced the measurement site while (NH(4))(2)SO(4) and OMC did when both biomass burning and industrial emissions influenced it. The effect of aerosol water content on the total light-extinction coefficient was estimated to be 34.2%, of which 25.8% was due to aerosol water in (NH(4))(2)SO(4), 5.1% that in NH(4)NO(3), and 3.3% that in SS. The average mass-scattering efficiency (MSE) of PM(10) particles was determined to be 2.2+/-0.6 and 4.6+/-1.7m(2)g(-1) under dry (RH<40%) and ambient conditions, respectively. The average single-scattering albedo (SSA) was 0.80+/-0.08 and 0.90+/-0.04 under dry and ambient conditions, respectively. Not only are the extinction and scattering coefficients greatly enhanced by aerosol water content, but MSE and SSA are also highly sensitive. It can be concluded that sulfate and carbonaceous aerosol, as well as aerosol water content, play important roles in the processes that determine visibility impairment and radiative forcing in the ambient atmosphere of the Guangzhou urban area.

Characteristics and source apportionment of organic matter in PM(2.5) from cities in different climatic zones of China

NASA Astrophysics Data System (ADS)

Feng, Jialiang

For the first time, the dependency of the characteristics of organic matter in PM2.5 on geographical and climatic zones in three metropolitan cities of China was studied. Seasonal samples were collected at suburban and urban sites in Beijing, Shanghai and Guangzhou in 2002 and 2003. To further support the above study, seasonal samples were also collected at Changdao Island, a remote island, in Bohai Sea/Yellow Sea. Concentrations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and solvent-extractable organic compounds (SEOC) were analyzed. The characteristics of the n-alkanes, polycyclic aromatic hydrocarbons, n-fatty acids, n-alkanols and molecular markers such as triterpanes were determined and used for source identification. Source apportionment was complemented by Chemical Mass Balance (CMB) modeling using the measured organic species as tracers. The impact of wind speed and wind direction on air quality was studied by back trajectory calculations and analysis. In general, traffic emissions were the largest contributors of OC followed by coal burning, kitchen emissions, vegetative detritus and biomass burning. However, in the space-heating season in Northern China, coal burning was the most important contributor of OC in the suburban areas of Beijing and at Changdao. Beijing had the highest concentration of organic aerosol followed by Guangzhou and Shanghai, while seasonal variation was in reverse order. Dispersion conditions determined by local topographies and meteorology were responsible for this trend. Contrary to common understanding, pollutant concentrations at the suburban sites were higher than the urban sites in all three cities. The main reason was the rapid urbanization of the suburban areas in the immediate vicinity of urban centers since China opened up for economic development, in addition, large numbers of manufacturing plants were relocated from the cities to the countryside in an attempt to clean up the urban environment. WSOC/TC ratios were comparable in all three cities at 0.2-0.3 and this value can be considered typical for urban aerosols from Chinese cities. Similar PAH/ALK ratios were found in the three cities, and PAHs were from a mixed contribution of coal burning and engine exhaust. More than half of the resolved SEOC was found to be n-fatty acids and they were mainly from kitchen emissions based on source profile comparisons and CMB analysis. The increase of contribution from coal burning in Beijing due to space heating was identified by the different distribution of triterpanes in summer and winter. The relative concentrations of semivolatile fossil fuel residue n-alkanes (<=C26) were inversely dependent on the ambient temperature. Similar trend was found in the concentrations of the semivolatile PAHs (molecular weight <=228). This was mainly caused by the gas/particle partitioning of semivolatile species in the different climatic zones. The enrichment of higher molecular weight plant wax compounds from Beijing to Shanghai to Guangzhou was a reflection of the variations of the vegetation in the different climatic zones. The seasonal variations in the concentrations and compositions of organic matter at Changdao were similar to the three cities, especially to Beijing. The remote island was also impacted by anthropogenic pollutants, and transported particles played a significant role in the contribution of the organic matter exemplified by the high WSOC/TC, low C18:1/C18 fatty acid, and high BeP/(BeP+BaP) ratios.

Case study of water-soluble metal containing organic constituents of biomass burning aerosol.

PubMed

Chang-Graham, Alexandra L; Profeta, Luisa T M; Johnson, Timothy J; Yokelson, Robert J; Laskin, Alexander; Laskin, Julia

2011-02-15

Natural and prescribed biomass fires are a major source of aerosols that may persist in the atmosphere for several weeks. Biomass burning aerosols (BBA) can be associated with long-range transport of water-soluble N-, S-, P-, and metal-containing species. In this study, BBA samples were collected using a particle-into-liquid sampler (PILS) from laboratory burns of vegetation collected on military bases in the southeastern and southwestern United States. The samples were then analyzed using high resolution electrospray ionization mass spectrometry (ESI/HR-MS) that enabled accurate mass measurements for hundreds of species with m/z values between 70 and 1000 and assignment of elemental formulas. Mg, Al, Ca, Cr, Mn, Fe, Ni, Cu, Zn, and Ba-containing organometallic species were identified. The results suggest that the biomass may have accumulated metal-containing species that were re-emitted during biomass burning. Further research into the sources, dispersion, and persistence of metal-containing aerosols, as well as their environmental effects, is needed.

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.

Biomarkers as indicators of fungal biomass in the atmosphere of São Paulo, Brazil.

PubMed

Emygdio, Ana Paula Mendes; Andrade, Maria de Fátima; Gonçalves, Fabio Luiz Teixeira; Engling, Guenter; Zanetti, Rafael Henrique de Souza; Kumar, Prashant

2018-01-15

The biogenic aerosol contribution to atmospheric particulate matter (PM) mass concentration is usually neglected due to the difficulty in identifying its components, although it can be significant. In the Metropolitan Area of São Paulo (MASP)-Brazil, several studies have been performed to identify sources for PM, revealing vehicular emissions and soil re-suspension as the main identified sources. The organic fraction has been related primarily to biomass burning (BB) and fuel combustion, although there is significant presence of green areas in the city which render biogenic emissions as an additional source of organic carbon (OC). The objectives of this work are to (i) characterise the composition of the PM 10 (ii) estimate the relative mass contribution of fungal spores to PM concentrations with sizes smaller than 10μm (PM 10 ) in MASP and (iii) assess the main sources of PM 10 . To achieve these objectives, we measured markers of biogenic sources and BB, during the fall-winter transition, which along with other constituents, such as ions, organic/elemental carbon, elemental composition and fungal spore concentrations, help assess the PM 10 sources. We used receptor models to identify distinct source-related PM 10 fractions and conversion factors to convert biomarker concentrations to fungal mass. Our results show the mean contributions of fungal aerosol to PM 10 and OC mass were 2% and 8%, respectively, indicating the importance of fungal spores to the aerosol burden in the urban atmosphere. Using specific rotation factor analysis, we identified the following factors contributing to PM: soil re-suspension, biogenic aerosol, secondary inorganic aerosol, vehicular emissions and BB/isoprene-related secondary organic aerosol (I-SOA). BB/I-SOA was the main source representing 28% of the PM 10 mass, while biogenic aerosol explained a significant (11%) fraction of the PM 10 mass as well. Our findings suggest that primary biogenic aerosol is an important fraction of PM 10 mass, yet not considered in most studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Diagnostic Evaluation of Carbon Sources in CMAQ

EPA Science Inventory

Traditional monitoring networks measure only total elemental carbon (EC) and organic carbon (OC) routinely. Diagnosing model biases with such limited information is difficult. Measurements of organic tracer compounds have recently become available and allow for more detailed di...

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

Organic Elemental Analysis.

ERIC Educational Resources Information Center

Ma, T. S.; Gutterson, Milton

1980-01-01

Reviews general developments in computerization and data processing of organic elemental analyses; carbon, hydrogen, and nitrogen analyzers; procedures for determining oxygen, sulfur, and halogens, as well as other nometallic elements and organometallics. Selected papers on trace analysis of nonmetals and determination of metallic elements are…

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.

Characterization of chemical and particulate emissions from aircraft engines

NASA Astrophysics Data System (ADS)

Agrawal, Harshit; Sawant, Aniket A.; Jansen, Karel; Wayne Miller, J.; Cocker, David R.

2008-06-01

This paper presents a series of measurements from four on-wing, commercial aircraft engines, including two newer CFM56-7 engines and two earlier CFM56-3 engines. Samples were collected from each engine using a probe positioned behind the exhaust nozzle of the aircraft, chocked on a concrete testing pad. The emission factors for particulate matter mass, elemental and organic carbon, carbonyls, polycyclic aromatic hydrocarbons, n-alkanes, dioxins, metals and ions are reported for four different engine power setting modes. The emissions indices of particulate matter, elemental and organic carbon are highly power dependent for these engines. Particulate matter emission indices (g kg-1 fuel) are found to increase from 1.1E-02 to 2.05E-01 with increase in power from idle to 85%. The elemental carbon to organic carbon varies from 0.5 to 3.8 with change in power from idle to 85%. The carbonyl emissions are dominated by formaldehyde. The emission index of formaldehyde ranges from 2.3E-01 to 4.8E-01 g kg-1 fuel. The distribution of metals depends on the difference in the various engines. The dioxin emissions from the aircraft engines are observed to be below detection limit.

Elemental composition of PM 10 and PM 2.5 in urban environment in South Brazil

NASA Astrophysics Data System (ADS)

Braga, C. F.; Teixeira, E. C.; Meira, L.; Wiegand, F.; Yoneama, M. L.; Dias, J. F.

The purpose of the present study is to analyze the elemental composition and the concentrations of PM 10 and PM 2.5 in the Guaíba Hydrographic Basin with HV PM 10 and dichotomous samplers. Three sampling sites were selected: 8° Distrito, CEASA and Charqueadas. The sampling was conducted from October 2001 to December 2002. The mass concentrations of the samplers were evaluated, while the elemental concentrations of Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu and Zn were determined using the Particle-Induced X-ray Emission (PIXE) technique. Factor Analysis and Canonical Correlation Analysis were applied to the chemical and meteorological variables in order to identify the sources of particulate matter. Industrial activities such as steel plants, coal-fired power plants, hospital waste burning, vehicular emissions and soil were identified as the sources of the particulate matter. Concentration levels higher than the daily and the annual average air quality standards (150 and 50 μg m -3, respectively) set by the Brazilian legislation were not observed.

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.

Lightning-produced Carbon Species in the Atmosphere of Saturn

NASA Astrophysics Data System (ADS)

Delitsky, Mona; Baines, K. H.

2010-10-01

Recent studies by Baines et al (2009) indicate that thunderstorm-associated clouds on Saturn are spectrally dark from 0.7 to 4 um, darker than regular clouds. This darkening is found to be consistent with the presence of particles of elemental carbon, such as in the form of soot particles mixed in with spectrally bright condensates. This carbon is thought to be generated by lightning-induced dissociation of methane. Lightning on Saturn will input large amounts of energy to a narrow column of atmosphere and generate products at high energies such as radicals and ions. After the column cools down, the new chemical species recombine and are frozen into a new chemical equilibrium. Experimental studies in the literature of reactions of methane and other gases in plasma discharges (which simulate lightning) indicate that, even with high ratios of hydrogen/methane, the elemental carbon obtained will form solid dark particles that persist and have a very high C/H ratio. Basically, they are mostly pure carbon, in the form of soot, amorphous carbon, graphite, graphene, polycyclic aromatic hydrocarbons, carbon black, carbon onions, etc. Hydrogen will act as a sealant onto the particles and attach to dangling bonds on their growing surfaces. Even in experiments to form the most crystalline allotrope of carbon, that is, diamond, the presence of hydrogen does not inhibit diamond formation, even at the low pressures in the atmospheres of the Jovian planets or in the interstellar medium (Allamandola et al 1991). Therefore, some form of elemental carbon is likely produced in Saturnian storm clouds and may occur as dark particles of either amorphous carbon, PAHs or crystalline carbon in a form such as graphite. ..Refs: Baines et al., PSS 57, 1650-1658 (2009) ; Allamandola et al., Meteoritics 26, 313 (1991).

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.

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.

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...

Quantitative ion beam analysis of M-C-O systems: application to an oxidized uranium carbide sample

NASA Astrophysics Data System (ADS)

Martin, G.; Raveu, G.; Garcia, P.; Carlot, G.; Khodja, H.; Vickridge, I.; Barthe, M. F.; Sauvage, T.

2014-04-01

A large variety of materials contain both carbon and oxygen atoms, in particular oxidized carbides, carbon alloys (as ZrC, UC, steels, etc.), and oxycarbide compounds (SiCO glasses, TiCO, etc.). Here a new ion beam analysis methodology is described which enables quantification of elemental composition and oxygen concentration profile over a few microns. It is based on two procedures. The first, relative to the experimental configuration relies on a specific detection setup which is original in that it enables the separation of the carbon and oxygen NRA signals. The second concerns the data analysis procedure i.e. the method for deriving the elemental composition from the particle energy spectrum. It is a generic algorithm and is here successfully applied to characterize an oxidized uranium carbide sample, developed as a potential fuel for generation IV nuclear reactors. Furthermore, a micro-beam was used to simultaneously determine the local elemental composition and oxygen concentration profiles over the first microns below the sample surface. This method is adapted to the determination of the composition of M?C?O? compounds with a sensitivity on elemental atomic concentrations around 1000 ppm.

Core-shell carbon nanosphere-TiO2 composite and hollow TiO2 nanospheres prepared by atomic layer deposition

NASA Astrophysics Data System (ADS)

Bakos, L. P.; Justh, N.; Hernádi, K.; Kiss, G.; Réti, B.; Erdélyi, Z.; Parditka, B.; Szilágyi, I. M.

2016-10-01

Core-shell carbon-TiO2 composite and hollow TiO2 nanospheres were prepared using carbon nanospheres as hard-templates, coating them with TiO2 using atomic layer deposition, and subsequent burning out of the carbon cores. The bare carbon, the composite carbon-TiO2 and the hollow TiO2 nanospheres were characterized with TG/DTA-MS, FTIR, XRD and SEM-EDX.

Changes in soil chemistry six months after prescribed fire in a longleaf pine plantation in Mississippi

Treesearch

John R. Butnor; Kurt H. Johnsen; C. Dana Nelson

2016-01-01

Prescribed fire is used to reduce hardwood competition, enhance herbaceous biodiversity, and improve forage quality in longleaf pine stands. These are primarily low intensity, dormant season burns, during which a portion of the biomass in shrub, herb, and the forest floor layers are combusted. Burning releases elemental nutrients bound in biomass, and there are several...

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

PubMed

Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

Method of removing and recovering elemental sulfur from highly reducing gas streams containing sulfur gases

DOEpatents

Gangwal, Santosh K.; Nikolopoulos, Apostolos A.; Dorchak, Thomas P.; Dorchak, Mary Anne

2005-11-08

A method is provided for removal of sulfur gases and recovery of elemental sulfur from sulfur gas containing supply streams, such as syngas or coal gas, by contacting the supply stream with a catalyst, that is either an activated carbon or an oxide based catalyst, and an oxidant, such as sulfur dioxide, in a reaction medium such as molten sulfur, to convert the sulfur gases in the supply stream to elemental sulfur, and recovering the elemental sulfur by separation from the reaction medium.

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.

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.

Disentangling the major source areas for an intense aerosol advection in the Central Mediterranean on the basis of Potential Source Contribution Function modeling of chemical and size distribution measurements

NASA Astrophysics Data System (ADS)

Petroselli, Chiara; Crocchianti, Stefano; Moroni, Beatrice; Castellini, Silvia; Selvaggi, Roberta; Nava, Silvia; Calzolai, Giulia; Lucarelli, Franco; Cappelletti, David

2018-05-01

In this paper, we combined a Potential Source Contribution Function (PSCF) analysis of daily chemical aerosol composition data with hourly aerosol size distributions with the aim to disentangle the major source areas during a complex and fast modulating advection event impacting on Central Italy in 2013. Chemical data include an ample set of metals obtained by Proton Induced X-ray Emission (PIXE), main soluble ions from ionic chromatography and elemental and organic carbon (EC, OC) obtained by thermo-optical measurements. Size distributions have been recorded with an optical particle counter for eight calibrated size classes in the 0.27-10 μm range. We demonstrated the usefulness of the approach by the positive identification of two very different source areas impacting during the transport event. In particular, biomass burning from Eastern Europe and desert dust from Sahara sources have been discriminated based on both chemistry and size distribution time evolution. Hourly BT provided the best results in comparison to 6 h or 24 h based calculations.

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.

Nuclear reactions in type IA supernovae: Effects of progenitor composition and detonation asymmetry

NASA Astrophysics Data System (ADS)

Chamulak, David A.

Type Ia supernovae go through three distinct phases before their progenitor star is obliterated in a thermonuclear explosion. First is "simmering," during which the 12 C + 12 C reaction gradually heats the white dwarf on a long (~10^3 yr) timescale. Next is a period of subsonic burning. Finally, a detonation is thought to occur that finishes unbinding the star. This thesis investigates the nuclear reactions that take place in these three phases and considers what that may be able to tell us about the progenitor systems and the mechanics behind the detonation. First, we investigate the nuclear reactions during this simmering with a series of self-heating, at constant pressure, reaction network calculations. As an aid to hydrodynamical simulations of the simmering phase, we present fits to the rates of heating, electron capture, change in mean atomic mass, and consumption of 12 C in terms of the screened thermally averaged cross section for 12 C + 12 C. Our evaluation of the net heating rate includes contributions from electron captures into the 3.68 MeV excited state of 13 C. We compare our one-zone results to more accurate integrations over the white dwarf structure to estimate the amount of 12 C that must be consumed to raise the white dwarf temperature, and hence to determine the net reduction of Y e during simmering. Second, we consider the effects of 22 Ne on flame speed. Carbon-oxygen white dwarfs contain 22 Ne formed from a-captures onto 14 N during core He burning in the progenitor star. In a white dwarf (Type Ta) supernova, the 22 Ne abundance determines, in part, the neutron-to-proton ratio and hence the abundance of radioactive 56 Ni that powers the lightcurve. The 22 Ne abundance also changes the burning rate and hence the laminar flame speed. We tabulate the flame speedup for different initial 12 C and 22 Ne abundances and for a range of densities. This increase in the laminar flame speed--about 30% for a 22 Ne mass fraction of 6%--affects the deflagration just after ignition near the center of the white dwarf, where the laminar speed of the flame dominates over the buoyant rise, and in regions of lower density ~10^7 g cm -3 where a transition to distributed burning is conjectured to occur. The increase in flame speed will decrease the density of any transition to distributed burning. Finally, we look at how a surface detonation affects the composition of nuclides across the supernovae remnant. Several scenarios have been proposed as to how this delayed detonation may actually occur but careful nucleosynthesis calculations to determine the isotopic abundances produced by these scenarios have not been done. The surface detonation produces a clear compositional gradient in elemental Ni in layers of the white dwarf that do not burn to nuclear statistical equilibrium (NSE). A number of nuclides show a gradient but when combined into elemental abundances Ni shows the largest change over the face of the star. The Ni abundance varies by as much as an order of magnitude across the star. Tins may be a way to observationally test detonation models.

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.

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.

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.

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.

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

PubMed Central

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

2016-01-01

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, HO2, and RO2 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. PMID:27833145

Carbonaceous and inorganic aerosols over a sub-urban site in peninsular India: Temporal variability and source characteristics

NASA Astrophysics Data System (ADS)

Aswini, A. R.; Hegde, Prashant; Nair, Prabha R.

2018-01-01

PM10 aerosol samples collected from a sub-urban site in Coimbatore during pre-monsoon, monsoon, post-monsoon and winter from 2014 to 2016 showed a large variability from 7.6 to 89 μg m- 3 with an annual average of 41 ± 21 μg m- 3 (N = 69). High abundance of PM10 and other components were recorded during winter and lowest during monsoon period. Total carbonaceous aerosols and water soluble ionic species contributed to 31% and 45% of PM10 mass respectively. SO42 - was the most abundant species (average 9.8 ± 4.8 μg m- 3) and constituted for 24% of total mass. Organic Carbon (OC) was the next most abundant species ranging from 1 to 16 μg m- 3 with an average of 7 ± 3.6 μg m- 3 accounting for 17% of PM10 mass concentration. POC (primary organic carbon) and SOC (secondary organic carbon) accounted for 56% and 44% of OC respectively. A major portion of OC ( 60%) was found to be water soluble. The correlation between OC and EC (elemental carbon) was found to be higher for night-time compared to daytime suggesting their origin from common sources during night-time. K+ was found to be strongly correlated with OC during night-time. WSOC showed good correlation with POC and K+ which was high especially during night-time. WSON (water soluble organic nitrogen) accounted for 34% of water soluble total nitrogen (WSTN). HCO3- exhibited significant positive correlation with Ca2 + during daytime indicating their crustal origin. The observations suggest that the region is influenced by biomass burning sources, however during day-time, secondary production and terrestrial sources (due to high temperature and wind) significantly influence the atmospheric aerosols over this region.

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...

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...

Effects of soil attributes and straw accumulation on the sorption of hexazinone and tebuthiuron in tropical soils cultivated with sugarcane.

PubMed

Pereira-Junior, Ernani V; Giori, Fabrício G; Nascimento, Altina L; Tornisielo, Valdemar L; Regitano, Jussara B

2015-01-01

Brazil is the largest sugarcane producer in the world in which hexazinone (3-cyclohexyl-6-dimethylamino-1-methyl-1,3,5-triazine-2,4-dione) and tebuthiuron (1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethylurea) are heavily used. Sugarcane harvesting is changing from the manual system with previous straw burning to the mechanized system without straw burning. The lack of burning results in soil organic carbon accumulation mainly in clayey soils, which should affect herbicides availability and fate. Therefore, we evaluated sorption of these herbicides in soil samples with and without straw burning. Both herbicides presented low apparent sorption coefficients (mean K(d,app)= 0.6 and 2.4 L kg(-1) for hexazinone and tebuthiuron, respectively), suggesting that they may leach to groundwater. Moreover, their sorption correlated primarily with soil organic carbon (SOC), but iron oxide contents extracted with ammonium oxalate (Fe2O3(AOX)) also affected it (K(d,app) = -0.228 + 0.0397 SOC + 0.117 Fe2O3(AOX) for hexazinone and K(d,app) = -1.407 + 0.201 SOC + 0.348 Fe2O3(AOX) for tebuthiuron). Soil organic carbon accumulation due to straw maintenance in the field positively affected sorption of both herbicides, but its effects were not enough to classify them as "non-leachers."

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.

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.

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.;

Annual air pollution caused by the Hungry Ghost Festival.

PubMed

Khezri, B; Chan, Y Y; Tiong, L Y D; Webster, R D

2015-09-01

Burning of joss paper and incense is still a very common traditional custom in countries with a majority Chinese population. The Hungry Ghost Festival which is celebrated in the 7 month of the Chinese calendar is one of the events where joss paper and incense are burned as offerings. This study investigates the impact of the Ghost Month Festival (open burning event) on air quality by analysis of the chemical composition of particulate matter (PM) and rainwater samples collected during this event, compared with data collected throughout the year, as well as bottom ash samples from burning the original joss paper and incense. The results showed that the change in the chemical composition of the rainwater and PM2.5 (PM ≤ 2.5 μm) atmospheric samples could be correlated directly with burning events during this festival, with many elements increasing between 18% and 60% during August and September compared to the yearly mean concentrations. The order of percentage increase in elemental composition (in rain water and PM2.5) during the Hungry Ghost Festival is as follows: Zn > Ca > K > Mg > Fe > Al > Na ∼ Mn ∼ Ti ∼ V > Cu > As > Ni > Co > Cd > Cr > Pb. The chemical composition of the original source materials (joss paper and incense for combustion) and their associated bottom ash were analysed to explain the impact of burning on air quality.

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

Comparison of methods for the quantification of the different carbon fractions in atmospheric aerosol samples

NASA Astrophysics Data System (ADS)

Nunes, Teresa; Mirante, Fátima; Almeida, Elza; Pio, Casimiro

2010-05-01

Atmospheric carbon consists of: organic carbon (OC, including various organic compounds), elemental carbon (EC, or black carbon [BC]/soot, a non-volatile/light-absorbing carbon), and a small quantity of carbonate carbon. Thermal/optical methods (TOM) have been widely used for quantifying total carbon (TC), OC, and EC in ambient and source particulate samples. Unfortunately, the different thermal evolution protocols in use can result in a wide elemental carbon-to-total carbon variation. Temperature evolution in thermal carbon analysis is critical to the allocation of carbon fractions. Another critical point in OC and EC quantification by TOM is the interference of carbonate carbon (CC) that could be present in the particulate samples, mainly in the coarse fraction of atmospheric aerosol. One of the methods used to minimize this interference consists on the use of a sample pre-treatment with acid to eliminate CC prior to thermal analysis (Chow et al., 2001; Pio et al., 1994). In Europe, there is currently no standard procedure for determining the carbonaceous aerosol fraction, which implies that data from different laboratories at various sites are of unknown accuracy and cannot be considered comparable. In the framework of the EU-project EUSAAR, a comprehensive study has been carried out to identify the causes of differences in the EC measured using different thermal evolution protocols. From this study an optimised protocol, the EUSAAR-2 protocol, was defined (Cavali et al., 2009). During the last two decades thousands of aerosol samples have been taken over quartz filters at urban, industrial, rural and background sites, and also from plume forest fires and biomass burning in a domestic closed stove. These samples were analysed for OC and EC, by a TOM, similar to that in use in the IMPROVE network (Pio et al., 2007). More recently we reduced the number of steps in thermal evolution protocols, without significant repercussions in the OC/EC quantifications. In order to evaluate the possibility of continue using, for trend analysis, the historical data set, we performed an inter-comparison between our method and an adaptation of EUSAAR-2 protocol, taking into account that this last protocol will possibly be recommended for analysing carbonaceous aerosols at European sites. In this inter-comparison we tested different types of samples (PM2,5, PM2,5-10, PM10) with large spectra of carbon loadings, with and without pre-treatment acidification. For a reduced number of samples, five replicates of each one were analysed by each method for statistical purposes. The inter-comparison study revealed that when the sample analysis were performed in similar room conditions, the two thermo-optic methods give similar results for TC, OC and EC, without significant differences at a 95% confidence level. The correlation between the methods, DAO and EUSAAR-2 for EC is smaller than for TC and OC, although showing a coefficient correlation over 0,95, with a slope close to one. For samples performed in different periods, room temperatures seem to have a significant effect over OC quantification. The sample pre-treatment with HCl fumigation tends to decrease TC quantification, mainly due to the more volatile organic fraction release during the first heating step. For a set of 20 domestic biomass burning samples analyzed by the DAO method we observed an average decrease in TC quantification of 3,7 % in relation to non-acidified samples, even though this decrease is accompanied by an average increase in the less volatile organic fraction. The indirect measurement of carbon carbonate, usually a minor carbon component in the carbonaceous aerosol, based on the difference between TC measured by TOM of acidified and non-acidified samples is not a robust measurement, considering the biases affecting his quantification. The present study show that the two thermo-optic temperature program used for OC and EC quantification give similar results, and if in the future the EUSAAR-2 protocol will be adopted the past measurement of carbonaceous fractions can be used for trend analysis. However this study demonstrates that the temperature control during post-sampling handling is a critical point in total OC and TC quantification that must be assigned in the new European protocol. References: Cavali et al., 2009, AMTD 2, 2321-2345, 2009 Chow et al., 2001, Aerosol. Sci. Technol., 34, 23-34, 2001. Pio et al., 1994, Proceedings of the Sixth European Symposium on Physico-Chemical Behavior of Atmospheric Pollutants. Report EUR 15609/2 EN, pp. 706-711. Pio et al, 2007, J. Geophys. Res. 112, D23S02 Acknowledgement: This work was funded by the Portuguese Science Foundation through the projects POCI/AMB/60267/2004 and PTDC/AMB/65706/2006 (BIOEMI). F. Mirante acknowledges the PhD grant SFRH/BD/45473/2008.

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.

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.

BC measurement activities at the U.S. Environmental Protection Agency

EPA Science Inventory

Black carbon (BC)--sometimes referred to as soot, char, or elemental carbon (EC)--is a refractory form of light-absorbing carbon produced from incomplete combustion. Accurate measurement of BC in combustion source emissions is important for understanding anthropogenic climate for...

Distributions of Trace Gases and Aerosols during the Dry Biomass Burning Season in Southern Africa

NASA Technical Reports Server (NTRS)

Sinha, Parikhit; Hobbs, Peter V.; Yokelson, Robert J.; Blake, Donald R.; Gao, Song; Kirchstetter, Thomas W.

2003-01-01

Vertical profiles in the lower troposphere of temperature, relative humidity, sulfur dioxide (SO2), ozone (O3), condensation nuclei (CN), and carbon monoxide (CO), and horizontal distributions of twenty gaseous and particulate species, are presented for five regions of southern Africa during the dry biomass burning season of 2000. The regions are the semiarid savannas of northeast South Africa and northern Botswana, the savanna-forest mosaic of coastal Mozambique, the humid savanna of southern Zambia, and the desert of western Namibia. The highest average concentrations of carbon dioxide (CO2), CO, methane (CH4), O3, black particulate carbon, and total particulate carbon were in the Botswana and Zambia sectors (388 and 392 ppmv, 369 and 453 ppbv, 1753 and 1758 ppbv, 79 and 88 ppbv, 2.6 and 5.5 micrograms /cubic meter and 13.2 and 14.3 micrograms/cubic meter). This was due to intense biomass burning in Zambia and surrounding regions. The South Africa sector had the highest average concentrations of SO2, sulfate particles, and CN (5.1 ppbv, 8.3 micrograms/cubic meter, and per 6400 cubic meter , respectively), which derived from biomass burning and electric generation plants and mining operations within this sector. Air quality in the Mozambique sector was similar to the neighboring South Africa sector. Over the arid Namibia sector there were polluted layers aloft, in which average SO2, O3, and CO mixing ratios (1.2 ppbv, 76 ppbv, and 3 10 ppbv, respectively) were similar to those measured over the other more polluted sectors. This was due to transport of biomass smoke from regions of widespread savanna burning in southern Angola. Average concentrations over all sectors of CO2 (386 +/- 8 ppmv), CO (261 +/- 81 ppbv), SO2 (2.5 +/- 1.6 ppbv), O3 (64 +/- 13 ppbv), black particulate carbon (2.3 +/- 1.9 microgram/cubic meter), organic particulate carbon (6.2 +/- 5.2 microgram/cubic meter), total particle mass (26.0 +/- 4.7 microgram/cubic meter), and potassium particles (0.4 +- 0.1 microgram/cubic meter) were comparable to those in polluted, urban air. Since the majority of the measurements in this study were obtained in locations well removed from industrial sources of pollution, the high average concentrations of pollutants reflect the effects of widespread biomass burning. On occasions, relatively thin (-0.5 km) layers of remarkably clean air were located at -3 km above mean sea level, sandwiched between heavily polluted air. The data presented here can be used for inputs to and validation of regional and global atmospheric chemical models.

Distributions of trace gases and aerosols during the dry biomass burning season in southern Africa

NASA Astrophysics Data System (ADS)

Sinha, Parikhit; Hobbs, Peter V.; Yokelson, Robert J.; Blake, Donald R.; Gao, Song; Kirchstetter, Thomas W.

2003-09-01

Vertical profiles in the lower troposphere of temperature, relative humidity, sulfur dioxide (SO2), ozone (O3), condensation nuclei (CN), and carbon monoxide (CO), and horizontal distributions of twenty gaseous and particulate species, are presented for five regions of southern Africa during the dry biomass burning season of 2000. The regions are the semiarid savannas of northeast South Africa and northern Botswana, the savanna-forest mosaic of coastal Mozambique, the humid savanna of southern Zambia, and the desert of western Namibia. The highest average concentrations of carbon dioxide (CO2), CO, methane (CH4), O3, black particulate carbon, and total particulate carbon were in the Botswana and Zambia sectors (388 and 392 ppmv, 369 and 453 ppbv, 1753 and 1758 ppbv, 79 and 88 ppbv, 2.6 and 5.5 μg m-3, and 13.2 and 14.3 μg m-3). This was due to intense biomass burning in Zambia and surrounding regions. The South Africa sector had the highest average concentrations of SO2, sulfate particles, and CN (5.1 ppbv, 8.3 μg m-3, and 6400 cm-3, respectively), which derived from biomass burning and electric generation plants and mining operations within this sector. Air quality in the Mozambique sector was similar to the neighboring South Africa sector. Over the arid Namibia sector there were polluted layers aloft, in which average SO2, O3, and CO mixing ratios (1.2 ppbv, 76 ppbv, and 310 ppbv, respectively) were similar to those measured over the other more polluted sectors. This was due to transport of biomass smoke from regions of widespread savanna burning in southern Angola. Average concentrations over all sectors of CO2 (386 ± 8 ppmv), CO (261 ± 81 ppbv), SO2 (2.5 ± 1.6 ppbv), O3 (64 ± 13 ppbv), black particulate carbon (2.3 ± 1.9 μg m-3), organic particulate carbon (6.2 ± 5.2 μg m-3), total particle mass (26.0 ± 4.7 μg m-3), and potassium particles (0.4 ± 0.1 μg m-3) were comparable to those in polluted, urban air. Since the majority of the measurements in this study were obtained in locations well removed from industrial sources of pollution, the high average concentrations of pollutants reflect the effects of widespread biomass burning. On occasions, relatively thin (˜0.5 km) layers of remarkably clean air were located at ˜3 km above mean sea level, sandwiched between heavily polluted air. The data presented here can be used for inputs to and validation of regional and global atmospheric chemical models.

Emission characteristics of refractory black carbon aerosols from fresh biomass burning: a perspective from laboratory experiments

NASA Astrophysics Data System (ADS)

Pan, Xiaole; Kanaya, Yugo; Taketani, Fumikazu; Miyakawa, Takuma; Inomata, Satoshi; Komazaki, Yuichi; Tanimoto, Hiroshi; Wang, Zhe; Uno, Itsushi; Wang, Zifa

2017-11-01

The emission characteristics of refractory black carbon (rBC) from biomass burning are essential information for numerical simulations of regional pollution and climate effects. We conducted combustion experiments in the laboratory to investigate the emission ratio and mixing state of rBC from the burning of wheat straw and rapeseed plants, which are the main crops cultivated in the Yangtze River Delta region of China. A single particle soot photometer (SP2) was used to measure rBC-containing particles at high temporal resolution and with high accuracy. The combustion state of each burning case was indicated by the modified combustion efficiency (MCE), which is calculated using the integrated enhancement of carbon dioxide and carbon monoxide concentrations relative to their background values. The mass size distribution of the rBC particles showed a lognormal shape with a mode mass equivalent diameter (MED) of 189 nm (ranging from 152 to 215 nm), assuming an rBC density of 1.8 g cm-3. rBC particles less than 80 nm in size (the lower detection limit of the SP2) accounted for ˜ 5 % of the total rBC mass, on average. The emission ratios, which are expressed as ΔrBC / ΔCO (Δ indicates the difference between the observed and background values), displayed a significant positive correlation with the MCE values and varied between 1.8 and 34 ng m-3 ppbv-1. Multi-peak fitting analysis of the delay time (Δt, or the time of occurrence of the scattering peak minus that of the incandescence peak) distribution showed that rBC-containing particles with rBC MED = 200 ± 10 nm displayed two peaks at Δt = 1.7 µs and Δt = 3.2 µs, which could be attributed to the contributions from both flaming and smoldering combustion in each burning case. Both the Δt values and the shell / core ratios of the rBC-containing particles clearly increased as the MCE decreased from 0.98 (smoldering-dominant combustion) to 0.86 (flaming-dominant combustion), implying the great importance of the rapid condensation of semi-volatile organics. This laboratory study found that the mixing state of rBC particles from biomass burning strongly depends on its combustion processes, and overall MCE should be taken carefully into consideration while the climate effect of rBC particles from open biomass burning is simulated.

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...

Analysis of Individual Carbonaceous Particles Emitted from the Las Conchas Wildfire, Los Alamos, NM, in June-July 2011

NASA Astrophysics Data System (ADS)

Mazzoleni, C.; China, S.; Gorkowski, K.; Flowers, B. A.; Aiken, A. C.; Dubey, M. K.

2012-12-01

Carbonaceous aerosol emitted from biomass burning contributes significantly to atmospheric aerosol loadings regionally and globally. The net direct radiative forcing of biomass burning aerosol can be positive and/or negative and this depends on its composition, morphology and mixing state. Biomass burning aerosols can also change the cloud properties as they can act as cloud condensation nuclei. In this study we investigated biomass burning particles emitted from the Las Conchas wildfire in northern New Mexico that started on June 26, 2011 and burned an area of 245 square miles. Aerosol samples were collected on nucleopore filters at the Los Alamos National Laboratory during the third week of the wildfire event. Individual particles (~4000) were investigated using field-emission scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) to distinguish different carbonaceous particles and their shape, size, elemental composition and mixing state. A thermo-denuder was used to remove compounds that are volatile at temperatures up to 200 C, leaving behind the black carbon and any compounds that did not volatize completely. Smoke particles consisted of a) tar balls, which are amorphous spherical carbonaceous organic aerosols; b) organic particles with inorganic inclusions, c) soot particles and (d) soot with various inclusions. Two distinct kinds of tar balls, "electronically" dark and bright, were found using the field-emission scanning electron microscopy and were characterized for ambient and denuded conditions to understand coating effects and aging. It was found that dark tar balls are generally larger in size than the bright ones. Additionally, the difference between the size of ambient-bright and the size of denuded-bright tar balls was larger than the difference between the size of ambient-dark and the size of denuded-dark tar balls. EDS analysis showed that 70% of the dark tar balls had higher (~60%) relative oxygen content than in the bright tar balls. We conclude that there are two distinct kinds of biomass burning tar balls and that dark tar balls are less volatile than bright tar balls. The morphology of soot particles was also investigated by evaluating their fractal dimension for both ambient (coated with organic and inorganic material) and denuded samples at two different times of the day. The fractal dimension for ambient soot was found to be higher than for denuded soot due to the coating on the ambient soot particles. Finally, the monomer diameter decreased by up to 25% after denuding the particles. This study provides insights on the link between electron microscopy images of single particles and the mixing state, morphology, and evolution of different biomass burning aerosol at the beginning of their lifecycle.

Characterization of PM2.5 and the major chemical components during a 1-year campaign in rural Guangzhou, Southern China

NASA Astrophysics Data System (ADS)

Lai, Senchao; Zhao, Yan; Ding, Aijun; Zhang, Yingyi; Song, Tianli; Zheng, Junyu; Ho, Kin Fai; Lee, Shun-cheng; Zhong, Liuju

2016-01-01

A 1-year campaign was conducted in the rural area of Guangzhou, a megacity in southern China, to collect fine particulate matter (PM2.5) from March 2012 to February 2013. The mass concentrations of PM2.5 and the major chemical components including 6 water-soluble ions, organic carbon (OC), elemental carbon (EC), and 13 additional elements were measured. The annual average concentration of PM2.5 was 44.2 ± 25.8 μg/m3. Sulfate was the most dominant component, accounting for 28.6% of PM2.5, followed by organic matter (21.9%). Both sea salt and crustal material accounted for only a small fraction of PM2.5 (< 5%). Seasonal enhancement of PM2.5 was observed in autumn 2012, especially with high-PM2.5 events (more than 100 μg/m3) in October. The backward Lagrangian particle dispersion modeling (LPDM) and the cluster analysis of the back-trajectories indicate that the northern area is an important source region of long-range transport. An enhancement of PM2.5 as well as sulfate, OC, and EC was observed in the samples with the influence of northern air masses. However, the footprint retroplume of the samples shows that the sources in the Pearl River Delta Region should also be considered, especially secondary aerosol formation and biomass/biofuel burning. Two high-PM2.5 case studies show that both local and long-range transport can play important roles in the PM2.5 elevation episode.

ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON

EPA Science Inventory

Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

The chemical composition and sources of PM2.5 during the 2009 Chinese New Year's holiday in Shanghai

NASA Astrophysics Data System (ADS)

Feng, Jialiang; Sun, Peng; Hu, Xiaoling; Zhao, Wei; Wu, Minghong; Fu, Jiamo

2012-11-01

China is virtually shut down during the week-long Chinese New Year's holiday. This implies that the anthropogenic emissions would be greatly decreased during the period thus providing an opportunity to study the air quality in China under reduced emissions, and the drastic emission changes during a short period of time allows the comparison of source contributions under significantly different conditions. Seventeen PM2.5 samples were collected during the 2009 Chinese New Year's holiday in Shanghai to study the composition and sources of the fine particles. Organic carbon (OC), elemental carbon (EC), eight water-soluble ions, fourteen metals and solvent extractable organic compounds (SEOC) including alkanes, hopanes, polycyclic aromatic hydrocarbons (PAHs) and fatty acids were measured. Diagnostic PAH ratios, correlation analysis of OC, EC, n-alkanes, hopanes and PAHs showed that vehicle emissions were the main source of n-alkanes and EC, and an important source of the locally emitted particulate PAHs in urban Shanghai, while coal burning should be the main source of the transported PAHs from the inland areas. The composition of n-fatty acids also provided some clue on the significance of the contribution by kitchen activities. In the New Year's Eve's sample, 75% of the particle mass was estimated to be from fireworks, and K+, SO42 -, Cl-, OC, Al and Ba were the main components. Firework fine particles had high OC/EC ratio and low NO3-/SO42 - ratio.

Non-destructive elemental analysis of a carbonaceous chondrite with direct current Muon beam at MuSIC.

PubMed

Terada, K; Sato, A; Ninomiya, K; Kawashima, Y; Shimomura, K; Yoshida, G; Kawai, Y; Osawa, T; Tachibana, S

2017-11-13

Electron- or X-ray-induced characteristic X-ray analysis has been widely used to determine chemical compositions of materials in vast research fields. In recent years, analysis of characteristic X-rays from muonic atoms, in which a muon is captured, has attracted attention because both a muon beam and a muon-induced characteristic X-ray have high transmission abilities. Here we report the first non-destructive elemental analysis of a carbonaceous chondrite using one of the world-leading intense direct current muon beam source (MuSIC; MUon Science Innovative Channel). We successfully detected characteristic muonic X-rays of Mg, Si, Fe, O, S and C from Jbilet Winselwan CM chondrite, of which carbon content is about 2 wt%, and the obtained elemental abundance pattern was consistent with that of CM chondrites. Because of its high sensitivity to carbon, non-destructive elemental analysis with a muon beam can be a novel powerful tool to characterize future retuned samples from carbonaceous asteroids.

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.

Implications of elevated CO2 on pelagic carbon fluxes in an Arctic mesocosm study - an elemental mass balance approach

NASA Astrophysics Data System (ADS)

Czerny, J.; Schulz, K. G.; Boxhammer, T.; Bellerby, R. G. J.; Büdenbender, J.; Engel, A.; Krug, S. A.; Ludwig, A.; Nachtigall, K.; Nondal, G.; Niehoff, B.; Silyakova, A.; Riebesell, U.

2013-05-01

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air-sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification applying KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation), all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down the mentioned uncertainties. Water-column concentrations of particulate and dissolved organic and inorganic matter were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution as well as estimates of wall growth were developed to close the gaps in element budgets. However, losses elements from the budgets into a sum of insufficiently determined pools were detected, and are principally unavoidable in mesocosm investigation. The comparison of variability patterns of all single measured datasets revealed analytic precision to be the main issue in determination of budgets. Uncertainties in dissolved organic carbon (DOC), nitrogen (DON) and particulate organic phosphorus (POP) were much higher than the summed error in determination of the same elements in all other pools. With estimates provided for all other major elemental pools, mass balance calculations could be used to infer the temporal development of DOC, DON and POP pools. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in two of the three experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic carbon under nutrient-recycling summer conditions. This carbon over-consumption effect becomes evident from mass balance calculations, but was too small to be resolved by direct measurements of dissolved organic matter. Faster nutrient uptake by comparatively small algae at high CO2 after nutrient addition resulted in reduced production rates under future ocean CO2 conditions at the end of the experiment. This CO2 mediated shift towards smaller phytoplankton and enhanced cycling of dissolved matter restricted the development of larger phytoplankton, thus pushing the system towards a retention type food chain with overall negative effects on export potential.

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

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...

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.

Comparison of SOC estimates and uncertainties from aerosol chemical composition and gas phase data in Atlanta

NASA Astrophysics Data System (ADS)

Pachon, Jorge E.; Balachandran, Sivaraman; Hu, Yongtao; Weber, Rodney J.; Mulholland, James A.; Russell, Armistead G.

2010-10-01

In the Southeastern US, organic carbon (OC) comprises about 30% of the PM 2.5 mass. A large fraction of OC is estimated to be of secondary origin. Long-term estimates of SOC and uncertainties are necessary in the evaluation of air quality policy effectiveness and epidemiologic studies. Four methods to estimate secondary organic carbon (SOC) and respective uncertainties are compared utilizing PM 2.5 chemical composition and gas phase data available in Atlanta from 1999 to 2007. The elemental carbon (EC) tracer and the regression methods, which rely on the use of tracer species of primary and secondary OC formation, provided intermediate estimates of SOC as 30% of OC. The other two methods, chemical mass balance (CMB) and positive matrix factorization (PMF) solve mass balance equations to estimate primary and secondary fractions based on source profiles and statistically-derived common factors, respectively. CMB had the highest estimate of SOC (46% of OC) while PMF led to the lowest (26% of OC). The comparison of SOC uncertainties, estimated based on propagation of errors, led to the regression method having the lowest uncertainty among the four methods. We compared the estimates with the water soluble fraction of the OC, which has been suggested as a surrogate of SOC when biomass burning is negligible, and found a similar trend with SOC estimates from the regression method. The regression method also showed the strongest correlation with daily SOC estimates from CMB using molecular markers. The regression method shows advantages over the other methods in the calculation of a long-term series of SOC estimates.

Multi-pollutant emissions from the burning of major agricultural residues in China and the related health-economic effects

NASA Astrophysics Data System (ADS)

Li, Chunlin; Hu, Yunjie; Zhang, Fei; Chen, Jianmin; Ma, Zhen; Ye, Xingnan; Yang, Xin; Wang, Lin; Tang, Xingfu; Zhang, Renhe; Mu, Mu; Wang, Guihua; Kan, Haidong; Wang, Xinming; Mellouki, Abdelwahid

2017-04-01

Multi-pollutants in smoke particulate matter (SPM) were identified and quantified for the biomass burning of five major agricultural residues (wheat, rice, corn, cotton, and soybean straw) in China by an aerosol chamber system combined with various measurement techniques. The primary emission factors (EFs) for PM1. 0 and PM2. 5 are 3.04-12.64 and 3.25-15.16 g kg-1. Organic carbon (OC), elemental carbon (EC), water-soluble inorganics (WSIs), water-soluble organic acids (WSOAs), water-soluble amine salts (WSAs), trace mineral elements (THMs), polycyclic aromatic hydrocarbons (PAHs), and phenols in smoke PM1. 0/PM2. 5 are 1.34-6.04/1.54-7.42, 0.58-2.08/0.61-2.18, 0.51-3.52/0.52-3.81, 0.13-0.64/0.14-0.77, (4.39-85.72/4.51-104.79) × 10-3, (11.8-51.1/14.0-131.6) × 10-3, (1.1-4.0/1.8-8.3) × 10-3, and (7.7-23.5/9.7-41.5) × 10-3 g kg-1, respectively. Black carbon (BC) mainly exists in PM1. 0; heavy-metal-bearing particles favour residing in the range of smoke PM1. 0-2. 5, which is also confirmed by individual particle analysis. With respect to the five scenarios of burning activities, the average emissions and overall propagation of uncertainties at the 95 % confidence interval (CI) of SPM from agricultural open burning in China in 2012 were estimated to be 1005.7 (-24.6, 33.7 %), 901.4 (-24.4, 33.5 %), 432.4 (-24.2, 33.5 %), 134.2 (-24., 34.0 %), 249.8 (-25.4, 34.9 %), 25.1 (-33.3, 41.4 %), 5.8 (-30.1, 38.5 %), 8.7 (-26.6, 35.6 %), 0.5 (-26.0, 34.9 %), and 2.7 (-26.1, 35.1 %) Gg for PM2. 5, PM1. 0, OC, EC, WSI, WSOA, WSA, THM, PAHs, and phenols , respectively. The emissions were further spatio-temporally characterized using a geographic information system (GIS) in different regions in the summer and autumn post-harvest periods. It was found that less than 25 % of the total emissions were released during the summer harvest, which was mainly contributed by the North Plain and the centre of China, especially Henan, Shandong, and Anhui, which are the top three provinces regarding smoke particle emissions. Flux concentrations of primarily emitted smoke PM2. 5 that were calculated using the box-model method based on five versions of emission inventories all exceed the carcinogenic-risk permissible exposure limits (PEL). The health impacts and health-related economic losses from the smoke PM2. 5 short-term exposure were assessed. The results show that China suffered from 7836 cases (95,% CI: 3232, 12362) of premature mortality and 7 267 237 cases (95 % CI: 2 961 487, 1 130 784) of chronic bronchitis in 2012, which led to losses of USD 8822.4 million (95 % CI: 3574.4, 13 034.2) or 0.1 % of the total GDP. We suggest that the percentage of open-burnt crop straw in the post-harvest period should be cut down by over 97 % to ensure a reduction in carcinogenicity risk, especially in the North Plain and the northeast, where the emissions should decrease at least by 94 % to meet the PEL. With such emission control, over 92 % of the mortality and morbidity attributed to agricultural fire smoke PM2. 5 can be avoided in China.

NOVEL OXIDANT FOR ELEMENTAL MERCURY CONTROL FROM FLUE GAS

EPA Science Inventory

A novel economical oxidant has been developed for elemental mercury (Hg(0)) removal from coal-fired boilers. The oxidant was rigorously tested in a lab-scale fixed-bed system with the Norit America's FGD activated carbon (DOE's benchmark sorbent) in a typical PRB subbituminous/l...

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.

Organotrichlorogermane synthesis by the reaction of elemental germanium, tetrachlorogermane and organic chloride via dichlorogermylene intermediate.

PubMed

Okamoto, Masaki; Asano, Takuya; Suzuki, Eiichi

2004-08-07

Organotrichlorogermanes were synthesized by the reaction of elemental germanium, tetrachlorogermane and organic chlorides, methyl, propyl, isopropyl and allyl chlorides. Dichlorogermylene formed by the reaction of elemental germanium with tetrachlorogermane was the reaction intermediate, which was inserted into the carbon-chlorine bond of the organic chloride to give organotrichlorogermane. When isopropyl or allyl chloride was used as an organic chloride, organotrichlorogermane was formed also in the absence of tetrachlorogermane. These chlorides were converted to hydrogen chloride, which subsequently reacted with elemental germanium to give the dichlorogermylene intermediate. The reaction of elemental germanium, tetrachlorogermane and organic chlorides provides a simple and easy method for synthesizing organotrichlorogermanes, and all the raw materials are easily available.

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...

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.

Microbial Transformations of Selenium

PubMed Central

Doran, J. W.; Alexander, M.

1977-01-01

Resting cell suspensions of a strain of Corynebacterium isolated from soil formed dimethyl selenide from selenate, selenite, elemental selenium, selenomethionine, selenocystine, and methaneseleninate. Extracts of the bacterium catalyzed the production of dimethyl selenide from selenite, elemental selenium, and methaneseleninate, and methylation of the inorganic Se compounds was enhanced by S-adenosylmethionine. Neither trimethylselenonium nor methaneselenonate was metabolized by the Corynebacterium. Resting cell suspensions of a methionine-utilizing pseudomonad converted selenomethionine to dimethyl diselenide. Six of 10 microorganisms able to grow on cystine used selenocystine as a sole source of carbon and formed elemental selenium, and one of the isolates, a pseudomonad, was found also to produce selenide. Soil enrichments converted trimethylselenonium to dimethyl selenide. Bacteria capable of utilizing trimethylselenonium, dimethyl selenide, and dimethyl diselenide as carbon sources were isolated from soil. PMID:16345188

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.

Source apportionment of fine particulate matter organic carbon in Shenzhen, China by chemical mass balance and radiocarbon methods.

PubMed

Al-Naiema, Ibrahim M; Yoon, Subin; Wang, Yu-Qin; Zhang, Yuan-Xun; Sheesley, Rebecca J; Stone, Elizabeth A

2018-09-01

Chemical mass balance (CMB) modeling and radiocarbon measurements were combined to evaluate the sources of carbonaceous fine particulate matter (PM 2.5 ) in Shenzhen, China during and after the 2011 summer Universiade games when air pollution control measurements were implemented to achieve air quality targets. Ambient PM 2.5 filter samples were collected daily at two sampling sites (Peking University Shenzhen campus and Longgang) over 24 consecutive days, covering the controlled and uncontrolled periods. During the controlled period, the average PM 2.5 concentration was less than half of what it was after the controls were lifted. Organic carbon (OC), organic molecular markers (e.g., levoglucosan, hopanes, polycyclic aromatic hydrocarbons), and secondary organic carbon (SOC) tracers were all significantly lower during the controlled period. After pollution controls ended, at Peking University, OC source contributions included gasoline and diesel engines (24%), coal combustion (6%), biomass burning (12.2%), vegetative detritus (2%), biogenic SOC (from isoprene, α-pinene, and β-caryophyllene; 7.1%), aromatic SOC (23%), and other sources not included in the model (25%). At Longgang after the controls ended, similar source contributions were observed: gasoline and diesel engines (23%), coal combustion (7%), biomass burning (17.7%), vegetative detritus (1%), biogenic SOC (from isoprene, α-pinene, and β-caryophyllene; 5.3%), aromatic SOC (13%), and other sources (33%). The contributions of the following sources were smaller during the pollution controls: biogenic SOC (by a factor of 10-16), aromatic SOC (4-12), coal combustion (1.5-6.8), and biomass burning (2.3-4.9). CMB model results and radiocarbon measurements both indicated that fossil carbon dominated over modern carbon, regardless of pollution controls. However, the CMB model needs further improvement to apportion contemporary carbon (i.e. biomass burning, biogenic SOC) in this region. This work defines the major contributors to carbonaceous PM 2.5 in Shenzhen and demonstrates that control measures for primary emissions could significantly reduce secondary organic aerosol (SOA) formation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparison of the morphology, chemical composition and microstructure of cryptocrystalline graphite and carbon black

NASA Astrophysics Data System (ADS)

Quan, Ying; Liu, Qinfu; Zhang, Shilong; Zhang, Shuai

2018-07-01

The structures of cryptocrystalline graphite (CG) and carbon black (CB) have been analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), organic elemental analysis (OEA), X-ray diffraction (XRD), RAMAN and high-resolution transmission electron microscopy (HRTEM). These results indicate that CG has the same elemental composition as CB, with carbon being the major element present. SL sample (CG with low graphitization degree) and CB exhibit similar microcrystalline structures. CG was shown to contain a layered graphitic structure that was significantly different to the primary spherical particles present in CB. It is proposed that these CG sheets may potentially be reduced and delaminated to afford multilayer graphene structures with improved material properties.

OPTIMIZATION OF THERMAL OPTICAL ANALYSIS FOR THE MEASUREMENT OF BLACK CARBON IN REGIONAL PM2.5: A CHEMOMETRIC APPROACH

EPA Science Inventory

Thermal-optical analysis (TOA) is the principal method of the U.S. EPA's National Air Monitoring System for determining refractory carbon from combustion, or elemental carbon (EC), in particulate matter <2.5 µm (PM_2.5). To isolate and quantify EC from organic carbon (...

Energetic materials and methods of tailoring electrostatic discharge sensitivity of energetic materials

DOEpatents

Daniels, Michael A.; Heaps, Ronald J.; Wallace, Ronald S.; Pantoya, Michelle L.; Collins, Eric S.

2016-11-01

An energetic material comprising an elemental fuel, an oxidizer or other element, and a carbon nanofiller or carbon fiber rods, where the carbon nanofiller or carbon fiber rods are substantially homogeneously dispersed in the energetic material. Methods of tailoring the electrostatic discharge sensitivity of an energetic material are also disclosed.

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...

Airborne characterization of smoke marker ratios from prescribed burning

Treesearch

A. P. Sullivan; A. A. May; T. Lee; G. R. McMeeking; S. M. Kreidenweis; S. K. Akagi; R. J. Yokelson; S. P. Urbanski; J. L. Collett

2014-01-01

A Particle-Into-Liquid Sampler - Total Organic Carbon (PILS-TOC) and fraction collector system was flown aboard a Twin Otter aircraft sampling prescribed burning emissions in South Carolina in November 2011 to obtain smoke marker measurements. The fraction collector provided 2 min time-integrated offline samples for carbohydrate (i.e., smoke markers levoglucosan,...

78 FR 10546 - Approval and Promulgation of Implementation Plans; State of Alaska; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-14

... submittal identifies organic carbon emissions from natural wildfires as the primary contributor to... 20% worst days in Denali National Park were composed of organic carbon from natural fires. Alaska... Organic Matter Carbon (OMC) and Elemental Carbon (EC), it attributes all OMC and EC in the Denali region...

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...

Changes in composition and porosity occurring during the thermal degradation of wood and wood components

USGS Publications Warehouse

Rutherford, David W.; Wershaw, Robert L.; Cox, Larry G.

2005-01-01

Samples of pine and poplar wood, pine bark, and purified cellulose and lignin were charred at temperatures ranging from 250?C to 500?C for times ranging from 1 hour to 168 hours. Changes in composition were examined by Fourier Transform Infrared (FTIR) and 13C Nuclear Magnetic Resonance (NMR) spectrometry, mass loss, and elemental composition (carbon, hydrogen, and oxygen) of the char. Structural changes were examined by changes in porosity as measured by nitrogen gas adsorption. 13C NMR spectrometry, mass loss, and elemental composition were combined to estimate the mass of aromatic and aliphatic carbon remaining in the char. Mass loss and elemental composition were combined to estimate the chemical composition of material lost for various time intervals of heating. These analyses showed that aliphatic components in the test materials were either lost or converted to aromatic carbon early in the charring process. Nitrogen adsorption showed that no porosity develops for any of the test materials with heating at 250?C, even though substantial loss of material and changes in composition occurred. Porosity development coincided with the loss of aromatic carbon, indicating that micropores were developing within a fused-ring matrix.

Cashew nut roasting: Chemical characterization of particulate matter and genotocixity analysis

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

Oliveira Galvão, Marcos Felipe de; Melo Cabral, Thiago de; André, Paulo Afonso de

Background: Particulate matter (PM) is potentially harmful to health and related to genotoxic events, an increase in the number of hospitalizations and mortality from respiratory and cardiovascular diseases. The present study conducted the first characterization of elemental composition and polycyclic aromatic hydrocarbon (PAH) analysis of PM, as well as the biomonitoring of genotoxic activity associated to artisanal cashew nut roasting, an important economic and social activity worldwide. Methods: The levels of PM{sub 2.5} and black carbon were also measured by gravimetric analysis and light reflectance. The elemental composition was determined using X-ray fluorescence spectrometry and PAH analysis was carried outmore » by gas chromatography–mass spectrometry. Genotoxic activity was measured by the Tradescantia pallida micronucleus bioassay (Trad-MCN). Other biomarkers of DNA damage, such as nucleoplasmic bridges and nuclear fragments, were also quantified. Results: The mean amount of PM{sub 2.5} accumulated in the filters (January 2124.2 µg/m{sup 3}; May 1022.2 µg/m{sup 3}; September 1291.9 µg/m{sup 3}), black carbon (January 363.6 µg/m{sup 3}; May 70 µg/m{sup 3}; September 69.4 µg/m{sup 3}) and concentrations of Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br and Pb were significantly higher than the non-exposed area. Biomass burning tracers K, Cl, and S were the major inorganic compounds found. Benzo[k]fluoranthene, indene[1,2,3-c,d]pyrene, benzo[ghi]perylene, phenanthrene and benzo[b]fluoranthene were the most abundant PAHs. Mean benzo[a]pyrene-equivalent carcinogenic power values showed a significant cancer risk. The Trad-MCN bioassay revealed an increase in micronucleus frequency, 2–7 times higher than the negative control and significantly higher in all the months analyzed, possibly related to the mutagenic PAHs found. Conclusions: This study demonstrated that artisanal cashew nut roasting is a serious occupational problem, with harmful effects on workers' health. Those involved in this activity are exposed to higher PM{sub 2.5} concentrations and to 12 PAHs considered potentially mutagenic and/or carcinogenic. The Trad-MCN with T. pallida was sensitive and efficient in evaluating the genotoxicity of the components and other nuclear alterations may be used as effective biomarkers of DNA damage. - Highlights: • The cashew nut roasting generated high concentrations of particulate matter fine. • The biomass burning tracers K, Cl, S were the major inorganic compounds found. • It was identified 12 PAHs considered to be potentially mutagenic and/or carcinogenic. • The genotoxic potential of this activity was confirmed by the Trad MCN assay. • This activity is a serious occupational problem with harmful effects to health workers.« less

Lab Analyses of Fenceline PM10 Air Filters

EPA Pesticide Factsheets

These spreadsheets show the analytical data on PM10 concentration, organic carbon, elemental carbon, and several trace metals at KCBX petroleum coke (also known as pet coke or petcoke) storage terminals in Chicago, Illinois.

The Diversity of Carbon in Cometary Refractory Dust Particles

NASA Technical Reports Server (NTRS)

Wooden, D. H.

2018-01-01

When comparing the dark icy surfaces of outer solar system small bodies and the composition of carbonaceous chondrites derived from dark asteroids we find a significant discrepancy in the assessed amounts of elemental carbon: up to 80% amorphous carbon is used to model the dark surfaces of Kuiper Belt Objects and Centaurs whereas at most 5% of elemental carbon is found in carbonaceous chondrites. If we presume that regimes of comet nuclei formation are analogous to disk regimes where other outer solar system ice-rich bodies formed then we can turn to comet dust to gain insights into the diversity in the concentration and forms of carbon available in the outer disk. Comet dust offers important insights into the diversity in the amounts and forms of carbon that were incorporated into aggregate dust particles in the colder parts of the protoplanetary disk out of which comet nuclei accreted. Comet nuclei are amongst the most primitive bodies because they have remained cold and unequilibrated. Comet dust particles reveal the presence of forms of elemental carbon and of soluble and insoluble organic matter, and in a great diversity of concentrations from very little, e.g., Stardust samples of comet 81P/Wild 2, to 80% by volume for Ultra Carbonaceous Antarctic Micro Meteorites (UCAMMs). Cometary outbursts and/or jet activity also demonstrate variations in the concentration of carbon in the grains at different grain sizes within a single comet. We review the diversity of carbon-bearing dust grains in cometary samples, flyby measurements and deduced from remote-sensing to enrich the discussion about the diversity of carbonaceous matter available in the outer ice-rich disk at the time of comet nuclei formation.

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.

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.

Sulfide catalysts for reducing SO2 to elemental sulfur

DOEpatents

Jin, Yun; Yu, Qiquan; Chang, Shih-Ger

2001-01-01

A highly efficient sulfide catalyst for reducing sulfur dioxide to elemental sulfur, which maximizes the selectivity of elemental sulfur over byproducts and has a high conversion efficiency. Various feed stream contaminants, such as water vapor are well tolerated. Additionally, hydrogen, carbon monoxide, or hydrogen sulfides can be employed as the reducing gases while maintaining high conversion efficiency. This allows a much wider range of uses and higher level of feed stream contaminants than prior art catalysts.

The colors of biomass burning aerosols in the atmosphere.

PubMed

Liu, Chao; Chung, Chul Eddy; Zhang, Feng; Yin, Yan

2016-06-16

Biomass burning aerosols mainly consist of black carbon (BC) and organic aerosols (OAs), and some of OAs are brown carbon (BrC). This study simulates the colors of BrC, BC and their mixture with scattering OAs in the ambient atmosphere by using a combination of light scattering simulations, a two-stream radiative transfer model and a RGB (Red, Green, Blue) color model. We find that both BCs and tar balls (a class of BrC) appear brownish at small particle sizes and blackish at large sizes. This is because the aerosol absorption Ångström exponent (AAE) largely controls the color and larger particles give smaller AAE values. At realistic size distributions, BCs look more blackish than tar balls, but still exhibit some brown color. However, when the absorptance of aerosol layer at green wavelength becomes larger than approximately 0.8, all biomass burning aerosols look blackish. The colors for mixture of purely scattering and absorptive carbonaceous aerosol layers in the atmosphere are also investigated. We suggest that the brownishness of biomass burning aerosols indicates the amount of BC/BrC as well as the ratio of BC to BrC.

Emissions of volatile organic compounds from maize residue open burning in the northern region of Thailand

NASA Astrophysics Data System (ADS)

Sirithian, Duanpen; Thepanondh, Sarawut; Sattler, Melanie L.; Laowagul, Wanna

2018-03-01

Emission factors for speciated volatile organic compounds (VOCs) from maize residue burning were determined in this study based on chamber experiments. Thirty-six VOC species were identified by Gas Chromatography/Mass Spectrometer (GC/MS). They were classified into six groups, including alkanes, alkenes, oxygenated VOCs, halogenated VOCs, aromatics and other. The emission factor for total VOCs was estimated as about 148 mg kg-1 dry mass burned. About 68.4% of the compounds were aromatics. Field samplings of maize residues were conducted to acquire the information of fuel characteristics including fuel loading, fraction of maize residues that were actually burned as well as proximate and elemental analysis of maize residues. The emission factors were then applied to estimate speciated VOC emissions from maize residue open burning at the provincial level in the upper-northern region of Thailand for the year 2014. Total burned area of maize covered an area of about 500,000 ha which was about 4.7% of the total area of upper-northern region of the country. It was found that total VOC emissions released during the burning season (January-April) was about 79.4 tons. Ethylbenzene, m,p-xylene, 1,2,4-trimethylbenzene, acetaldehyde and o-xylene were the major contributors, accounting for more than 65% of total speciated VOC emissions.

Enhanced light absorption due to the mixing state of black carbon in fresh biomass burning emissions

NASA Astrophysics Data System (ADS)

Wang, Qiyuan; Cao, Junji; Han, Yongming; Tian, Jie; Zhang, Yue; Pongpiachan, Siwatt; Zhang, Yonggang; Li, Li; Niu, Xinyi; Shen, Zhenxing; Zhao, Zhuzi; Tipmanee, Danai; Bunsomboonsakul, Suratta; Chen, Yang; Sun, Jian

2018-05-01

A lack of information on the radiative effects of refractory black carbon (rBC) emitted from biomass burning is a significant gap in our understanding of climate change. A custom-made combustion chamber was used to simulate the open burning of crop residues and investigate the impacts of rBC size and mixing state on the particles' optical properties. Average rBC mass median diameters ranged from 141 to 162 nm for the rBC produced from different types of crop residues. The number fraction of thickly-coated rBC varied from 53 to 64%, suggesting that a majority of the freshly emitted rBC were internally mixed. By comparing the result of observed mass absorption cross-section to that calculated with Mie theory, large light absorption enhancement factors (1.7-1.9) were found for coated particles relative to uncoated cores. These effects were strongly positively correlated with the percentage of coated particles but independent of rBC core size. We suggest that rBC from open biomass burning may have strong impact on air pollution and radiative forcing immediately after their production.

Effects of sulfur impregnation temperature on the properties and mercury adsorption capacities of activated carbon fibers (ACFs)

USGS Publications Warehouse

Hsi, H.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

2001-01-01

Laboratory studies were conducted to determine the role of sulfur functional groups and micropore surface area of carbon-based adsorbents on the adsorption of Hg0 from simulated coal combustion flue gases. In this study, raw activated carbon fibers that are microporous (ACF-20) were impregnated with elemental sulfur between 250 and 650 ??C. The resulting samples were saturated with respect to sulfur content. Total sulfur content of the sulfur impregnated ACF samples decreased with increasing impregnation temperatures from 250 and 500 ??C and then remained constant to 650 ??C. Results from sulfur K-edge X-ray absorption near-edge structure (S-XANES) spectroscopy showed that sulfur impregnated on the ACF samples was in both elemental and organic forms. As sulfur impregnation temperature increased, however, the relative amounts of elemental sulfur decreased with a concomitant increase in the amount of organic sulfur. Thermal analyses and mass spectrometry revealed that sulfur functional groups formed at higher impregnation temperatures were more thermally stable. In general, sulfur impregnation decreased surface area and increased equilibrium Hg0 adsorption capacity when compared to the raw ACF sample. The ACF sample treated with sulfur at 400 ??C had a surface area of only 94 m2/g compared to the raw ACF sample's surface area of 1971 m2/g, but at least 86% of this sample's surface area existed as micropores and it had the largest equilibrium Hg0adsorption capacities (2211-11343 ??g/g). Such a result indicates that 400 ??C is potentially an optimal sulfur impregnation temperature for this ACF. Sulfur impregnated on the ACF that was treated at 400 ??C was in both elemental and organic forms. Thermal analyses and CS2extraction tests suggested that elemental sulfur was the main form of sulfur affecting the Hg0 adsorption capacity. These findings indicate that both the presence of elemental sulfur on the adsorbent and a microporous structure are important properties for improving the performance of carbon-based adsorbents for the removal of Hg0 from coal combustion flue gases.

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.

An assessment of dispersing pollutants from the pre-harvest burning of sugarcane in rural areas in the northeast of Brazil

NASA Astrophysics Data System (ADS)

Rangel, Maria Gabriela L.; Henríquez, Jorge R.; Costa, José A. P.; de Lira Junior, José C.

2018-04-01

In recent years, the Brazilian government has been applying several restrictions with regard to preventing environmental pollution. Although Brazilian legislation is becoming stricter as to the pre-harvest burning of sugarcane, this practice is frequently used in order to assist manual harvesting. In the northeast region of Brazil, sugarcane is an important crop, which accounts for about 15% of the national production in a total area of 1,060,660 ha, the average production being 51,119 kg per hectare. The pre-harvest burning of sugarcane generates smoke, which has a high concentration of atmospheric pollutants such as carbon dioxide (CO2), carbon monoxide (CO), particulate matter (P.M. 2.5 and 10), polycyclic aromatic hydrocarbons (PAH), volatile organic compounds (VOC) and nitrogen oxides (NOX). This article estimates the volume of CO, P.M. 2.5 and NOX generated and how they are dispersed in the atmosphere when this arises from the burning of sugarcane biomass in rural areas of Northeast Brazil, and does so by using AERMOD VIEW® simulation software. Using the characteristics of the emissions and environmental (meteorological and topographical) data, quality air profiles based on pollutant dispersion were obtained. Three studies were taken into account in order to determine the relationship between pollutant dispersion and some parameters of the burning process, such as those for the spatial distribution of resources, the duration of pre-harvest burning and the influence of undertaking burning in different months. As to spatial distribution, to divide an area into small lots contributes to decreasing the maximum concentration of pollutants by 53% compared to burning a single area of equivalent size. The study of the burning duration indicated that doing so gradually (using a lengthier procedure) could decrease the maximum concentration of the pollutants by an inverse relation. The harvesting period in this region is between November and April. The pollutants dispersion process was greatest in February. April presented the worst dispersion conditions, and was associated with the highest pollutant concentrations.

Chemical and physical properties of biomass burning aerosols and their CCN activity: A case study in Beijing, China.

PubMed

Wu, Zhijun; Zheng, Jing; Wang, Yu; Shang, Dongjie; Du, Zhoufei; Zhang, Yuanhang; Hu, Min

2017-02-01

Biomass burning emits large amounts of both trace gases and particles into the atmosphere. It plays a profound role in regional air quality and climate change. In the present study, an intensive campaign was carried out at an urban site in Beijing, China, in June 2014, which covered the winter wheat harvest season over the North China Plain (NCP). Meanwhile, two evident biomass-burning events were observed. A clear burst in ultrafine particles (below 100nm in diameter, PM 1 ) and subsequent particle growth took place during the events. With the growth of the ultrafine particles, the organic fraction of PM 1 increased significantly. The ratio of oxygen to carbon (O:C), which had an average value of 0.23±0.04, did not show an obvious enhancement, indicating that a significant chemical aging process of the biomass-burning aerosols was not observed during the course of events. This finding might have been due to the fact that the biomass-burning events occurred in the late afternoon and grew during the nighttime, which is associated with a low atmospheric oxidation capacity. On average, organics and black carbon (BC) were dominant in the biomass-burning aerosols, accounting for 60±10% and 18±3% of PM 1 . The high organic and BC fractions led to a significant suppression of particle hygroscopicity. Comparisons among hygroscopicity tandem differential mobility analyzer (HTDMA)-derived, cloud condensation nuclei counter (CCNc)-derived, and aerosol mass spectrometer-based hygroscopicity parameter (κ) values were consistent. The mean κ values of biomass-burning aerosols derived from both HTDMA and CCNc measurements were approximately 0.1, regardless of the particle size, indicating that the biomass-burning aerosols were less active. The burst in particle count during the biomass-burning events resulted in an increased number of cloud condensation nuclei (CCN) at supersaturation (SS)=0.2-0.8%. Copyright © 2016 Elsevier B.V. All rights reserved.

ORGANIC AEROSOL SAMPLING AND ANALYSIS METHODS RESEARCH

EPA Science Inventory

Carbonaceous material is a major component of ambient PM at all locations in the U.S. and it is composed of two major classes: organic carbon (OC, composed of hundreds of individual compounds) and elemental carbon (EC, also referred to as soot, black carbon, or light adsorbing ca...

Gas and aerosol carbon in California: comparison of measurements and model predictions in Pasadena and Bakersfield.

EPA Science Inventory

Co-located measurements of fine particulate matter (PM2.5) organic carbon (OC), elemental carbon, radiocarbon (14C), speciated volatile organic compounds (VOCs),and OH radicals during the CalNex field campaign provide a unique opportunity to evaluate the Community Multiscale Air ...

Waterlogging accelerates the loss of soil organic carbon from abandoned paddy fields in the hilly terrain in subtropical China.

PubMed

Xie, Xiao Li; Wang, Wei; Tian, Wen Wen; Xie, Ke Jun

2017-11-06

Paddy soils have been widely recognized as important carbon sinks. However, paddy field abandonment is increasing in the hilly area in subtropical China. Soil waterlogging and weed burning are common practices in abandoned paddy fields, which could affect vegetation cover and carbon sequestration. An rice cultivation experiment was ceased in 2006, and four new treatments were applied as waterlogging (W), drainage (D), waterlogging combined with burning (WB), and drainage combined with burning (DB). Waterlogging altered the vegetation cover and caused an associated change in biomass. Paspalum paspaloides, Murdannia triquetra, and Bidens frondosa dominated W and WB plots, and Microstegium vimineum and Bidens frondosa dominated D and DB plots. Abandonment of paddy fields led to a rapid decrease in soil organic carbon (SOC), and waterlogging accelerates SOC loss which should be attributed mainly to alteration of the vegetation cover. Six years' rice cultivation increased SOC content by 13.5% (2.4 g kg -1 ) on average. In contrast, six years' abandonment reduced SOC content by 14.5% (3.0 g kg -1 ) on average. Decline rate of SOC was 0.38, 0.64, 0.30, and 0.65 g kg -1 a -1 for D, W, DB, and WB, respectively. Such results indicate a significant risk of SOC loss from abandoned paddy fields.

Broadband optical properties of biomass-burning aerosol and identification of brown carbon chromophores: OPTICAL AND CHEMICAL PROPERTIES OF BROWN CARBON AEROSOLS

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

Bluvshtein, Nir; Lin, Peng; Flores, J. Michel

The radiative effects of biomass burning aerosols on regional and global scale is substantial. Accurate modeling of the radiative effects of smoke aerosols require wavelength-dependent measurements and parameterizations of their optical properties in the UV and visible spectral ranges along with improved description of their chemical composition. To address this issue, we used a recently developed approach to retrieve the time- and spectral-dependent optical properties of ambient biomass burning aerosols between 300 and 650 nm wavelength during a regional bonfire festival in Israel. During the biomass burning event, the overall absorption at 400 nm increased by about two orders ofmore » magnitude, changing the size-weighted single scattering albedo from a background level of 0.95 to 0.7. Based on the new retrieval method, we provide parameterizations of the wavelength-dependent effective complex refractive index from 350 to 650 nm for freshly emitted and aged biomass burning aerosols. In addition, PM2.5 filter samples were collected for detailed off-line chemical analysis of the water soluble organics that contribute to light absorption. Nitrophenols were identified as the main organic species responsible for the increased absorption at 400-500 nm. These include species such as 4- nitrocatechol, 4-nitrophenol, nitro-syringol and nitro-guaiacol; oxidation-nitration products of methoxyphenols, known products of lignin pyrolysis. Our findings emphasize the importance of both primary and secondary organic aerosol from biomass burning in absorption of solar radiation and in effective radiative forcing.« less

Seasonal, interannual, and long-term variabilities in biomass burning activity over South Asia.

PubMed

Bhardwaj, P; Naja, M; Kumar, R; Chandola, H C

2016-03-01

The seasonal, interannual, and long-term variations in biomass burning activity and related emissions are not well studied over South Asia. In this regard, active fire location retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS), the retrievals of aerosol optical depth (AOD) from MODIS Terra, and tropospheric column NO2 from Ozone Monitoring Instrument (OMI) are used to understand the effects of biomass burning on the tropospheric pollution loadings over South Asia during 2003-2013. Biomass burning emission estimates from Global Fire Emission Database (GFED) and Global Fire Assimilation System (GFAS) are also used to quantify uncertainties and regional discrepancies in the emissions of carbon monoxide (CO), nitrogen oxide (NOx), and black carbon (BC) due to biomass burning in South Asia. In the Asian continent, the frequency of fire activity is highest over Southeast Asia, followed by South Asia and East Asia. The biomass burning activity in South Asia shows a distinct seasonal cycle that peaks during February-May with some differences among four (north, central, northeast, and south) regions in India. The annual biomass burning activity in north, central, and south regions shows an increasing tendency, particularly after 2008, while a decrease is seen in northeast region during 2003-2013. The increase in fire counts over the north and central regions contributes 24 % of the net enhancement in fire counts over South Asia. MODIS AOD and OMI tropospheric column NO2 retrievals are classified into high and low fire activity periods and show that biomass burning leads to significant enhancement in tropospheric pollution loading over both the cropland and forest regions. The enhancement is much higher (110-176 %) over the forest region compared to the cropland (34-62 %) region. Further efforts are required to understand the implications of biomass burning on the regional air quality and climate of South Asia.

Local source impacts on primary and secondary aerosols in the Midwestern United States

NASA Astrophysics Data System (ADS)

Jayarathne, Thilina; Rathnayake, Chathurika M.; Stone, Elizabeth A.

2016-04-01

Atmospheric particulate matter (PM) exhibits heterogeneity in composition across urban areas, leading to poor representation of outdoor air pollutants in human exposure assessments. To examine heterogeneity in PM composition and sources across an urban area, fine particulate matter samples (PM2.5) were chemically profiled in Iowa City, IA from 25 August to 10 November 2011 at two monitoring stations. The urban site is the federal reference monitoring (FRM) station in the city center and the peri-urban site is located 8.0 km to the west on the city edge. Measurements of PM2.5 carbonaceous aerosol, inorganic ions, molecular markers for primary sources, and secondary organic aerosol (SOA) tracers were used to assess statistical differences in composition and sources across the two sites. PM2.5 mass ranged from 3 to 26 μg m-3 during this period, averaging 11.2 ± 4.9 μg m-3 (n = 71). Major components of PM2.5 at the urban site included organic carbon (OC; 22%), ammonium (14%), sulfate (13%), nitrate (7%), calcium (2.9%), and elemental carbon (EC; 2.2%). Periods of elevated PM were driven by increases in ammonium, sulfate, and SOA tracers that coincided with hot and dry conditions and southerly winds. Chemical mass balance (CMB) modeling was used to apportion OC to primary sources; biomass burning, vegetative detritus, diesel engines, and gasoline engines accounted for 28% of OC at the urban site and 24% of OC at the peri-urban site. Secondary organic carbon from isoprene and monoterpene SOA accounted for an additional 13% and 6% of OC at the urban and peri-urban sites, respectively. Differences in biogenic SOA across the two sites were associated with enhanced combustion activities in the urban area and higher aerosol acidity at the urban site. Major PM constituents (e.g., OC, ammonium, sulfate) were generally well-represented by a single monitoring station, indicating a regional source influence. Meanwhile, nitrate, biomass burning, food cooking, suspended dust, and biogenic SOA were not well-represented by a single site and demonstrated local influences. For isoprene SOA, product distributions indicated a larger role for the high-NOx pathway at the urban site. These local sources are largely responsible for differences in population exposures to outdoor PM in the study domain located within the Midwestern US.

Evaluation of the carbon content of aerosols from the burn- ing of biomass in the Brazilian Amazon using thermal, op- tical and thermal-optical analysis methods

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

Soto-Garcia, Lydia L.; Andreae, Meinrat O.; Andreae, Tracey W.

2011-06-03

Aerosol samples were collected at a pasture site in the Amazon Basin as part of the project LBA-SMOCC-2002 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall and Climate: Aerosols from Biomass Burning Perturb Global and Regional Climate). Sampling was conducted during the late dry season, when the aerosol composition was dominated by biomass burning emissions, especially in the submicron fraction. A 13-stage Dekati low-pressure impactor (DLPI) was used to collect particles with nominal aerodynamic diameters (D{sub p}) ranging from 0.03 to 0.10 m. Gravimetric analyses of the DLPI substrates and filters were performed to obtain aerosol mass concentrations.more » The concentrations of total, apparent elemental, and organic carbon (TC, EC{sub a}, and OC) were determined using thermal and thermal-optical analysis (TOA) methods. A light transmission method (LTM) was used to determine the concentration of equivalent black carbon (BC{sub e}) or the absorbing fraction at 880 nm for the size-resolved samples. During the dry period, due to the pervasive presence of fires in the region upwind of the sampling site, concentrations of fine aerosols (D{sub p} < 2.5 {mu}m: average 59.8 {mu}g m{sup -3}) were higher than coarse aerosols (D{sub p} > 2.5 {mu}m: 4.1 {mu}g m{sup -3}). Carbonaceous matter, estimated as the sum of the particulate organic matter (i.e., OC x 1.8) plus BC{sub e}, comprised more than 90% to the total aerosol mass. Concentrations of EC{sub a} (estimated by thermal analysis with a correction for charring) and BCe (estimated by LTM) averaged 5.2 {+-} 1.3 and 3.1 {+-} 0.8 {mu}g m{sup -3}, respectively. The determination of EC was improved by extracting water-soluble organic material from the samples, which reduced the average light absorption {angstrom} exponent of particles in the size range of 0.1 to 1.0 {mu}m from > 2.0 to approximately 1.2. The size-resolved BC{sub e} measured by the LTM showed a clear maximum between 0.4 and 0.6 m in diameter. The concentrations of OC and BC{sub e} varied diurnally during the dry period, and this variation is related to diurnal changes in boundary layer thickness and in fire frequency.« less

Effect of secondary organic aerosol coating thickness on the real-time detection and characterization of biomass-burning soot by two particle mass spectrometers

DOE PAGES

Ahern, Adam T.; Subramanian, Ramachandran; Saliba, Georges; ...

2016-12-22

Biomass burning is a large source of light-absorbing refractory black carbon (rBC) particles with a wide range of morphologies and sizes. The net radiative forcing from these particles is strongly dependent on the amount and composition of non-light-absorbing material internally mixed with the rBC and on the morphology of the mixed particles. Understanding how the mixing state and morphology of biomass-burning aerosol evolves in the atmosphere is critical for constraining the influence of these particles on radiative forcing and climate. We investigated the response of two commercial laser-based particle mass spectrometers, the vacuum ultraviolet (VUV) ablation LAAPTOF and the IRmore » vaporization SP-AMS, to monodisperse biomass-burning particles as we sequentially coated the particles with secondary organic aerosol (SOA) from α-pinene ozonolysis. We studied three mobility-selected soot core sizes, each with a number of successively thicker coatings of SOA applied. Using IR laser vaporization, the SP-AMS had different changes in sensitivity to rBC compared to potassium as a function of applied SOA coatings. We show that this is due to different effective beam widths for the IR laser vaporization region of potassium versus black carbon. The SP-AMS's sensitivity to black carbon (BC) mass was not observed to plateau following successive SOA coatings, despite achieving high OA : BC mass ratios greater than 9. We also measured the ion fragmentation pattern of biomass-burning rBC and found it changed only slightly with increasing SOA mass. The average organic matter ion signal measured by the LAAPTOF demonstrated a positive correlation with the condensed SOA mass on individual particles, despite the inhomogeneity of the particle core compositions. This demonstrates that the LAAPTOF can obtain quantitative mass measurements of aged soot-particle composition from realistic biomass-burning particles with complex morphologies and composition.« less

Source apportionments of PM2.5 organic carbon using molecular marker Positive Matrix Factorization and comparison of results from different receptor models

NASA Astrophysics Data System (ADS)

Heo, Jongbae; Dulger, Muaz; Olson, Michael R.; McGinnis, Jerome E.; Shelton, Brandon R.; Matsunaga, Aiko; Sioutas, Constantinos; Schauer, James J.

2013-07-01

Four hundred fine particulate matter (PM2.5) samples collected over a 1-year period at two sites in the Los Angeles Basin were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) and organic molecular markers. The results were used in a Positive Matrix Factorization (PMF) receptor model to obtain daily, monthly and annual average source contributions to PM2.5 OC. Results of the PMF model showed similar source categories with comparable year-long contributions to PM2.5 OC across the sites. Five source categories providing reasonably stable profiles were identified: mobile, wood smoke, primary biogenic, and two types of secondary organic carbon (SOC) (i.e., anthropogenic and biogenic emissions). Total primary emission factors and total SOC factors contributed approximately 60% and 40%, respectively, to the annual-average OC concentrations. Primary sources showed strong seasonal patterns with high winter peaks and low summer peaks, while SOC showed a reverse pattern with highs in the spring and summer in the region. Interestingly, smoke from forest fires which occurred episodically in California during the summer and fall of 2009 was identified and combined with the primary biogenic source as one distinct factor to the OC budget. The PMF resolved factors were further investigated and compared to a chemical mass balance (CMB) model and a second multi-variant receptor model (UNMIX) using molecular markers considered in the PMF. Good agreement between the source contribution from mobile sources and biomass burning for three models were obtained, providing additional weight of evidence that these source apportionment techniques are sufficiently accurate for policy development. However, the CMB model did not quantify primary biogenic emissions, which were included in other sources with the SOC. Both multivariate receptor models, the PMF and the UNMIX, were unable to separate source contributions from diesel and gasoline engines.

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.

Transport of Biomass Burning Emissions from Southern Africa

NASA Technical Reports Server (NTRS)

Sinha, Parikhit; Jaegle,Lyatt; Hobbs, Peter V.; Liang, Qing

2004-01-01

The transport of biomass burning emissions from southern Africa to the neighboring Atlantic and Indian Oceans during the dry season (May-October) of 2000 is characterized using ground, ozonesonde, and aircraft measurements of carbon monoxide (CO) and ozone (O3) in and around southern Africa, together with the GEOS-CHEM global model of tropospheric chemistry. The model shows a positive bias of approximately 20% for CO and a negative bias of approximately 10-25% for O3 at oceanic sites downwind of fire emissions. Near areas of active fire emissions the model shows a negative bias of approximately 60% and approximately 30% for CO and O3, respectively, likely due to the coarse spatial (2 deg. x 2.5 deg.) and temporal (monthly) resolution of the model compared to that of active fires. On average, from 1994 to 2000, approximately 60 Tg of carbon monoxide (CO) from biomass burning in southern Africa was transported eastward to the Indian Ocean across the latitude band 0 deg. -60 S during the 6 months of the dry season. Over the same time period, approximately 40 Tg of CO from southern African biomass burning was transported westward to the Atlantic Ocean over the latitudes 0 deg. -20 S during the 6-month dry season, but most of that amount was transported back eastward over higher latitudes to the south (21 deg. -60 S). Eastward transport of biomass burning emissions from southern Africa enhances CO concentrations by approximately 4- 13 ppbv per month over the southern subtropical Indian Ocean during the dry season, with peak enhancements in September. Carbon monoxide from southern African and South American biomass burning is seen in the model simulations as far away as Australia, contributing approximately 8 ppbv and approximately 12-15 ppbv CO, respectively, and thus explaining the approximately 20- 25 ppbv observed enhancement of CO over Melbourne in mid-September 2000.

Effects of elemental composition on the incorporation of dietary nitrogen and carbon isotopic signatures in an omnivorous songbird

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

Pearson, Scott, F.; Levey, Douglas, J.; Greenberg, Catheryn, H.

2003-02-28

Pearson, S.F., D.J. Levey, C.H. Greenberg, and C.M. del Rio. 2003. Effects of elemental composition on the incorporation of dietary nitrogen and carbon isotopic signatures in an omnivorous songbird. Oecologia. 135:516-523. The use of stable isotopes to infer diet requires quantifying the relationship between diet and tissues and, in particular, knowing of how quickly isotopes turnover in different tissues and how isotopic concentrations of different food components change (discriminate) when incorporated into consumer tissues. We used feeding trials with wild-caught yellow-rumped warblers (Dendroica coronata) to determine d15N and d13C turnover rates for blood, d15N and d13C diet-tissue discrimination factors, andmore » diet-tissue relationships for blood and feathers. After 3 weeks on a common diet, 36 warblers were assigned to one of four diets differing in the relative proportion of fruit and insects. Plasma half-life estimates ranged from 0.4 to 0.7 days for d13C and from 0.5 to 1.7 days for d15N. Half-life did not differ among diets. Whole blood half-life for d13C ranged from 3.9 to 6.1 days. Yellow-rumped warbler tissues were enriched relative to diet by 1.7.3.6% for nitrogen isotopes and by 1.2 to 4.3% for carbon isotopes, depending on tissue and diet. Consistent with previous studies, feathers were the most enriched and whole blood and plasma were the least enriched or, in the case of carbon, slightly depleted relative to diet. In general, tissues were more enriched relative to diet for birds with high percentages of insects. For all tissues, carbon and nitrogen isotope discrimination factors increased with carbon and nitrogen concentrations of diets. The isotopic signature of plasma increased linearly with the sum of the isotopic signature of the diet and the discrimination factor. Because the isotopic signature of tissues depends on both elemental concentration and isotopic signature of the diet, attempts to reconstruct diet from stable isotope signatures require mixing models that incorporate elemental concentration.« less

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...

Potential release of fibers from burning carbon composites. [aircraft fires

NASA Technical Reports Server (NTRS)

Bell, V. L.

1980-01-01

A comprehensive experimental carbon fiber source program was conducted to determine the potential for the release of conductive carbon fibers from burning composites. Laboratory testing determined the relative importance of several parameters influencing the amounts of single fibers released, while large-scale aviation jet fuel pool fires provided realistic confirmation of the laboratory data. The dimensions and size distributions of fire-released carbon fibers were determined, not only for those of concern in an electrical sense, but also for those of potential interest from a health and environmental standpoint. Fire plume and chemistry studies were performed with large pool fires to provide an experimental input into an analytical modelling of simulated aircraft crash fires. A study of a high voltage spark system resulted in a promising device for the detection, counting, and sizing of electrically conductive fibers, for both active and passive modes of operation.

Long-term measurements (2010-2014) of carbonaceous aerosol and carbon monoxide at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia

NASA Astrophysics Data System (ADS)

Mikhailov, Eugene F.; Mironova, Svetlana; Mironov, Gregory; Vlasenko, Sergey; Panov, Alexey; Chi, Xuguang; Walter, David; Carbone, Samara; Artaxo, Paulo; Heimann, Martin; Lavric, Jost; Pöschl, Ulrich; Andreae, Meinrat O.

2017-12-01

We present long-term (5-year) measurements of particulate matter with an upper diameter limit of ˜ 10 µm (PM10), elemental carbon (EC), organic carbon (OC), and water-soluble organic carbon (WSOC) in aerosol filter samples collected at the Zotino Tall Tower Observatory in the middle-taiga subzone (Siberia). The data are complemented with carbon monoxide (CO) measurements. Air mass back trajectory analysis and satellite image analysis were used to characterise potential source regions and the transport pathway of haze plumes. Polluted and background periods were selected using a non-parametric statistical approach and analysed separately. In addition, near-pristine air masses were selected based on their EC concentrations being below the detection limit of our thermal-optical instrument. Over the entire sampling campaign, 75 and 48 % of air masses in winter and in summer, respectively, and 42 % in spring and fall are classified as polluted. The observed background concentrations of CO and EC showed a sine-like behaviour with a period of 365 ± 4 days, mostly due to different degrees of dilution and the removal of polluted air masses arriving at the Zotino Tall Tower Observatory (ZOTTO) from remote sources. Our analysis of the near-pristine conditions shows that the longest periods with clean air masses were observed in summer, with a frequency of 17 %, while in wintertime only 1 % can be classified as a clean. Against a background of low concentrations of CO, EC, and OC in the near-pristine summertime, it was possible to identify pollution plumes that most likely came from crude-oil production sites located in the oil-rich regions of Western Siberia. Overall, our analysis indicates that most of the time the Siberian region is impacted by atmospheric pollution arising from biomass burning and anthropogenic emissions. A relatively clean atmosphere can be observed mainly in summer, when polluted species are removed by precipitation and the aerosol burden returns to near-pristine conditions.

[Pollution Level and Source Apportionment of Atmospheric Particles PM₂.₅ in Southwest Suburb of Chengdu in Spring].

PubMed

Lin, Yu; Ye, Zhi-xiang; Yang, Huai-jin; Zhang, Ju; Yin, Wei-wen; Li, Xiao-fen

2016-05-15

In order to understand the characteristics of PM₂.₅ pollution in the atmosphere of Chengdu southwest suburb, PM₂.₅ particles in Chengdu southwest suburb were collected and analyzed from March 18 to March 31st, 2015. The results showed that the daily average concentration of PM₂.₅ in the southwest suburb of Chengdu reached 121.21 µg · m⁻³, and the average daily concentration of 24 samples in 31 PM₂.₅ samples was over 75 µg · m⁻³, the daily excessive rate was 77%, indicating the PM₂.₅ pollution in the study area was serious in March. When studying the relationship between atmospheric and meteorological factors, it was found that there was a significant index correlation between PM₂.₅ concentration and atmospheric visibility, and it had a positive correlation with temperature and humidity, but the correlation was not obvious. NH₄⁺ (16.24%), SO₄²- (12.58%) and NO₃⁻ (9.91%) were dominant in PM₂.₅ The ratio of NO₃⁻/SO₄²⁻ was 0.77, which indicated that the pollution of stationary sources in the southwest suburb was more severe than that of mobile sources. Organic carbon (OC)/elemental carbon (EC) ratios were higher than 2, which indicated the existence of second organic carbon (SOC). Using OC/EC ratio method to estimate the concentration of SOC, it was found that the average concentration of SOC in the southwest suburb of Chengdu in March was 3.49 µ · m⁻³, and the contribution rate of OC was 20.6%, which showed that the main source of OC in the southwest suburb of Chengdu was primary discharge. The correlation analysis of OC and EC showed that the correlation coefficient reached 0.95, indicating that the OC and EC sources were similar and relatively stable, and there was a great impact of local source emissions on Chengdu southwest suburb in spring, and primary discharge played a dominant role, while the contribution of SOC to OC was relatively small, which was consistent with the SOC characteristics obtained by estimation. Using principal component analysis method to analyze the sources of PM₂.₅ in the southwest of Chengdu, it was found that the main pollution sources of PM₂.₅ in southwest suburb of Chengdu were coal burning and biomass burning, secondary nitrate/sulfate, soil and dust, vehicle emissions, electronic production source, and mechanical processing source.

Combustion of Metals in Carbon Dioxide and Reduced-Gravity Environments

NASA Technical Reports Server (NTRS)

Branch, M. C.; Abbud-Madrid, A.; Modak, A.; Dreyer, C. B.; Daily, J. W.

2001-01-01

Ongoing exploration and future mission2001110444 s to Mars have given impetus to research on the use of natural resources of the planet. Since carbon dioxide (CO2) constitutes approximately 95% of the Mars atmosphere and since it reacts directly and vigorously with several metals, this investigation focuses on metal-CO2 reactions as a possible combination for rocket-propellant production and energy generation. Magnesium (Mg) has been initially selected as the metal fuel owing to its low ignition temperature and high specific impulse and burning rate in CO2. Our studies in this field started with low gravity (g) combustion tests of Mg in O2, CO2, and CO. Reduced gravity provided a clear picture of the burning phenomena by eliminating the intrusive buoyant flows in high-temperature metal reactions and by removing the destructive effect of gravity on the shape of molten metal samples. Suspended cylindrical metal samples of 2, 3, and 4-mm in diameter and length were radiatively ignited in low-g to generate free-floating samples exhibiting a spherically symmetric flame with increasing metal-oxide accumulation in an outer shell. For the Mg-CO2 combination, burning times twice as long as in normal-g and five times longer than in Mg-O2 flames were observed, revealing a diffusion-controlled reaction. The burning time is proportional to the square of the sample diameter. In tests conducted with pure CO, combustion was not possible without constant heating of the sample due to the formation of a thick carbon-containing coating around the Mg sample generated by surface reactions. The following work presents two new studies that attempt to explain some of the low-g experimental observations. First, a simplified one-dimensional, quasi-steady numerical model is developed to obtain temperature, species concentrations, and burning rates of the spherically symmetric diffusion flame around the Mg sample burning in O2 and CO2. Second, a Planar Laser Induced Fluorescence (PLIF) technique is implemented to provide spatially resolved measurements of magnesium oxide (MgO) in the reaction zone of Mg samples burning in O2 and CO2. These experiments reveal fundamental differences between the two combustion systems.

40 CFR Table 8 to Subpart Ddddd of... - Demonstrating Continuous Compliance

Code of Federal Regulations, 2010 CFR

2010-07-01

...(c). 5. Dry Scrubber Sorbent or Carbon Injection Rate a. Collecting the sorbent or carbon injection... the data to 3-hour block averages; and c. Maintaining the 3-hour average sorbent or carbon injection... established during the performance test according to §§ 63.7530(c). 7. Fuel Pollutant Content a. Only burning...

40 CFR Table 8 to Subpart Ddddd of... - Demonstrating Continuous Compliance

Code of Federal Regulations, 2012 CFR

2012-07-01

...(c). 5. Dry Scrubber Sorbent or Carbon Injection Rate a. Collecting the sorbent or carbon injection... the data to 3-hour block averages; and c. Maintaining the 3-hour average sorbent or carbon injection... established during the performance test according to §§ 63.7530(c). 7. Fuel Pollutant Content a. Only burning...

Effect of secondary organic aerosol coating thickness on the real-time detection and characterization of biomass-burning soot by two particle mass spectrometers

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

Ahern, Adam T.; Subramanian, Ramachandran; Saliba, Georges

Biomass burning is a large source of light-absorbing refractory black carbon (rBC) particles with a wide range of morphologies and sizes. The net radiative forcing from these particles is strongly dependent on the amount and composition of non-light-absorbing material internally mixed with the rBC and on the morphology of the mixed particles. Understanding how the mixing state and morphology of biomass-burning aerosol evolves in the atmosphere is critical for constraining the influence of these particles on radiative forcing and climate. We investigated the response of two commercial laser-based particle mass spectrometers, the vacuum ultraviolet (VUV) ablation LAAPTOF and the IRmore » vaporization SP-AMS, to monodisperse biomass-burning particles as we sequentially coated the particles with secondary organic aerosol (SOA) from α-pinene ozonolysis. We studied three mobility-selected soot core sizes, each with a number of successively thicker coatings of SOA applied. Using IR laser vaporization, the SP-AMS had different changes in sensitivity to rBC compared to potassium as a function of applied SOA coatings. We show that this is due to different effective beam widths for the IR laser vaporization region of potassium versus black carbon. The SP-AMS's sensitivity to black carbon (BC) mass was not observed to plateau following successive SOA coatings, despite achieving high OA : BC mass ratios greater than 9. We also measured the ion fragmentation pattern of biomass-burning rBC and found it changed only slightly with increasing SOA mass. The average organic matter ion signal measured by the LAAPTOF demonstrated a positive correlation with the condensed SOA mass on individual particles, despite the inhomogeneity of the particle core compositions. This demonstrates that the LAAPTOF can obtain quantitative mass measurements of aged soot-particle composition from realistic biomass-burning particles with complex morphologies and composition.« less

Diagnosis of aged prescribed burning plumes impacting an urban area.

PubMed

Lee, Sangil; Kim, Hyeon K; Yan, Bo; Cobb, Charles E; Hennigan, Chris; Nichols, Sara; Chamber, Michael; Edgerton, Eric S; Jansen, John J; Hu, Yongtao; Zheng, Mei; Weber, Rodney J; Russell, Armistead G

2008-03-01

An unanticipated wind shift led to the advection of plumes from two prescribed burning sites that impacted Atlanta, GA, producing a heavy smoke event late in the afternoon on February 28, 2007. Observed PM2.5 concentrations increased to over 140 microg/m3 and O3 concentrations up to 30 ppb in a couple of hours, despite the late hour in February when photochemistry is less vigorous. A detailed investigation of PM2.5 chemical composition and source apportionment analysis showed that the increase in PM2.5 mass was driven mainly by organic carbon (OC). However, both results from source apportionment and an observed nonlinear relationship between OC and PM2.5 potassium (K) indicate that the increased OC was not due solely to primary emissions. Most of the OC was water-soluble organic carbon (WSOC) and was dominated by hydrophobic compounds. The data are consistent with large enhancements in isoprenoid (isoprene and monoterpenes) and other volatile organic compounds emitted from prescribed burning that led to both significant O3 and secondary organic aerosol (SOA) production. Formation of oligomers from oxidation products of isoprenoid compounds or condensation of volatile organic compounds (VOCs) with multiple functional groups emitted during prescribed burning appears to be a major component of the secondary organic contributor of the SOA. The results from this study imply that enhanced emissions due to the fire itself and elevated temperature in the burning region should be considered in air quality models (e.g., receptor and emission-based models) to assess impacts of prescribed burning emissions on ambient air quality.

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.

Direct radiative effect of carbonaceous aerosols from crop residue burning during the summer harvest season in East China

NASA Astrophysics Data System (ADS)

Yao, Huan; Song, Yu; Liu, Mingxu; Archer-Nicholls, Scott; Lowe, Douglas; McFiggans, Gordon; Xu, Tingting; Du, Pin; Li, Jianfeng; Wu, Yusheng; Hu, Min; Zhao, Chun; Zhu, Tong

2017-04-01

East China experiences extensive crop residue burnings in fields during harvest season. The direct radiative effect (DRE) of carbonaceous aerosols from crop residue burning in June 2013 in East China was investigated using the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem). Absorption of organic aerosol (OA) in the presence of brown carbon was considered using the parameterization of Saleh et al. (2014), in which the imaginary part of the OA refractive index is a function of wavelength and the ratio of black carbon (BC) and OA. The carbonaceous emissions from crop fires were estimated using the Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) product with a localized crop-burning-sourced BC-to-organic carbon (OC) ratio emission ratio of 0.27. Evaluation of the model results with in situ measurements of particulate matter with aerodynamic diameter less than 2.5 µm (PM2. 5) chemical composition, MODIS aerosol optical depth (AOD) detections and meteorological observations showed that this model was able to reproduce the magnitude, spatial variation and optical characteristics of carbonaceous aerosol pollution. The observed BC and OC peak concentrations at the site in Suixi, Anhui province, during the 2013 wheat burning season reached 55.3 µg m-3 and 157.9 µg m-3. WRF-Chem simulations reproduced these trends with a correlation coefficient of 0.74, estimating that crop residue burning contributed 86 and 90 % of peak BC and OC, respectively. The simulated hourly DRE from crop residue burning at the top of atmosphere (TOA) reached a maximum of +22.66 W m-2 at the Suixi site. On average, the simulations showed that the crop residue burning introduced a net positive DRE of +0.14 W m-2 at TOA throughout East China, with BC from this source as the main heating contributor (+0.79 W m-2). The OA DRE from crop burning (-0.22 W m-2) was a combined effect of the positive DRE of absorption (+0.21 W m-2) and a stronger negative DRE of scattering (-0.43 W m-2). Sensitivity tests showed that the DRE of OA absorption strongly depended on the imaginary part of the OA refractive index, the BC-to-OA emission ratio from crop residue burning and the assumed mixing state of the aerosol, whereby the volume mixing treatment resulted in a higher positive DRE compared to the core-shell treatment. The BC mixing state and associated absorption enhancement during BC aging processes will be investigated in detail in future research.

Correcting a fundamental error in greenhouse gas accounting related to bioenergy.

PubMed

Haberl, Helmut; Sprinz, Detlef; Bonazountas, Marc; Cocco, Pierluigi; Desaubies, Yves; Henze, Mogens; Hertel, Ole; Johnson, Richard K; Kastrup, Ulrike; Laconte, Pierre; Lange, Eckart; Novak, Peter; Paavola, Jouni; Reenberg, Anette; van den Hove, Sybille; Vermeire, Theo; Wadhams, Peter; Searchinger, Timothy

2012-06-01

Many international policies encourage a switch from fossil fuels to bioenergy based on the premise that its use would not result in carbon accumulation in the atmosphere. Frequently cited bioenergy goals would at least double the present global human use of plant material, the production of which already requires the dedication of roughly 75% of vegetated lands and more than 70% of water withdrawals. However, burning biomass for energy provision increases the amount of carbon in the air just like burning coal, oil or gas if harvesting the biomass decreases the amount of carbon stored in plants and soils, or reduces carbon sequestration. Neglecting this fact results in an accounting error that could be corrected by considering that only the use of 'additional biomass' - biomass from additional plant growth or biomass that would decompose rapidly if not used for bioenergy - can reduce carbon emissions. Failure to correct this accounting flaw will likely have substantial adverse consequences. The article presents recommendations for correcting greenhouse gas accounts related to bioenergy.

Long-term simulations of forest management impacts on carbon storage from loblolly pine plantations in the Southern U.S.

Treesearch

Huei-Jin Wang; Philip J. Radtke; Stephen P. Prisley

2012-01-01

Accounting for forest components in carbon accounting systems may be insufficient when substantial amounts of sequestered carbon are harvested and converted to wood products in use and in landfill. The potential of forest offset – in-woods aboveground carbon storage, carbon stored in harvested wood, and energy offset by burning harvested wood – from loblolly pine...

Catalyst for elemental sulfur recovery process

DOEpatents

Flytzani-Stephanopoulos, M.; Liu, W.

1995-01-24

A catalytic reduction process is described for the direct recovery of elemental sulfur from various SO[sub 2]-containing industrial gas streams. The catalytic process provides high activity and selectivity, as well as stability in the reaction atmosphere, for the reduction of SO[sub 2] to elemental sulfur product with carbon monoxide or other reducing gases. The reaction of sulfur dioxide and reducing gas takes place over a metal oxide composite catalyst having one of the following empirical formulas: [(FO[sub 2])[sub 1[minus]n](RO)[sub n

Carbon fiber counting. [aircraft structures

NASA Technical Reports Server (NTRS)

Pride, R. A.

1980-01-01

A method was developed for characterizing the number and lengths of carbon fibers accidentally released by the burning of composite portions of civil aircraft structure in a jet fuel fire after an accident. Representative samplings of carbon fibers collected on transparent sticky film were counted from photographic enlargements with a computer aided technique which also provided fiber lengths.

40 CFR Table 8 to Subpart Ddddd of... - Demonstrating Continuous Compliance

Code of Federal Regulations, 2011 CFR

2011-07-01

...(c). 5. Dry Scrubber Sorbent or Carbon Injection Rate a. Collecting the sorbent or carbon injection... the data to 3-hour block averages; and c. Maintaining the 3-hour average sorbent or carbon injection... established during the performance test according to §§ 63.7530(c). 7. Fuel Pollutant Content a. Only burning...

CHEMICAL ANALYSIS METHODS FOR ATMOSPHERIC AEROSOL COMPONENTS

EPA Science Inventory

This chapter surveys the analytical techniques used to determine the concentrations of aerosol mass and its chemical components. The techniques surveyed include mass, major ions (sulfate, nitrate, ammonium), organic carbon, elemental carbon, and trace elements. As reported in...

Occupational Diesel Exposure, Duration of Employment, and Lung Cancer

PubMed Central

Picciotto, Sally; Costello, Sadie; Eisen, Ellen A.

2016-01-01

Background: If less healthy workers terminate employment earlier, thus accumulating less exposure, yet remain at greater risk of the health outcome, estimated health effects of cumulative exposure will be biased downward. If exposure also affects termination of employment, then the bias cannot be addressed using conventional methods. We examined these conditions as a prelude to a reanalysis of lung cancer mortality in the Diesel Exhaust in Miners Study. Methods: We applied an accelerated failure time model to assess the effect of exposures to respirable elemental carbon (a surrogate for diesel) on time to termination of employment among nonmetal miners who ever worked underground (n = 8,307). We then applied the parametric g-formula to assess how possible interventions setting respirable elemental carbon exposure limits would have changed lifetime risk of lung cancer, adjusting for time-varying employment status. Results: Median time to termination was 36% shorter (95% confidence interval = 33%, 39%), per interquartile range width increase in respirable elemental carbon exposure. Lung cancer risk decreased with more stringent interventions, with a risk ratio of 0.8 (95% confidence interval = 0.5, 1.1) comparing a limit of ≤25 µg/m3 respirable elemental carbon to no intervention. The fraction of cases attributable to diesel exposure was 27% in this population. Conclusions: The g-formula controlled for time-varying confounding by employment status, the signature of healthy worker survivor bias, which was also affected by diesel exposure. It also offers an alternative approach to risk assessment for estimating excess cumulative risk, and the impact of interventions based entirely on an observed population. PMID:26426944

Elemental sulfur recovery process

DOEpatents

Flytzani-Stephanopoulos, Maria; Hu, Zhicheng

1993-01-01

An improved catalytic reduction process for the direct recovery of elemental sulfur from various SO.sub.2 -containing industrial gas streams. The catalytic process provides combined high activity and selectivity for the reduction of SO.sub.2 to elemental sulfur product with carbon monoxide or other reducing gases. The reaction of sulfur dioxide and reducing gas takes place over certain catalyst formulations based on cerium oxide. The process is a single-stage, catalytic sulfur recovery process in conjunction with regenerators, such as those used in dry, regenerative flue gas desulfurization or other processes, involving direct reduction of the SO.sub.2 in the regenerator off gas stream to elemental sulfur in the presence of a catalyst.

Functional Group Analysis of Biomass Burning Particles Using Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Horrell, K.; Lau, A.; Bond, T.; Iraci, L. T.

2008-12-01

Biomass burning is a significant source of particulate organic carbon in the atmosphere. These particles affect the energy balance of the atmosphere directly by absorbing and scattering solar radiation, and indirectly through their ability to act as cloud condensation nuclei (CCN). The chemical composition of biomass burning particles influences their ability to act as CCN, thus understanding the chemistry of these particles is required for understanding their effects on climate and air quality. As climate change influences the frequency and severity of boreal forest fires, the influence of biomass burning aerosols on the atmosphere may become significantly greater. Only a small portion of the organic carbon (OC) fraction of these particles has been identified at the molecular level, although several studies have explored the general chemical classes found in biomass burning smoke. To complement those studies and provide additional information about the reactive functional groups present, we are developing a method for polarity-based separation of compound classes found in the OC fraction, followed by infrared (IR) spectroscopic analysis of each polarity fraction. It is our goal to find a simple, relatively low-tech method which will provide a moderate chemical understanding of the entire suite of compounds present in the OC fraction of biomass burning particles. Here we present preliminary results from pine and oak samples representative of Midwestern United States forests burned at several different temperatures. Wood type and combustion temperature are both seen to affect the composition of the particles. The latter seems to affect relative contributions of certain functional groups, while oak demonstrates at least one additional chemical class of compounds, particularly at lower burning temperatures, where gradual solid-gas phase reactions can produce relatively large amounts of incompletely oxidized products.

A Review of Events That Expose Children to Elemental Mercury in the United States

PubMed Central

Lee, Robin; Middleton, Dan; Caldwell, Kathleen; Dearwent, Steve; Jones, Steven; Lewis, Brian; Monteilh, Carolyn; Mortensen, Mary Ellen; Nickle, Richard; Orloff, Kenneth; Reger, Meghan; Risher, John; Rogers, Helen Schurz; Watters, Michelle

2009-01-01

Objective Concern for children exposed to elemental mercury prompted the Agency for Toxic Substances and Disease Registry and the Centers for Disease Control and Prevention to review the sources of elemental mercury exposures in children, describe the location and proportion of children affected, and make recommendations on how to prevent these exposures. In this review, we excluded mercury exposures from coal-burning facilities, dental amalgams, fish consumption, medical waste incinerators, or thimerosal-containing vaccines. Data sources We reviewed federal, state, and regional programs with information on mercury releases along with published reports of children exposed to elemental mercury in the United States. We selected all mercury-related events that were documented to expose (or potentially expose) children. We then explored event characteristics (i.e., the exposure source, location). Data synthesis Primary exposure locations were at home, at school, and at other locations such as industrial property not adequately remediated or medical facilities. Exposure to small spills from broken thermometers was the most common scenario; however, reports of such exposures are declining. Discussion and conclusions Childhood exposures to elemental mercury often result from inappropriate handling or cleanup of spilled mercury. The information reviewed suggests that most releases do not lead to demonstrable harm if the exposure period is short and the mercury is properly cleaned up. Recommendations Primary prevention should include health education and policy initiatives. For larger spills, better coordination among existing surveillance systems would assist in understanding the risk factors and in developing effective prevention efforts. PMID:19590676

Open burning of rice, corn and wheat straws: primary emissions, photochemical aging, and secondary organic aerosol formation

NASA Astrophysics Data System (ADS)

Fang, Zheng; Deng, Wei; Zhang, Yanli; Ding, Xiang; Tang, Mingjin; Liu, Tengyu; Hu, Qihou; Zhu, Ming; Wang, Zhaoyi; Yang, Weiqiang; Huang, Zhonghui; Song, Wei; Bi, Xinhui; Chen, Jianmin; Sun, Yele; George, Christian; Wang, Xinming

2017-12-01

Agricultural residues are among the most abundant biomass burned globally, especially in China. However, there is little information on primary emissions and photochemical evolution of agricultural residue burning. In this study, indoor chamber experiments were conducted to investigate primary emissions from open burning of rice, corn and wheat straws and their photochemical aging as well. Emission factors of NOx, NH3, SO2, 67 non-methane hydrocarbons (NMHCs), particulate matter (PM), organic aerosol (OA) and black carbon (BC) under ambient dilution conditions were determined. Olefins accounted for > 50 % of the total speciated NMHCs emission (2.47 to 5.04 g kg-1), indicating high ozone formation potential of straw burning emissions. Emission factors of PM (3.73 to 6.36 g kg-1) and primary organic carbon (POC, 2.05 to 4.11 gC kg-1), measured at dilution ratios of 1300 to 4000, were lower than those reported in previous studies at low dilution ratios, probably due to the evaporation of semi-volatile organic compounds under high dilution conditions. After photochemical aging with an OH exposure range of (1.97-4.97) × 1010 molecule cm-3 s in the chamber, large amounts of secondary organic aerosol (SOA) were produced with OA mass enhancement ratios (the mass ratio of total OA to primary OA) of 2.4-7.6. The 20 known precursors could only explain 5.0-27.3 % of the observed SOA mass, suggesting that the major precursors of SOA formed from open straw burning remain unidentified. Aerosol mass spectrometry (AMS) signaled that the aged OA contained less hydrocarbons but more oxygen- and nitrogen-containing compounds than primary OA, and carbon oxidation state (OSc) calculated with AMS resolved O / C and H / C ratios increased linearly (p < 0.001) with OH exposure with quite similar slopes.

Standardization of the carbon-phenolic materials and processes. Vol. 1: Experimental studies

NASA Technical Reports Server (NTRS)

Hall, William B.

1988-01-01

Carbon-phenolic composite materials are used as ablative material in the solid rocket motor nozzle of the Space Shuttle. The nozzle is lined with carbon cloth-phenolic resin composites. The nominal effects of the completely consumed solid propellant on the carbon-phenolic material are given. The extreme heat and erosion of the burning propellant are controlled by the carbon-phenolic composite by ablation, the heat and mass transfer process in which a large amount of heat is absorbed by sacrificially removing material from the nozzle 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 very poor heat conductor so it protects the underlying phenolic composite from the high heat of the burning propellant. The nozzle component ablative liners (carbon cloth-phenolic composites) are tape wrapped, hydroclave and/or autoclave cured, machined, and assembled. The tape consists of a prepreg broadcloth. The materials flow sheet for the nozzle ablative liners is shown. The prepreg is a three component system: phenolic resin, carbon cloth, and carbon filler. This is Volume 1 of two, Experimental Studies.

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.

[Quantitative estimation source of urban atmospheric CO2 by carbon isotope composition].

PubMed

Liu, Wei; Wei, Nan-Nan; Wang, Guang-Hua; Yao, Jian; Zeng, You-Shi; Fan, Xue-Bo; Geng, Yan-Hong; Li, Yan

2012-04-01

To effectively reduce urban carbon emissions and verify the effectiveness of currently project for urban carbon emission reduction, quantitative estimation sources of urban atmospheric CO2 correctly is necessary. Since little fractionation of carbon isotope exists in the transportation from pollution sources to the receptor, the carbon isotope composition can be used for source apportionment. In the present study, a method was established to quantitatively estimate the source of urban atmospheric CO2 by the carbon isotope composition. Both diurnal and height variations of concentrations of CO2 derived from biomass, vehicle exhaust and coal burning were further determined for atmospheric CO2 in Jiading district of Shanghai. Biomass-derived CO2 accounts for the largest portion of atmospheric CO2. The concentrations of CO2 derived from the coal burning are larger in the night-time (00:00, 04:00 and 20:00) than in the daytime (08:00, 12:00 and 16:00), and increase with the increase of height. Those derived from the vehicle exhaust decrease with the height increase. The diurnal and height variations of sources reflect the emission and transport characteristics of atmospheric CO2 in Jiading district of Shanghai.

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 -...

A regional estimate of convective transport of CO from biomass burning

NASA Technical Reports Server (NTRS)

Pickering, Kenneth E.; Scala, John R.; Thompson, Anne M.; Tao, Wei-Kuo; Simpson, Joanne

1992-01-01

A regional-scale estimate of the fraction of biomass burning emissions that are transported to the free troposphere by deep convection is presented. The focus is on CO and the study region is a part of Brazil that underwent intensive deforestation in the 1980s. The method of calculation is stepwise, scaling up from a prototype convective event, the dynamics of which are well-characterized, to the vertical mass flux of carbon monoxide over the region. Given uncertainties in CO emissions from biomass burning and the representativeness of the prototype event, it is estimated that 10-40 percent of CO emissions from the burning region may be rapidly transported to the free troposphere over the burning region. These relatively fresh emissions will produce O3 efficiently in the free troposphere where O3 has a longer lifetime than in the boundary layer.

Accuracy and Precision in Measurements of Biomass Oxidative Ratio and Carbon Oxidation State

NASA Astrophysics Data System (ADS)

Gallagher, M. E.; Masiello, C. A.; Randerson, J. T.; Chadwick, O. A.; Robertson, G. P.

2007-12-01

Ecosystem oxidative ratio (OR) is a critical parameter in the apportionment of anthropogenic CO2 between the terrestrial biosphere and ocean carbon reservoirs. OR is the ratio of O2 to CO2 in gas exchange fluxes between the terrestrial biosphere and atmosphere. Ecosystem OR is linearly related to biomass carbon oxidation state (Cox), a fundamental property of the earth system describing the bonding environment of carbon in molecules. Cox can range from -4 to +4 (CH4 to CO2). Variations in both Cox and OR are driven by photosynthesis, respiration, and decomposition. We are developing several techniques to accurately measure variations in ecosystem Cox and OR; these include elemental analysis, bomb calorimetry, and 13C nuclear magnetic resonance spectroscopy. A previous study, comparing the accuracy and precision of elemental analysis versus bomb calorimetry for pure chemicals, showed that elemental analysis-based measurements are more accurate, while calorimetry- based measurements yield more precise data. However, the limited biochemical range of natural samples makes it possible that calorimetry may ultimately prove most accurate, as well as most cost-effective. Here we examine more closely the accuracy of Cox and OR values generated by calorimetry on a large set of natural biomass samples collected from the Kellogg Biological Station-Long Term Ecological Research (KBS-LTER) site in Michigan.

Chemical characterisation of PM10 emissions from combustion in a closed stove of common woods grown in Portugal

NASA Astrophysics Data System (ADS)

Gonçalves, C.; Alves, C.; Pio, C.; Rzaca, M.; Schmidl, C.; Puxbaum, H.

2009-04-01

A series of source tests were conducted to determine the wood elemental composition, combustion gases and the chemical constitution of PM10 emissions from the closed stove combustion of four species of woods grown in Portugal: Eucalyptus globulos, Pinus pinaster, Quercus suber and Acacia longifolia. The burning tests were made in a closed stove with a dilution source sampler. To ascertain the combustion phase and conditions, continuous emission monitors measured O2, CO2, CO, NO, hydrocarbons, temperature and pressure, during each burning cycle. Woodsmoke samples have been collected and analysed to estimate the contribution of plant debris and biomass smoke to atmospheric aerosols. At this stage of work, cellulose, anhydrosugars and humic-like substances (HULIS) have been measured. Cellulose was determined photometrically after its conversion to D-Glucose. The determination of levoglucosan and other anhydrosugars, including mannosan and galactosan, was carried out by high performance liquid chromatography with electrochemical detection. HULIS determination was made with a total organic carbon analyser and an infrared non dispersive detector, after the isolation of substances. Cellulose was present in PM10 at mass fractions (w/w) of 0.13%, 0.13%, 0.05% and 0.08% for Eucalyptus globulos, Pinus pinaster, Quercus suber and Acacia longifolia, respectively. Levoglucosan was the major anhydrosugar present in the samples, representing mass fractions of 14.71%, 3.80%, 6.78% and 1.91%, concerning the above mentioned wood species, respectively. The levoglucosan-to-mannosan ratio, usually used to evaluate the proportion of hardwood or softwood smoke in PM10, gave average values of 34.9 (Eucalyptus globulos), 3.40 (Pinus pinaster), 24.8 (Quercus suber) and 10.4 (Acacia longifolia). HULIS were present at mass fractions of 2.35%, 2.99%, 1.52% and 1.72% for the four wood species listed in the same order as before.

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), ...

Carbon kagome lattice and orbital-frustration-induced metal-insulator transition for optoelectronics.

PubMed

Chen, Yuanping; Sun, Y Y; Wang, H; West, D; Xie, Yuee; Zhong, J; Meunier, V; Cohen, Marvin L; Zhang, S B

2014-08-22

A three-dimensional elemental carbon kagome lattice, made of only fourfold-coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60° bond angles in the triangle rings, widely perceived to be energetically unfavorable, the carbon kagome lattice is found to display exceptional stability comparable to that of C(60). The system allows us to study the effects of triangular frustration on the electronic properties of realistic solids, and it demonstrates a metal-insulator transition from that of graphene to a direct gap semiconductor in the visible blue region. By minimizing s-p orbital hybridization, which is an intrinsic property of carbon, not only the band edge states become nearly purely frustrated p states, but also the band structure is qualitatively different from any known bulk elemental semiconductors. For example, the optical properties are similar to those of direct-gap semiconductors GaN and ZnO, whereas the effective masses are comparable to or smaller than those of Si.

On the influence of biomass burning on the seasonal CO2 signal as observed at monitoring stations

USGS Publications Warehouse

Wittenberg, U.; Heimann, Martin; Esse, G.; McGuire, A.D.; Sauf, W.

1998-01-01

We investigated the role of biomass burning in simulating the seasonal signal in both prognostic and diagnostic analyses. The prognostic anaysis involved the High-Resolution Biosphere Model, a prognostic terrestrial biosphere model, and the coupled vegetation fire module, which together produce a prognostic data set of biomass burning. The diagnostic analysis invovled the Simple Diagnostic Biosphere Model (SDBM) and the Hao and Liu [1994] diagnostic data set of bimass burning, which have been scaled to global 2 and 4 Pg C yr-1, respectively. The monthly carbon exchange fields between the atmosphere and the biosphere with a spatial resolution of 0.5?? ?? 0.5??, the seasonal atmosphere-ocean exchange fields, and the emissions from fossil fuels have been coupled to the three-dimensional atmospheric transport model TM2. We have chosen eight monitoring stations of the National Oceanic and Atmospheric Administration network to compare the predicted seasonal atmospheric CO2 signals with those deduced from atmosphere-biosphere carbon exchange fluxes without any contribution from biomass burning. The prognostic analysis and the diagnostic analysis with global burning emissions of 4 Pg C yr-1 agree with respect to the change in the amplitude of the seasonal CO2 concentration introduced through biomass burning. We find that the seasonal CO2 signal at stations in higher northern latitudes (north of 30??N) is marginally influenced by biomass burning. For stations in tropical regions an increase in the CO2 amplitude of more an 1 oppmv (up to 50% with respect to the observed trough to peak amplitude) has been calculated. Biomass burning at stations farther south accounts for an increase in the CO2 amplitude of up to 59% (0.6 ppmv). A change in the phase of the seasonal CO2 signal at tropical and southern stations has been shown to be strongly influenced by the onset of biomass burning in southern tropical Africa and America. Comparing simulated and observed seasonal CO2 signals, we find higher discrepancies at southern troical stations if biomass burning emissions are included. This is caused by the additional increase in the amplitude in the prognostic analysis and a phase shift in a diagnostic analysis. In contrast, at the northern tropical stations biomass burning tends to improve the estimates of the seasonal CO2 signal in the prognostic analysis because of strengthening of the amplitude. Since the SDCM predicts the seasonal CO2 signal resonably well for the northern hemisphere tropical stations, no general improvement of the fit occurs if biomass burning emissions are considered.

Changing with the climate

Treesearch

Rhonda Mazza

2008-01-01

Carbon is a naturally occurring compound, essential to life on this planet. We exhale it, while plants absorb it as part of the photosynthetic process. Human activities have altered the carbon balance, however, and as a result have triggered changes in climates around the world. By extracting and burning oil, coal, and natural gas, carbon that was locked in long-term...

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), ...

Forest fires in Mediterranean countries: CO2 emissions and mitigation possibilities through prescribed burning.

PubMed

Vilén, Terhi; Fernandes, Paulo M

2011-09-01

Forest fires are an integral part of the ecology of the Mediterranean Basin; however, fire incidence has increased dramatically during the past decades and fire is expected to become more prevalent in the future due to climate change. Fuel modification by prescribed burning reduces the spread and intensity potential of subsequent wildfires. We used the most recently published data to calculate the average annual wildfire CO(2) emissions in France, Greece, Italy, Portugal and Spain following the IPCC guidelines. The effect of prescribed burning on emissions was calculated for four scenarios of prescribed burning effectiveness based on data from Portugal. Results show that prescribed burning could have a considerable effect on the carbon balance of the land use, land-use change and forestry (LULUCF) sector in Mediterranean countries. However, uncertainty in emission estimates remains large, and more accurate data is needed, especially regarding fuel load and fuel consumption in different vegetation types and fuel layers and the total area protected from wildfire per unit area treated by prescribed burning, i.e. the leverage of prescribed burning.

Dynamic light absorption of biomass burning organic carbon photochemically aged under natural sunlight

NASA Astrophysics Data System (ADS)

Zhong, M.; Jang, M.

2013-08-01

Wood burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross-section (integrated between 280 nm and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of POA with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line Wildfire in Florida. We conclude that the biomass burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood burning OC.

PM2.5 pollution from household solid fuel burning practices in central India: 1. Impact on indoor air quality and associated health risks.

PubMed

Matawle, Jeevan Lal; Pervez, Shamsh; Shrivastava, Anjali; Tiwari, Suresh; Pant, Pallavi; Deb, Manas Kanti; Bisht, Diwan Singh; Pervez, Yasmeen F

2017-10-01

PM 2.5 concentrations were measured in residential indoor environment in slums of central India during 2012-2013. In addition, a suite of chemical components including metals (Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, Mo, Se, Sb, Na, Mg, K and Hg), ions (Na + , Mg 2+ , K + , Ca 2+ , F - , Cl - , NH 4 + , NO 3 - and SO 4 2- ) and carbon (OC and EC) were analyzed for all samples. Indoor PM 2.5 concentrations were found to be several folds higher than the 24-h national ambient air quality standard (60 µg/m 3 ) for PM 2.5 in India, and the concentrations were found to vary from season to season. Mass closure was attempted for PM 2.5 data, and close to 100 % mass was accounted for by organic matter, crustal material, secondary organic and inorganic aerosols and elemental carbon. Additionally, carcinogenic and non-carcinogenic health risks associated with exposure to indoor PM 2.5 (inhalation, dermal and ingestion) were estimated and while exposures associated with dermal contact and ingestion were found to be within the acceptable limits, risk associated with inhalation exposure was found to be high for children and adults. Elements including Al, Cd, Co, Cr, Mn, Ni, As and Pb were present in high concentrations and contributed to carcinogenic and non-carcinogenic risks for residents' health. Results from this study highlight the need for efforts to reduce air pollution exposure in slum areas.