scholarly journals Comment on “Comparison of ozone measurement methods in biomass burning smoke: an evaluation under field and laboratory conditions” (Long et al. 2021)

2022 ◽  
Author(s):  
Noah Bernays ◽  
Daniel Jaffe ◽  
Irina Petropavlovskikh ◽  
Peter Effertz
Keyword(s):  
Biomass Burning ◽  
Solid Phase ◽  
Uv Spectroscopy ◽  
Measurement Methods ◽  
Erroneous Conclusion ◽  
Ozone Measurement ◽  
Substantial Bias ◽  
Work Done ◽  
Field And Laboratory Conditions ◽  
Surface O3

Abstract. Long et al (2021) conducted a detailed study of possible interferents in measurements of surface O3 by UV spectroscopy, which measures the UV transmission in ambient and O3 scrubbed air. While we appreciate the careful work done in this analysis, there were several omissions and, in one case, the type of scrubber used was mis-identified as manganese dioxide (MnO2), when in fact it was manganese chloride (MnCl2). This misidentification led to the erroneous conclusion that all UV-based O3 instruments employing solid-phase catalytic scrubbers exhibit significant positive artifacts, whereas previous research found this not to be the case when employing MnO2 scrubber types. While the Long study, and our results, confirm the substantial bias in instruments employing an MnCl2 scrubber, a replication of the earlier work with an MnO2 scrubber type and no humidity correction is needed.

scholarly journals Tropospheric Ozone Assessment Report: Tropospheric ozone from 1877 to 2016, observed levels, trends and uncertainties

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
David Tarasick ◽  
Ian E. Galbally ◽  
Owen R. Cooper ◽  
Martin G. Schultz ◽  
Gerard Ancellet ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Mixed Boundary ◽  
Surface Ozone ◽  
Great Majority ◽  
Measurement Methods ◽  
Uv Absorption ◽  
Lower Atmosphere ◽  
Polar Regions ◽  
Free Troposphere ◽  
Ozone Measurement

From the earliest observations of ozone in the lower atmosphere in the 19th century, both measurement methods and the portion of the globe observed have evolved and changed. These methods have different uncertainties and biases, and the data records differ with respect to coverage (space and time), information content, and representativeness. In this study, various ozone measurement methods and ozone datasets are reviewed and selected for inclusion in the historical record of background ozone levels, based on relationship of the measurement technique to the modern UV absorption standard, absence of interfering pollutants, representativeness of the well-mixed boundary layer and expert judgement of their credibility. There are significant uncertainties with the 19th and early 20th-century measurements related to interference of other gases. Spectroscopic methods applied before 1960 have likely underestimated ozone by as much as 11% at the surface and by about 24% in the free troposphere, due to the use of differing ozone absorption coefficients. There is no unambiguous evidence in the measurement record back to 1896 that typical mid-latitude background surface ozone values were below about 20 nmol mol–1, but there is robust evidence for increases in the temperate and polar regions of the northern hemisphere of 30–70%, with large uncertainty, between the period of historic observations, 1896–1975, and the modern period (1990–2014). Independent historical observations from balloons and aircraft indicate similar changes in the free troposphere. Changes in the southern hemisphere are much less. Regional representativeness of the available observations remains a potential source of large errors, which are difficult to quantify. The great majority of validation and intercomparison studies of free tropospheric ozone measurement methods use ECC ozonesondes as reference. Compared to UV-absorption measurements they show a modest (~1–5% ±5%) high bias in the troposphere, but no evidence of a change with time. Umkehr, lidar, and FTIR methods all show modest low biases relative to ECCs, and so, using ECC sondes as a transfer standard, all appear to agree to within one standard deviation with the modern UV-absorption standard. Other sonde types show an increase of 5–20% in sensitivity to tropospheric ozone from 1970–1995. Biases and standard deviations of satellite retrieval comparisons are often 2–3 times larger than those of other free tropospheric measurements. The lack of information on temporal changes of bias for satellite measurements of tropospheric ozone is an area of concern for long-term trend studies.

Levoglucosan in speleothems: An evaluation of various sample preparation methods.

2021 ◽  
Author(s):  
Julia Homann ◽  
Thorsten Hoffmann ◽  
Denis Scholz ◽  
Sebastian Breitenbach
Keyword(s):  
Sample Preparation ◽  
Biomass Burning ◽  
Solid Phase ◽  
Ice Cores ◽  
Soxhlet Extraction ◽  
Atmospheric Particulate Matter ◽  
Preparation Methods ◽  
Local Climate ◽  
Solid Liquid ◽  
Global And Local

<p>Secondary mineral deposits in caves, such as stalagmites or flowstones, are valuable paleoclimate archives because they have several advantages over other environmental archives. These include stable in-cave conditions, protecting the speleothems from external influences, and the potential to precisely date samples up to 600,000 years using <sup>230</sup>Th/U-dating. [1] Supplementing established climate proxies, such as stable isotopes and trace elements, organic proxies have been increasingly used in recent years to inform on local vegetation and soil dynamics. [2]</p><p>Biomass burning events are major sources of atmospheric particulate matter that influences global and local climate. [3] Investigating fire proxies in paleoclimate archives may therefore help determine the interactions of climate, hydrology, and fire activity. Levoglucosan, an anhydrosugar, naturally only originates from the combustion of cellulose and thus constitutes a biomass burning marker. Analysis of levoglucosan in sediments has shown high correlation with traditional burning markers, such as black charcoal. [4] Mannosan and galactosan, both stereoisomers of levoglucosan, are formed during combustion of hemicellulose. Previous work suggests that rather than absolute levoglucosan concentrations the ratio of levoglucosan to its isomers should be considered when characterizing burning events. [5] To date, no data on levoglucosan or its isomers in speleothems has been published, whereas the anhydrosugars are already utilised in other paleoclimate archives, such as sediments and ice cores. [2,3]</p><p>We test three approaches (solid phase extraction (SPE), soxhlet extraction and solid/liquid extraction) for the isolation and quantification of anhydrosugars using HILIC-MS instrumentation. As the anhydrosugars are highly polar molecules, extraction from the calcium carbonate matrix and subsequent sample preparation proved challenging. We evaluate the different approaches and compare the resulting concentrations and assumed recoveries. We find that the anhydrosugars do not show significant retention on any of the evaluated SPE materials. While solid/liquid extractions lead to detectable analyte concentrations, soxhlet extractions with methanol or dichloromethane/methanol mixtures are more efficient.</p><p> </p><p>[1] D. Scholz, D. Hoffmann, Quat. Sci. J. 57 (2008) 52–76 [2] A. Blyth et al. Quat. Sci. Rev. 149 (2016) 1-17 [3] P. Yao et al. J. of Glaciology 59 (2013) 599-611 [4] V. O. Elias et al. Geochim. et Cosmochim. Acta 65 (2001) 267-272. [5] D. Fabbri et al. Atmos. Env. 43 (2009) 2286–2295</p>

scholarly journals Measurements of I/SVOCs in biomass-burning smoke using solid-phase extraction disks and two-dimensional gas chromatography

2018 ◽  
Author(s):  
Lindsay E. Hatch ◽  
Albert Rivas-Ubach ◽  
Coty N. Jen ◽  
Mary Lipton ◽  
Allen H. Goldstein ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Solid Phase Extraction ◽  
Biomass Burning ◽  
Solid Phase ◽  
Phase Extraction ◽  
Two Dimensional ◽  
Heterogeneous Oxidation ◽  
Flight Mass Spectrometry ◽  
Volatile Organic ◽  
Heteroatomic Compounds

Abstract. Biomass-burning organic-aerosol (OA) emissions are known to exhibit semi-volatile behavior that impacts OA loading during plume transport. Because such semi-volatile behavior depends in part on OA composition, improved speciation of intermediate and semi-volatile organic compounds (I/SVOCs) emitted during fires is needed to assess the competing effects of primary OA volatilization and secondary OA production. In this study, we sampled 18 laboratory fires in which a range of fuel types were burned. Emitted I/SVOCs were collected onto Teflon filters and solid-phase extraction (SPE) disks to characterize particulate and gaseous I/SVOCs, respectively. Derivatized filter extracts were analyzed using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC − TOFMS). Quality control tests were performed using biomass-burning relevant standards and demonstrate the utility of SPE disks for untargeted analysis of air samples. The speciation profiles of I/SVOCs in coniferous fuel-derived smoke samples determined by GC × GC − TOFMS were well correlated with each other, but poorly correlated with other fuel types (e.g., herbaceous and chaparral fuels). Benzenediol isomers were also shown to display fuel-dependent emissions. Differences in gas-particle partitioning of the benzenediol isomers were captured using combined Teflon and SPE filter data, with hydroquinone significantly less volatile than catechol. Additionally, the speciated volatility distribution of I/SVOCs in smoke from a rotten-log fire was estimated to evaluate the composition of potentially volatilized primary OA, which was entirely attributed to oxygenated (or other heteroatomic) compounds. Because the chemistry of such compounds has not been extensively studied, more work is needed to assess the relative importance of gas-phase vs. heterogeneous oxidation pathways for biomass-burning-derived I/SVOCs.

scholarly journals Identification of residual non-biodegradable organic compounds in wastewater effluent after two-stage biochemical treatment

2016 ◽  
Vol 11 (1) ◽  
pp. 396-401 ◽  
Author(s):  
Liu Xuqing ◽  
Li Yayun ◽  
Liu Chao ◽  
Zhang Li ◽  
Yuan Hao ◽  
...  
Keyword(s):  
Solid Phase ◽  
Uv Spectroscopy ◽  
Scientific Basis ◽  
Unsaturated Ketone ◽  
Biochemical Treatment ◽  
Two Stage ◽  
Microbial Product ◽  
River Region ◽  
Chishui River ◽  
Complex Polymers

AbstractThe main non-biodegradable compounds (soluble microbial product – SMP) of wastewater from the Maotai aromatic factories, located in the Chishui river region, were analyzed by UV spectroscopy, and by solid-phase extraction followed by gas chromatography coupled to mass spectrometry, after a two-stage biochemical treatment. The UV-Vis spectra revealed that the wastewater contained two double-bonds in conjugated systems (conjugated diene or α, β- unsaturated ketone, etc.) and simple non-conjugated chromophores containing n electrons from carbonyl groups or the like. The residual organic non-biodegradable substances were identified using SPE-GC/MS analysis as complex polymers containing hydroxyl, carbonyl, and carboxyl functional groups with multiple connections to either benzene rings or heterocyclic rings. As these compounds are difficult to remove by conventional biochemical treatments, our findings provide a scientific basis for the design of efficient new strategies to remove SMP from wastewater.

scholarly journals Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

2007 ◽  
Vol 7 (2) ◽  
pp. 3589-3627 ◽  
Author(s):  
A. Asa-Awuku ◽  
A. Nenes ◽  
A. P. Sullivan ◽  
C. J. Hennigan ◽  
R. J. Weber
Keyword(s):  
Surface Tension ◽  
Molar Volume ◽  
Biomass Burning ◽  
Solid Phase ◽  
Relative Proportion ◽  
Water Soluble ◽  
Original Sample ◽  
Biomass Burning Aerosol ◽  
Hydrophobic Fraction ◽  
Ccn Activity

Abstract. In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH4)2SO4) in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH4)2SO4. For our analysis, average thermodynamic properties (i.e., molar volume) are determined for samples using our newly developed Köhler Theory Analysis (KTA) method. We have found that, the molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol−1 and 780±231 g mol−1, respectively. KTA also suggests that the relative proportion (in moles) of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

scholarly journals Harmonization of piece-by-piece measurement methods in all stages of roundwood manufacturing processes

2015 ◽  
Vol 2 ◽  
pp. 207
Author(s):  
Ziedonis Miklašēvičs
Keyword(s):  
Automatic Measurement ◽  
Accurate Method ◽  
Measurement Methods ◽  
Total Production ◽  
Wood Volume ◽  
Volume Calculation ◽  
Short Intervals ◽  
Round Wood ◽  
Calculation Results ◽  
Work Done

<p>In the sawmill industry in Latvia the roundwood represents about 70 % of the total production cost. The quantity measurements of the round wood are required throughout the logic chain of wood from forest to the sawmills but inspite of a large proportion of the total cost the term “true volume” of roundwood is equally actual for supplies and processors of wood.  The roundwood volume results differ measured the same load by measuring the diameters of log in short intervals using harvester measurement systems and in sawmills by measuring the diameters of log in short intervals using electronic 3D systems or measured manually using the most accurate method according to the requirements of standard LVS 82:2003 by measuring top and butt diameter.  This means that it is a great interest in industry to develop the measurement methods and systems to have a lower cost and more efficient algorithm to determine the wood volume.</p><p>The purpose of this study is to compare the wood volume calculation results made by the most accurate manual and automatic measurement methods and give the recommendations for minimizing difference between them.</p><p>The research is a continuation to the work done in the project „Harmonisation of piece-by-piece measurement methods of roundwood approved by Standard LVS 82:2003 „Apaļo kokmateriālu uzmērīšana” (Miklasevics, Z., 2013).</p>

Developing efficient methods of mixing during chemical treatment of wastewater suspension

2021 ◽  
pp. 48-54
Author(s):  
А.Н. Григорьева ◽  
Р.Ш. Абиев ◽  
Ф.И. Лобанов ◽  
О.Ю. Тарарыков
Keyword(s):  
Angular Velocity ◽  
Chemical Treatment ◽  
Rotation Speed ◽  
Solid Phase ◽  
Particle Diameter ◽  
Wastewater Sludge ◽  
Similarity Criteria ◽  
Sludge Disposal ◽  
Work Done ◽  
Municipal Economy

Проблема утилизации осадка сточных вод в последние годы становится все более актуальной для коммунального хозяйства. Приведены результаты исследования процесса суспендирования осадка известьсодержащим реагентом Дезолак, определены размеры твердых включений, что позволило рассчитать необходимую скорость вращения перемешивающего устройства: средний заутеровский диаметр частиц составил 55 мкм, плотность твердой фазы – 2211 кг/м3. Для эффективного суспендирования реагента необходимо обеспечить угловую скорость мешалки не менее 0,03 м/с. Исследованы основные критерии подобия для масштабирования аппаратов, определено, что при выборе мешалки следует учитывать критерий Фруда Fr, так как именно этот показатель для трех исследованных реакторов практически постоянен. На основании проделанной работы определено, что отношение мощности к объему перемешиваемой жидкости не может являться критерием для расчета аппаратов, оснащенных перемешивающими устройствами GMS: для данных мешалок справедливо снижение мощности на перемешивание с увеличением размеров аппарата. In recent years the problem of wastewater sludge disposal has become more and more urgent for the municipal economy. The results of a study of the process of sludge suspending with Dezolak, a lime-containing agent, are presented; the size of solid inclusions is determined to provide for calculating the required rotation speed of the mixing device: the average Sauter particle diameter was 55 μm, the density of the solid phase was 2211 kg/m3. For effective chemical suspending the angular velocity of the mixer should be more than 0.03 m/s. The main similarity criteria for scaling the apparatus were investigated; it was determined that while choosing a mixer, the Froude criterion Fr should be taken into account, since that very indicator was practically constant for the three investigated reactors. Based on the work done, it was determined that the ratio of power to the volume of the mixed liquid cannot be a criterion for calculating devices equipped with GMS mixing devices: for these mixers, a decrease in the mixing power with an increase in the size of the device is valid.

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