Signaling from below: rodents select for deeper fruiting truffles with stronger volatile emissions.

Many plant and fungal species use volatile organic compounds (VOCs) as chemical signals to convey information about the location or quality of their fruits or fruiting bodies to animal dispersers. Identifying the environmental factors and biotic interactions that shape fruit selection by animals is key to understanding the evolutionary processes that underpin chemical signaling. Using four Elaphomyces truffle species, we explored the role of fruiting depth, VOC emissions, and protein content in selection by five rodent species. We used stable isotope analysis of nitrogen (δ15 N) in truffles to estimate fruiting depth, proton-transfer-reaction mass spectrometry to determine volatile emission composition, and nitrogen concentrations to calculate digestible protein of truffles. We coupled field surveys of truffle availability with truffle spore loads in rodent scat to determine selection by rodents. Despite presumably easier access to the shallow fruiting species, E. americanus (0.5-cm depth) and E. verruculosus (2.5-cm depth), most rodents selected for truffles fruiting deeper in the soil, E. macrosporus (4.1-cm depth) and E. bartlettii (5.0-cm depth). The deeper fruiting species had distinct VOC profiles and produced significantly higher quantities of odiferous compounds. Myodes gapperi (southern red-backed vole), a fungal specialist, also selected for truffles with high levels of digestible protein, E. verruculosus and E. macrosporus. Our results highlight the importance of chemical signals in truffle selection by rodents and suggest that VOCs are under strong selective pressures relative to protein rewards. Strong chemical signals likely allow detection of truffles deep within the soil and reduce foraging effort by rodents. For rodents that depend on fungi as a major food source, protein content may also be important in selecting truffles.

Characterization of methane emissions from five cold heavy oil production with sands (CHOPS) facilities.

Cold heavy oil production with sands (CHOPS) is a common oil extraction method in the Canadian provinces of Alberta and Saskatchewan that can result in significant methane emissions due to annular venting. Little is known about the magnitude of these emissions, nor their contributions to the regional methane budget. Here the authors present the results of field measurements of methane emissions from CHOPS wells and compare them with self-reported venting rates. The tracer ratio method was used not only to analyze total site emissions but at one site it was also used to locate primary emission sources and quantify their contributions to the facility-wide emission rate, revealing the annular vent to be a dominant source. Emissions measured from five different CHOPS sites in Alberta showed large discrepancies between the measured and reported rates, with emissions being mainly underreported. These methane emission rates are placed in the context of current reporting procedures and the role that gas-oil ratio (GOR) measurements play in vented volume estimates. In addition to methane, emissions of higher hydrocarbons were also measured; a chemical "fingerprint" associated with CHOPS wells in this region reveals very low emission ratios of ethane, propane, and aromatics versus methane. The results of this study may inform future studies of CHOPS sites and aid in developing policy to mitigate regional methane emissions. IMPLICATIONS: Methane measurements from cold heavy oil production with sand (CHOPS) sites identify annular venting to be a potentially major source of emissions at these facilities. The measured emission rates are generally larger than reported by operators, with uncertainty in the gas-oil ratio (GOR) possibly playing a large role in this discrepancy. These results have potential policy implications for reducing methane emissions in Alberta in order to achieve the Canadian government's goal of reducing methane emissions by 40-45% below 2012 levels within 8 yr.

Rapid total volatile organic carbon quantification from microbial fermentation using a platinum catalyst and proton transfer reaction-mass spectrometry.

A novel analytical system was developed to rapidly and accurately quantify total volatile organic compound (VOC) production from microbial reactor systems using a platinum catalyst and a sensitive CO2 detector. This system allows nearly instantaneous determination of total VOC production by utilizing a platinum catalyst to completely and quantitatively oxidize headspace VOCs to CO2 in coordination with a CO2 detector. Measurement of respiratory CO2 by bypassing the catalyst allowed the total VOC content to be determined from the difference in the two signals. To the best of our knowledge, this is the first instance of a platinum catalyst and CO2 detector being used to quantify the total VOCs produced by a complex bioreactor system. Continuous recording of these CO2 data provided a record of respiration and total VOC production throughout the experiments. Proton transfer reaction-mass spectrometry (PTR-MS) was used to identify and quantify major VOCs. The sum of the individual compounds measured by PTR-MS can be compared to the total VOCs quantified by the platinum catalyst to identify potential differences in detection, identification and calibration. PTR-MS measurements accounted on average for 94 % of the total VOC carbon detected by the platinum catalyst and CO2 detector. In a model system, a VOC producing endophytic fungus Nodulisporium isolate TI-13 was grown in a solid state reactor utilizing the agricultural byproduct beet pulp as a substrate. Temporal changes in production of major volatile compounds (ethanol, methanol, acetaldehyde, terpenes, and terpenoids) were quantified by PTR-MS and compared to the total VOC measurements taken with the platinum catalyst and CO2 detector. This analytical system provided fast, consistent data for evaluating VOC production in the nonhomogeneous solid state reactor system.

Atmospheric emission characterization of Marcellus shale natural gas development sites.

Limited direct measurements of criteria pollutants emissions and precursors, as well as natural gas constituents, from Marcellus shale gas development activities contribute to uncertainty about their atmospheric impact. Real-time measurements were made with the Aerodyne Research Inc. Mobile Laboratory to characterize emission rates of atmospheric pollutants. Sites investigated include production well pads, a well pad with a drill rig, a well completion, and compressor stations. Tracer release ratio methods were used to estimate emission rates. A first-order correction factor was developed to account for errors introduced by fenceline tracer release. In contrast to observations from other shale plays, elevated volatile organic compounds, other than CH4 and C2H6, were generally not observed at the investigated sites. Elevated submicrometer particle mass concentrations were also generally not observed. Emission rates from compressor stations ranged from 0.006 to 0.162 tons per day (tpd) for NOx, 0.029 to 0.426 tpd for CO, and 67.9 to 371 tpd for CO2. CH4 and C2H6 emission rates from compressor stations ranged from 0.411 to 4.936 tpd and 0.023 to 0.062 tpd, respectively. Although limited in sample size, this study provides emission rate estimates for some processes in a newly developed natural gas resource and contributes valuable comparisons to other shale gas studies.

Ethylene glycol emissions from on-road vehicles.

Ethylene glycol (HOCH2CH2OH), used as engine coolant for most on-road vehicles, is an intermediate volatility organic compound (IVOC) with a high Henry's law coefficient. We present measurements of ethylene glycol (EG) vapor in the Caldecott Tunnel near San Francisco, using a proton transfer reaction mass spectrometer (PTR-MS). Ethylene glycol was detected at mass-to-charge ratio 45, usually interpreted as solely coming from acetaldehyde. EG concentrations in bore 1 of the Caldecott Tunnel, which has a 4% uphill grade, were characterized by infrequent (approximately once per day) events with concentrations exceeding 10 times the average concentration, likely from vehicles with malfunctioning engine coolant systems. Limited measurements in tunnels near Houston and Boston are not conclusive regarding the presence of EG in sampled air. Previous PTR-MS measurements in urban areas may have overestimated acetaldehyde concentrations at times due to this interference by ethylene glycol. Estimates of EG emission rates from the Caldecott Tunnel data are unrealistically high, suggesting that the Caldecott data are not representative of emissions on a national or global scale. EG emissions are potentially important because they can lead to the formation of secondary organic aerosol following oxidation in the atmospheric aqueous phase.

Air Pollutant Mapping with a Mobile Laboratory During the BEE-TEX Field Study.

The Aerodyne Mobile Laboratory was deployed to the Houston Ship Channel and surrounding areas during the Benzene and Other Toxics Exposure field study in February 2015. We evaluated atmospheric concentrations of volatile organic hydrocarbons and other hazardous air pollutants of importance to human health, including benzene, 1,3-butadiene, toluene, xylenes, ethylbenzenes, styrene, and NO2. Ambient concentration measurements were focused on the neighborhoods of Manchester, Harrisburg, and Galena Park. The most likely measured concentration of 1,3-butadiene in the Manchester neighborhood (0.17 ppb) exceeds the Environmental Protection Agency's E-5 lifetime cancer risk level of 0.14 ppb. In all the three neighborhoods, the measured benzene concentration falls below or within the E-5 lifetime cancer risk levels of 0.4-1.4 ppb for benzene. Pollution maps as a function of wind direction show the impact of nearby sources.

Functionalized para-substituted benzenes as 1,8-cineole production modulators in an endophytic Nodulisporium species.

A Nodulisporium species (designated Ti-13) was isolated as an endophyte from Cassia fistula. The fungus produces a spectrum of volatile organic compounds (VOCs) that includes ethanol, acetaldehyde and 1,8-cineole as major components. Initial observations of the fungal isolate suggested that reversible attenuation of the organism via removal from the host and successive transfers in pure culture resulted in a 50 % decrease in cineole production unrelated to an overall alteration in fungal growth. A compound (CPM1) was obtained from Betula pendula (silver birch) that increases the production of 1,8-cineole by an attenuated Ti-13 strain to its original level, as measured by a novel bioassay method employing a 1,8-cineole-sensitive fungus (Sclerotinia sclerotiorum). The host plant produces similar compounds possessing this activity. Bioactivity assays with structurally similar compounds such as ferulic acid and gallic acid suggested that the CPM1 does not act as a simple precursor to the biosynthesis of 1,8-cineole. NMR spectroscopy and HPLC-ES-MS indicated that the CPM1 is a para-substituted benzene with alkyl and carboxyl substituents. The VOCs of Ti-13, especially 1,8-cineole, have potential applications in the industrial, fuel and medical fields.

Contribution of nitrated phenols to wood burning brown carbon light absorption in Detling, United Kingdom during winter time.

We show for the first time quantitative online measurements of five nitrated phenol (NP) compounds in ambient air (nitrophenol C6H5NO3, methylnitrophenol C7H7NO3, nitrocatechol C6H5NO4, methylnitrocatechol C7H7NO4, and dinitrophenol C6H4N2O5) measured with a micro-orifice volatilization impactor (MOVI) high-resolution chemical ionization mass spectrometer in Detling, United Kingdom during January-February, 2012. NPs absorb radiation in the near-ultraviolet (UV) range of the electromagnetic spectrum and thus are potential components of poorly characterized light-absorbing organic matter ("brown carbon") which can affect the climate and air quality. Total NP concentrations varied between less than 1 and 98 ng m(-3), with a mean value of 20 ng m(-3). We conclude that NPs measured in Detling have a significant contribution from biomass burning with an estimated emission factor of 0.2 ng (ppb CO)(-1). Particle light absorption measurements by a seven-wavelength aethalometer in the near-UV (370 nm) and literature values of molecular absorption cross sections are used to estimate the contribution of NP to wood burning brown carbon UV light absorption. We show that these five NPs are potentially important contributors to absorption at 370 nm measured by an aethalometer and account for 4 ± 2% of UV light absorption by brown carbon. They can thus affect atmospheric radiative transfer and photochemistry and with that climate and air quality.

Determination of the emissions from an aircraft auxiliary power unit (APU) during the Alternative Aviation Fuel Experiment (AAFEX).

The emissions from a Garrett-AiResearch (now Honeywell) Model GTCP85-98CK auxiliary power unit (APU) were determined as part of the National Aeronautics and Space Administration's (NASA's) Alternative Aviation Fuel Experiment (AAFEX) using both JP-8 and a coal-derived Fischer Tropsch fuel (FT-2). Measurements were conducted by multiple research organizations for sulfur dioxide (SO2, total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), speciated gas-phase emissions, particulate matter (PM) mass and number, black carbon, and speciated PM. In addition, particle size distribution (PSD), number-based geometric mean particle diameter (GMD), and smoke number were also determined from the data collected. The results of the research showed PM mass emission indices (EIs) in the range of 20 to 700 mg/kg fuel and PM number EIs ranging from 0.5 x 10(15) to 5 x 10(15) particles/kg fuel depending on engine load and fuel type. In addition, significant reductions in both the SO2 and PM EIs were observed for the use of the FT fuel. These reductions were on the order of approximately 90% for SO2 and particle mass EIs and approximately 60% for the particle number EI, with similar decreases observed for black carbon. Also, the size of the particles generated by JP-8 combustion are noticeably larger than those emitted by the APU burning the FT fuel with the geometric mean diameters ranging from 20 to 50 nm depending on engine load and fuel type. Finally, both particle-bound sulfate and organics were reduced during FT-2 combustion. The PM sulfate was reduced by nearly 100% due to lack of sulfur in the fuel, with the PM organics reduced by a factor of approximately 5 as compared with JP-8.

Resolution of volatile fuel compound profiles from Ascocoryne sarcoides: a comparison by proton transfer reaction-mass spectrometry and solid phase microextraction gas chromatography-mass spectrometry.

Volatile hydrocarbon production by Ascocoryne sacroides was studied over its growth cycle. Gas-phase compounds were measured continuously with a proton transfer reaction-mass spectrometry (PTR-MS) and at distinct time points with gas chromatography-mass spectrometry (GC-MS) using head space solid phase microextraction (SPME). The PTR-MS ion signal permitted temporal resolution of the volatile production while the SPME results revealed distinct compound identities. The quantitative PTR-MS results showed the volatile production was dominated by ethanol and acetaldehyde, while the concentration of the remainder of volatiles consistently reached 2,000 ppbv. The measurement of alcohols from the fungal culture by the two techniques correlated well. Notable compounds of fuel interest included nonanal, 1-octen-3-ol, 1-butanol, 3-methyl- and benzaldehyde. Abiotic comparison of the two techniques demonstrated SPME fiber bias toward higher molecular weight compounds, making quantitative efforts with SPME impractical. Together, PTR-MS and SPME GC-MS were shown as valuable tools for characterizing volatile fuel compound production from microbiological sources.

Aircraft hydrocarbon emissions at Oakland International Airport.

To help airports improve emission inventory data, speciated hydrocarbon emission indices have been measured from in-use commercial, airfreight, and general aviation aircraft at Oakland International Airport. The compounds reported here include formaldehyde, acetaldehyde, ethene, propene, and benzene. At idle, the magnitude of hydrocarbon emission indices was variable and reflected differences in engine technology, actual throttle setting, and ambient temperature. Scaling the measured emission indices to the simultaneously measured formaldehyde (HCHO) emission index eliminated most of the observed variability. This result supports a uniform hydrocarbon emissions profile across engine types when the engine is operating near idle, which can greatly simplify how speciated hydrocarbons are handled in emission inventories. The magnitude of the measured hydrocarbon emission index observed in these measurements (ambient temperature range 12-22 degrees C) is a factor of 1.5-2.2 times larger than the certification benchmarks. Using estimates of operational fuel flow rates at idle, this analysis suggests that current emission inventories at the temperatures encountered at this airport underestimate hydrocarbon emissions from the idle phase of operation by 16-45%.

Laboratory evaluation of an aldehyde scrubber system specifically for the detection of acrolein.

We demonstrate the use of an aldehyde scrubber system to resolve isobaric aldehyde/alkene interferences in a proton transfer reaction mass spectrometer (PTR-MS) by selectively removing the aldehydes from the gas mixture without loss of quantitative information for the alkene components. The aldehyde scrubber system uses a bisulfite solution, which scrubs carbonyl compounds from the gas stream by forming water-soluble carbonyl bisulfite addition products, and has been evaluated using a synthetic mixture of acrolein and isoprene. Trapping efficiencies of acrolein exceeded 97%, whereas the transmission efficiency of isoprene was better than 92%. Quantification of the PTR-MS response to acrolein was validated through an intercomparison study that included two derivatization methods, dinitrophenylhydrazine (DNPH) and O-(4-cyano-2-ethoxybenzyl)hydroxylamine (CNET), and a spectroscopic method using a quantum cascade laser infrared absorption spectroscopy (QCL) instrument. Finally, using cigarette smoke as a complex matrix, the acrolein content was assessed using the scrubber and compared with direct QCL-based detection.

Influence of strawberry yogurt composition on aroma release.

The primary objective of this study was to determine how yogurt ingredients affect aroma release in the mouth during eating. A model strawberry flavor consisting of ethyl butanoate, ethyl 3-methylbutanoate, (Z)-hex-3-enol, 2-methylbutanoic acid, 5-hexylhydro-2(3H)-furanone, and 3-methyl-3-phenylglycidic acid ethyl ester was added to unflavored, unsweetened yogurt that had different added sweeteners and hydrocolloids. In all, 12 yogurt formulations were examined to determine the effects of gelatin, modified food starch, pectin, sucrose, high-fructose corn syrup, and aspartame on aroma release. Aroma release was monitored by breath-by-breath analysis (proton-transfer reaction-mass spectrometry) during eating of the test yogurts. Results showed aroma release of the ethyl butanoate, (Z)-hex-3-enol, and ethyl 3-methylbutanoate to be suppressed by sweeteners, with 55 DE high-fructose corn syrup having the greatest effect. Addition of thickening agents had no significant effect on the aroma release profiles of the compounds under study.