Wintertime Nitrous Oxide Emissions in the San Joaquin Valley of California Estimated from Aircraft Observations.

Nitrous oxide (N2O) is a long-lived greenhouse gas that also destroys stratospheric ozone. N2O emissions are uncertain and characterized by high spatiotemporal variability, making individual observations difficult to upscale, especially in mixed land use source regions like the San Joaquin Valley (SJV) of California. Here, we calculate spatially integrated N2O emission rates using nocturnal and convective boundary-layer budgeting methods. We utilize vertical profile measurements from the NASA DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality) campaign, which took place January-February, 2013. For empirical constraints on N2O source identity, we analyze N2O enhancement ratios with methane, ammonia, carbon dioxide, and carbon monoxide separately in the nocturnal boundary layer, nocturnal residual layer, and convective boundary layer. We find that an established inventory (EDGAR v4.3.2) underestimates N2O emissions by at least a factor of 2.5, that wintertime emissions from animal agriculture are important to annual totals, and that there is evidence for higher N2O emissions during the daytime than at night.

Intra-puff CO and CO2 measurements of cigarettes with iron oxide cigarette paper using quantum cascade laser spectroscopy.

The objective of this research was to apply Fourier transform infrared spectroscopy (FTIR) and tunable infrared laser differential absorption spectroscopy (TILDAS) for measuring selected gaseous constituents in mainstream (MS) and sidestream (SS) smoke for experimental cigarettes designed to reduce MS CO using iron oxide cigarette papers. These two complimentary analytical techniques are well suited for providing per puff smoke deliveries and intra-puff evolution profiles in cigarette smoke respectively. The quad quantum cascade (QC) laser high resolution infrared spectroscopy system has the necessary temporal and spectral resolution and whole smoke analysis capabilities to provide detailed information for CO and CO(2) as they are being formed in both MS and SS smoke. The QC laser system has an optimal data rate of 20 Hz and a unique puffing system, with a square wave shaped puff, that allows whole smoke to enter an 18 m, 0.3 L multi-pass gas cell in real time (0.1s cell response time) requiring no syringe or Cambridge filter pad. Another similar multi-pass gas cell with a 36 m pathlength simultaneously monitors the sidestream cigarette smoke. The smoke from experimental cigarettes manufactured with two types of iron oxide papers were compared to the smoke from cigarettes manufactured similarly without iron oxide in the paper using both instrument systems. The delivery per puff determined by the QC laser method agreed with FTIR results. MS CO intra-puff evolution profiles for iron oxide prototype cigarettes demonstrated CO reduction when compared to cigarettes without iron oxide paper. Additionally, both CO and CO(2) intra-puff evolution profiles of the cigarettes with iron oxide paper showed a significant reduction at the initial portion of the 2 s puff not observed in the non-iron oxide prototype cigarettes. This effect also was observed for ammonia and ethylene, suggesting that physical parameters such as paper porosity and burn rate are important. The SS CO and CO(2) deliveries for the experimental cigarettes evaluated remained unaffected. The iron oxide paper technology remains under development and continues to be evaluated.

Measurement of acrolein and 1,3-butadiene in a single puff of cigarette smoke using lead-salt tunable diode laser infrared spectroscopy.

Acrolein and 1,3-butadiene in cigarette smoke generally are measured using two separate analytical methods, a carbonyl derivative HPLC method for acrolein and a volatile organic compound (VOC) GC/MS method for 1,3-butadiene. However, a single analytical method having improved sensitivity and real-time per puff measurement will offer more specific information for evaluating experimental carbon filtered cigarettes designed to reduce the smoke deliveries of these constituents. This paper describes an infrared technique using two lead-salt tunable diode lasers (TDLs) operating with liquid nitrogen cooling with emissions at 958.8 cm(-1) and 891.0 cm(-1) respectively for the simultaneous measurement of acrolein and 1,3-butadiene, respectively, in each puff of mainstream cigarette smoke in real time. The dual TDL system uses a 3.1l volume, 100 m astigmatic multiple pass absorption gas cell. Quantitation is based on a spectral fit that uses previously determined infrared molecular line parameters generated in our laboratory, including line positions, line strengths and nitrogen-broadened half-widths for these species. Since acrolein and ethylene absorption lines overlap and 1,3-butadiene, ethylene and propylene absorption lines overlap, the per puff deliveries of ethylene and propylene were determined since their overlapping absorption lines must be taken into account by the spectral fit. The acrolein and 1,3-butadiene total cigarette deliveries for the 1R5F Kentucky Reference cigarette were in agreement with the HPLC and GC/MS methods, respectively. The limit of detection (LOD) for 1,3-butadiene and acrolein was 4 ng/puff and 24 ng/puff, respectively, which is more than adequate to determine at which puff they break through the carbon filter. The retention and breakthrough behavior for the two primary smoke constituents depend on the cigarette design and characteristics of the carbon filter being evaluated.

Determination of molecular line parameters for acrolein (C(3)H(4)O) using infrared tunable diode laser absorption spectroscopy.

Acrolein (C(3)H(4)O) molecular line parameters, including infrared (IR) absorption positions, strengths, and nitrogen broadened half-widths, must be determined since they are not included in the high resolution transmission (HITRAN) molecular absorption database of spectral lines. These parameters are required for developing a quantitative analytical method for measuring acrolein in a single puff of cigarette smoke using tunable diode laser absorption spectroscopy (TDLAS). The task is complex since acrolein has many highly overlapping infrared absorption lines in the room temperature spectrum and the cigarette smoke matrix contains thousands of compounds. This work describes the procedure for estimating the molecular line parameters for these overlapping absorption lines in the wavenumber range (958.7-958.9 cm(-1)) using quantitative reference spectra taken with the infrared lead-salt TDLAS instrument at different pressures and concentrations. The nitrogen broadened half-width for acrolein is 0.0937 cm(-1)atm(-1) and to our knowledge, is the first time it has been reported in the literature.

Iron pentacarbonyl detection limits in the cigarette smoke matrix using FT-IR spectroscopy.

Endogenous metals present in tobacco from agricultural practices have been purported to generate metal carbonyls in cigarette smoke. Transition metal catalysts, such as iron oxide, have been investigated for the reduction of carbon monoxide (CO) in cigarette smoke. These studies motivated the development of an analytical method to determine if iron pentacarbonyl [Fe(CO)(5)] is present in mainstream smoke from cigarette models having cigarette paper made with iron oxide. An FT-IR puff-by-puff method was developed and the detection limit was determined using two primary reference spectra from different sources to estimate the amount of Fe(CO)(5) present in a high-pressure steel cylinder of CO. We do not detect Fe(CO)(5) in a single 35 mL puff from reference cigarettes or from those cigarette models having cigarette paper made with iron oxide, with a 30-ppbV limit of detection (LOD). Also, it was shown that a filter containing activated carbon would remove Fe(CO)(5).

Determination of molecular parameters for 1,3-butadiene and propylene using infrared tunable diode laser absorption spectroscopy.

A technique has been developed for the determination of molecular parameters, including infrared absorption line positions, strengths, and nitrogen-broadened half-widths for 1,3-butadiene (C(4)H(6)) and propylene (C(3)H(6)). The parameters for these two molecules are required for quantitation using Tunable Diode Laser Absorption Spectroscopy (TDLAS). These molecules have populations of highly overlapping infrared absorption lines in their room temperature spectra. The technique reported here provides a procedure for estimating the molecular parameters for these overlapping absorption lines from quantitative reference spectra taken with the TDLAS instrument at different pressures and concentrations. The system was developed for the quantitation of gaseous constituents in a single puff of cigarette smoke and this paper will describe the procedure and some of the factors that influence the accuracy of quantitation for 1,3-butadiene, including the approach taken to minimize the adverse effects of the absorption due to propylene in the same spectral region.

Quad quantum cascade laser spectrometer with dual gas cells for the simultaneous analysis of mainstream and sidestream cigarette smoke.

A compact, fast response, infrared spectrometer using four pulsed quantum cascade (QC) lasers has been applied to the analysis of gases in mainstream (MS) and sidestream (SS) cigarette smoke. QC lasers have many advantages over the traditional lead-salt tunable diode lasers, including near room temperature operation with thermoelectric cooling and single mode operation with improved long-term stability. The new instrument uses two 36 m, 0.3 l multiple pass absorption gas cells to obtain a time response of 0.1s for the MS smoke system and 0.4s for the SS smoke system. The concentrations of ammonia, ethylene, nitric oxide, and carbon dioxide for three different reference cigarettes were measured simultaneously in MS and SS smoke. A data rate of 20Hz provides sufficient resolution to determine the concentration profiles during each 2s puff in the MS smoke. Concentration profiles before, during and after the puffs also have been observed for these smoke constituents in SS smoke. Also, simultaneous measurements of CO(2) from a non-dispersive infrared (NDIR) analyzer are obtained for both MS and SS smoke. In addition, during this work, nitrous oxide was detected in both the MS and SS smoke for all reference cigarettes studied.

Evaluation of hydrazine reduction by cellulose acetate filters using infrared tunable diode laser spectroscopy.

Cellulose acetate (CA) filters have been investigated to determine their hydrazine (N2H4) breakthrough characteristics using a system based on tunable diode laser absorption spectroscopy (TDIAS). The breakthrough mass loading sorption curves for hydrazine were dependent on both the flow rate and the concentration. In experiments using a 4.5 ppmv hydrazine standard, the amounts of hydrazine retained by the CA filter were 4.25 microg at a flow rate of 2.82 L/min and 65 microg at a flow rate of 0.28 L/min. These loadings are much greater than the 31.5 ng/cigarette of hydrazine reported in smoke for unfiltered cigarettes. Further, CA filters exposed to four and eight puffs of smoke actually made the filter more efficient in retaining hydrazine compared to CA filters that had not been exposed to smoke. Therefore, if hydrazine is present in smoke at the levels reported in unfiltered cigarettes, all of the hydrazine would be trapped by the CA filter, and would be unable to break through during smoking. A unique feature of this analytical method is that the instrument does not require calibration after molecular parameters have been determined, in this case from previously acquired quantitative hydrazine FT-IR reference spectra.