[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.
[Guazzotti2003] "Characterization of carbonaceous aerosols outflow from India and Arabia: Biomass/biofuel burning and fossil fuel combustion",
Journal of geophysical research
, vol. 108, no. D15: American Geophysical Union, pp. 4485, 2003.
A major objective of the Indian Ocean Experiment (INDOEX) involves the characterization of the extent and chemical composition of pollution outflow from the Indian Subcontinent during the winter monsoon. During this season, low-level flow from the continent transports pollutants over the Indian Ocean toward the Intertropical Convergence Zone (ITCZ). Traditional standardized aerosol particle chemical analysis, together with real-time single particle and fast-response gas-phase measurements provided characterization of the sampled aerosol chemical properties. The gas- and particle-phase chemical compositions of encountered air parcels changed according to their geographic origin, which was traced by back trajectory analysis. The temporal evolutions of acetonitrile, a long-lived specific tracer for biomass/biofuel burning, number concentration of submicrometer carbon-containing particles with potassium (indicative of combustion sources), and mass concentration of submicrometer non-sea-salt (nss) potassium are compared. High correlation coefficients (0.84 < r2 < 0.92) are determined for these comparisons indicating that most likely the majority of the species evolve from the same, related, or proximate sources. Aerosol and trace gas measurements provide evidence that emissions from fossil fuel and biomass/biofuel burning are subject to long-range transport, thereby contributing to anthropogenic pollution even in areas downwind of South Asia. Specifically, high concentrations of submicrometer nss potassium, carbon-containing particles with potassium, and acetonitrile are observed in air masses advected from the Indian subcontinent, indicating a strong impact of biomass/biofuel burning in India during the sampling periods (74 (±9)% biomass/biofuel contribution to submicrometer carbonaceous aerosol). In contrast, lower values for these same species were measured in air masses from the Arabian Peninsula, where dominance of fossil fuel combustion is suggested by results from single-particle analysis and supported by results from gas-phase measurements (63 (±9))% fossil fuel contribution to submicrometer carbonaceous aerosol). Results presented here demonstrate the importance of simultaneous, detailed gas- and particle-phase measurements of related species when evaluating possible source contributions to aerosols in different regions of the world.
[Salisbury2003] "Ground-based PTR-MS measurements of reactive organic compounds during the MINOS campaign in Crete, July–August 2001",
Atmospheric Chemistry and Physics
, vol. 3, no. 4: Copernicus GmbH, pp. 925–940, 2003.
This study presents measurements of acetonitrile, benzene, toluene, methanol and acetone made using the proton-transfer-reaction mass spectrometry (PTR-MS) technique at the Finokalia ground station in Crete during the Mediterranean INtensive Oxidant Study (MINOS) in July-August 2001. Three periods during the campaign with broadly consistent back trajectories are examined in detail. In the first, air was advected from Eastern Europe without significant biomass burning influence (mean acetonitrile mixing ratio 154 pmol/mol). In the second period, the sampled air masses originated in Western Europe, and were advected approximately east-south-east, before turning south-west over the Black Sea and north-western Turkey. The third well-defined period included air masses advected from Eastern Europe passing east and south of/over the Sea of Azov, and showed significant influence by biomass burning (mean acetonitrile mixing ratio 436 pmol/mol), confirmed by satellite pictures. The mean toluene:benzene ratios observed in the three campaign periods described were 0.35, 0.37 and 0.22, respectively; the use of this quantity to determine air mass age is discussed. Methanol and acetone were generally well-correlated both with each other and with carbon monoxide throughout the campaign. Comparison of the acetone and methanol measurements with the MATCH-MPIC model showed that the model underestimated both species by a factor of 4, on average. The correlations between acetone, methanol and CO implied that the relatively high levels of methanol observed during MINOS were largely due to direct biogenic emissions, and also that biogenic sources of acetone were highly significant during MINOS ( 35%). This in turn suggests that the model deficit in both species may be due, at least in part, to missing biogenic emissions.
[Mayr2003a] "In-vivo analysis of banana aroma by Proton Transfer Reaction-Mass Spectrometry.",
Flavour Research at the Dawn of the Twenty-first Century-Proceedings of the 10th Weurman Flavour Research Symposium, Beaune, France, 25-28 June, 2002.
: Editions Tec & Doc, pp. 256–259, 2003.
We report on in-vivo breath-by-breath analysis of volatiles released in the mouth during eating of ripe and unripe banana using Proton Transfer Reaction-Mass Spectrometry (PTR-MS). The time-intensity profiles of isopentyl and isobutyl acetate, two key odour compounds of ripe, and (E)2-hexenal and hexanal, typical for unripe banana, are discussed. The questions we address is: how do retronasal aroma (nosespace, NS) and orthonasal aroma (headspace, HS) differ? Two main differences were noticed. First, the NS concentrations of some compounds are increased, compared to the HS, while others are decreased. Second, aroma in the mouth is dynamic, evolving with time. The in-mouth situation has characteristics of its own that may lead to an aromatic experience specific to the eating situation.
[Gros2003] "Origin of anthropogenic hydrocarbons and halocarbons measured in the summertime European outflow (on Crete in 2001)",
Atmospheric Chemistry and Physics
, vol. 3, no. 4: Copernicus GmbH, pp. 1223–1235, 2003.
[Wert2003] "Signatures of terminal alkene oxidation in airborne formaldehyde measurements during TexAQS 2000",
Journal of Geophysical Research: Atmospheres (1984–2012)
, vol. 108, no. D3: Wiley Online Library, 2003.
Airborne formaldehyde (CH2O) measurements were made by tunable diode laser absorption spectroscopy (TDLAS) at high time resolution (1 and 10 s) and precision (±400 and ±120 parts per trillion by volume (pptv) (2σ), respectively) during the Texas Air Quality Study (TexAQS) 2000. Measurement accuracy was corroborated by in-flight calibrations and zeros and by overflight comparison with a ground-based differential optical absorption spectroscopy (DOAS) system. Throughout the campaign, the highest levels of CH2O precursors and volatile organic compound (VOC) reactivity were measured in petrochemical plumes. Correspondingly, CH2O and ozone production was greatly enhanced in petrochemical plumes compared with plumes dominated by power plant and mobile source emissions. The photochemistry of several isolated petrochemical facility plumes was accurately modeled using three nonmethane hydrocarbons (NMHCs) (ethene (C2H4), propene (C3H6) (both anthropogenic), and isoprene (C5H8) (biogenic)) and was in accord with standard hydroxyl radical (OH)-initiated chemistry. Measurement-inferred facility emissions of ethene and propene were far larger than reported by inventories. Substantial direct CH2O emissions were not detected from petrochemical facilities. The rapid production of CH2O and ozone observed in a highly polluted plume (30+ parts per billion by volume (ppbv) CH2O and 200+ ppbv ozone) originating over Houston was well replicated by a model employing only two NMHCs, ethene and propene.