[Pollien2003a] "Absolute quantification of headspace volatiles by PTR-MS",
1st International Conference on Proton Transfer Reaction Mass Spectrometry and its Applications. Innsbruck, Austria: Universitaet Innsbruck
, pp. 153–6, 2003.
[Ngwabie2008] "Abundances and flux estimates of volatile organic compounds from a dairy cowshed in Germany",
Journal of environmental quality
, vol. 37, no. 2: American Society of Agronomy, Crop Science Society of America, Soil Science Society, pp. 565–573, 2008.
Animal husbandry and manure treatment have been specifically documented as significant sources of methane, ammonia, nitrous oxide, and particulate matter. Although volatile organic compounds (VOCs) are also produced, much less information exists concerning their impact. We report on chemical ionization mass spectrometry and photo-acoustic spectroscopy measurements of mixing ratios of VOCs over a 2-wk measurement period in a large cowshed at the Federal Agricultural Research Centre (FAL) in Mariensee, Germany. The high time resolution of these measurements enables insight into the sources of the emissions in a typical livestock management setting. During feeding hours and solid manure removal, large mixing ratio spikes of several VOCs were observed and correlated with simultaneous methane, carbon dioxide, and ammonia level enhancements. The subsequent decay of cowshed concentration due to passive cowshed ventilation was used to model emission rates, which were dominated by ethanol and acetic acid, followed by methanol. Correlations of VOC mixing ratios with methane or ammonia were also used to calculate cowshed emission factors and to estimate potential nationwide VOC emissions from dairy cows. The results ranged from around 0.1 Gg carbon per year (1 Gg = 109 g) for nonanal and dimethylsulfide, several Gg carbon per year for volatile fatty acids and methanol, to over 10 Gg carbon per year of emitted ethanol. While some estimates were not consistent between the two extrapolation methods, the results indicate that animal husbandry VOC emissions are dominated by oxygenated compounds and may be a nationally but not globally significant emission to the atmosphere.
[Sprung2001] "Acetone and acetonitrile in the tropical Indian Ocean boundary layer and free troposphere: Aircraft-based intercomparison of AP-CIMS and PTR-MS measurements",
Journal of Geophysical Research: Atmospheres (1984–2012)
, vol. 106, no. D22: Wiley Online Library, pp. 28511–28527, 2001.
[Sprung2010] "Acetone in the upper troposphere/lowermost stratosphere measured by the CARIBIC passenger aircraft: Distribution, seasonal cycle, and variability",
Journal of Geophysical Research
, vol. 115, no. D16: American Geophysical Union, pp. D16301, 2010.
Mass-spectrometric measurements of acetone (CH3COCH3) have been performed monthly using a Lufthansa Airbus A340-600 passenger aircraft between February 2006 and December 2008. In total, 106 measurement flights (4 per month) were conducted between Germany and South America, North America, South Asia, and East Asia. Here measurements collected between 33°N and 56°N in the upper troposphere (UT) and lowermost stratosphere (LMS) at 9–12 km altitude are analyzed. By integrating data collected at 12 ozonesonde stations, ozone concentrations measured on flight are translated into a representative (mixing-based) altitude above the thermal tropopause. A strong seasonal variation of acetone occurs at the midlatitude tropopause with maxima of ∼900 parts per 1012 vol (pptv) in summer and minima of ∼200 pptv in midwinter. This seasonality propagates into the LMS in approximately 6 weeks with rapidly decreasing concentrations and increasing phase shifts reaching 2 km above the tropopause. Throughout the year, acetone and ozone are highly negatively correlated in the LMS with a mean linear correlation coefficient (R) of −0.93. This linear relationship marks the O3–acetone-based extratropical tropopause mixing layer (exTL). A “stratospheric intrusion height of acetone” (Zacetone) is defined that concurs with the vertical depth of the O3–CO-based exTL, namely, averaging ∼2.2 km but with slightly lower values in winter. Probability density functions (PDFs) and the course of the seasonal variation of acetone relative to the tropopause are interpreted regarding the in-mixing and subsequent dispersion of acetone in the LMS.
[Warneke1999] "Acetone, methanol, and other partially oxidized volatile organic emissions from dead plant matter by abiological processes: Significance for atmospheric HOx chemistry",
Global Biogeochem. Cycles
, vol. 13, no. 1, pp. 9–17, 1999.
[Prazeller1999] "Acetonitril als Biomarker zur Quantifizierung des Passivrauchens",
Ber. nat-med. Verein Innsbruck
, vol. 86: Ber. nat-.med. Verein Innsbruck, pp. 13-19, 1999.
[Jordan1995] "Acetonitrile and benzene in the breath of smokers and non-smokers investigated by proton transfer reaction mass spectrometry (PTR-MS)",
International Journal of Mass Spectrometry and Ion Processes
, vol. 148, no. 1-2, pp. L1 - L3, 1995.
Benzene and acetonitrile are both present in greater concentrations in the breath of smokers than in non-smokers. The concentrations of these neutrals can be readily detected in the gas phase by their proton transfer reactions with H3O+. The concentration of benzene in the breath of smokers rapidly decreases with the time since the last cigarette was smoked, declining to values similar to those of non-smokers within an hour. In contrast, the concentration of acetonitrile in the breath of smokers takes nearly a week to decrease to that of non-somokers, once smoking stops. Thus the analysis of acetonitrile in the breath is a most suitable indicator of whether a given subject is or is not a smoker.
[Park2013] "Active atmosphere-ecosystem exchange of the vast majority of detected volatile organic compounds.",
, vol. 341, no. 6146: Department of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, CA 94720, USA., pp. 643–647, Aug, 2013.
<p>Numerous volatile organic compounds (VOCs) exist in Earth's atmosphere, most of which originate from biogenic emissions. Despite VOCs' critical role in tropospheric chemistry, studies for evaluating their atmosphere-ecosystem exchange (emission and deposition) have been limited to a few dominant compounds owing to a lack of appropriate measurement techniques. Using a high-mass resolution proton transfer reaction-time of flight-mass spectrometer and an absolute value eddy-covariance method, we directly measured 186 organic ions with net deposition, and 494 that have bidirectional flux. This observation of active atmosphere-ecosystem exchange of the vast majority of detected VOCs poses a challenge to current emission, air quality, and global climate models, which do not account for this extremely large range of compounds. This observation also provides new insight for understanding the atmospheric VOC budget.</p>
[Knighton2009a] "Adaptation of a proton transfer reaction mass spectrometer instrument to employ NO+ as reagent ion for the detection of 1, 3-butadiene in the ambient atmosphere",
Rapid Communications in Mass Spectrometry
, vol. 23, no. 20: Wiley Online Library, pp. 3301–3308, 2009.
A proton transfer reaction mass spectrometer (PTR-MS) instrument was adapted to employ NO+ as a chemical reagent ion without any hardware changes by switching the reagent ion source gas from water vapor to dry air. Ionization of dry air within the hollow cathode ion source generates a very intense source of NO+ with only a minor impurity of NOmath image. The intensities of the primary NO+ reagent ion and the unwanted impurity NOmath image are controllable and dependent on the operational conditions of the hollow cathode ion source. Ion source tuning parameters are described, which maintain an intense source of NO+ while keeping the impurity NOmath image signal to less than 2% of the total reagent ion intensity. This method is applied to the detection of 1,3-butadiene. NO+ reacts efficiently with 1,3-butadiene via a charge exchange reaction to produce only the molecular ion, which is detected at m/z 54. Detection sensitivities of the order of 45 pptv for a 1-s measurement of 1,3-butadiene are demonstrated. We present the first real-time on-line sub parts per billion measurement of 1,3-butadiene in the ambient atmosphere. The only likely interference is from 1,2-butadiene. Concurrent measurements of benzene are provided and suggest that the vehicular emissions are the predominant source of 1,3-butadiene in a suburban Boston area monitoring location.
 "Adaptation of a proton transfer reaction mass spectrometer instrument to employ NO+ as reagent ion for the detection of 1,3-butadiene in the ambient atmosphere.",
Rapid Commun Mass Spectrom
, vol. 23, pp. 3301–3308, Oct, 2009.
<p>A proton transfer reaction mass spectrometer (PTR-MS) instrument was adapted to employ NO+ as a chemical reagent ion without any hardware changes by switching the reagent ion source gas from water vapor to dry air. Ionization of dry air within the hollow cathode ion source generates a very intense source of NO+ with only a minor impurity of NO2+. The intensities of the primary NO+ reagent ion and the unwanted impurity NO2+ are controllable and dependent on the operational conditions of the hollow cathode ion source. Ion source tuning parameters are described, which maintain an intense source of NO+ while keeping the impurity NO2+ signal to less than 2% of the total reagent ion intensity. This method is applied to the detection of 1,3-butadiene. NO+ reacts efficiently with 1,3-butadiene via a charge exchange reaction to produce only the molecular ion, which is detected at m/z 54. Detection sensitivities of the order of 45 pptv for a 1-s measurement of 1,3-butadiene are demonstrated. We present the first real-time on-line sub parts per billion measurement of 1,3-butadiene in the ambient atmosphere. The only likely interference is from 1,2-butadiene. Concurrent measurements of benzene are provided and suggest that the vehicular emissions are the predominant source of 1,3-butadiene in a suburban Boston area monitoring location.</p>
 "Addressing odour abatement and assessment knowledge gaps using PTR–ToFMS",
, vol. 18-078, 2018.
<p>Effective odour management underpins the sustainable growth and expansion of the Australian chicken meat industry, yet, odour abatement strategies are largely ‘black boxes’ in terms of their action and efficacy. This is because our knowledge of the complex biochemical and physical processes driving odour emissions is rudimentary. While an improved understanding of these processes is necessary to develop better odour abatement strategies in the future, the critical requirement is the ability able to assess abatement strategies objectively. To that end, AgriFutures Australia is heavily invested in odour research to better understand and objectively assess poultry odour emissions, including the evaluation of alternative odour measurement techniques that do not rely on the human nose. This latest research builds on previous mass spectrometry findings, and demonstrates that state-of-the-art, high-resolution, mass spectrometry using a proton transfer reaction time-of-flight mass spectrometer (PTR–ToFMS), complemented by other odour assessment methods, provides significant benefits to industry-funded odour research projects. PTR–ToFMS analysis enabled the detection of a wide range of poultry production-related odorants at the sheds (source) and downwind. Several key compounds that likely implicated in odour nuisance (low detection thresholds; unpleasant odour characteristics) were detected in the samples. PTR– ToFMS also enabled detection of odorant differences in a variety of litter conditions. Additionally, the project demonstrated that PTR–ToFMS data can be used to develop a useful odour prediction model that may reduce reliance on human-based evaluations (e.g. olfactometry) in the future. Odour abatement strategies can be critically evaluated in terms of odour and odorant reductions at-shed and downwind, using odour prediction modelling and PTR–ToFMS data, and cross-checked by olfactometry. Effectively reducing odour nuisance will likely require management of the key odorants that can be detected by receptors. Future research should focus on identifying and suppressing these key odorants. This project was funded from industry revenue, which was matched by funds provided by the Australian Government. This report is an addition to AgriFutures Australia’s diverse range of over 2000 research publications and it forms part of our Chicken Meat R&D program, which aims to stimulate and promote RD&E that will deliver a productive and sustainable Australian chicken meat industry that provides quality wholesome food to the nation.</p>
[Gutmann2012] "Advanced bioprocess monitoring by implementation of Proton Transfer Reaction - Mass Spectrometry (PTR-MS) for measurement of volatile components in the bioreactor",
ACIB, Book of abstracts, vol. -, pp. -, 2012.
 "Advanced off-gas measurement using proton transfer reaction mass spectrometry to predict cell culture parameters",
, vol. 7, pp. P14, 2013.
<p>Mass spectrometry is a well-known technology to detect O2 and CO2 in the off-gas of cell culture fermentations. In contrast to classical mass spectrometers, the proton transfer reaction mass spectrometer (PTR MS) enables the noninvasive analysis of a broad spectrum of volatile organic compounds (VOCs) in real time. The thereby applied soft ionization technology generates spectra of less fragmentation and facilitates their interpretation. This gave us the possibility to identify process relevant compounds in the bioreactor off-gas stream in addition to O2 and CO2. In our study the PTR-MS technology was applied for the first time to monitor volatile organic compounds (VOC) and to predict cell culture parameters in an industrial mammalian cell culture process.</p>
 "Advanced online monitoring of cell culture off-gas using proton transfer reaction mass spectrometry",
, pp. n/a–n/a, 2014.
<p>Mass spectrometry has been frequently applied to monitor the O2 and CO2 content in the off-gas of animal cell culture fermentations. In contrast to classical mass spectrometry the proton transfer reaction mass spectrometry (PTR-MS) provides additional information of volatile organic compounds by application of a soft ionization technology. Hence, the spectra show less fragments and can more accurately assigned to particular compounds. In order to discriminate between compounds of non-metabolic and metabolic origin cell free experiments and fed-batch cultivations with a recombinant CHO cell line were conducted. As a result, in total eight volatiles showing high relevance to individual cultivation or cultivation conditions could be identified. Among the detected compounds methanethiol, with a mass-to-charge ratio of 49, qualifies as a key candidate in process monitoring due to its strong connectivity to lactate formation. Moreover, the versatile and complex data sets acquired by PTR MS provide a valuable resource for statistical modeling to predict non direct measurable parameters. Hence, partial least square regression was applied to the complete spectra of volatiles measured and important cell culture parameters such as viable cell density estimated (R2 = 0.86). As a whole, the results of this study clearly show that PTR-MS provides a powerful tool to improve bioprocess-monitoring for mammalian cell culture. Thus, specific volatiles emitted by cells and measured online by the PTR-MS and complex variables gained through statistical modeling will contribute to a deeper process understanding in the future and open promising perspectives to bioprocess control. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 2014</p>
[Aprea2005] "Advanced oxidation in olive oil: monitoring of secondary reaction products and detection of rancid defect",
Mass Spectrometry and Its Applications
, vol. -, pp. 144, 2005.
[Sulzer2009] "Advantages of Proton Transfer Reaction Advantages of Proton Transfer Reaction–Mass Spectrometry (PTR Mass Spectrometry (PTR-MS) in the Analysis of Potentially Dangerous Substances",
: IONICON Analytik, 2009.
[Holzinger2010] "Aerosol analysis using a Thermal-Desorption Proton-Transfer-Reaction Mass Spectrometer (TD-PTR-MS): a new approach to study processing of organic aerosols",
Atmospheric chemistry and physics
, vol. 10, no. 5: Copernicus Publications, pp. 2257–2267, 2010.
We present a novel analytical approach to measure the chemical composition of organic aerosol. The new instrument combines proton-transfer-reaction mass-spectrometry (PTR-MS) with a collection-thermal-desorption aerosol sampling technique. For secondary organic aerosol produced from the reaction of ozone with isoprenoids in a laboratory reactor, the TD-PTR-MS instrument detected typically 80% of the mass that was measured with a scanning mobility particle sizer (SMPS). The first field deployment of the instrument was the EUCAARI-IOP campaign at the CESAR tall tower site in the Netherlands. For masses with low background values (∼30% of all masses) the detection limit of aerosol compounds was below 0.2 ng/m3 which corresponds to a sampled compound mass of 35 pg. Comparison of thermograms from ambient samples and from chamber-derived secondary organic aerosol shows that, in general, organic compounds from ambient aerosol samples desorb at much higher temperatures than chamber samples. This suggests that chamber aerosol is not a good surrogate for ambient aerosol and therefore caution is advised when extrapolating results from chamber experiments to ambient conditions
[Wonaschuetz2012] "Aerosol and gas re-distribution by shallow cumulus clouds: An investigation using airborne measurements",
Journal of Geophysical Research: Atmospheres
, vol. 117, no. D17, pp. n/a–n/a, 2012.
Aircraft measurements during the 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) are used to examine the influence of shallow cumulus clouds on vertical profiles of aerosol chemical composition, size distributions, and secondary aerosol precursor gases. The data show signatures of convective transport of particles, gases and moisture from near the surface to higher altitudes, and of aqueous-phase production of aerosol mass (sulfate and organics) in cloud droplets and aerosol water. In cloudy conditions, the average aerosol volume concentration at an altitude of 2850 m, above typical cloud top levels, was found to be 34% of that at 450 m; for clear conditions, the same ratio was 13%. Both organic and sulfate mass fractions were on average constant with altitude (around 50%); however, the ratio of oxalate to organic mass increased with altitude (from 1% at 450 m to almost 9% at 3450 m), indicative of the influence of in-cloud production on the vertical abundance and characteristics of secondary organic aerosol (SOA) mass. A new metric termed â€œresidual cloud fractionâ€� is introduced as a way of quantifying the â€œcloud processing historyâ€� of an air parcel. Results of a parcel model simulating aqueous phase production of sulfate and organics reproduce observed trends and point at a potentially important role of SOA production, especially oligomers, in deliquesced aerosols. The observations emphasize the importance of shallow cumulus clouds in altering the vertical distribution of aerosol properties that influence both their direct and indirect effect on climate.
 "Airborne flux measurements of biogenic volatile organic compounds over California",
Atmospheric Chemistry and Physics Discussions
, vol. 14, pp. 7965–8013, Mar, 2014.
<p>Biogenic Volatile Organic Compound (BVOC) fluxes were measured onboard the CIRPAS Twin Otter aircraft as part of the California Airborne BVOC Emission Research in Natural Ecosystem Transects (CABERNET) campaign during June 2011. The airborne virtual disjunct eddy covariance (AvDEC) approach used measurements from a PTR-MS and a wind radome probe to directly determine fluxes of isoprene, MVK + MAC, methanol, monoterpenes, and MBO over 10 000 km of flight paths focusing on areas of California predicted to have the largest emissions of isoprene. The Fast Fourier Transform (FFT) approach was used to calculate fluxes over long transects of more than 15 km, most commonly between 50 and 150 km. The Continuous Wavelet Transformation (CWT) approach was used over the same transects to also calculate "instantaneous" fluxes with localization of both frequency and time independent of non-stationarities. Vertical flux divergence of isoprene is expected due to its relatively short lifetime and was measured directly using "racetrack" profiles at multiple altitudes. It was found to be linear and in the range 5% to 30% depending on the ratio of aircraft altitude to PBL height (z / zi). Fluxes were generally measured by flying consistently at 400 ± 50 m (a.g.l.) altitude, and extrapolated to the surface according to the determined flux divergence. The wavelet-derived surface fluxes of isoprene averaged to 2 km spatial resolution showed good correspondence to Basal Emission Factor (BEF) landcover datasets used to drive biogenic VOC (BVOC) emission models. The surface flux of isoprene was close to zero over Central Valley crops and desert shrublands, but was very high (up to 15 mg m−2 h−1) above oak woodlands, with clear dependence of emissions on temperature and oak density. Isoprene concentrations of up to 8 ppb were observed at aircraft height on the hottest days and over the dominant source regions. While isoprene emissions from agricultural crop regions, shrublands, and coniferous forests were extremely low, high concentrations of methanol and monoterpenes were found above some of these regions. These observations demonstrate the ability to measure fluxes from specific sources by eddy covariance from an aircraft, and suggest the utility of measurements using fast response chemical sensors to constrain emission inventories and map out source distributions for a much broader array of trace gases than was observed in this study. This paper reports the first regional direct eddy covariance fluxes of isoprene. The emissions of VOCs measured from aircraft with 2 km spatial resolution can quantify the distribution of major sources providing the observations required for testing statewide emission inventories of these important trace gases. These measurements will be used in a future study to assess BVOC emission models and their driving variable datasets.</p>
 "Airborne Flux Measurements of BVOCs above Californian Oak Forests: Experimental Investigation of Surface and Entrainment Fluxes, OH Densities, and Damköhler Numbers",
J. Atmos. Sci.
, vol. 70, pp. 3277–3287, Oct, 2013.
Link: http://nature.berkeley.edu/ahg/pubs/Karl et al 2013 JAS.pdf
<p>Airborne flux measurements of isoprene were performed over the Californian oak belts surrounding the Central Valley. The authors demonstrate for the first time 1) the feasibility of airborne eddy covariance measurements of reactive biogenic volatile organic compounds; 2) the effect of chemistry on the vertical transport of reactive species, such as isoprene; and 3) the applicability of wavelet analysis to estimate regional fluxes of biogenic volatile organic compounds. These flux measurements demonstrate that instrumentation operating at slower response times (e.g., 1–5 s) can still be used to determine eddy covariance fluxes in the mixed layer above land, where typical length scales of 0.5–3 km were observed. Flux divergence of isoprene measured in the planetary boundary layer (PBL) is indicative of OH densities in the range of 4–7 × 106 molecules per cubic centimeter and allows extrapolation of airborne fluxes to the surface with Damköhler numbers (ratio between the mixing time scale and the chemical time scale) in the range of 0.3–0.9. Most of the isoprene is oxidized in the PBL with entrainment fluxes of about 10% compared to the corresponding surface fluxes. Entrainment velocities of 1–10 cm s−1 were measured. The authors present implications for parameterizing PBL schemes of reactive species in regional and global models.</p>
[Warneke2011] "Airborne formaldehyde measurements using PTR-MS: calibration, humidity dependence, inter-comparison and initial results",
Atmospheric Measurement Techniques Discussions
, vol. 4, no. 4: Copernicus GmbH, pp. 4631–4665, 2011.
We present quantitative, fast time response measurements of formaldehyde (HCHO) onboard an aircraft using a Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) instrument. The HCHO measurement by PTR-MS is strongly humidity dependent and therefore airborne measurements are difficult and have not been reported. The PTR-MS instrument was run in the normal operating mode, where about 15 volatile organic compounds (VOCs) are measured together with HCHO onboard the NOAA WP-3 aircraft during the CalNex 2010 campaign in California. We compare the humidity dependence determined in the laboratory with in-flight calibrations of HCHO and calculate the HCHO mixing ratio during all flights using the results from both. The detection limit for HCHO was between 100 pptv in the dry free troposphere and 300 pptv in the humid marine boundary layer for a one second acquisition time every 17 s. The PTR-MS measurements are compared with HCHO measurements using a DOAS instrument and a Hantzsch monitor at a ground site in Pasadena. The PTR-MS agreed with both instruments within the stated uncertainties. We also compare HCHO enhancement ratios in the Los Angeles basin and in the free troposphere with literature values and find good agreement. The usefulness of the PTR-MS HCHO measurements in atmospheric observations is demonstrated by following an isolated anthropogenic plume. The photochemical production of HCHO can be observed simultaneously with production of acetaldehyde and the photochemical degradation of aromatic compounds using the PTR-MS.
[Colomb2006] "Airborne measurements of trace organic species in the upper troposphere over Europe: the impact of deep convection",
, vol. 3, no. 4: CSIRO, pp. 244–259, 2006.
The volume mixing ratios of several organic trace gases and ozone (O3) were measured in the upper troposphere over Europe during the UTOPIHAN-ACT aircraft campaign in July 2003. The organic trace gases included alkanes, isoprene, aromatics, iodomethane, and trichloroethylene, oxygenates such as acetone, methanol, formaldehyde, carbon monoxide, and longer-lived tracer species such as chlorofluorocarbons and halochloroflurocarbons. The aim of the UTOPIHAN-ACT project was to study the chemical impact of deep convection on the continental upper troposphere. A Lear Jet aircraft, based in Germany, was flown at heights between 6 and 13 km in the region 59°N–42°N to 7°W–13°E during July 2003. Overall, the convectively influenced measurements presented here show a weaker variability lifetime dependence of trace gases than similar measurements collected over the Mediterranean region under more stable high-pressure conditions. Several cases of convective outflow are identified by the elevated mixing ratios of organic species relative to quiescent background conditions, with both biogenic and anthropogenic influences detectable in the upper troposphere. Enhancement at higher altitudes, notably of species with relatively short chemical lifetimes such as benzene, toluene, and even isoprene indicates deep convection over short timescales during summertime. The impact of deep convection on the local upper tropospheric formaldehyde and HOx budgets is assessed.
 "Airborne measurements of western U.S. wildfire emissions: Comparison with prescribed burning and air quality implications",
Journal of Geophysical Research: Atmospheres
, vol. 122, pp. 6108–6129, jun, 2017.
<p>Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured from aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Biomass Burning Observation Project (BBOP), both in summer 2013. This study reports an extensive set of emission factors (EFs) for over 80 gases and 5 components of submicron particulate matter (PM1) from these temperate wildfires. These include rarely, or never before, measured oxygenated volatile organic compounds and multifunctional organic nitrates. The observed EFs are compared with previous measurements of temperate wildfires, boreal forest fires, and temperate prescribed fires. The wildfires emitted high amounts of PM1 (with organic aerosol (OA) dominating the mass) with an average EF that is more than 2 times the EFs for prescribed fires. The measured EFs were used to estimate the annual wildfire emissions of carbon monoxide, nitrogen oxides, total nonmethane organic compounds, and PM1 from 11 western U.S. states. The estimated gas emissions are generally comparable with the 2011 National Emissions Inventory (NEI). However, our PM1 emission estimate (1530 ± 570 Gg yr−1) is over 3 times that of the NEI PM2.5 estimate and is also higher than the PM2.5 emitted from all other sources in these states in the NEI. This study indicates that the source of OA from biomass burning in the western states is significantly underestimated. In addition, our results indicate that prescribed burning may be an effective method to reduce fine particle emissions.</p>
[Hawes2003] "Airborne observations of vegetation and implications for biogenic emission characterization",
Journal of Environmental Monitoring
, vol. 5, no. 6: Royal Society of Chemistry, pp. 977–983, 2003.
Measuring hydrocarbons from aircraft represents one way to infer biogenic emissions at the surface. The focus of this paper is to show that complementary remote sensing information can be provided by optical measurements of a vegetation index, which is readily measured with high temporal coverage using reflectance data. We examine the similarities between the vegetation index and in situ measurements of the chemicals isoprene, methacrolein, and alpha-pinene to estimate whether the temporal behavior of the in situ measurements of these chemicals could be better understood by the addition of the vegetation index. Data were compared for flights conducted around Houston in August and September 2000. The three independent sets of chemical measurements examined correspond reasonably well with the vegetation index curves for the majority of flight days. While low values of the vegetation index always correspond to low values of the in situ chemical measurements, high values of the index correspond to both high and low values of the chemical measurements. In this sense it represents an upper limit when compared with in situ data (assuming the calibration constant is adequately chosen). This result suggests that while the vegetation index cannot represent a purely predictive quantity for the in situ measurements, it represents a complementary measurement that can be useful in understanding comparisons of various in situ observations, particularly when these observations occur with relatively low temporal frequency. In situ isoprene measurements and the vegetation index were also compared to an isoprene emission inventory to provide additional insight on broad issues relating to the use of vegetation indices in emission database development.