Characterizing amino compounds in indoor poultry farms: air quality and its impact on workers and chickens in Canadian egg farms.

Indoor air pollution is a common problem in poultry and many livestock facilities. Small airborne amino chemicals (AACs), such as ammonia and short-chain amines, are common air pollutants in poultry farms. An elevated concentration of AACs can reduce the indoor air quality (IAQ) of the farm, affecting the production of chicken eggs, the welfare of the animals, and the occupational health of producers.

Measurement of Henry's law constants of ethyl nitrate in deionized water, synthetic sea salt solutions, and n-octanol.

Ethyl nitrate (EN; CHONO) is an important component of atmospheric "odd nitrogen" (NO) whose main source is marine emissions. To correctly describe its air-water transfer and model its global distribution, accurate values for its temperature- and salinity-dependent Henry's law solubility constants are needed. Here, we report Henry's law (H) constants for EN in deionized (DI) water, synthetic sea salt solutions (SSS), and n-octanol at temperatures between 278.

Interference from HONO in the measurement of ambient air NO via photolytic conversion and quantification of NO.

The reference method to quantify mixing ratios of the criteria air pollutant nitrogen dioxide (NO) is NO-O chemiluminescence (CL), in which mixing ratios of nitric oxide (NO) are measured by sampling ambient air directly, and mixing ratios of NO (= sum of NO and NO) are measured by converting NO to NO using, for example, heated molybdenum catalyst or, more selectively, photolytic conversion (P-CL). In this work, the nitrous acid (HONO) interference in the measurement of NO by P-CL was investigated. Results with two photolytic NO converters are presented.

Quantification of Non-refractory Aerosol Nitrate in Ambient Air by Thermal Dissociation Cavity Ring-Down Spectroscopy.

A thermal dissociation cavity ring-down spectrometer (TD-CRDS) for real-time quantification of non-refractory aerosol nitrate in ambient air is described. The instrument uses four parallel detection channels and heated quartz inlets to convert particulate organic nitrate (pON) (at 350 °C) and ammonium nitrate (NHNO) aerosol (at 540 °C) to nitrogen dioxide (NO), whose mixing ratio is monitored via its absorption at 405 nm. Concentrations of aerosol nitrate are determined by difference relative to a parallel TD-CRDS channel in which aerosol is removed by in-line filtering.

Potential interferences in photolytic nitrogen dioxide converters for ambient air monitoring: Evaluation of a prototype.

Unlabelled: Mixing ratios of the criteria air contaminant nitrogen dioxide (NO) are commonly quantified by reduction to nitric oxide (NO) using a photolytic converter followed by NO-O chemiluminescence (CL). In this work, the performance of a photolytic NO converter prototype originally designed for continuous emission monitoring and emitting light at 395 nm was evaluated. Mixing ratios of NO and NO (= NO + NO) entering and exiting the converter were monitored by blue diode laser cavity ring-down spectroscopy (CRDS).

Detection of triacetone triperoxide by thermal decomposition peroxy radical chemical amplification coupled to cavity ring-down spectroscopy.

Triacetone triperoxide (TATP) is frequently used in improvised explosive devices because of its ease of manufacture and tremendous explosive force. In this paper, we describe a new method for detection of TATP, thermal decomposition peroxy radical chemical amplification cavity ring-down spectroscopy (TD-PERCA-CRDS). In this method, air is sampled through a heated inlet to which ~ 1 ppmv nitric oxide (NO) is added.

Nitrate radicals and biogenic volatile organic compounds: oxidation, mechanisms, and organic aerosol.

Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol.

Oil sands operations as a large source of secondary organic aerosols.

Worldwide heavy oil and bitumen deposits amount to 9 trillion barrels of oil distributed in over 280 basins around the world, with Canada home to oil sands deposits of 1.7 trillion barrels. The global development of this resource and the increase in oil production from oil sands has caused environmental concerns over the presence of toxic compounds in nearby ecosystems and acid deposition.

Vertically resolved measurements of nighttime radical reservoirs in Los Angeles and their contribution to the urban radical budget.

Photolabile nighttime radical reservoirs, such as nitrous acid (HONO) and nitryl chloride (ClNO(2)), contribute to the oxidizing potential of the atmosphere, particularly in early morning. We present the first vertically resolved measurements of ClNO(2), together with vertically resolved measurements of HONO. These measurements were acquired during the California Nexus (CalNex) campaign in the Los Angeles basin in spring 2010.

Parahalogenated phenols accelerate the photochemical release of nitrogen oxides from frozen solutions containing nitrate.

The photolysis of nitrate anion (NO(3)(-)) contained in surface ice and snow can be a regionally significant source of gas-phase nitrogen oxides and affect the composition of the planetary boundary layer. In this study, the photochemical release of nitrogen oxides from frozen solutions containing NO(3)(-) in the presence of organic compounds was investigated. Gas-phase nitrogen oxides were quantified primarily by NO-O(3) chemiluminescence detection of NO and NO(y) (=NO + NO(2) + HONO + HNO(3) + ∑PAN + ∑AN .

A compact diode laser cavity ring-down spectrometer for atmospheric measurements of NO3 and N2O5 with automated zeroing and calibration.

A compact rack-mounted cavity ring-down spectrometer (CRDS) for simultaneous measurements of the nocturnal nitrogen oxides NO(3) and N(2)O(5) in ambient air is described. The instrument uses a red diode laser to quantify mixing ratios of NO(3) (at its absorption maximum at 662 nm) and of N(2)O(5) following its thermal dissociation to NO(3) in a second detection channel. The spectrometer is equipped with an automated zeroing and calibration setup to determine effective NO(3) absorption cross-sections and NO(3) and N(2)O(5) inlet transmission efficiencies.

Observation of ClNO₂ in a mid-continental urban environment.

In the troposphere, nitryl chloride (ClNO₂), produced from uptake of dinitrogen pentoxide (N₂O₅) on chloride containing aerosol, can be an important nocturnal reservoir of NO(x) (= NO + NO₂) and a source of atomic Cl, particularly in polluted coastal environments. Here, we present measurements of ClNO₂ mixing ratios by chemical ionization mass spectrometry (CIMS) in Calgary, Alberta, Canada over a 3-day period. The observed ClNO₂ mixing ratios exhibited a strong diurnal profile, with nocturnal maxima in the range of 80 to 250 parts-per-trillion by volume (pptv) and minima below the detection limit of 5 pptv in the early afternoon.

Quantification of nitryl chloride at part per trillion mixing ratios by thermal dissociation cavity ring-down spectroscopy.

Nitryl chloride (ClNO(2)) is an important nocturnal nitrogen oxide reservoir species in the troposphere. Here, we report a novel method, thermal dissociation cavity ring-down spectroscopy (TD-CRDS), to quantify ClNO(2) mixing ratios with tens of parts-per-trillion by volume (pptv) sensitivity. The mixing ratios of ClNO(2) are determined by blue diode laser CRDS of NO(2), produced from quantitative thermal dissociation of ClNO(2) in an inlet heated to 450 °C, relative to NO(2) observed in an unheated reference channel.

Absolute measurements of total peroxy nitrate mixing ratios by thermal dissociation blue diode laser cavity ring-down spectroscopy.

Peroxycarboxylic nitric anhydrides (PANs) have long been recognized as important trace gas constituents of the troposphere. Here, we describe a blue diode laser thermal dissociation cavity ring-down spectrometer for rapid and absolute measurements of total peroxyacyl nitrate (SigmaPAN) abundances at ambient concentration levels. The PANs are thermally dissociated and detected as NO2, whose mixing ratios are quantified by optical absorption at 405 nm relative to a reference channel kept at ambient temperature.

Measurements of total peroxy and alkyl nitrate abundances in laboratory-generated gas samples by thermal dissociation cavity ring-down spectroscopy.

A novel measurement technique, thermal dissociation cavity ring-down spectroscopy (TD-CRDS), for rapid (1 s time resolution) and sensitive (precision approximately 100 parts per trillion by volume (10(-12); pptv)) quantification of total peroxy nitrate (SigmaPN) and total alkyl nitrate (SigmaAN) abundances in laboratory-generated gas mixtures is described. The organic nitrates are dissociated in a heated inlet to produce NO(2), whose concentration is monitored by pulsed-laser CRDS at 532 nm. Mixing ratios are determined by difference relative to a cold inlet reference channel.

N2O5 oxidizes chloride to Cl2 in acidic atmospheric aerosol.

Molecular chlorine (Cl2) is an important yet poorly understood trace constituent of the lower atmosphere. Although a number of mechanisms have been proposed for the conversion of particle-bound chloride (Cl-) to gas-phase Cl2, the detailed processes involved remain uncertain. Here, we show that reaction of dinitrogen pentoxide (N2O5) with aerosol-phase chloride yields Cl2 at low pH (<2) and should constitute an important halogen activation pathway in the atmosphere.

Temperature dependence of the NO3 absorption cross-section above 298 K and determination of the equilibrium constant for NO3 + NO2 <--> N2O5 at atmospherically relevant conditions.

The reaction NO3 + NO2 <--> N2O5 was studied over the 278-323 K temperature range. Concentrations of NO3, N2O5, and NO2 were measured simultaneously in a 3-channel cavity ring-down spectrometer. Equilibrium constants were determined over atmospherically relevant concentration ranges of the three species in both synthetic samples in the laboratory and ambient air samples in the field.

Photoredox, photodecarboxylation, and photo-retro-aldol chemistry of p-nitrobiphenyls.

The photochemistry of three p-nitrobiphenyl derivatives 9-11 has been investigated to explore the ability of photoexcited nitro groups to induce chemistry through the biphenyl ring system. Previous work has shown that the nitro group is highly electron withdrawing at both the meta and para positions (on the benzene ring) in the excited triplet state, inducing decarboxylations and retro-Aldol type reactions, as well as a novel intramolecular redox-type reaction. The mechanisms of all of these reactions are believed to involve photogenerated nitrobenzyl carbanion-type intermediates.

Enhanced photoreactivity of the nitrobiphenyl chromophore.

Several p-nitrobiphenyl derivatives show significantly higher photoreactivity compared to their p-nitrophenyl analogs, in addition to displaying a new acid-catalyzed photodecarboxylation mechanism in p-(p'-nitrophenyl)-phenylacetic acid.