Atmospheric Gas Analysis Research Articles

Transceiving telescope for a mobile TDLAS system for remote sounding of anthropogenic methane

In this paper, we report on stages of the development of a transceiving telescope for atmospheric gas analysis TDLAS systems. Design of transmitters and receivers for active remote sounding systems is an important problem when creating instruments for studying atmospheric parameters. Transmitter and receiver aperture size directly influences the minimum permissible and maximum practicable sounding ranges. The work describes the stages of designing the receiving and transmitting parts of an atmospheric gas analysis tunable diode laser absorption spectroscopy (TDLAS) system (with anthropogenic methane as a target gas). Calculations show that a backscattered signal is reliably detected over an optical path 0–1000 m long with the use of a transceiving telescope with aperture 50–80 mm diameter and magnification of no less than 5. This design enables minimizing the dead zone of the coaxial TDLAS system within the 1645–1655 nm spectral range, which is informative for anthropogenic methane sounding. The use of a transceiving telescope will ensure resistance to misalignment, namely, resistance to mismatch between the mutual overlap of the device field of view and the laser radiation spot on the topographic target. Results of this work can be useful when designing and manufacturing telescopes for TDLAS systems methane (CH4) and also other atmospheric gas analysis.

Laser-Induced Breakdown Spectroscopy in Mineral Exploration and Ore Processing

Laser-induced breakdown spectroscopy (LIBS) is a type of optical emission spectroscopy capable of rapid, simultaneous multi-element analysis. LIBS is effective for the analysis of atmospheric gases, geological fluids, and a broad spectrum of minerals, rocks, sediments, and soils both in and outside the traditional laboratory setting. With the recent introduction of commercial laboratory systems and handheld analyzers for use outside the laboratory for real-time in situ analysis in the field, LIBS is finding increasing application across the geosciences. This article first overviews the LIBS technique and then reviews its application in the domain of mineral exploration and ore processing, where LIBS offers some unique capabilities.

Design and technical characteristics of a three-channel mobile lidar for atmospheric gas analysis

The technical appearance of the developed three-channel mobile IR-band lidar system is presented. The output energy characteristics of the lidar channels for H2O, CO2, CH4 sounding were experimentally determined and the signals were registered on selected horizontal sounding paths.

Development of the technology of nonlinear optical ZnGeP<sub>2</sub> crystals and laser radiation frequency converters for atmospheric gas analysis systems

Development of the technology of nonlinear optical ZnGeP<sub>2</sub> crystals and laser radiation frequency converters for atmospheric gas analysis systems

Analysis of atmospheric greenhouse gases in north Xinjiang

Flask air samples were collected weekly at the Akedala (AKD) regional atmosphere station in north Xinjiang, China, and atmospheric carbon dioxide (CO2) and methane (CH4) mole fractions were measured using cavity-ring down spectroscopy. AKD station is under a typical temperate continental semiarid and arid monsoon climate with westerly air flow. This paper presents the long-term trends and seasonal variations in atmospheric CO2 and CH4 concentrations for the first time and discusses the possible influencing mechanisms. The CO2 and CH4 background mixing ratios were 412.1 ± 0.36 ppm and 1968.9 ± 0.95 ppb, respectively, in 2018. The growth rates were 2.62 ppm y−1 and 9.67 ppb y−1 for CO2 and CH4, respectively, during 2010–2018, which were higher than the surface measurements at Waliguan Baseline Observatory at similar latitudes. The averaged CO2 seasonal cycle showed a minimum in summer and a maximum in winter, and the annual amplitude was high at 18.7 ppm. The CH4 seasonal cycle showed a rapid recovery in summer during July and August. Back-trajectory analysis showed that the atmospheric information at AKD station can provide some implications for uptake from Kazakhstan and Russia, as well as information about natural and anthropogenic emissions in northern Xinjiang. This study revealed that the long-term upward trend of the CO2 concentration in AKD might be attributed to emissions from energy consumption of heavy industry. The comprehensive effects of livestock, geological micro seepage and oil and gas production, and vertical transport also enhanced the atmospheric CH4 concentrations. The results of this study may improve our basic understanding of observed atmospheric CO2 and CH4 in China and Central Asia and the underlying fluxes to be used in atmospheric inversion models.

Dominance of Arcobacter in the white filaments from the thermal sulfidic spring of Fetida Cave (Apulia, southern Italy)

The thermal spring of Fetida Cave, a still active sulfuric acid cave opening at sea level and located in Santa Cesarea Terme, southeastern Salento (Apulia region, Southern Italy) hosts abundant floating white filaments. The white filaments were mainly composed of sulfur crystals surrounded by microbial mass of the phyla Epsilonbacteraeota, Proteobacteria, Bacteroidetes, and Patescibacteria. The most abundant genus in the white filaments collected from the waters in the innermost part of the cave dominated by sulfidic exhalations was Arcobacter. This abundance can be related to the higher concentration of sulfide dissolved in water, and low oxygen and pH values. Conversely, lower Arcobacter abundances were obtained in the filaments collected in the entrance and middle part of the cave, where sulfidic water mixes with seawater, as the cave is subjected to tides and the mixing of fresh (continental) with marine water. The geochemical analysis of water and atmospheric gases confirmed these environmental constraints. In fact, the highest concentrations of H2S in the air and water were recorded closest to the spring upwelling in the innermost part of the cave, and the lowest ones near the cave entrance. The metabolic versatility of Arcobacter might provide a competitive advantage in the colonization of water bodies characterized by high sulfide, low oxygen, and dynamic fluid movement.

Inelastic scattering dynamics of naphthalene and 2-octanone on highly oriented pyrolytic graphite.

The inelastic scattering dynamics of the isobaric molecules, naphthalene (C10H8) and 2-octanone (C8H16O), on highly oriented pyrolytic graphite (HOPG) have been investigated as part of a broader effort to inform the inlet design of a mass spectrometer for the analysis of atmospheric gases during a flyby mission through the atmosphere of a planet or moon. Molecular beam-surface scattering experiments were conducted, and the scattered products were detected with the use of a rotatable mass spectrometer detector. Continuous, supersonic beams were prepared, with average incident translational energies, ⟨Ei⟩, of 247.3 kJ mol-1 and 538.2 kJ mol-1 for naphthalene and 268.6 kJ mol-1 and 433.8 kJ mol-1 for 2-octanone. These beams were directed toward an HOPG surface, held at 530 K, at incident angles, θi, of 30°, 45°, and 70°, and scattered products were detected as functions of their translational energies and scattering angles. The scattering dynamics of both molecules are very similar and mimic the scattering of atoms and small molecules on rough surfaces, where parallel momentum is not conserved, suggesting that the dynamics are dominated by a corrugated interaction potential between the incident molecule and the surface. The effective corrugation of the molecule-surface interaction is apparently caused by the structure of the incident molecule and the consequent myriad available energy transfer pathways between the molecule and the surface during a complex collision event. In addition, the HOPG surface contributes to the corrugation of the interaction potential because it can absorb significant energy from collisions with incident molecules that have high mass and incident energy. Small differences in the scattering dynamics of the two molecules are inferred to arise from the details of the molecule-surface interaction potential, with 2-octanone exhibiting dynamics that suggest a slightly stronger interaction with the surface than naphthalene. These results add to a growing body of work on the scattering dynamics of organic molecules on HOPG, from which insight into the hypervelocity sampling and analysis of such molecules may be obtained.

Towards an understanding of surface effects: testing of various materials in a small volume measurement chamber and its relevance for atmospheric trace gas analysis

Abstract. A critical issue for the long-term monitoring of atmospheric trace gases is precision and accuracy of the measurement systems employed. Both measuring and preparing reference gas mixtures for trace gases are challenging due to, for example, adsorption and desorption of the substances of interest on surfaces; this is particularly critical at low amount fractions and/or for reactive gases. Therefore, to ensure the best preparation and measurement conditions for trace gases in very low amount fractions, usage of coated materials is in demand in gas metrology and atmospheric measurement communities. This study focuses on testing potential adsorption and desorption effects for different materials or coatings that are currently used or that may be relevant in the future for the measurements of greenhouse gases. For this study we used small volume chambers designed to be used for adsorption studies. Various materials with or without coatings were loaded into the small cylinder to test their adsorption and desorption behavior. We used the aluminum cylinder as the measurement chamber and glass, aluminum, copper, brass, steel and three different commercially available coatings as test materials. Inserting the test materials into the measurement chamber doubles the available geometric area for the surface processes. The presented experiments were designed to investigate the pressure dependency of adsorption up to 15 bar and its temperature dependency up to 80 ∘C for the test materials placed in the measurement chamber. Here, we focused on the species CO2, CH4, CO and H2O measured by a cavity ring-down spectroscopy analyzer. Our results show that the materials currently used in atmospheric measurements are well suited. The investigated coatings were not superior to untreated aluminum or to stainless steel at the tested pressure ranges, whereas under changing temperature aluminum showed better performance for CO2 (<0.05 µmol mol−1 change in measured amount fractions) than stainless steel (>0.1 µmol mol−1). To our knowledge, this study is one of the first attempts to investigate surface effects of different materials in such a setup for the abovementioned gases.

Investigation of adsorption and desorption behavior of small-volume cylinders and its relevance for atmospheric trace gas analysis

Abstract. Atmospheric trace gas measurements of greenhouse gases are critical in their precision and accuracy. In the past 5 years, atmospheric measurement and gas metrology communities have turned their attention to possible surface effects due to pressure and temperature variations during a standard cylinder's lifetime. This study concentrates on this issue by introducing newly built small-volume aluminum and steel cylinders which enable the investigation of trace gases and their affinity for adsorption and desorption on various surfaces over a set of temperature and pressure ranges. The presented experiments are designed to test the filling pressure dependencies up to 30 bar and temperature dependencies from −10 ∘C up to 180 ∘C for these prototype cylinders. We present measurements of CO2, CH4, CO and H2O using a cavity ring-down spectroscopy analyzer under these conditions. Moreover, we investigated CO2 amount fractions using a novel quantum cascade laser spectrometer system enabling measurements at pressures as a low as 5 mbar. This extensive dataset revealed that for absolute pressures down to 150 mbar the enhancement in the amount fraction of CO2 relative to its initial value (at 1200 mbar absolute) is limited to 0.12 µmol mol−1 for the prototype aluminum cylinder. Up to 80 ∘C, the aluminum cylinder showed superior results and less response to varying temperature compared to the steel cylinder. For CO2, these changes were insignificant at 80 ∘C for the aluminum cylinder, whereas a 0.11 µmol mol−1 enhancement for the steel cylinder was observed. High-temperature experiments showed that for both cylinders irreversible temperature effects occur especially above 130 ∘C.

Analysis of Local Climate Variations Using Correlation between Satellite Measurements of Methane Emission and Temperature Trends within Physiographic Regions of Ukraine

Paper aimed to the description of the methods of analysis and measurements of atmospheric greenhouse gases (GHG), especially, methane concentration using satellite tools for climate change model improvement. The experimental accuracy estimation of narrow-band spectral indices restoration by the wide-band multispectral image is performed. Three methods for narrow-band spectral indices restoration are analyzed. The method on the basis of spectra translation is recommended for practical application.

Software system for numerical simulation of broadband laser gas analysis of the atmosphere

Introduction: Successful monitoring of environmental parameters requires the development of flexible software complexes with evolvable calculation functionality. Purpose: Developing a modular system for numerical simulation of atmospheric laser gas analysis. Results: Based on differential absorption method, a software system has been developed which provides the calculation of molecular absorption cross-sections, molecular absorption coefficients, atmospheric transmission spectra, and lidar signals. Absorption line contours are calculated using the Voigt profile. The prior information sources are HITRAN spectroscopic databases and statistical models of the distribution of temperature, pressure and gas components in the atmosphere. For modeling lidar signals, software blocks of calculating the molecular scattering coefficient and aerosol absorption/scattering coefficients were developed. For testing the applicability of various laser sources in the problems of environmental monitoring of the atmosphere, a concentration reconstruction error calculation block was developed for the atmospheric gas components, ignoring the interfering absorption of laser radiation by foreign gases. To verify the correct functioning of the software, a program block was developed for comparing the results of the modeling of atmospheric absorption and transmission spectra by using the standard SPECTRA information system. The discrepancy between the calculation of the atmospheric transmission spectra obtained using the developed system as compared to the SPECTRA results is less than 1%. Thus, a set of the presented program blocks allows you to carry out complex modeling of remote atmospheric gas analysis. Practical relevance: The software complex allows you to rapidly assess the possibilities of using a wide range of laser radiation sources for the problems of remote gas analysis.

Advanced Life Support Research and Technology Transfer at the University of Guelph

Abstract Research and technology developments surrounding Advanced Life-Support (ALS) began at the University of Guelph in 1992 as the Space and Advanced Life Support Agriculture (SALSA) program, which now represents Canada’s primary contribution to ALS research. The early focus was on recycling hydroponic nutrient solutions, atmospheric gas analysis and carbon balance, sensor research and development, inner/intra-canopy lighting and biological filtration of air in closed systems. With funding from federal, provincial and industry partners, a new generation of technology emerged to address the challenges of deploying biological systems as fundamental components of life-support infrastructure for long-duration human space exploration. Accompanying these advances were a wide range of technology transfer opportunities in the agri-food and health sectors, including air and water remediation, plant and environment sensors, disinfection technologies, recyclable growth substrates and advanced light emitting diode (LED) lighting systems. This report traces the evolution of the SALSA program and catalogues the benefits of ALS research for terrestrial and non-terrestrial applications.

Trace gas and dynamic process monitoring by Raman spectroscopy in metal-coated hollow glass fibres

Quantitative capillary Raman spectroscopy measurements are described, in which improved speed and sensitivity for atmospheric trace gas analysis and real-time monitoring of catalytic hydrogen-exchange reactions were demonstrated.

Kinetic studies of heterogeneous reactions of particulate phosmet and parathion with NO3 radicals

Organophosphorous pesticides (OPPs) are ubiquitous pollutants in the atmospheric environment with adverse effects on human health. In this study, heterogeneous kinetics of particulate phosmet and parathion with NO3 radicals were investigated with a mixed-phase relative rate method. A vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an atmospheric gas analysis mass spectrometer were used to monitor online the decays of particulate OPPs and reference compound, respectively. Reactive uptake coefficients of NO3 radicals on phosmet and parathion particles were (0.12±0.03) and (0.14±0.04), respectively, calculated according to the measured OPPs loss ratios and the average NO3 concentrations. Additionally, the average effective rate constants for heterogeneous reactions of particulate phosmet and parathion with NO3 radicals measured under experimental conditions were (2.80±0.16)×10−12 and (2.97±0.13)×10−12cm3molecule−1s−1, respectively. The experimental results of these heterogeneous reactions in the aerosol state provide supplementary knowledge for kinetic behaviors of airborne OPPs particles.

Products and kinetics of the heterogeneous reaction of particulate ametryn with NO3 radicals.

As a renowned s-triazine herbicide, ametryn is worldwide emitted into the atmosphere in both gaseous and particulate phases via spray drifts from treatments and post application emissions, but its chemical degradation in the atmosphere has not been well characterized. In this study, the heterogeneous kinetics of particulate ametryn with NO3 radicals were investigated with a mixed-phase relative rate method. A vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an atmospheric gas analysis mass spectrometer were synchronously used to online monitor the decays of particulate ametryn and gas-phase isoprene. The reactive uptake coefficient of NO3 radicals on ametryn particles was calculated to be 2.9 × 10(-2), according to the measured ametryn loss ratio and the average NO3 concentration. The effective rate constant for the heterogeneous reaction of particulate ametryn with NO3 radicals measured under experimental conditions was 8.4 × 10(-13) cm(3) molecule(-1) s(-1). In addition, atraton, ametryn sulfoxide and ametryn sulfone were identified as the reaction products by gas-chromatography-mass spectrometry (GC-MS) analysis. The experimental results might shed light on the chemical behavior of atmospheric ametryn at night-time.

Heterogeneous reaction of particulate chlorpyrifos with NO3 radicals: Products, pathways, and kinetics

Chlorpyrifos is a typical chlorinated organophosphorus pesticide. The heterogeneous reaction of chlorpyrifos particles with NO3 radicals was investigated using a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and a real-time atmospheric gas analysis mass spectrometer. Chlorpyrifos oxon, 3,5,6-trichloro-2-pyridinol, O,O-diethyl O-hydrogen phosphorothioate, O,O-diethyl ester thiophosphoric acid, diethyl hydrogen phosphate and a phosphinyl disulfide compound were identified as the main degradation products. The heterogeneous reaction pathways were proposed and their kinetic processes were investigated via a mixed-phase relative rate method. The observed effective rate constant is 3.4±0.2×10−12cm3molecule−1s−1.

Heterogeneous reactions of particulate benzo[b]fluoranthene and benzo[k]fluoranthene with NO3 radicals

Benzo[b]fluoranthene (B[b]F) and benzo[k]fluoranthene (B[k]F) are widespread priority pollutants of polycyclic aromatic hydrocarbons (PAHs), which can react with atmospheric oxidants during transport in the troposphere and lead to the formation of more toxic compounds. At present, the rates of heterogeneous reactions of B[b]F and B[k]F aerosols with NO3 radicals, an important atmospheric oxidant, are not fully understood. Thus, this study investigated the products and kinetics of heterogeneous reactions of suspended B[b]F and B[k]F particles with NO3 radicals in an aerosol reaction chamber at room temperature (293±2K) under atmospheric pressure. The reactions are monitored online using a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an atmospheric gas analysis mass spectrometer. The mono-nitro-, di-nitro-, tri-nitro-products, and those products containing both nitro and ketone groups are observed with VUV-ATOFMS. The effective rate constants for heterogeneous reactions of particulate B[b]F and B[k]F with NO3 radicals under the experimental conditions are respectively estimated to (1.2±0.1)×10−12cm3molecule−1s−1 and (5.8±0.3)×10−13cm3molecule−1s−1 using a mixed-phase relative rate method, and the corresponding effective uptake coefficients are respectively estimated to 0.22 and 0.65. The lifetimes of particulate B[b]F and B[k]F at a typical concentration of NO3 radicals (5×108moleculecm−3) in the lower troposphere during the night are estimated to 3.0 and 3.9h, respectively. The experimental results of these heterogeneous reactions in the aerosol state provide supplementary knowledge for kinetic behaviors of airborne PAHs particles.

Heterogeneous Reactions of Particulate Methoxyphenols with NO3 Radicals: Kinetics, Products, and Mechanisms

Methoxyphenols, tracers for wood smoke, are emitted into the atmosphere in large quantities, but their chemical degradation in the atmosphere has not been well characterized. In this study, heterogeneous kinetics of particulate syringaldehyde (SA), vanillic acid (VA), and coniferyl aldehyde (CA) with NO₃ radicals is investigated with a mixed-phase relative rate method. A vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer and an atmospheric gas analysis mass spectrometer are used to monitor online the decays of particulate methoxyphenols and gas-phase isoprene synchronously. The reactive uptake coefficients of NO₃ radicals on SA, VA, and CA particles are calculated to be 0.33, 0.31, and 0.28, respectively, according to the measured methoxyphenol loss ratios and the average NO₃ concentrations. The effective rate constants for heterogeneous reactions of particulate SA, VA, and CA with NO₃ radicals measured under experimental conditions are 5.7 × 10⁻¹², 5.2 × 10⁻¹², and 3.5 × 10⁻¹² cm³ molecule⁻¹ s⁻¹, respectively. In addition, oxalic acid, 2,6-dimethoxybenzoquinone, 5-nitro-VA, 4,6-dinitrogaiacol, protocatechuic acid, vanillin, 5-nitrovanillin, VA, and 5-nitro-CA are identified as the reaction products by gas chromatography-mass spectrometry analysis. On the basis of the identified products, the reaction mechanisms of methoxyphenols with NO₃ radicals are proposed. The main transformation pathway of methoxyphenols is the NO₃ electrophilic addition, followed by H-abstraction and nitro-substituted processes. The experimental results might shed light on the chemical behaviors of methoxyphenols at night.

Heterogeneous Reactions of Pirimiphos-Methyl and Pirimicarb with NO3 Radicals

Pirimiphos-methyl (PMM) and pirimicarb (PM) are two typical N,N-dialkyl substituted pyrimidine pesticides. The heterogeneous reactions of suspended PMM and PM particles with NO(3) radicals are investigated using an online aerosol time-of-flight mass spectrometer and a real-time atmospheric gas analysis mass spectrometer. Three products for PMM and five products for PM are observed and assigned with the aid of GC/MS. Phosphoric acid 2-diethylamino-6-methyl-4-pyrimidinyl dimethyl ester and 2-(dimethylamino)-5,6-dimethyl-4-hydroxy-pyrimidine are the main reaction products observed for PMM and PM, respectively. The effective rate constants for the reactions of PMM and PM particles with NO(3) radicals are (9.9 ± 0.3) × 10(-12) and (7.5 ± 0.3) × 10(-13) cm(3) molecule(-1) s(-1), respectively, obtained using a mixed-phase relative rate method. Geometries and energies of transition states (TS) and intermediates (IM) are obtained by DFT calculation to elucidate the detailed mechanism of the P═S group oxidation into the P═O group for PMM. The theoretical studies present the reasonable intermediates including the S-oxide and the diradical (IM1(a) and IM2(a)). The mechanism explanation may provide useful information for understanding the degradation mechanism of organothionophosphorus compounds in the environment.

Kinetic and product study of the heterogeneous reactions of NO3 radicals with suspended resmethrin, phenothrin, and fenvalerate particles

Resmethrin, phenothrin, and fenvalerate are the synthetic pyrethroids that have been used widely against groundling or flying insect pests both indoors and outdoors. In this study, the heterogeneous reactions of the three pyrethroid particles with NO3 radicals are investigated with a mixed-phase relative rate method. The reactions are performed in a reaction chamber equipped with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an atmospheric gas analysis mass spectrometer. The uptake coefficients of NO3 radicals on resmethrin, phenothrin, and fenvalerate particles are ∼0.20, 0.04, and 0.03 respectively, calculated with a spherical shell model. And the atmospheric lifetimes of the three pyrethroid particles toward NO3 radicals are estimated to be ∼2.6, 7.5, and 9.3h, respectively. The molecular structures of reaction products and the reaction pathways are suggested based on the measurements of VUV-ATOFMS and off-line GC–MS.