Emission Ratio Research Articles

Ubiquity of Anthropogenic Terpenoids in Cities Worldwide: Emission Ratios, Emission Quantification and Implications for Urban Atmospheric Chemistry

AbstractTerpenoids (isoprene and monoterpenes) are highly reactive Volatile Organic Compounds (VOCs) known for decades for their biogenic origin. Here, we discuss the nature and magnitude of their anthropogenic emissions. We compiled and re‐analyzed 14 data sets of in situ VOC observations collected over the last decade in contrasting urban areas from mid‐latitudes to subtropical regions. We show the systematic presence of anthropogenic terpenoids in urban ambient air with clear covariations with anthropogenic compounds (R2 > 0.50) even during mid‐latitude winters. Despite the emerging importance of monoterpene emissions from consumer products in North American cities, there is some evidence of monoterpene emissions from tailpipe exhaust in cities of the developing world. The traffic‐related fraction of monoterpenes is estimated and can account for up to 40% of their ambient levels. The anthropogenic emission ratios (ER) of some terpenoids (isoprene, α‐pinene and limonene) are estimated and spatially compared. The anthropogenic emissions of terpenoids are indirectly estimated from those ER combined to regional and global emission inventories (CAMS‐GLOB‐ANT_v4.2) at urban and country scale focusing on France, Lebanon, and Vietnam. Those anthropogenic emissions do not represent more than 3% of other anthropogenic VOC emissions. However, they dominate by one to three orders of magnitude the reactivity of other anthropogenic VOCs regarding NO3 oxidation and ozonolysis. This study raises two questions which need further investigations in the future: (a) the significance of terpenoid emissions from traffic, especially in urban areas of the developing world and (b) the role of anthropogenic terpenoids in nighttime and wintertime atmospheric chemistry at mid‐latitudes.

Carbon Emissions Assessment Fly ash and Steel Slag As a Substitute for Cement in Concrete Mixing Using the Method Artificial Neural Networks

Concrete is a construction material made from a mixture of Portland cement, air, coarse aggregate, fine aggregate, and sometimes also uses admixture materials with a certain ratio. Cement, which is the binding agent in the concrete mixture, contributes to 8% of the world's carbon dioxide (CO2) emissions. Fly ash and steel slag are one of the wastes that are currently being researched and developed as cement ingredients in concrete mixtures. This is because the chemical composition of fly ash and slag associated with cement is very suitable when added to concrete mixtures.This study aims to find out of the optimal of fly ash and slag content in the concrete mixture in terms of strength by using the Artificial Neural Network (ANN) method and in accordance with SNI 7656: 2012. Furthermore, this study also aims to measure the ratio of CO2 emissions that are produced from normal concrete, concrete with fly ash, and concrete with steel slag, using references from Idemat2014 and Ecoinvent V3.The results showed that the optimum content of fly ash class F, fly ash class C, and steel slag in the concrete mixture were 30%, 20%, and 55%, respectively. The results also concluded that steel concrete slag as the lowest emitter of CO2 compared to normal concrete, class F fly ash concrete, and class C fly ash concrete. Keywords: concrete, fly ash, steel slag, ANN, comppresive strength, CO2 emission

Research Methods of Carbon Emissions

As a pillar industry, the construction industry generates 28% of the total carbon emissions of the whole society throughout its life cycle. Through the carbon emission ratio of the whole life cycle of existing buildings, it is found that the carbon emission per unit time in the construction phase is the highest among all phases, and the various environmental pollution caused by it is also the most concentrated. In order to achieve low carbon construction and reduce environmental pollution, relevant parts of the country have promulgated building construction management documents since 2007. The documents put forward clear requirements for green and low-carbon urban and rural construction to ensure green and low-carbon construction activities. It can be seen that in the context of the "two carbon" strategy, carbon emission monitoring and carbon emission reduction of construction have attracted wide attention from all walks of life. In this paper, through the analysis of carbon emission monitoring methods of construction projects, a carbon emission calculation model based on carbon sources and sinks of the construction process is established to realize the quantitative calculation of carbon emission in the construction phase of construction projects. It also establishes a carbon emission monitoring method for the construction phase of the construction project, which provides practical guidance for the carbon emission data monitoring of each construction project and guides the real-time monitoring of carbon emission during the construction phase of the construction project.

Synthesis, structural and temperature-sensing properties of nanosized Y2Ba3B4O12: Nd3+/Yb3+ phosphors

This work involved the synthesis and characterization of the Y2Ba3B4O12 phase that has undergone various heat treatment periods and temperatures. This study concentrated on optical nanothermometry applications, with an emphasis on the near-infrared (NIR) spectrum and the temperature range of 25–55 °C to assess potential biological applications. The polymeric precursor method was used for the synthesis of Y2Ba3B4O12 nanoparticles co-doped with Nd3+ and Yb3+ with (0; 0.2; 0.5; 1.0 and 2.0) mol% treated at 1000 °C for 5 min, after the structural and spectroscopic thermal characterizations were performed. In order to confirm the heat treatment temperature (1000 °C for 5 min) for the production of crystalline phases, measurements employing thermal analysis (thermogravimetry and differential exploratory calorimetry) were used. The creation of the materials' pure phase was confirmed by the structural characterization performed using Raman spectroscopy and X-ray diffraction. Through Transmission Electron Microscopy it was possible to measure the size (∼110 nm) and different shapes of the particles and by electron diffraction the crystallite monocrystalline character was observed. We were able to analyze the doping ions' absorption bands using diffuse reflectance spectroscopy, to evaluate the high reflectance region of the matrix (areas where the pure matrix does not absorb), and to determinate the optical bandgap using the Kubelka-Munk equation. Additionally, it was examined how the fluorescence intensity ratios of Stark components changed as a function of temperature. In relation to the intensity ratio of the powder's emissions at 897 nm and 978 nm, the maximum sensor thermal sensitivity of 0.31%.°C−1 was determined.

Spatiotemporal mapping of atmospheric aldehydes over Beijing in summer during 2019–2021 via their source apportionment study

Atmospheric aldehydes have the important impacts on human health and air pollutions, however, their surface concentrations are never captured due to the sparse monitoring works and need to be studied. Here, we tried to map the aldehyde pollutions over Beijing in summer of recent years, via monitoring their levels in one urban site, simulating their chemical formations based on box chemical model, and developing their prediction formulae by using CO and O3 as explanatory variables based on statistical technique. Our monitoring showed that HCHO and CH3CHO were the dominant components respectively at the level of 4.5–27.2 and 0.9–10.78 ppb, and explained 86.9% of total aldehydes detected. Their mixing ratios to CO were higher by a factor of 2.5–4.0 than the corresponding emission ratios from combustion sources, which implied a big contribution of photochemistry to secondary aldehyde formation. Hence, we used box model coupled with MCM to simulate the evolutions of HCHO, CH3CHO and O3 from the emission plumes of this city, and found the production ratio of 0.14 for HCHO:O3 and 0.07 for CH3CHO:O3 on daytime average. Afterwards, we developed the prediction formulae separately for the two aldehydes based on multiple linear regression by using CO and O3 as explanatory variables, and obtained the regression coefficients of ∼0.15 (HCHO) and ∼ 0.04 (CH3CHO) with O3, which were well consistent with the corresponding simulated ratios by box model. Thus, these prediction formulae were applied to map the spatiotemporal concentrations of the two aldehydes in summer over this city, combining CO and O3 monitoring data. In result, the area means of HCHO and CH3CHO over Beijing (except north rural areas) reached 11.8 and 3.6 ppb in 2021 summer, decreasing by 11.9% and 9.3% relative to 2019 respectively; and their spatial difference became smaller apparently within three years. Such spatiotemporal variations were approved by HCHO satellite observations. Overall, the aldehyde pollutions in this city are still severe and deserve more studies in future.

Potential global warming impact of 1 kW polymer electrolyte membrane fuel cell system for residential buildings on operation phase

This study established global warming potential(GWP) emission factors through a life cycle assessment on the operation phases of two different 1 kW polymer electrolyte membrane fuel cell (PEMFC) systems for residential buildings (NG-PEMFC, fed with hydrogen from natural gas reforming; WE-PEMFC, fed with hydrogen from photovoltaics-powered water electrolyzer). Their effectiveness was also compared with conventional power grid systems in Korea, specifically in the area of greenhouse gas emissions.The operation phases of the NG-PEMFC and the WE-PEMFC were divided into burner, reformer, and stack, and into water electrolysis and stack, respectively. The functional unit of each fuel cell system was defined as 1 kWh of electricity production. In the case of NG-PEMFC, the GWP was 3.72E-01 kg-CO2eq/kWh, the embodied carbon emissions due to using city gas during the life cycle process was about 20.87 %, the carbon emission ratio according to the reformer's combustion burner was 6.07 %, and the direct carbon emission ratio of the air emissions from the reformer was 73.06 %, indicating that the carbon emission from the reformer contributed over 80 % of the total GWP. As for the WE-PEMFC, the GWP was 1.76E-01 kg-CO2eq/kWh, and the embodied carbon emissions from photovoltaic power generation during the life cycle process contributed over 99 % of the total GWP.

Estimating enhancement ratios of nitrogen dioxide, carbon monoxide and carbon dioxide using satellite observations

Abstract. Using co-located space-based measurements of carbon dioxide (CO2) from the Orbiting Carbon Observatory-2 and Orbiting Carbon Observatory-3 (OCO-2/3) and carbon monoxide (CO) and nitrogen dioxide (NO2) from the TROPOspheric Monitoring Instrument (TROPOMI), we calculate total column enhancements for observations influenced by anthropogenic emissions from urban regions relative to clean background values. We apply this method to observations taken over or downwind of 27 large (population of >1 million) urban areas from around the world. Enhancement ratios between species are calculated and compared to emissions ratios derived from four globally gridded anthropogenic emissions inventories. We find that these global inventories underestimate CO emissions in many North American and European cities relative to our observed enhancement ratios, while smaller differences were found for NO2 emissions. We further demonstrate that the calculation and intercomparison of enhancement ratios of multiple tracers can help to identify the underlying biases leading to disagreement between observations and inventories. Additionally, we use high-resolution CO2 inventories for two cities (Los Angeles and Indianapolis) to estimate emissions of CO and NO2 using our calculated enhancement ratios and find good agreement with both a previous modelling study for the megacity of Los Angeles and California Air Resources Board (CARB) inventory estimates.

A Förster resonance energy transfer-based d-2-hydroxyglutarate biosensor

d-2-Hydroxyglutarate (d-2-HG) is an oncometabolite aberrantly accumulated in patients with d-2-hydroxyglutaric aciduria or various isocitrate dehydrogenases mutation-associated cancers. The detection of d-2-HG is of great significance for the diagnostic and therapeutic aspects of these diseases. Herein, a Förster resonance energy transfer (FRET)-based d-2-HG biosensor was developed. The d-2-HG-specific allosteric transcription factor DhdR from Achromobacter denitrificans NBRC 15125 was used as its biorecognition element and inserted between two fluorescent proteins Clover and mRuby2. The response magnitude of the biosensor was improved by truncation of the terminal amino acids of DhdR and addition of artificial linkers. The optimized variant DHGFR1.0 exhibited excellent sensitivity and specificity with a maximum emission ratio change (ΔRmax) of 30.77%, a half-maximal effective concentration (EC50) of 2.78 μM, and a dynamic detection range of 0.17–36.22 μM. It was able to detect the concentration of d-2-HG in body fluids and cell-related samples with high accuracy and precision in vitro. The ligand-binding site of DhdR was predicted and several biosensors with low affinity for d-2-HG were also generated by site-directed mutagenesis of DhdR.

Intraoperative Real-Time Near-Infrared Image-Guided Endoscopic Endonasal Surgery for Pituitary Tumors

For endoscopic endonasal surgery of pituitary tumors, tissue identification and intraoperative judgment depend largely on surgeon expertise. In the present study, we assess whether the delayed-window indocyanine green (ICG) technique can identify pituitary gland tumors in real-time during surgery and analyze the mechanism of ICG fluorescence in the pituitary gland and tumor. Twenty-five patients with a pituitary adenoma were administered 12.5 mg of ICG intravenously during surgery. Thereafter, near-infrared (NIR) visualization was performed from 0 to 180 minutes. Only 8 patients underwent dynamic contrast-enhanced perfusion magnetic resonance imaging (MRI) owing to predicaments with insurance coverage. Consequently, we analyzed these 8 patients extensively. The pituitary gland and pituitary adenoma were visualized in all 25 patients with NIR fluorescence. The relative ratio of the fluorescence emission of the normal gland to that of the tumor (signal/background ratio [SBR] of the normal gland vs. the tumor) had increased after 15 minutes, peaking (5.8) at 90 minutes, demonstrating that the pituitary gland was distinctly visualized during that period. The tumor/blood (SBR tumor) and normal gland/blood (SBR gland) NIR fluorescence was significantly and positively correlated with each transfer constant on dynamic contrast-enhanced MRI, indicating vascular permeability. The results from the present study exhibit the utility of the delayed-window ICG technique in distinguishing the normal pituitary gland from a tumor during endoscopic endonasal surgery from 15 to 90 minutes after ICG administration. Permeability can contribute to gadolinium enhancement on MRI, as well as ICG retention and NIR fluorescence in a normal pituitary gland and tumor.

Using Space‐Based CO2 and NO2 Observations to Estimate Urban CO2 Emissions

AbstractAs the majority of fossil fuel carbon dioxide (CO2) emissions originate from cities, the use of novel techniques to leverage available satellite observations of CO2 and proxy species to constrain urban CO2 is of great importance. In this study, we seek to empirically determine relationships between satellite observations of CO2 and the proxy species nitrogen dioxide (NO2), applying these relationships to NO2 fields to generate NO2‐derived CO2 fields (NDCFs) from which CO2 emissions can be estimated. We first establish this method using simulations of CO2 and NO2 for the cities of Buenos Aires, Melbourne, and Mexico City, finding that the method is viable throughout the year. For the same three cities, we next calculate empirical relationships (slopes) between co‐located observations of NO2 from the Tropospheric Monitoring Instrument and Snapshot Area Mode observations of CO2 from Orbiting Carbon Observatory‐3. Applying varying combinations of slopes to generate NDCFs, we evaluate methodological uncertainties for each slope application method and use a simple mass balance method to estimate CO2 emissions from NDCFs. We demonstrate monthly urban CO2 emissions estimates that are comparable to emissions inventory estimates. We additionally prove the utility of our method by demonstrating how large uncertainties at a grid cell level (equivalent to ∼1–3 ppm) can be reduced substantially when aggregating emissions estimates from NDCFs generated from all NO2 swaths (about 1%–6%). Rather than rely on prior knowledge of emission ratios, our method circumvents such assumptions and provides a valuable observational constraint on urban CO2 emissions.

Cs2SnCl6:Bi3+, Te4+ flexibility polysiloxane luminescent ceramics and application

In recent years, lead-free metal halide luminescent materials have attracted extensive attention because of their excellent properties including but not limited to good environmental compatibility, ultrawide emission band, and high photoluminescence quantum yield. They are considered to have great application potential in the photoelectric field. We modified the previously reported synthesis and prepared pure phase Cs2SnCl6 : Bi3 + , Te4 + using simple solution method. Then the emitter was further coated with polysiloxane to form polysiloxane luminescent ceramic (PSOLC). The prepared PSOLCs have almost the same luminescence as the powders, and their color coordinates and color temperature can be tuned freely by adjusting the ratio of blue and yellow emission, which both encourage outdoor-lighting application. Additionally, they are demonstrated to support flexible luminescence and show highly improved machinability. To test their performance in practical application, we apply the PSOLCs to safety identification board and finally get a satisfactory result, directly indicating that the PSOLCs prepared from lead-free perovskite are quite suitable for flexible-lighting-related display applications.

Emission ratio determination from road vehicles using a range of remote emission sensing techniques

The development of remote emission sensing techniques such as plume chasing and point sampling has progressed significantly and is providing new insight into vehicle emissions behaviour. However, the analysis of remote emission sensing data can be highly challenging and there is currently no standardised method available. In this study we present a single data processing approach to quantify vehicle exhaust emissions measured using a range of remote emission sensing techniques. The method uses rolling regression calculated over short time intervals to derive the characteristics of diluting plumes. We apply the method to high time-resolution plume chasing and point sampling data to quantify gaseous exhaust emission ratios from individual vehicles. Data from a series of vehicle emission characterisation experiments conducted under controlled conditions is used to demonstrate the potential of this approach. First, the method is validated through comparison with on-board emission measurements. Second, the ability of this approach to detect changes in NOx / CO2 ratios associated with aftertreatment system tampering and different engine operating conditions is shown. Third, the flexibility of the approach is demonstrated by varying the pollutants used as regression variables and quantifying the NO2 / NOx ratios for different vehicle types. A higher proportion of total NOx is emitted as NO2 when the selective catalytic reduction system of the measured heavy duty truck is tampered. In addition, the applicability of this approach to urban environments is illustrated using mobile measurements conducted in Milan, Italy in 2021. Emissions from local combustion sources are distinguished from a complex urban background and the spatiotemporal variability in emissions is shown. The mean NOx / CO2 ratio of 1.61 ppb/ppm is considered representative of the local vehicle fleet. It is envisaged that this approach can be used to quantify emissions from a range of mobile and stationary fuel combustion sources, including non-road vehicles, ships, trains, boilers and incinerators.

Near-real-time estimation of fossil fuel CO2 emissions from China based on atmospheric observations on Hateruma and Yonaguni Islands, Japan

We developed a near-real-time estimation method for temporal changes in fossil fuel CO2 (FFCO2) emissions from China for 3 months [January, February, March (JFM)] based on atmospheric CO2 and CH4 observations on Hateruma Island (HAT, 24.06° N, 123.81° E) and Yonaguni Island (YON, 24.47° N, 123.01° E), Japan. These two remote islands are in the downwind region of continental East Asia during winter because of the East Asian monsoon. Previous studies have revealed that monthly averages of synoptic-scale variability ratios of atmospheric CO2 and CH4 (ΔCO2/ΔCH4) observed at HAT and YON in JFM are sensitive to changes in continental emissions. From the analysis based on an atmospheric transport model with all components of CO2 and CH4 fluxes, we found that the ΔCO2/ΔCH4 ratio was linearly related to the FFCO2/CH4 emission ratio in China because calculating the variability ratio canceled out the transport influences. Using the simulated linear relationship, we converted the observed ΔCO2/ΔCH4 ratios into FFCO2/CH4 emission ratios in China. The change rates of the emission ratios for 2020–2022 were calculated relative to those for the preceding 9-year period (2011–2019), during which relatively stable ΔCO2/ΔCH4 ratios were observed. These changes in the emission ratios can be read as FFCO2 emission changes under the assumption of no interannual variations in CH4 emissions and biospheric CO2 fluxes for JFM. The resulting average changes in the FFCO2 emissions in January, February, and March 2020 were 17 ± 8%, − 36 ± 7%, and − 12 ± 8%, respectively, (− 10 ± 9% for JFM overall) relative to 2011–2019. These results were generally consistent with previous estimates. The emission changes for January, February, and March were 18 ± 8%, − 2 ± 10%, and 29 ± 12%, respectively, in 2021 (15 ± 10% for JFM overall) and 20 ± 9%, − 3 ± 10%, and − 10 ± 9%, respectively, in 2022 (2 ± 9% for JFM overall). These results suggest that the FFCO2 emissions from China rebounded to the normal level or set a new high record in early 2021 after a reduction during the COVID-19 lockdown. In addition, the estimated reduction in March 2022 might be attributed to the influence of a new wave of COVID-19 infections in Shanghai.

Varying Calcium Abundances in Solar Flares Seen by the Solar Maximum Mission

We report on calcium abundance A(Ca) estimates during the decay phases of 194 solar X-ray flares using archived data from the Bent Crystal Spectrometer (BCS) on the Solar Maximum Mission (operational 1980–1989). The abundances are derived from the ratio of the total calcium X-ray line emission in BCS channel 1 to that in neighboring continuum, with temperature from a satellite-to-resonance line ratio. Generally, the calcium abundance is found to be about 3 times the photospheric abundance, as previously found, indicating a “first ionization potential” (FIP) effect for calcium, which has a relatively low FIP value. The precision of the abundance estimates (referred to hydrogen on a logarithmic scale with A(H) = 12), is typically ∼± 0.01, enabling any time variations of A(Ca) during the flare decay to be examined. For a total of 270 short time segments with A(Ca) determined to better than 2.3% accuracy, many (106; 39%) showed variations in A(Ca) at the 3σ level. For the majority, in 74 (70%) of these 106 segments A(Ca) decreased with time, and for 32 (30%) A(Ca) increased with time. For 79 out of 270 (29%) we observed constant or nearly constant A(Ca), and the remaining 85 (31%) with irregular time behavior. A common feature was the presence of discontinuities in the time behavior of A(Ca). Relating these results to the ponderomotive force theory of Laming, we attribute the nature of varying A(Ca) to the emergence of loop structures in addition to the initial main loop, each with its characteristic calcium abundance.

Conversion of CO2 and Its Utilization in the Preparation of Cement-Slag-CaCO3 Ternary Blends

A reduction in CO2 emissions is necessary in the concrete industry. This study proposes a CO2 conversion technique by which CO2 gas is converted into solid nano CaCO3 and used to replace the partial binder of cement-slag blends in ratios of 2%, 4%, and 6%. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analyses confirmed the formation of hemicarboaluminate (Hc) and monocarboaluminate (Mc) due to the chemical reaction between nano CaCO3 and the Al2O3 phase in the binder. XRD analysis revealed that at 28 days, the addition of nano CaCO3 can inhibit the transformation of ettringite (AFt) to monosulfate (AFm). As the contents of nano CaCO3 increased, the hydration heat, strength, ultrasonic pulse velocity (UPV), electrical resistivity, and combined water content increased. The degree of increment of the electrical resistivity was more pronounced than that of the strength. For various specimens, the strength and combined water content presented a linear relationship, and the strength and UPV presented an exponential function. The reduction rate of normalized CO2 emissions (the ratio of CO2 emissions of the paste to its strength) was much higher than the replacement percentage of nano CaCO3. This was because nano CaCO3 increased the late strength and had a negative CO2 emission value.

Long-term dietary DHA intervention prevents telomere attrition and lipid disturbance in telomerase-deficient male mice.

Previous evidence indicated anti-ageing potential of docosahexaenoic acid (DHA), but the underlying mechanism remains unclear. We investigated protective effect of DHA on telomere attrition and lipid disturbance in male mice with premature ageing caused by telomerase deficiency. Wild-type (WT) and fourth-generation telomerase-deficient (G4 Terc-/-, Terc knockout, KO) male mice (C57BL/6, 2months old) were fed control diet (WT-C and KO-C groups) or DHA-enriched diet containing 0.80% DHA by weight (WT-DHA and KO-DHA groups) for 10months. The ageing phenotypes and metabolic level [carbon dioxide emission, oxygen consumption, and respiratory exchange ratio (RER)] were assessed at the end of the experiment. Telomere length in various tissues and the hepatic gene and protein expression for regulating lipid synthesis and lipolysis were measured. Data were tested using one- or two-factor ANOVA. In KO male mice, DHA prevented weight loss, corrected high RER, and reduced fat loss. Telomere shortening was reduced by 22.3%, 25.5%, and 13.5% in heart, liver, and testes of the KO-DHA group compared with those in the KO-C group. The KO-DHA group exhibited higher gene transcription involved in glycerol-3-phosphate pathway [glycerol-3-phosphate acyltransferase (Gpat)], lower gene expression of β-oxidation [carnitine palmitoyltransferase 1a (Cpt1a)], and upregulation of proteins in lipid synthesis [mammalian target of rapamycin complex 1 (mTORC1) and sterol responsive element binding protein 1 (SREBP1)] in liver than the KO-C group. Long-term DHA intervention attenuates telomere attrition and promotes lipid synthesis via the tuberous sclerosis complex 2 (TSC2)-mTORC1-SREBP1 pathway in KO male mice.

Is There a Formaldehyde Deficit in Emissions Inventories for Southeast Michigan?

Formaldehyde is a key Volatile Organic Compound (VOC) and ozone precursor that plays a vital role in the urban atmospheric radical budget on par with water vapor, ozone, and nitrous acid. In addition to modulating radical and ozone production, ambient formaldehyde has both carcinogenic and non-carcinogenic inhalation health effects. This study concludes that ambient formaldehyde in the Southeast Michigan (SEMI) ozone nonattainment area may be underestimated up to a factor of two or more by regional air quality models. The addition of plausible amounts of primary formaldehyde to the U.S. National Emissions Inventory based on estimated formaldehyde-to-CO emission ratios partially alleviates this modeling deficit and indicates the presence of formaldehyde concentrations above 5 ppb at a previously unsuspected location northeast of Detroit. Standard 24-h formaldehyde samples obtained during the Michigan-Ontario Ozone Source Experiment (MOOSE) verified the presence of high ambient formaldehyde concentrations at this location. Moreover, the addition of plausible amounts of primary formaldehyde to VOC emissions inventories may add more than 1 ppb of ozone to ambient air in the SEMI nonattainment area, where ozone design values exceeded the U.S. National Ambient Air Quality Standard (NAAQS) by 1–2 ppb for the 2018–2020 design value period.

Optimizing the operation strategy of a combined cooling, heating and power system based on energy storage technology

Energy storage technology is the key to achieving a carbon emission policy. The purpose of the paper is to improve the overall performance of the combined cooling, heating and power-ground source heat pump (CCHP-GSHP) system by the battery. A new operation strategy (the two-point operation) is proposed by controlling the power generation unit work. The power generation unit has two operation modes of non-operation and rated efficiency operation by the storage electricity battery. The new operation strategy is compared with the traditional CCHP-GSHP that without a battery. The optimization goals include the primary energy saving ratio, the reduction ratio of carbon dioxide emissions, and the annual total cost saving ratio. The independent GSHP system is used as a reference system. Multipopulation genetic algorithms are selected to achieve the problem of optimization. A hotel building is selected for a case study. The optimal configuration of the coupling system is computed following the electric load strategy. Finally, the results show that the CCHP-GSHP system has a better performance under the new operation strategy compared with the traditional CCHP-GSHP (the primary energy saving ratio increases by 5.5%; the annual carbon dioxide emission reduction ratio increases by 1%; the annual total cost reduction ratio increases by 5.1%). This paper provides reference and suggestions for the integration and operation strategy of CCHP-GSHP in the future.

Biosignature line ratios of [P ii] in exoplanetary and nebular environments

ABSTRACT Being the backbone element of deoxyribonucleic acid, phosphorus is a key component in the search for life in the Universe. To aid in its detection, we present line emissivity ratios for the five lowest-lying forbidden [P ii] transitions, namely those among the levels 3s23p2(3P0, 3P1, 3P2, 1D2, and 1S0). The wavelengths range between 0.44 and 70 µm, and several lie within the spectroscopic domain observable with the JWST. These line ratios have been calculated using a new collisional-radiative-cascade (CRR) model combining calculated collision strengths and level-specific recombination rate coefficients, with both data sets computed using the accurate Breit–Pauli R-matrix method. The CRR model includes a new scheme for (e + ion) recombination to emission-line formation. We compare its effect to models incorporating only electron-impact excitation and spontaneous radiative decay. We find that (e + ion) recombination has a significant impact on all line ratios, and represents a major improvement in physical accuracy of emission-line models.

Inferred vehicular emissions at a near-road site: Impacts of COVID-19 restrictions, traffic patterns, and ambient air temperature

Vehicles are a major source of anthropogenic emissions of carbon monoxide (CO), nitrogen oxides (NOx), and black carbon (BC). CO and NOx are known to be harmful to human health and contribute to ozone formation, while BC absorbs solar radiation that contributes to global warming and also has negative impacts on human health and visibility. Travel restrictions implemented during the COVID-19 pandemic provide researchers the opportunity to study the impact of large, on-road traffic reductions on local air quality. Traffic counts collected along Interstate-95, a major eight-lane highway in Maryland (US), reveal a 60% decrease in passenger car totals and an 8.6% (combination-unit) and 21% (single-unit) decrease in truck traffic counts in April 2020 relative to prior Aprils. The decrease in total on-road vehicles led to the near-elimination in stop-and-go traffic and a 14% increase in the mean vehicle speed during April 2020. Ambient near-road (NR) BC, CO, NOx, and carbon dioxide (CO2) measurements were used to determine vehicular emission ratios (ΔBC/ΔCO, ΔBC/ΔCO2, ΔNOx/ΔCO, ΔNOx/ΔCO2, and ΔCO/ΔCO2), with each ratio defined as the slope value of a linear regression performed on the concentrations of two pollutants within an hour. A decrease of up to a factor of two in ΔBC/ΔCO, ΔBC/ΔCO2, ΔNOx/ΔCO2, and in the fraction of on-road diesel vehicles from weekdays to weekends shows diesel vehicles to be the dominant source of BC and NOx emissions at this NR site. We estimate up to a 70% reduction in BC emissions in April 2020 compared to earlier years, and attribute much of this to lower diesel BC emissions resulting from improvements in traffic flow and fewer instances of acceleration and braking. Future efforts to reduce vehicular BC emissions should focus on improving traffic flow or turbocharger lag within diesel engines. Inferred BC emissions from the NR site also depend on ambient temperature, with an increase of 54% in ΔBC/ΔCO from −5 to 20 °C during the cold season, similar to previous studies that reported increasing BC emissions with rising temperature. The default setting of MOVES3, the current version of the mobile emission model used by the US EPA, does not adjust hot-running BC emissions for ambient temperature. Future work will focus on improving the accuracy of mobile emissions in air quality modeling by incorporating the effects of temperature and traffic flow in the system used to generate mobile emissions input for commonly used air quality models.