Development of a new smog chamber for studying the impact of different UV lamps on SAPRC chemical mechanism predictions and aerosol formation

2018 ◽  
Vol 15 (3) ◽  
pp. 171 ◽  
Author(s):  
Stephen White ◽  
Dennys Angove ◽  
Kangwei Li ◽  
Ian Campbell ◽  
Adrian Element ◽  
...  
Keyword(s):  
Light Source ◽  
Atmospheric Chemistry ◽  
Chemical Mechanism ◽  
Light Sources ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Wall Loss ◽  
Smog Chambers ◽  
Uv Lamps ◽  
The Impact

Environmental contextChemical mechanisms are an important component of predictive air quality models that are developed using smog chambers. In smog chamber experiments, UV lamps are often used to simulate sunlight, and the choice of lamp can influence the obtained data, leading to differences in model predictions. We investigate the effect of various UV lamps on the prediction accuracy of a key mechanism in atmospheric chemistry. AbstractA new smog chamber was constructed at CSIRO following the decommissioning of the previous facility. The new chamber has updated instrumentation, is 35 % larger, and has been designed for chemical mechanism and aerosol formation studies. To validate its performance, characterisation experiments were conducted to determine wall loss and radical formation under irradiation by UV lamps. Two different types of blacklights commonly used in indoor chambers are used as light sources, and the results using these different lamps are investigated. Gas-phase results were compared against predictions from the latest version of the SAPRC chemical mechanism. The SAPRC mechanism gave accurate results for hydrocarbon reaction and oxidation formation for propene and o-xylene experiments, regardless of the light source used, with variations in ozone concentrations between experiment and modelled results typically less than 10 % over 6-h irradiation. The SAPRC predictions for p-xylene photooxidation showed overprediction in the rate of oxidation, although no major variations were determined in mechanism results for different blacklight sources. Additionally, no significant differences in the yields of aerosol arising from new particle formation were discernible regardless of the light source used under these conditions.

scholarly journals Design and characterization of a smog chamber for studying gas-phase chemical mechanisms and aerosol formation

2014 ◽  
Vol 7 (1) ◽  
pp. 301-313 ◽  
Author(s):  
X. Wang ◽  
T. Liu ◽  
F. Bernard ◽  
X. Ding ◽  
S. Wen ◽  
...  
Keyword(s):  
Gas Phase ◽  
Chemical Mechanism ◽  
Quality Data ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Product Model ◽  
Yield Data ◽  
Dry Conditions ◽  
Wall Loss

Abstract. We describe here characterization of a new state-of-the-art smog chamber facility for studying atmospheric gas-phase and aerosol chemistry. The chamber consists of a 30 m3 fluorinated ethylene propylene (FEP) Teflon film reactor housed in a temperature-controlled enclosure equipped with black lamps as the light source. Temperature can be set in the range from −10 to 40 °C at accuracy of ±1 °C as measured by eight temperature sensors inside the enclosure and one just inside the reactor. Matrix air can be purified with non-methane hydrocarbons (NMHCs) < 0.5 ppb, NOx/O3/carbonyls < 1 ppb and particles < 1 cm−3. The photolysis rate of NO2 is adjustable between 0 and 0.49 min−1. At 298 K under dry conditions, the average wall loss rates of NO, NO2 and O3 were measured to be 1.41 × 10−4 min−1, 1.39 × 10−4 min−1 and 1.31 × 10−4 min−1, respectively, and the particle number wall loss rate was measured to be 0.17 h−1. Auxiliary mechanisms of this chamber are determined and included in the Master Chemical Mechanism to evaluate and model propene–NOx–air irradiation experiments. The results indicate that this new smog chamber can provide high-quality data for mechanism evaluation. Results of α-pinene dark ozonolysis experiments revealed secondary organic aerosol (SOA) yields comparable to those from other chamber studies, and the two-product model gives a good fit for the yield data obtained in this work. Characterization experiments demonstrate that our Guangzhou Institute of Geochemistry, Chinese Academy Sciences (GIG-CAS), smog chamber facility can be used to provide valuable data for gas-phase chemistry and secondary aerosol formation.

scholarly journals Impact of chamber wall loss of gaseous organic compounds on secondary organic aerosol formation: explicit modeling of SOA formation from alkane and alkene oxidation

2016 ◽  
Vol 16 (3) ◽  
pp. 1417-1431 ◽  
Author(s):  
Y. S. La ◽  
M. Camredon ◽  
P. J. Ziemann ◽  
R. Valorso ◽  
A. Matsunaga ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chamber Wall ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Organic Vapors ◽  
Alkene Oxidation ◽  
Branched Alkanes ◽  
Wall Loss ◽  
Kinetics Of

Abstract. Recent studies have shown that low volatility gas-phase species can be lost onto the smog chamber wall surfaces. Although this loss of organic vapors to walls could be substantial during experiments, its effect on secondary organic aerosol (SOA) formation has not been well characterized and quantified yet. Here the potential impact of chamber walls on the loss of gaseous organic species and SOA formation has been explored using the Generator for Explicit Chemistry and Kinetics of the Organics in the Atmosphere (GECKO-A) modeling tool, which explicitly represents SOA formation and gas–wall partitioning. The model was compared with 41 smog chamber experiments of SOA formation under OH oxidation of alkane and alkene series (linear, cyclic and C12-branched alkanes and terminal, internal and 2-methyl alkenes with 7 to 17 carbon atoms) under high NOx conditions. Simulated trends match observed trends within and between homologous series. The loss of organic vapors to the chamber walls is found to affect SOA yields as well as the composition of the gas and the particle phases. Simulated distributions of the species in various phases suggest that nitrates, hydroxynitrates and carbonylesters could substantially be lost onto walls. The extent of this process depends on the rate of gas–wall mass transfer, the vapor pressure of the species and the duration of the experiments. This work suggests that SOA yields inferred from chamber experiments could be underestimated up a factor of 2 due to the loss of organic vapors to chamber walls.

scholarly journals Investigation of particle and vapor wall-loss effects on controlled wood-smoke smog-chamber experiments

2015 ◽  
Vol 15 (11) ◽  
pp. 15243-15288
Author(s):  
Q. Bian ◽  
A. A. May ◽  
S. M. Kreidenweis ◽  
J. R. Pierce
Keyword(s):  
Mass Loss ◽  
Gas Phase ◽  
Basis Set ◽  
Wood Smoke ◽  
Smog Chamber ◽  
Organic Mass ◽  
Final Particle ◽  
Wall Losses ◽  
Wall Loss ◽  
Smog Chambers

Abstract. Smog chambers are extensively used to study processes that drive gas and particle evolution in the atmosphere. A limitation of these experiments is that particles and gas-phase species may be lost to chamber walls on shorter timescales than the timescales of the atmospheric processes being studied in the chamber experiments. These particle and vapor wall losses have been investigated in recent studies of secondary organic aerosol (SOA) formation, but they have not been systematically investigated in experiments of primary emissions from combustion. The semi-volatile nature of combustion emissions (e.g. from wood smoke) may complicate the behavior of particle and vapor wall deposition in the chamber over the course of the experiments due to the competition between gas/particle and gas/wall partitioning. Losses of vapors to the walls may impact particle evaporation in these experiments, and potential precursors for SOA formation from combustion may be lost to the walls, causing underestimates of aerosol yields. Here, we conduct simulations to determine how particle and gas-phase wall losses contributed to the observed evolution of the aerosol during experiments in the third Fire Lab At Missoula Experiment (FLAME III). We use the TwO-Moment Aerosol Sectional (TOMAS) microphysics algorithm coupled with the organic volatility basis set (VBS) and wall-loss formulations to examine the predicted extent of particle and vapor wall losses. We limit the scope of our study to the dark periods in the chamber before photo-oxidation to simplify the aerosol system for this initial study. Our model simulations suggest that over one third of the initial particle-phase organic mass (36%) was lost during the experiments, and roughly half of this particle organic mass loss was from direct particle wall loss (56% of the loss) with the remainder from evaporation of the particles driven by vapor losses to the walls (44% of the loss). We perform a series of sensitivity tests to understand uncertainties in our simulations. Uncertainty in the initial wood-smoke volatility distribution contributes 23% uncertainty to the final particle organic mass remaining in the chamber (relative to base-assumptions simulation). We show that the total mass loss may depend on the effective saturation concentration of vapor with respect to the walls as these values currently vary widely in the literature. The details of smoke dilution during the filling of smog chambers may influence the mass loss to the walls, and a dilution of ~ 25:1 during the experiments increased particle organic mass loss by 64% compared to a simulation where we assume the particles and vapors are initially in equilibrium in the chamber. Finally, we discuss how our findings may influence interpretations of emission factors and SOA production in wood-smoke smog-chamber experiments.

scholarly journals A portable dual smog chamber system for atmospheric aerosol field studies

2018 ◽  
Author(s):  
Christos Kaltsonoudis ◽  
Spiro D. Jorga ◽  
Evangelos Louvaris ◽  
Kalliopi Florou ◽  
Spyros N. Pandis
Keyword(s):  
Ambient Air ◽  
Field Studies ◽  
Atmospheric Particulate Matter ◽  
Smog Chamber ◽  
Chamber System ◽  
Physical Processes ◽  
Starting Point ◽  
Hexagonal Arrangement ◽  
Smog Chambers ◽  
Uv Lamps

Abstract. Smog chamber experiments using as a starting point ambient air can improve our understanding of the evolution of atmospheric particulate matter at timescales longer than those achieved by traditional laboratory experiments. These types of studies can take place under more realistic environmental conditions addressing the interactions among multiple pollutants. The use of two identical smog chambers, with the first serving as the baseline chamber and the second as the perturbation chamber (in which addition or removal of pollutants, addition of oxidants, change in the relative humidity, etc.), can facilitate the interpretation of the results in such inherently complex experiments. The differences of the measurements in the two chambers can be used as the basis for the analysis of the corresponding chemical or physical processes of ambient air. A portable dual smog chamber system was developed using two identical pillow-shaped smog chambers (1.5 m3 each). The two chambers are surrounded by UV lamps in a hexagonal arrangement yielding a total JNO2 of 0.1 min−1. The system can be easily disassembled and transported enabling the study of various atmospheric environments. Moreover, it can be used with natural sunlight. The results of test experiments using ambient air as starting point are discussed as examples of applications of this system.

scholarly journals Influence of a Light Source Installed in a Luminaire of Opal Sphere Type on the Effect of Light Pollution

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 306 ◽  
Author(s):  
Przemyslaw Tabaka ◽  
Pawel Rozga
Keyword(s):  
Light Source ◽  
Spectral Distribution ◽  
Spectral Characteristics ◽  
Measurement Data ◽  
Luminous Flux ◽  
Light Pollution ◽  
Light Sources ◽  
Pollution Effect ◽  
The Impact ◽  
Effect Of Light

The article presents the results of the studies concerning the influence of a light source installed in luminaire of opal sphere type on the light pollution effect of the night sky. It is known from literature reports that the effect of light pollution is influenced by the spectral distribution of light. Although the influence of the spectral distribution has been widely studied from different perspectives, there is still a need to study this phenomenon—for example, from the point of view of the spectral reflection properties of the ground, on which the lanterns are installed. Hence, the above-mentioned aspect was considered in the authors’ investigations. The luminaire considered has been equipped with 20 different light sources, including the latest generation of lamps (light-emitting diodes, LEDs) as well as the conventional ones. With respect to these light sources, the measurements of light distribution and spectral distribution of emitted radiation of the luminaire were performed. Having these measurement data, the simulations were carried out using the DIALux software, and the calculations were made using the specially prepared calculation tool. On the basis of the results obtained in this way this was stated that the type of light source installed in the luminaire has a significant effect on the sky glow. An important factor affecting light pollution is not only the value of the luminous flux emitted upward but also the spectral characteristics of the emitted radiation, the impact of which is most noticeable. The conclusions from the studies indicate the next steps in the analysis of the light pollution effect. These steps will be focused on extended analysis of LEDs as modern and developed light sources.

scholarly journals Monochromatic light-emitting diode (LED) source in layers hens during the second production cycle

2015 ◽  
Vol 19 (9) ◽  
pp. 877-881 ◽  
Author(s):  
Rodrigo Borille ◽  
Rodrigo G. Garcia ◽  
Irenilza A. Nääs ◽  
Fabiana R. Caldara ◽  
Mayara R. Santana
Keyword(s):  
Light Source ◽  
Laying Hens ◽  
Egg Quality ◽  
Monochromatic Light ◽  
Latin Square ◽  
Continuous Illumination ◽  
Production Cycle ◽  
Light Sources ◽  
Light Regimen ◽  
The Impact

ABSTRACTLight is an important environmental factor for birds, allowing not only their vision, but also influencing their physiological responses, such as behavioral and reproductive activity. The objective of this experiment was to evaluate the impact of different colors of monochromatic light (LED) sources in laying hens production during the second laying cycle. The study was conducted in an experimental laying house during 70 days. A total of 300 laying hens Isa Brown® genetic strain, aged 95 weeks, in the second laying cycle were used in the study. The artificial light sources used were blue, yellow, green, red and white. The light regimen was continuous illumination of 17 h per day (12 h natural and 5 h artificial) in a daily light regimen of 17L:5D (light: dark). The Latin Square design was adopted with five treatments (five colors) divided into five periods, and five boxes, with six replicates of ten birds in each box. The production and egg quality were evaluated. The different colors of light source did not affect production parameters or egg quality (p > 0.05). The monochromatic light source may be considered as an alternative to artificial lighting in laying hens during the second production cycle.

scholarly journals Improvements to the representation of BVOC chemistry–climate interactions in UKCA (v11.5) with the CRI-Strat 2 mechanism: incorporation and evaluation

2021 ◽  
Vol 14 (8) ◽  
pp. 5239-5268
Author(s):  
James Weber ◽  
Scott Archer-Nicholls ◽  
Nathan Luke Abraham ◽  
Youngsub M. Shin ◽  
Thomas J. Bannan ◽  
...  
Keyword(s):  
United Kingdom ◽  
Rate Constants ◽  
Inorganic Nitrogen ◽  
Peroxy Radical ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Aerosol Formation ◽  
Reaction Rate Constants ◽  
Climate Interactions ◽  
The Impact

Abstract. We present the first incorporation of the Common Representative Intermediates version 2.2 tropospheric chemistry mechanism, CRI v2.2, combined with stratospheric chemistry, into the global chemistry–climate United Kingdom Chemistry and Aerosols (UKCA) model to give the CRI-Strat 2 mechanism. A rigorous comparison of CRI-Strat 2 with the earlier version, CRI-Strat, is performed in UKCA in addition to an evaluation of three mechanisms, CRI-Strat 2, CRI-Strat and the standard UKCA chemical mechanism, StratTrop v1.0, against a wide array of surface and airborne chemical data. CRI-Strat 2 comprises a state-of-the-art isoprene scheme, optimized against the Master Chemical Mechanism v3.3.1, which includes isoprene peroxy radical isomerization, HOx recycling through the addition of photolabile hydroperoxy aldehydes (HPALDs), and isoprene epoxy diol (IEPOX) formation. CRI-Strat 2 also features updates to several rate constants for the inorganic chemistry, including the reactions of inorganic nitrogen and O(1D). The update to the isoprene chemistry in CRI-Strat 2 increases OH over the lowest 500 m in tropical forested regions by 30 %–50 % relative to CRI-Strat, leading to an improvement in model–observation comparisons for surface OH and isoprene relative to CRI-Strat and StratTrop. Enhanced oxidants also cause a 25 % reduction in isoprene burden and an increase in oxidation fluxes of isoprene and other biogenic volatile organic compounds (BVOCs) at low altitudes with likely impacts on subsequent aerosol formation, atmospheric lifetime, and climate. By contrast, updates to the rate constants of O(1D) with its main reactants relative to CRI-Strat reduces OH in much of the free troposphere, producing a 2 % increase in the methane lifetime, and increases the tropospheric ozone burden by 8 %, primarily from reduced loss via O(1D)+H2O. The changes to inorganic nitrogen reaction rate constants increase the NOx burden by 4 % and shift the distribution of nitrated species closer to that simulated by StratTrop. CRI-Strat 2 is suitable for multi-decadal model integrations and the improved representation of isoprene chemistry provides an opportunity to explore the consequences of HOx recycling in the United Kingdom Earth System Model (UKESM1). This new mechanism will enable a re-evaluation of the impact of BVOCs on the chemical composition of the atmosphere and further probe the feedback between the biosphere and the climate.

scholarly journals Parameterising secondary organic aerosol from α-pinene using a detailed oxidation and aerosol formation model

2012 ◽  
Vol 12 (12) ◽  
pp. 5343-5366 ◽  
Author(s):  
K. Ceulemans ◽  
S. Compernolle ◽  
J.-F. Müller
Keyword(s):  
Water Uptake ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Model Parameters ◽  
Full Model ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Formation Model ◽  
Volatile Products

Abstract. A new parameter model for α-pinene secondary organic aerosol (SOA) is presented, based on simulations with the detailed model BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model). The parameterisation takes into account the influence of temperature, type of oxidant, NOx-regime, photochemical ageing and water uptake, and is suitable for use in global chemistry transport models. BOREAM is validated against recent photooxidation smog chamber experiments, for which it reproduces SOA yields to within a factor of 2 in most cases. In the simple chemical mechanism of the parameter model, oxidation of α-pinene generates peroxy radicals, which, upon reaction with NO or HO2, yield products corresponding to high or low-NOx conditions, respectively. The model parameters – i.e. the temperature-dependent stoichiometric coefficients and partitioning coefficients of 10 semi-volatile products – are obtained from simulations with BOREAM, including a prescribed diurnal cycle for the radiation, oxidant and emission levels, as well as a deposition sink for the particulate and gaseous products. The effects of photooxidative ageing are implicitly included in the parameterisation, since it is based on near-equilibrium SOA concentrations, obtained through simulations of a two-week period. In order to mimic the full BOREAM model results both during SOA build-up and when SOA has reached an equilibrium concentration, the revolatilisation of condensable products due to photochemical processes is taken into account through a fitted pseudo-photolysis reaction of the lumped semi-volatile products. Modelled SOA mass yields are about ten times higher in low-NOx than in high-NOx conditions, with yields of more than 50% in the low-NOx OH-initiated oxidation of α-pinene, considerably more than in previous parameterisations based on smog chamber experiments. Sensitivity calculations indicate that discrepancies between the full model and the parameterisation due to variations in assumed oxidant levels are limited, but that changes in the radiation levels can lead to larger deviations. Photolysis of species in the particulate phase is found to strongly reduce SOA yields in the full model. Simulations of ambient conditions at 17 different sites (using oxidant, radiation and meteorological data from a global chemistry-transport model) show that overall, the parameterisation displays only little bias (2%) compared with the full model, whereas averaged relative deviations amount to about 11%. Water uptake is parameterised using fitted activity coefficients, resulting in a good agreement with the full model.

Influence of Light Source and Cathodoluminescence on the Color Parameters of Ruby Red

2011 ◽  
Vol 492 ◽  
pp. 379-383 ◽  
Author(s):  
Xiang Li ◽  
Ying Guo
Keyword(s):  
Light Source ◽  
Power Distribution ◽  
Light Sources ◽  
Visual Appearance ◽  
Color Parameters ◽  
Red Color ◽  
Strong Luminescence ◽  
Hue Angle ◽  
The Impact ◽  
Sun Light

According to different light sources and cathodoluminescence (CL) intensity, the performance of color parameters (lightness L*, chromaticity a* and b*, chroma C*, hue angle ho) and chromophore contents (Cr3+, åFe) are studied to analyze the impact of all these elements on ruby red color. Ruby red under the standard light source D65 (a*=5.65 ~ 26.97, b*= -5.43~3.98) is similar with the color under natural sun-light. Purplish red ho Î (354.14°, 0.7°) with medium-low lightness (L*= 32 ~ 40) under D65 displays the best visual appearance, showing a relatively high value. Comparing with D65, standard light source A reveals ruby a deep red hue (a*= 10.61 ~ 37.39, b*= -6.59 ~ 7.50). Because of the strongest spectrum power distribution in the orange range and fluorescence of light source U30, the hue of orangish tone is mixed in ruby red (a*= 6.92 ~ 31.23, b*= 0.31 ~ 9.34). It is illustrated that åFe can inhibit the intensity of CL which is compared in different voltages. Low lightness purplish red is easy to be influenced by CL and always shows strong luminescence correspondingly. It is concluded that ruby purplish red has strong luminescence of CL which is usually supported by a few of åFe and medium-low lightness under D65, which has an excellent visual perception.

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