Plume Emission Research Articles

Turbulent mixed convection in vertical and horizontal channels

Turbulent shear flows driven by a combination of a pressure gradient and buoyancy forcing are investigated using direct numerical simulations. Specifically, we consider the set-up of a differentially heated vertical channel subject to a Poiseuille-like horizontal pressure gradient. We explore the response of the system to its three control parameters: the Grashof number $Gr$ , the Prandtl number $Pr$ , and the Reynolds number $Re$ of the pressure-driven flow. From these input parameters, the relative strength of buoyancy driving to the pressure gradient can be quantified by the Richardson number $Ri=Gr/Re^2$ . We compare the response of the mixed vertical convection configuration to that of mixed Rayleigh–Bénard convection, and find a nearly identical behaviour, including an increase in wall friction at higher $Gr$ , and a drop in the heat flux relative to natural convection for $Ri=O(1)$ . This closely matched response is despite vastly different flow structures in the systems. No large-scale organisation is visible in visualisations of mixed vertical convection – an observation that is confirmed quantitatively by spectral analysis. This analysis, combined with a statistical description of the wall heat flux, highlights how moderate shear suppresses the growth of small-scale plumes and reduces the likelihood of extreme events in the local wall heat flux. Vice versa, starting from a pure shear flow, the addition of thermal driving enhances the drag due to the emission of thermal plumes.

Height-resolved emission spectroscopy and high-speed imaging of the TiAl6V4 vapor plume under laser powder bed fusion conditions

Optical emission spectroscopy is increasingly used as an in situ monitoring technique during laser powder bed fusion (LPBF) because plume emission holds elemental information not found in other in situ sensing techniques. This work explores the shape, stability, and temperature of the emission plume above the melt pool of Ti6Al4 V undergoing laser scans under LPBF-like processing conditions, using high-speed video and height-resolved spectroscopy to study the details of plume dynamics. Optical emission spectroscopy is conducted in the 480 nm to 525 nm region, where Ti emission is strong, with 0.3 mm vertical resolution above the baseplate. The Boltzmann plot method is used to determine temperature at each probed elevation, which indicates that the hottest location of the plume is occasionally elevated 0.3 mm to 0.6 mm above the scanning surface. The results show that the plume shape, stability, temperature, and spectra are highly dependent on the processing conditions. We highlight some of the complexities of optical emission spectroscopy and discuss potential challenges for implementing optical emission spectroscopy across an entire build.

Ecological State of Environmental Facilities in the Zone of Influence of the Lipetsk Industrial Agglomeration

It has been found that the accumulation of heavy metals (HM) in environmental facilities of the Lipetsk industrial agglomeration varies significantly and may depend on the technological mode of the companies, the composition of aerosol fallout, soil properties, distance and direction from the emission plume, biological characteristics of plants and other factors. In the area where the Novolipetsk Iron and Steel Works (NLMK) is located, the excess levels of kerosene, gasoline and hydrocarbons in the atmospheric air were detected, as well as increased dust concentrations in the area of the Lipetsk Tractor Plant. At that, the concentrations of gaseous hazardous chemicals in the air of other areas of Lipetsk and agricultural lands at different distances and directions from NLMK did not exceed the established maximum values. The maximum content of HM was recorded in the upper layers of virgin undisturbed soils in the near zone of influence of industrial companies. It was noted that on arable soils the content of HM does not exceed the standard values, with the exception of a number of cases where the content of Fe, Cr, Ni in the grass stand exceeds the permissible level. It was concluded that the research carried out made it possible to identify the main patterns and factors influencing the pollution of environmental facilities, including components of agroecosystems.

Paleoclimate Controls on West African Dust Inferred from Rb/Sr and Si/Al of Sediments in an Eastern Equatorial Atlantic Marine Core

Increased dust emissions from dryland areas and their effects on human health, ecosystem viability, and environmental change are a global concern in the face of the growing climate crisis. Dust plume emissions from the West African landmass, Sahara, and Sahel areas comprise a major fraction of the global aerosol budget. Dust plume intensity is closely related to regional winds (e.g., Harmattan, Sahara Air Layer), the Intertropical Convergence Zone, monsoonal seasonality, marine currents, and physiography. To study terrigenous material emitted from the continent over the last ~260 kyr (late Quaternary), we used X-ray fluorescence spectroscopy (XRF) to analyze a ~755 cm long marine sediment core from the eastern equatorial Atlantic Ocean, resulting in nearly 1400 discrete measurements. Spectral analysis results suggest that concentrations of elements (Rb, Sr, Si, Al) preserved in the sediments are correlated to different types of orbital climate forcing. Chemical weathering intensity indicated by the Rb/Sr ratio was sensitive to seasonal insolation variations controlled by precession cycles (23–18 kyr), which presumably reflects the relationship between monsoonal rainfall and sensible heating of the continent. Spectral analysis of silicate mineral grain size (Si/Al) showed significant 40 kyr cycles that were paced by obliquity. Based on these data, we infer that winter tradewind activity accelerated in response to the intertropical insolation gradient induced by high obliquity. High Rb/Sr ratios during the last glacial maximum and penultimate glacial maximum may have been due to a predominance of mechanical weathering over chemical weathering under dry/cool climates or the dissolution of Sr-bearing carbonates by corrosive glacial bottom waters.

Using metal oxide gas sensors to estimate the emission rates and locations of methane leaks in an industrial site: assessment with controlled methane releases

Abstract. Fugitive methane (CH4) emissions occur in the whole chain of oil and gas production, including from extraction, transportation, storage, and distribution. Such emissions are usually detected and quantified by conducting surveys as close as possible to the source location. However, these surveys are labour-intensive, are costly, and fail to not provide continuous emissions monitoring. The deployment of permanent sensor networks in the vicinity of industrial CH4 emitting facilities would overcome the limitations of surveys by providing accurate emission estimates, thanks to continuous sampling of emission plumes. Yet high-precision instruments are too costly to deploy in such networks. Low-cost sensors using a metal oxide semiconductor (MOS) are presented as a cheap alternative for such deployments due to their compact dimensions and to their sensitivity to CH4. In this study, we demonstrate the ability of two types of MOS sensors (TGS 2611-C00 and TGS 2611-E00) manufactured by Figaro® to reconstruct a CH4 signal, as measured by a high-precision reference gas analyser, during a 7 d controlled release campaign conducted by TotalEnergies® in autumn 2019 near Pau, France. We propose a baseline voltage correction linked to atmospheric CH4 background variations per instrument based on an iterative comparison of neighbouring observations, i.e. data points. Two CH4 mole fraction reconstruction models were compared: multilayer perceptron (MLP) and second-degree polynomial. Emission estimates were then computed using an inversion approach based on the adjoint of a Gaussian dispersion model. Despite obtaining emission estimates comparable with those obtained using high-precision instruments (average emission rate error of 25 % and average location error of 9.5 m), the application of these emission estimates is limited to adequate environmental conditions. Emission estimates are also influenced by model errors in the inversion process.

A review of the status of air quality monitoring in the Permian Basin, USA, and its implications for effective long-term monitoring of industrial operations

The Permian Basin is the largest petroleum producing region in the United States. Few studies have investigated impact the Petroleum Industry had on the air quality of the Permian Basin. Industry operations in the Basin has two primary impacts on air quality, (a) it significantly contributes carbon dioxide (CO2) and methane (CH4) to the atmosphere during extraction, transport and use of fossil fuels, (b) industry operations influence public health especially when populations are in proximity to all categories of oil and gas facilities. The advent of Covid-19 in late 2019 and a severe drought that began prior to 2019 in West Texas have created unusual circumstances regarding air quality and public health in the Permian Basin. This study has monitored airborne pollen, spores, fungal spores, and other organically derived particles, and inorganic particulate matter (1, 2.5, 10-micron particulate matter (PM) and total suspended particles (TSP)), volatile organic compounds (VOCs), and sulfur dioxide (SO2). The pandemic caused a historic reduction in oil and gas production slowing operations in the Permian Basin to near zero during the study period, reducing environmental effects on air quality and concomitantly an increase in flaring of natural gas. Although there were increases in the release of VOCs fixed base monitors detected no notable increase. However, an increase in the concentration of airborne pollutants (VOCs and SO2) shows a close correlation with proximity to oil and gas facilities and the intensity of industry operations. This phenomenon is attributed to the highly local nature of flaring and CH4 plume emissions from leaking oil and gas facilities. Air quality improved in the Permian Basin due to reduction in production activity because of the Covid-19 pandemic, and the reduction of particulate matter due to the ongoing drought during the study period.

Low-cost UAV coordinated carbon observation network: Carbon dioxide measurement with multiple UAVs

Improving the mitigation of global greenhouse effects requires drastic reductions in carbon emissions. Effective carbon management at different spatial scales is therefore crucial to a more sustainable path of economic development. Regional and local carbon management currently rely on the traditional bottom-up method of emission reports, which are known for their opaque and complex procedures. Novel top-down carbon monitoring methods including space-based, aerial and ground-based observations are tantalising alternatives to more reliable data sources of carbon emissions as well as sinks. Unmanned Aerial Vehicles (UAVs) based carbon monitoring is an upcoming field because of its lower costs, higher spatial-temporal resolution and operability at a wider range of weather conditions compared to satellite observations. UAVs equipped with Non-dispersive Infrared (NDIR) carbon dioxide (CO2) sensors can measure in the air with faster response and can intelligently navigate themselves within areas of greater interest. With the help of lighter NDIR payloads and multiple UAVs flying in synchrony, larger cross sections or areas for maximising information acquisition of emission plumes can be covered. In this article, we first introduce the design of a miniaturised NDIR payload, which is compatible with a lightweight UAV to achieve a single system weighing less than 4 kg. Then, we test our design via comparisons against another NDIR payload to determine its accuracy (−0.82 ppm and −0.44 ppm) and precision (0.12 ppm and −0.03 ppm) in measurements of two vertical concentration profiles. Finally, we deployed four UAVs on two major anthropogenic emission source monitoring campaigns with coordinated flight patterns. To fully understand the benefit of multi-UAV carbon monitoring, we attempted two flight patterns and computed power plant emission rates via the cross-sectional flux method. While all flights successfully captured the concentration enhancements downwind of the power plants, the single-sectional flight pattern measured an emission rate of 10ktCO2/day which is 44% less than that reported monthly and the multi-sectional flight pattern yielded relatively varied results (8.5ktCO2/day on average, which is 54% less) for the respective sections due to wind underestimations, plume section undersampling and wind fluctuations.

A survey of methane point source emissions from coal mines in Shanxi province of China using AHSI on board Gaofen-5B

Abstract. Satellite-based detection of methane (CH4) point sources is crucial in identifying and mitigating anthropogenic emissions of CH4, a potent greenhouse gas. Previous studies have indicated the presence of CH4 point source emissions from coal mines in Shanxi, China, which is an important source region with large CH4 emissions, but a comprehensive survey has remained elusive. This study aims to conduct a survey of CH4 point sources over Shanxi's coal mines based on observations of the Advanced Hyperspectral Imager (AHSI) on board the Gaofen-5B satellite (GF-5B/AHSI) between 2021 and 2023. The spectral shift in centre wavelength and change in full width at half-maximum (FWHM) from the nominal design values are estimated for all spectral channels, which are used as inputs for retrieving the enhancement of the column-averaged dry-air mole fraction of CH4 (ΔXCH4) using a matched-filter-based algorithm. Our results show that the spectral calibration on GF-5B/AHSI reduced estimation biases of the emission flux rate by up to 5.0 %. We applied the flood-fill algorithm to automatically extract emission plumes from ΔXCH4 maps. We adopted the integrated mass enhancement (IME) model to estimate the emission flux rate values from each CH4 point source. Consequently, we detected CH4 point sources in 32 coal mines with 93 plume events in Shanxi province. The estimated emission flux rate ranges from 761.78 ± 185.00 to 12 729.12 ± 4658.13 kg h−1. Our results show that wind speed is the dominant source of uncertainty contributing about 84.84 % to the total uncertainty in emission flux rate estimation. Interestingly, we found a number of false positive detections due to solar panels that are widely spread in Shanxi. This study also evaluates the accuracy of wind fields in ECMWF ERA5 reanalysis by comparing them with a ground-based meteorological station. We found a large discrepancy, especially in wind direction, suggesting that incorporating local meteorological measurements into the study CH4 point source are important to achieve high accuracy. The study demonstrates that GF-5B/AHSI possesses capabilities for monitoring large CH4 point sources over complex surface characteristics in Shanxi.

In-situ determination of micro-hardness in laser cladding of stellite using optical emission spectroscopy

Offline measurements in Laser Cladding (LC) processes, such as micro-hardness measurement, are destructive and time-consuming tests. Therefore, in-situ monitoring of clads parameters is of significant importance. In this study, we investigate the plasma plume emission produced during the LC process of Stellite 6 powder on a low-carbon steel substrate and its correlation with the micro-hardness of the clads over a wide range of LC parameters. It is demonstrated that a strong correlation between the spectral features in the UV region of 280–320 nm and micro-hardness exists, so that, the micro-hardness of samples can be determined by the total intensity of light in this range, within an average tolerance of 10 %. An exponential relation between hardness and UV radiation is empirically obtained that works very well for a wide range of dilutions, from 20 % to 70 %. It means that the UV spectra even determine the micro-hardness of samples with dilutions above 60 %, where the process shifts towards laser powder welding. This radiation is suggested to originate from the collisions of electrons with nano-sized clusters, which are produced during the laser interaction with the melt pool. The produced nanoparticles are the source of UV radiation and scatters the driving laser light, at the same time, processes that qualitatively explain the exponential relationship between the hardness and the UV light intensity.

Formation and evolution of laminar thermal structures: correlation to the thermal boundary layer and effects of heating time

We report an experimental study of the formation and evolution of laminar thermal structures generated by a small heat source, with a focus on their correlation to the thermal boundary layer and effects of heating time $t_{heat}$ . The experiments are performed over the flux Rayleigh number ( $Ra_f$ ) range $2.1\times 10^6 \leq Ra_f \leq 3.6\times 10^{7}$ and the Prandtl number ( $Pr$ ) range $28.6 \leq Pr \leq 904.7$ . The corresponding Rayleigh number ( $Ra= t_{heat}\,Ra_{f}/\tau _0\,Pr$ ) range is $900 \leq Ra \leq 4\times 10^{4}$ , where $\tau _0$ is a diffusion time scale. For thermal structures generated by continuous heating (i.e. starting plumes), their formation process exists three characteristic times that are well reflected by changes in the thermal boundary layer thickness. These characteristic times, denoted as $t_{emit}$ , $t_{recover}$ and $t_{static}$ , correspond to the moments when the plume emission begins and completes, and when the thermal boundary layer becomes quasi-static, respectively. Their $Ra_f$ – $Pr$ dependencies are found to be $t_{emit}/\tau _0\sim Ra_f^{-0.41}\,Pr^{0.41}$ , $t_{recover}/\tau _0\sim Ra_f^{-0.48}\,Pr^{0.48}$ and $t_{static}/\tau _0\sim Ra_f^{-0.49}\,Pr^{0.33}$ , respectively. Thermal structures generated by finite $t_{heat}$ exhibit similar evolution dynamics once $t_{heat} \ge t_{emit}$ , with the accelerating stage behaving like starting plumes and the decay stage like thermals (i.e. a finite amount of buoyant fluids). It is further found that their maximum rising velocity experiences a transition in the $Ra$ -dependence from $Ra$ to $(Ra\ln Ra)^{0.5}$ at $Ra \simeq 6000$ ; and their maximum acceleration reaches the value of starting plumes at $t_{heat}\simeq t_{recover}$ , and remains unchanged for larger $t_{heat}$ . In particular, the maximum rising velocity for the cases with $t_{heat} = t_{recover}$ follows a scaling relation $Ra_f^{0.37}\,Pr^{-0.37}$ , in contrast to the relation $Ra_f^{0.48}\,Pr^{-0.48}$ for starting plumes. This study provides a more comprehensive understanding of laminar thermal structures, which are relevant to a range of processes in nature and laboratory systems such as Rayleigh–Bénard convection.

Significant reductions of urban daytime ozone by extremely high concentration NOX from ship’s emissions: A case study

In this paper, a four nested Weather Research and Forecasting-Community Multiscale Air Quality (WRF-CMAQ) model was applied to analyze ozone (O3) concentration reductions under the influence of extremely high NOx concentrations emitted from ships at the Hankou Jiangtan (HJ) station adjacent to the Yangtze River in Wuhan, China. By adding NO emissions along the waterway for the sensitivity experiments, the model successfully reproduced two cases of high NOx concentrations on April 9 and April 28, 2020, and one case of persistent and extremely high NOx concentrations on the night of May 3, 2020. During daytime, strong photochemical reactions generated new O3, while the high concentration NOx from ship emissions continuously reduced O3 through catalytic cycling. This led to the O3 concentrations at the HJ station being consistently lower than the surrounding stations in the afternoon, with the high NOx plume dropping O3 concentrations by 51 ppb in 1 h, and NO2 concentrations up to 110 ppb. The presence of large amounts of fresh NO (up to 265 ppb) in the ship emission plumes rapidly reduces O3 concentrations through titration reactions during night, resulting in a wide area of low O3 concentrations (2–4 ppb) over a long period of time. This study demonstrates that the pollution and impact of emissions from ships traveling in waterways on the atmosphere of the surrounding area cannot be ignored.

Methane Retrieval Algorithms Based on Satellite: A Review

As the second most predominant greenhouse gas, methane-targeted emission mitigation holds the potential to decelerate the pace of global warming. Satellite remote sensing is an important monitoring tool, and we review developments in the satellite detection of methane. This paper provides an overview of the various types of satellites, including the various instrument parameters, and describes the different types of satellite retrieval algorithms. In addition, the currently popular methane point source quantification method is presented. Based on existing research, we delineate the classification of methane remote sensing satellites into two overarching categories: area flux mappers and point source imagers. Area flux mappers primarily concentrate on the assessment of global or large-scale methane concentrations, with a further subclassification into active remote sensing satellites (e.g., MERLIN) and passive remote sensing satellites (e.g., TROPOMI, GOSAT), contingent upon the remote sensing methodology employed. Such satellites are mainly based on physical models and the carbon dioxide proxy method for the retrieval of methane. Point source imagers, in contrast, can detect methane point source plumes using their ultra-high spatial resolution. Subcategories within this classification include multispectral imagers (e.g., Sentinel-2, Landsat-8) and hyperspectral imagers (e.g., PRISMA, GF-5), contingent upon their spectral resolution disparities. Area flux mappers are mostly distinguished by their use of physical algorithms, while point source imagers are dominated by data-driven methods. Furthermore, methane plume emissions can be accurately quantified through the utilization of an integrated mass enhancement model. Finally, a prediction of the future trajectory of methane remote sensing satellites is presented, in consideration of the current landscape. This paper aims to provide basic theoretical support for subsequent scientific research.

Toxic Potencies of Particulate Matter from Typical Industrial Plants Mediated with Acidity via Metal Dissolution.

Acidity is an important property of particulate matter (PM) in the atmosphere, but its association with PM toxicity remains unclear. Here, this study quantitively reports the effect of the acidity level on PM toxicity via pH-control experiments and cellular analysis. Oxidative stress and cytotoxicity potencies of acidified PM samples at pH of 1-2 were up to 2.8-5.2 and 2.1-13.2 times higher than those at pH of 8-11, respectively. The toxic potencies of PM samples from real-world smoke plumes at the pH of 2.3 were 9.1-18.2 times greater than those at the pH of 5.6, demonstrating a trend similar to that of acidified PM samples. Furthermore, the impact of acidity on PM toxicity was manifested by promoting metal dissolution. The dramatic increase by 2-3 orders of magnitude in water-soluble metal content dominated the variation in PM toxicity. The significant correlation between sulfate, the pH value, water-soluble Fe, IC20, and EC1.5 (p < 0.05) suggested that acidic sulfate could enhance toxic potencies by dissolving insoluble metals. The findings uncover the superficial association between sulfate and adverse health outcomes in epidemiological research and highlight the control of wet smoke plume emissions to mitigate the toxicity effects of acidity.

Lessons learned from a UAV survey and methane emissions calculation at a UK landfill

Accurate quantification of methane emissions from landfills is crucial for improving greenhouse gas inventories and mitigating climate change impacts. Existing methodologies, such as theoretical gas production models and labour-intensive measurement approaches, present limitations including large uncertainties and high operational costs. This study adds to a growing body of research and applications which aim to bridge this gap. To this end, we present a case study using Unmanned Aerial Vehicles (UAVs) equipped with methane and wind instrumentation for a survey of a landfill site in Bury, Manchester, UK, in summer 2022, in order to evaluate and reflect the challenges of the UAV-based mass balance method for quantification of methane emissions from a large heterogeneous source such as landfill. This study offers guidance on defining an appropriate methane background concentration, geospatial interpolation of sampled date, survey sampling strategy, and more importantly, addresses the challenges surrounding UAV wind measurements and spatial characterisation of emission plumes. For the period of the case study, we quantified methane flux for the landfill site to be 150.7 kg h−1 with a 1 standard deviation uncertainty range of 83.0 kg h−1 to 209.5 kg h−1.

A method for estimating localized CO2 emissions from co-located satellite XCO2 and NO2 images

Abstract. Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas. Its atmospheric concentration has increased by almost 50 % since the beginning of the industrial era, causing climate change. Fossil fuel combustion is responsible for most of the atmospheric CO2 increase, which originates to a large extent from localized sources such as power stations. Independent estimates of the emissions from these sources are key to tracking the effectiveness of implemented climate policies to mitigate climate change. We developed an automatic procedure to quantify CO2 emissions from localized sources based on a cross-sectional mass-balance approach and applied it to infer CO2 emissions from the Bełchatów Power Station (Poland) using atmospheric observations from the Orbiting Carbon Observatory 3 (OCO-3) in its snapshot area map (SAM) mode. As a result of the challenge of identifying CO2 emission plumes from satellite data with adequate accuracy, we located and constrained the shape of emission plumes using TROPOspheric Monitoring Instrument (TROPOMI) NO2 column densities. We automatically analysed all available OCO-3 overpasses over the Bełchatów Power Station from July 2019 to November 2022 and found a total of nine that were suitable for the estimation of CO2 emissions using our method. The mean uncertainty in the obtained estimates was 5.8 Mt CO2 yr−1 (22.0 %), mainly driven by the dispersion of the cross-sectional fluxes downwind of the source, e.g. due to turbulence. This dispersion uncertainty was characterized using a semivariogram, made possible by the OCO-3 imaging capability over a target region in SAM mode, which provides observations containing plume information up to several tens of kilometres downwind of the source. A bottom-up emission estimate was computed based on the hourly power-plant-generated power and emission factors to validate the satellite-based estimates. We found that the two independent estimates agree within their 1σ uncertainty in eight out of nine analysed overpasses and have a high Pearson's correlation coefficient of 0.92. Our results confirm the potential to monitor large localized CO2 emission sources from space-based observations and the usefulness of NO2 estimates for plume detection. They also illustrate the potential to improve CO2 monitoring capabilities with the planned Copernicus Anthropogenic CO2 Monitoring (CO2M) satellite constellation, which will provide simultaneously retrieved XCO2 and NO2 maps.

The effect of small perturbation on dynamics of absorptive LiBr–water solution

In a binary solution of lithium bromide–water, even a small disturbance in the initial homogeneous mass fraction at the absorbing interface has profound effects on the entire system dynamics. This perturbation of absorption disrupts the equilibrium, leading to the formation of surface tension gradients and subsequently, Marangoni flows. While these flows are relatively weak, they result in a non-uniform distribution of density within the bulk, initiating buoyant convection. We investigate complexities of the Marangoni, solutal, and buoyant convection caused by localized disruptions in uniform absorption, all in the absence of any surfactants. We have conducted numerical simulations to explore fluid dynamics and heat and mass transfer, revealing three different regimes. Initially, shortly after disturbance, variations in mass fraction and flow within the cell are primarily governed by the Marangoni force. After a finite period, the emergence of buoyant convection leads to the strong growth of velocity and significant changes in temperature and mass fraction. Finally, the destabilization of the boundary layer becomes so significant that the emission of plumes is observed. At later times, the parallel existence of two types of patterns takes on a spatially fixed form. The central part, occupied by bands (visible on space-time maps), exhibits minimal changes in time, while a periodic structure is established near the wall. This behavior can be characterized as a relaxation–oscillation mode of instability.

Severe photochemical pollution was found in large petrochemical complexes: A typical case study in North China

Large petrochemical complex (PC) widely exists in both developing and developed countries, and is expected to have a special photochemical pollution in local scale due to huge VOCs emissions. Here, a typical large-scale PC in North China was selected as the study case, to explore the character, formation and influence of local photochemical pollution regarding PCs based on an improved 0-D chemical model. In the study PC, VOCs-rich character was apparent with THCs level of 90.8 ± 28.0 ppb and THCs/NOx ratio of ∼26.2 mol/mol. Severe O3 pollution was found in warm months with monthly mean MDA1O3 of 67.3–96.0 ppb. Model simulations showed the heavy O3 pollution in this PC was attributed to high precursors rather than to unfavorable meteorology, and was more sensitive to NOx (with response of 1.42 g/g) than to THCs (with response of 0.12 g/g). The photochemical pollution formation potential of the emission plumes of this PC was very enormous, with production rate of 19.6 ppb h−1 for O3, 2.9 ppb h−1 for HCHO and 1.1 ppb h−1 for CH3CHO on daytime average, 1–5 greater than in normal urban areas. The higher production rates happened in morning hours, which explained the earlier peak time of observed O3 in PCs. And about 70% of photochemical pollution (represented by O3) would be transported to surroundings, leading to the significant photochemical-pollution hazard to the vicinity of PCs.

Greenhouse gases in the tall tower of El Arenosillo station in Southwestern Europe: First-year of measurements

Carbon dioxide (CO2), methane (CH4) and carbon monoxide (CO) were measured at 10, 50 and 100 m in a tall tower located at El Arenosillo observatory (Southwestern Europe) from December 2021 to December 2022. Depending on the height, hourly averages varied between 418 ± 5 at 100 m and 422 ± 8 μmol mol−1 at 10 m for CO2, while CH4 varied between 1999 ± 30 nmol mol−1 at 100 m and 1986 ± 25 at 10 m and ∼ 102 ± 19 nmol mol−1 for CO. A monthly variation with a common maximum in January–February was obtained while the minimum was found in June for CH4 and CO, whereas the minimum for CO2 was in August. The seasonal daily patterns showed a maximum between 5:00 and 10:00 UTC while the minimum was observed at 15:00–18:00 UTC. The daily variations are controlled by atmospheric stability, photochemical activity and vegetation influence, among other factors. The CO2 gradient was strongly conditioned by the photosynthesis, plant and soil respiration and vertical mixing with peaks higher than 19 × 10−2 μmol mol−1 m−1 at ∼5:00 UTC in spring and autumn. The CH4 gradient, greater in winter and autumn (12–27 × 10−2 μmol mol−1 m−1) is affected by vertical stability, local emissions and photochemical activity while CO depicted small vertical gradients. A different behavior was found in the CO2 and CH4 gradients, for CO2 the 10–50 m gradient is higher than 50–100 m while CH4 was the opposite; which could reflect a lower CO2 surface layer than CH4. The observations at 100 m registered CO and CH4 peaks that were not recorded at 10 m, which could be associated with the arrival of a forest fire plume and potential CH4 fugitive emissions.

Evaluation of detached plume and total organic carbon in the main chimney of the Indocement Plant 9-10 Palimanan to optimize clinker production and its influence on SO2 emissions

Detached Plume is the phenomenon of the formation of a cloud of gas/smoke that is interrupted in the main chimney of a cement Plant from the combustion of a kiln containing compounds consisting of Ammonia, Sulfur and Organic Carbon. The Detached Plume that occurred at Plant 9-10 of Indocement-Palimanan was analyzed and controlled so that the SO2 emissions produced could be reduced. This research aims to analyze the effect of Total Organic Carbon (TOC) on clinker production at Plant 9-10, understand the control of Detached Plume and SO2 emissions produced in the main chimney of Plant 9-10, and determine the optimization of the clinker production process at Plant 9-10 by Total Organic Carbon as a variable in Raw Meal. The analysis methods used include monitoring the Detached Plume phenomenon in the Main Chimney, its effect on SO2 Emissions, observing the effect of TOC changes in Raw Material on Clinker production capacity at Plant 9-10. The research results show that the TOC value of Plant 9 is 1.22%, thereby reducing Clinker production capacity to 3466 tpd from the target of 3600 tpd. On the other hand, the TOC value for Plant 10 in the month was 1.00%, thereby reducing Clinker production capacity to 4070 tpd from the target of 4200 tpd. This shows that a significant increase in TOC value in Raw Meal reduces Clinker production capacity. The Detached Plume is also influenced by the ammonia gas content in the main chimney emissions, where the ammonia content &gt; 2 mg/Nm3 increases the visibility of the Detached Plume in the main chimney of Plant 9-10, and the SO2 value

Advancing shipping NOx pollution estimation through a satellite-based approach.

Estimating shipping nitrogen oxides (NOx) emissions and their associated ambient NO2 impacts is a complex and time-consuming task. In this study, a satellite-based ship pollution estimation model (SAT-SHIP) is developed to estimate regional shipping NOx emissions and their contribution to ambient NO2 concentrations in China. Unlike the traditional bottom-up approach, SAT-SHIP employs satellite observations with varying wind patterns to improve the top-down emission inversion methods for individual sectors amidst irregular emission plume signals. Through SAT-SHIP, shipping NOx emissions for 17 ports in China are estimated. The results show that SAT-SHIP performed comparably with the bottom-up approach, with an R2 value of 0.8. Additionally, SAT-SHIP reveals that the shipping sector in port areas contributes ∼21 and 11% to NO2 concentrations in the Yangtze River Delta and Pearl River Delta areas of China, respectively, which is consistent with the results from chemical transportation model simulations. This approach has practical implications for policymakers seeking to identify pollution sources and develop effective strategies to mitigate air pollution.