Subsequent Emissions Research Articles

Are Hazardous Substance Rankings Effective? An Empirical Investigation of Information Dissemination About the Relative Hazards of Chemicals and Emissions Reductions

Problem definition: Whether information dissemination about chemical hazards drives managers at facilities to undertake corresponding environmental actions, remains an open question that has not been adequately examined in the literature. Academic/practical relevance: We fill this gap in the literature by empirically investigating reductions in chemical emissions by facilities in relation to changes in the assessed hazard levels of chemicals evidenced in periodically-updated public information. We also examine the moderating effects of operational leanness—an attribute that prior studies have shown to be associated with better environmental performance—in our setting wherein the assessed hazard levels of chemicals change over time. Methodology: We draw data from four U.S. sources—the Substance Priority List from the Agency for Toxic Substances and Disease Registry, the Toxics Release Inventory from the EPA, the National Establishment Time-Series, and Compustat. We employ a panel model with facility-chemical- and time-fixed effects. Results: We find that public information dissemination on chemical hazards is effective, as indicated by the significant association between increases in the assessed hazard levels of chemicals and greater subsequent emissions reductions. Specifically, we find that facilities reduce emissions by an additional 4.28% on average, and their use of source reduction increases by 3.07% on average when the relative assessed hazard level of a chemical increases compared to when it decreases. We find that, overall, leaner facilities outperform less lean facilities with respect to emissions reductions. However, when the assessed hazard level increases, less lean facilities increase their emissions reductions more than leaner facilities. Managerial implications: Our findings provide insights for managers prioritizing environmental actions, including the extent of emissions reductions achievable by practicing lean. Our results can also be leveraged by governmental/nongovernmental organizations to anticipate responses to informational updates on chemical hazards, depending on characteristics of the affected facilities.

Effects of a quenching treatment on PCDD/F reduction in the bottom ash of a lab waste incinerator to save the energy and cost incurred from post-thermal treatment

Bottom ash (BA) from incineration has been reused as a construction material for years. However, thermal treatments, which incur extra cost and higher energy demand, are essential to reduce/stabilize the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in BA, which can be released from BA during the next startup and cause peak emissions. In this study, the bottom ash from a laboratory waste incinerator (LWI) was collected and quenched at various temperatures during three shutdown operations to determine the results of the gradual cooling process. The PCDD/F content in the BA was quantified using gas chromatography-mass spectrometry. The PCDD/Fs in BA was significantly lower (0.0239 ng WHO-TEQ g−1) after being quenched at >400 °C, which was only 1/300 of that in the sample gradually cooled to <200 °C (6.21 ng WHO-TEQ g−1). The PCDD/PCDF ratios were less than 1 in all of the samples, suggesting that de novo synthesis might be the predominant formation mechanism, and exponential relationships between the PCDD/F growth ratio and quenching temperature were found, with an r2 > 0.97. In other words, careful operation of the cooling process is an important PCDD/F inhibition strategy and effectively reduces the subsequent startup emissions. Interestingly, the extremely low PCDD/F levels in the BA after quenching were found to further save the cost of thermal treatment, reduce electricity use by 500 MWh, and lower fuel consumption by 27 kL of diesel, as well as reducing annual CO2e emissions by 351 tons in an LWI. This finding could be further applied to simultaneously control PCDD/F emissions, save post-treatment costs, and reduce the secondary pollutants in other incinerators.

Ruminant urine patch nitrification and N2O flux: effects of urine aucubin rate in a laboratory trial

ABSTRACTLivestock urine deposition onto grazed New Zealand pastures drives soil nitrous oxide (N2O) emissions. Urine patch N2O emissions can be reduced by inhibiting nitrification, a key urine patch nitrogen (N) transformation pathway. Aucubin, a secondary metabolite found in the pasture herb species plantain (Plantago lanceolata), is a potential nitrification inhibitor and could be excreted in urine by animals grazing plantain. In this laboratory trial, three rates of aucubin application (10, 50, and 100% of the highest theoretical aucubin excretion rate from cows grazing 100% plantain pasture) were added to urine and assessed for their potential to inhibit nitrification and subsequent N2O emissions. Significantly reduced N2O flux and soil concentrations, aligned with significantly increased soil and soil surface pH, indicated that aucubin inhibited nitrification from 5 to 17 days after urine application. However, this period of inhibition was not sufficient to reduce overall N2O emissions during the 35 day experiment.

Embodied Energy and CO2 Emissions of Widely Used Building Materials: The Ethiopian Context

Buildings use a wide range of construction materials, and the manufacturing of each material consumes energy and emits CO2. Several studies have already been conducted to evaluate the embodied energy and the related CO2 emissions of building materials, which are mainly based on case studies from developed countries. There is a considerable gap in cases of developing countries regarding assessment of embodied energy and CO2 emissions of these building materials. This study identified the top five most used construction materials (cement, sand, coarse aggregates, hollow concrete blocks, and reinforcement bars), which are also prime sources of waste generation during construction in the Ethiopian building construction sector. Then, what followed was the evaluation of the embodied energies and CO2 emissions of these materials by examining five commercial and public buildings within the cradle-to-site lifecycle boundary. The evaluation results demonstrated that cement, hollow concrete blocks (HCB), and reinforcement bars (rebars) are the major consumers of energy and major CO2 emitters. Cumulatively, they were responsible for 94% of the embodied energy and 98% of the CO2 emissions. The waste part of the construction materials has inflated the embodied energy and the subsequent CO2 emissions considerably. The study also recommended several strategies for the reduction of embodied energy and the related CO2 emissions. The research delivers critical insights into embodied energy and CO2 emissions of the five most used building materials in the Ethiopian construction industry, as there are no prior studies on this theme. This might be a cause to arouse awareness and interest among the policy makers and the wider public to clearly understand the importance of research on this crucial issue to develop national energy and CO2 descriptors for construction materials, in order to take care of our naturally endowed, but yet fragile, human habitat.

Transesterification of high-acidity spent coffee ground oil and subsequent combustion and emissions characteristics in a compression-ignition engine

Lipids extracted from spent coffee grounds (SCG) are a potentially promising feedstock for biodiesel production if the relatively high free fatty acid (FFA) portion of the oil can be successfully converted into methyl esters, and the resulting biodiesel found to have acceptable combustion and emissions performance. This study presents experimental results obtained from transesterification of SCG-extracted oil with a FFA content of ∼30% w/w through a two-step process, followed by fuel characterization and combustion experiments with SCG-derived biodiesel, pure and blended with fossil diesel, and untreated SCG oil in a single cylinder research compression-ignition engine. The acid-catalyzed pretreatment reduced the FFA content of the oil below 1.5% w/w, with minor losses, and showed the methanol-to-FFA molar ratio to be more significant relative to the quantity of sulphuric acid used as a catalyst within the range of investigated conditions, while the subsequent base-catalyzed step converted ∼87% of the pretreated oil into biodiesel with a higher heating value (HHV) of 39.7 MJ/kg. The combustion and emission characteristics of pure and blended SCG biodiesel revealed similarities with those of commercial rapeseed and soya biodiesel samples tested. While ignition delay decreased with increasing SCG biodiesel content, the comparatively higher CO, total hydrocarbon (THC) and particulate emissions of the SCG biodiesel were attributed to higher fuel kinematic viscosity (KV). Combustion of the untreated SCG oil produced low in-cylinder peak pressure and peak heat release relative to other samples tested despite a longer ignition delay, suggesting that the oil physical properties were more important in determining combustion performance.

Potential future methane emission hot spots in Greenland

Climate models have been making significant progress encompassing an increasing number of complex feedback mechanisms from natural ecosystems. Permafrost thaw and subsequent induced greenhouse gas emissions, however, remain a challenge for climate models at large. Deducing permafrost conditions and associated greenhouse gas emissions from parameters that are simulated in climate models would be a helpful step towards estimating emission budgets from permafrost regions. Here we use a regional climate model with a 5 km horizontal resolution to assess future potential methane (CH4) emissions over presently unglaciated areas in Greenland under an RCP8.5 scenario. A simple frost index is applied to estimate permafrost conditions from the model output. CH4 flux measurements from two stations in Greenland; Nuuk representing sub-Arctic and Zackenberg high-Arctic climate, are used to establish a relationship between emissions and near surface air temperature. Permafrost conditions in Greenland change drastically by the end of the 21st century in an RCP8.5 climate. Continuous permafrost remains stable only in North Greenland, the north-west coast, the northern tip of Disko Island, and Nuussuaq. Southern Greenland conditions only sustain sporadic permafrost conditions and largely at high elevations, whereas former permafrost in other regions thaws. The increasing thawed soil leads to increasing CH4 emissions. Especially the area surrounding Kangerlussuaq, Scoresby Land, and the southern coast of Greenland exhibit potentially high emissions during the longer growing season. The constructed maps and budgets combining modelled permafrost conditions with observed CH4 fluxes from CH4 promoting sites represent a useful tool to identify areas in need of additional monitoring as they highlight potential CH4 hot spots.

Density Effects on Soil‐Water Characteristics, Soil‐Gas Diffusivity, and Emissions of N2O and N2 from a Re‐packed Pasture Soil

Core Ideas A predictive gas diffusivity model for undisturbed soils was modified for sieved‐repacked pasture soils. Density‐induced changes in soil physical attributes along with gaseous fluxes help identify N2O mitigation. Maintaining well‐aerated conditions and a soil‐gas diffusivity of &gt;0.038 may be a mechanism for keeping N2O and N2 fluxes low. Density‐induced soil structural changes may potentially alter both soil total porosity and soil pore size distribution, and thus change the soil's water retention characteristics, gas diffusion and transport properties, and subsequent greenhouse emissions. In this study, we characterized and parameterized water retention, pore size distribution, gas diffusivity and cumulative emissions of nitrous oxide (N2O) and nitrogen (N2) fluxes in a differently compacted silt‐loam sampled from a grazed pasture in Lincoln, New Zealand. The soils used for the simulations were subjected to five different density treatments (1.1, 1.2, 1.3. 1.4, 1.5 Mg m−3), subsequently saturated and successively drained to 11 matric potentials at which water retention, gas diffusivity and flux measurements were performed. Results show strong correlations between best‐fit soil‐water characteristic parameters and the density levels. A recent predictive gas diffusivity model developed for undisturbed soils was modified to better characterize the measured gas diffusivity data in sieved‐repacked pasture soils. Further, two exponential and linear parametric models were developed to adequately parameterize the observed fingerprints of cumulative (35‐d) N2O and N2 fluxes, respectively. Results clearly distinguished the density‐induced changes in pore structure, pore size distribution, gas diffusivity and emission of gas fluxes and hence provide useful implications for pasture management to reduce future emission of greenhouse gases. Results particularly highlighted the importance of ensuring a diffusivity ≥0.038 to limit extensive emission of N2O and N2 fluxes. The improved parametric models and parameter correlations provide valuable numerical insight to better characterize density‐dependent behavior in soil physical properties and functions.

Compound-Specific Carbon Isotopic Composition of Ethanol in Brazil and US Vehicle Emissions and Wet Deposition.

Global atmospheric ethanol budget models include large uncertainties in the magnitude of ethanol emission sources and sinks. To apply stable isotope techniques to constrain ethanol emission sources, a headspace solid phase microextraction gas chromatograph-combustion-isotope ratio mass spectrometry method (HS-SPME-GC-C-IRMS) was developed to measure the carbon isotopic composition of aqueous phase ethanol at natural abundance levels (1-30 μM) with a precision of 0.4‰. The method was applied to determine the carbon isotope signatures (δ13C) of vehicle ethanol emission sources in Brazil (-12.8 ± 2.4‰) and the US (-9.8 ± 2.5‰), and to measure the carbon isotope composition of ethanol in wet deposition (-22.6 to -12.7‰). A two end-member isotope mixing model was developed using anthropogenic and biogenic end members and fractionation scenarios to estimate ethanol source contributions to wet deposition collected in Brazil and US. Mixing model results indicate anthropogenic sources contribute two and a half to four times more ethanol to the atmosphere than previously predicted in modeled global ethanol inventories. As established and developing countries continue to rapidly increase ethanol fuel consumption and subsequent emissions, understanding the magnitude of all ethanol sources and sinks will be essential for modeling future atmospheric chemistry and air quality impacts.

Cluster Model of Nanoparticle and Meso-Object Formation in Shock Waves in Heavy Metals and under Emissions from Their Surface

Using the cluster model, we have calculated the most probable, average, and maximum possible sizes of nanoparticles and meso-objects formed in the processes of shock-induced restructuring of the microstructure of heavy metals and during subsequent emissions of particles from the surface of macroscopic samples near the lattice defects. The proposed model relates to the full range of characteristic sizes of the studied nano- and meso-objects from ~1 nm to ~370 μm.

Impacts of Dilution on Hydrogen Combustion Characteristics and NOx Emissions

Combustion characteristics at small scales have been studied continuously due to the potential applications in portable power devices. It is known that heat release impacts at small scales result in different flame behavior as compared to conventional scales. The impacts of geometry, stoichiometry, flow rates, wall temperatures, etc., are widely studied in the literature. However, dilution impacts still need to be further studied due to its important role on controlling the flame behavior and subsequent pollutants emissions at these scales. In this work, premixed hydrogen/air combustion is simulated at an axis-symmetric microchannel (with diameter D = 0.8 mm and length L = 10 mm), where detailed chemical kinetics are implemented in simulations (32 species and 173 reactions). The heat transfer on the wall is considered by imposing a hyperbolic temperature profile on the wall, where the wall temperature increases from 300 K at the inlet to 1300 K at the outlet. With this setup, a range of equivalence ratios including a typical fuel-lean regime (ϕ = 0.7), stoichiometric regime (ϕ = 1.0), and two cases at an ultra-rich regime (ϕ = 2.0 and ϕ = 3.0) are investigated. For each equivalence ratio, excess dilution (using N2) is introduced to the mixture, and its impact is compared with other cases. With that, the impacts of dilution variations on the combustion characteristics of premixed hydrogen/air are investigated for different equivalence ratios. More specifically, several incidents such as flame dynamics, flame stabilization, extinctions, and NOx emissions are studied for the aforementioned operating conditions.

Electron impact N-shell excitation of Se-like to Ga-like tungsten ions and polarization of their subsequent emissions

Study of electron impact excitation of W40+ (Se-like), W41+ (As-like), W42+ (Ge-like), and W43+ (Ga-like) ions using fully relativistic distorted wave theory has been presented. The excitation cross-sections of E1 and E2 allowed transitions of these ions are reported across the wide range of incident electron energies from excitation threshold to 20 keV. The obtained cross-sections of all the transitions of the four ions are fitted with an analytical expression for the applications in the plasma modelling. Further, using the magnetic sublevel cross-sections, the degree of linear polarization of the photon emissions from the electron impact excited anisotropic states of tungsten ions through the dipole allowed transitions are also calculated.

Blue, white, and red tunable light emission from (Y2O3:Sm3+)-benzoate hybrid nanophosphors

The synthesis and characterization of yttria-based organic–inorganic hybrid nanophosphors (HNP) are reported. These materials were synthesized by microwave-assisted solvothermal method in a short time of around 2 h and 30 min without any further thermal annealing. According to x-ray diffraction and transmission electron microscopy measurements, HNP have a lamellar structure formed by interleaved layers of organic species and inorganic yttria species. The luminescent properties of HNP are generated by the presence of Sm3 + ions, which produced light emission at 570, 610, 650, and 716 nm due to the G5 / 24 to H5 / 26, H7 / 26, H9 / 26, and H11 / 26 transitions, respectively; and a wide broadband centered at 446 nm as a result of the presence of organic species, particularly benzene rings. Hybrid phosphors have tunable luminescent properties as a function of the used excitation wavelength producing blue, white, and red light emission. Those properties are due to the hybrid’s absorption properties and the subsequent simultaneous organic and inorganic light emissions.

Holistic Assessment of Rumen Microbiome Dynamics through Quantitative Metatranscriptomics Reveals Multifunctional Redundancy during Key Steps of Anaerobic Feed Degradation.

Ruminant livestock is a major source of the potent greenhouse gas methane. The complex rumen microbiome, consisting of bacteria, archaea, and microbial eukaryotes, facilitates anaerobic plant biomass degradation in the cow rumen, leading to methane emissions. Using an integrated approach combining multidomain quantitative metatranscriptomics with gas and volatile fatty acid (VFA) profiling, we aimed at obtaining the most comprehensive picture of the active rumen microbiome during feed degradation to date. Bacterial, archaeal, and eukaryotic biomass, but also methane emissions and VFA concentrations, increased drastically within an hour after feed intake. mRNA profiling revealed a dynamic response of carbohydrate-active enzyme transcripts, transcripts involved in VFA production and methanogenesis. While the relative abundances of functional transcripts did not mirror observed processes, such as methane emissions, transformation to mRNA abundance per gram of rumen fluid echoed ruminant processes. The microbiome composition was highly individual, with, e.g., ciliate, Neocallimastigaceae, Prevotellaceae, Succinivibrionaceae, and Fibrobacteraceae abundances differing between cows. Microbiome individuality was accompanied by inter- and intradomain multifunctional redundancy among microbiome members during feed degradation. This likely enabled the robust performance of the anaerobic degradation process in each rumen. Neocallimastigaceae and ciliates contributed an unexpectedly large share of transcripts for cellulose- and hemicellulose-degrading enzymes, respectively. Methyl-reducing but not CO2-reducing methanogens were positively correlated with methane emissions. While Methanomassiliicoccales switched from methanol to methylamines as electron acceptors, Methanosphaera became the dominating methanol-reducing methanogen. This study for the first time linked rumen meta-omics with processes and enabled holistic insights into the contribution of all microbiome members to feed degradation. IMPORTANCE Ruminant animals, such as cows, live in a tight symbiotic association with microorganisms, allowing them to feed on otherwise indigestible plant biomass as food sources. Methane is produced as an end product of the anaerobic feed degradation in ruminants and is emitted to the atmosphere, making ruminant animals among the major anthropogenic sources of the potent greenhouse gas methane. Using newly developed quantitative metatranscriptomics for holistic microbiome analysis, we here identified bacterial, archaeal, and eukaryotic key players and the short-term dynamics of the rumen microbiome during anaerobic plant biomass degradation and subsequent methane emissions. These novel insights might pave the way for novel ecologically and economically sustainable methane mitigation strategies, much needed in times of global climate change.

Carbon Dioxide and Methane Dynamics in a Small Boreal Lake During Winter and Spring Melt Events

AbstractIn seasonally ice‐covered lakes, carbon dioxide (CO2) and methane (CH4) emission at ice‐off can account for a significant fraction of the annual budget. Yet knowledge of the mechanisms controlling below lake‐ice carbon (C) dynamics and subsequent CO2 and CH4 emissions at ice‐off is limited. To understand the control of below ice C dynamics, and C emissions in spring, we measured spatial variation in CO2, CH4, and dissolved inorganic and organic carbon from ice‐on to ice‐off, in a small boreal lake during a winter with sporadic melting events. Winter melt events were associated with decreased surface water DOC in the forest‐dominated basin and increased surface water CH4 in the mire‐dominated basin. At the whole‐lake scale, CH4 accumulated below ice throughout the winter, whereas CO2 accumulation was greatest in early winter. Mass‐balance estimates suggest that, in addition to the CO2 and CH4 accumulated during winter, external inputs of CO2 and CH4 and internal processing during ice‐melt could represent significant sources of C gas emissions during ice‐off. Moreover, internal processing of CO2 and CH4 worked in opposition, with production of CO2 and oxidation of CH4 dominating at ice‐off. These findings have important implications for how small boreal lakes will respond to warmer winters in the future; increased winter melt events will likely increase external inputs below ice and thus alter the extent and timing of CO2 and CH4 emissions to the atmosphere at ice‐off.

Electron-impact excitation of Xe+ and polarization of its subsequent emissions

Fully relativistic distorted wave calculations have been performed to study the electron impact excitation of singly ionized xenon from its ground 5p5 (J = 3/2) state to different fine structure excited states of the 5p46s, 5p46p, 5p47s, 5p47p, 5p45d and 5p46d configurations. The ground and excited bound states of Xe+ion have been represented through the relativistic multi-configuration Dirac-Fock wave functions while projectile electron distorted continuum wave functions are obtained by solving the Dirac equations. Results are reported for the excitation cross sections and the corresponding rate-coefficients of the considered different transitions. For each transition, analytic fitting to the calculated cross sections are also provided for plasma modeling purposes. In addition, using the density matrix theory and the calculated different magnetic sub-level excitation cross sections the linear polarization of the radiation emitted by the different optically allowed transitions are obtained and presented.

Propagation dynamics of successive emissions in laboratory and astrophysical jets and problem of their collimation

This paper presents the results of numerical simulation of the propagation of a sequence of plasma knots in laboratory conditions and in the astrophysical environment. The physical and geometric parameters of the simulation have been chosen close to the parameters of the PF-3 facility (Kurchatov Institute) and the jet of the star RW Aur. We found that the low-density region formed after the first knot propagation plays an important role in the collimation of the subsequent ones. Assuming only the thermal expansion of the subsequent emissions, qualitative estimates of the time taken to fill this area with the surrounding matter and the angle of jet scattering have been made. These estimates are consistent with observations and results of our modeling.

Long-term emission measurements at a floating roof tank for gasoline storage

In our paper we present the results of a long-term emission measurement of volatile organic compounds emitted by a single-hull floating-roof tank. The tank has a capacity of 12,000m3 and is used to stock commercially available gasoline. Due to imperfect seals and the formation of lubricating films during withdrawal, subsequent emissions of volatile compounds have to be expected. Therefore, a non-zero probability has to be assumed for the formation of ignitable concentrations of flammable gases, resulting in according an explosive gas area classification. Here a representative single-hull floating-roof tank is monitored using an appropriate network of infrared (IR) detectors, accompanied with measurements using a high resolution photoionization detector (PID). Measured values have been compared to the expectations estimated applying the API 2517/2519 and the VDI 3479 standards.The aim is to record data for an explosive gas area classification based on actual emissions, potentially allowing for a regrading of zone 1 to zone 2 classified locations.

Large scale simulation of CO2 emissions caused by urban car traffic: An agent-based network approach

Abstract CO2 emissions caused by private motorized traffic for the city of Graz, a typical European inland city with about 320 000 citizens, are investigated. The main methodology is a newly developed agent-based model that incorporates empirical data about the mobility behavior of the citizens in order to calculate the traveled routes, the resulting traffic and subsequent emissions. To assess the impact of different policies on CO2 emissions, different scenarios are simulated and their results are compared to a base line scenario. The model features a local and temporal resolution, effects like congestion and stop-and-go traffic as well as commuters to and from other regions. In addition to the evaluation of certain policies (like a focus on electric cars, telecommuting or an improvement of the road infrastructure), a method is provided, that makes it possible to compare many diverse scenarios, featuring technological changes, societal changes or changes in the road network, all within the same framework. The findings suggest that one of the most promising strategies to decrease urban CO2 emissions is to focus on the use of electric cars, especially if it is combined with offering alternatives to private car traffic and incentives for telecommuting. Banning the use of old cars only yields a significant result if a large amount of cars is affected, which would make such a policy difficult to implement. Expanding the road network has no significant positive effect and may even encourage using cars, therefore leading to even more CO2 emissions. Due to its flexible structure the presented model can be used to evaluate policies beyond what is presented in this study. It can easily be adapted to other conditions and geographical regions.

Acoustic Phenomena in Damaged Ceramic Capacitors

Multilayer ceramic capacitors are prone to mechanical defects and damage because of the fragility of the ceramic dielectric. Because these faults are often not recognized by visual or electrical inspection, a nondestructive fast way of detecting these defects would be very useful. Ceramic capacitors are known to generate acoustic emissions, caused by mechanical vibration of the capacitor body. Physical defects alter the mechanical properties of the capacitor, which, in turn, affect the acoustic signature of the capacitor. In this paper, acoustic information is acquired directly from both pristine and damaged capacitors. An experiment was conducted where capacitors were driven with a voltage chirp over a wide range of frequencies, and subsequent acoustic emissions were measured with a piezoelectric point contact sensor. Test boards were bent to cause flex cracks to the soldered capacitors, which were measured acoustically before and after bending. A comparison of these measurements showed that printed circuit board bending causes characteristic changes to the capacitor acoustic response, which can be correlated with the resulted damage.

Кластерная модель образования наночастиц и мезообъектов в ударных волнах в тяжелых металлах и при выбросах с их поверхности

AbstractUsing the cluster model, we have calculated the most probable, average, and maximum possible sizes of nanoparticles and meso-objects formed in the processes of shock-induced restructuring of the microstructure of heavy metals and during subsequent emissions of particles from the surface of macroscopic samples near the lattice defects. The proposed model relates to the full range of characteristic sizes of the studied nano- and meso-objects from ~1 nm to ~370 μm.