Average Emission Research Articles

Semimetal–dielectric–metal metasurface for infrared camouflage with high-performance energy dissipation in non-atmospheric transparency window

Abstract The development of novel camouflage technologies is of great significance, exerting an impact on both fundamental science and diverse military and civilian applications. Effective camouflage aims to reduce the recognizability of an object, making it to effortlessly blend with the environment. For infrared camouflage, it necessitates precise control over surface emissivity and temperature to ensure that the target blends effectively with the surrounding infrared background. This study presents a semimetal–dielectric–metal metasurface emitter engineered for the application of infrared camouflage. The metasurface, with a total thickness of only 545 nm, consists of a Bi micro-disk array and a continuous ZnS and Ti film beneath it. Unlike conventional metal-based metasurface design, our approach leverages the unique optical properties of Bi, achieving an average emissivity of 0.91 in the 5–8 μm non-atmospheric transparency window. Experimental results indicate that the metasurface emitter achieves lower radiation and actual temperatures compared to those observed in comparative experiments, highlighting its superior energy dissipation and thermal stability. The metasurface offers advantages such as structural simplicity, cost-effectiveness, angular insensitivity, and deep-subwavelength features, rendering it suitable for a range of applications including military camouflage and anti-counterfeiting, with potential for broad deployment in infrared technologies.

Ensemble estimates of global wetland methane emissions over 2000–2020

Abstract. Due to ongoing climate change, methane (CH4) emissions from vegetated wetlands are projected to increase during the 21st century, challenging climate mitigation efforts aimed at limiting global warming. However, despite reports of rising emission trends, a comprehensive evaluation and attribution of recent changes remains limited. Here we assessed global wetland CH4 emissions from 2000–2020 based on an ensemble of 16 process-based wetland models. Our results estimated global average wetland CH4 emissions at 158 ± 24 (mean ± 1σ) Tg CH4 yr−1 over a total annual average wetland area of 8.0 ± 2.0×106 km2 for the period 2010–2020, with an average increase of 6–7 Tg CH4 yr−1 in 2010–2019 compared to the average for 2000–2009. The increases in the four latitudinal bands of 90–30° S, 30° S–30° N, 30–60° N, and 60–90° N were 0.1–0.2, 3.6–3.7, 1.8–2.4, and 0.6–0.8 Tg CH4 yr−1, respectively, over the 2 decades. The modeled CH4 sensitivities to temperature show reasonable consistency with eddy-covariance-based measurements from 34 sites. Rising temperature was the primary driver of the increase, while precipitation and rising atmospheric CO2 concentrations played secondary roles with high levels of uncertainty. These modeled results suggest that climate change is driving increased wetland CH4 emissions and that direct and sustained measurements are needed to monitor developments.

Design Method of Infrared Stealth Film Based on Deep Reinforcement Learning

With the rapid advancement of infrared detection technology, the development of infrared stealth materials has become a pressing need. The study of optical micro/nano infrared stealth materials, which possess selective infrared radiation properties and precise structural features, is of significant importance. By integrating deep reinforcement learning with a multilayer perceptron, we have framed the design of radiation-selective films as a reinforcement learning problem. This approach led to the creation of a Ge/Ag/Ge/Ag multilayer micro/nano optical film that exhibits infrared stealth characteristics. During the design process, the agent continuously adjusts the thickness parameters of the optical film, exploring and learning within the defined design space. Upon completion of the training, the agent outputs the optimized thickness parameters. The results demonstrate that the film structure, optimized by the agent, exhibits a low average emissivities of 0.086 and 0.147 in the 3∼5 µm and 8∼14 µm atmospheric windows, respectively, meeting the infrared stealth requirements in terms of radiation characteristics. Additionally, the film demonstrates a high average emissivity of 0.75 in the 5∼8 µm range, making it effective for thermal radiation management. Furthermore, we coated the Si surface with the designed thin film and conducted experimental validation. The results show that the coated material exhibits excellent infrared stealth properties.

Tailoring dynamics of thermally activated delayed fluorescence molecules embedded in cavity by forming coupling-induced hybrid states

Light–matter coupling-induced hybrid states provide the potential to tune the emission dynamics of molecular chromophores having multilevel systems. We demonstrate the alteration of delayed fluorescence dynamics by hybrid states formation through the interaction of light with a thermally activated delayed fluorescence molecule embedded in a conventional Fabry–Pérot cavity. The proximity of cavity resonance with the excited state absorption is modified by manipulating the incident angles (with sample) instead of varying the active layer thickness. The coupling-induced hybrid states are observed by angle-dependent emission spectroscopy and lifetime measurements. The variation in average emission lifetime with respect to incident angle is over 10 μs and is accompanied by significant changes in the full width at half maxima (factor of three). The control of emission via a barrier-free route or reverse intersystem crossing transition is demonstrated from these measurements. These findings suggest the possibility of tailoring intermediate states for lasing, where exciton density inversion can enhance spontaneous emission.

Thermal Environmental Impact of Urban Development Scenarios from a Low Carbon Perspective: A Case Study of Wuhan

Amidst the increasingly escalating global concern regarding climate change, adopting a low-carbon approach has become crucial for charting the future developmental trajectory of urban areas. It also offers a novel angle for cities to avoid high-temperature risks. This paper estimates carbon emissions in Wuhan City from both direct and indirect aspects. Then, the ANN (artificial neural network)–CA (Cellular Automata) model is employed to establish three distinct development scenarios (Ecological Priority, Tight Growth, and Natural Growth) to predict future urban expansion. Additionally, the WRF (Weather Research and Forecasting Model)—UCM (Urban Canopy Model) model is used to investigate the thermal environmental impacts of varying urban development scenarios. This study uses a low-carbon perspective to explore how cities can develop scientifically sound urban strategies to meet climate change challenges and achieve sustainable development goals. The conclusions are as follows: (1) The net carbon emission for Wuhan in 2022 is estimated to be approximately 20.8353 million tonnes. Should the city maintain an average annual emission reduction rate of 10%, the carbon sink capacity of Wuhan would need to be enhanced by 382,200 tonnes by 2060. (2) In the absence of anthropogenic influence, there is a propensity for the urban construction zone of Wuhan to expand primarily towards the southeast and western sectors. (3) The Ecological Priority (EP) and Tight Growth (TG) scenarios are effective in alleviating the urban thermal environment, achieving a reduction of 0.88% and 2.48%, respectively, in the urban heat island index during afternoon hours. In contrast, the Natural Growth (NG) scenario results in a degradation of the urban thermal environment, with a significant increase of over 4% in the urban heat island index during the morning and evening periods. (4) An overabundance of urban green spaces and water bodies could exacerbate the urban heat island effect during the early morning and at night. The findings of this study enhance the comprehension of the climatic implications associated with various urban development paradigms and are instrumental in delineating future trajectories for low-carbon sustainable urban development models.

Polyethylene packaging and alternative materials in the United States: A life cycle assessment.

A comprehensive life cycle assessment was conducted to evaluate the potential environmental impacts of polyethylene (PE) packaging and its alternatives, including paper, glass, aluminum, and steel in the United States. The assessment focuses on five major packaging applications: collation shrink films, stretch films for pallet wraps, heavy-duty sacks, non-food bottles, and flexible food pouches. The study compares PE and the alternative packaging materials based on the following environmental impact categories: global warming potential (GWP), fossil energy use, mineral resource use, and water scarcity. The research integrates sales volume estimates for each application, examining the substitution ratios of PE-based materials and the GWP decrease capabilities of using PE as packaging material. The findings reveal that substituting PE for other packaging materials can lead to an average life cycle GWP emissions decrease of approximately 70%. This significant decrease highlights the potential GWP benefits of PE in the context of packaging solutions in the United States. We also provide a detailed analysis of the potential environmental impacts and trade-offs associated with PE and its alternatives. The insights gained from this study are intended to assist stakeholders and policymakers in making informed decisions that balance environmental impact mitigation with maintaining product functionality and achieving sustainability objectives.

Effects of Forest Land Mulching on the Soil CO2 Emission Rate of Phyllostachys violascens Forests

This study investigates the dynamics of soil CO2 emissions during the cover period of Phyllostachys violascens and the impact of different cover measures, aiming to provide references for reducing the environmental effects of bamboo cover. An L27 (913) orthogonal experimental design was employed, setting the following variables: (1) heating materials: chicken manure, straw cake, and wheat ash; (2) thickness of husk layer: 15 cm, 25 cm, and 35 cm; (3) soil moisture levels before covering: moisture to 10 cm, 15 cm, and 20 cm. The soil CO2 emission rate showed a unimodal curve, with a significant overall increase during the cover period. Throughout the entire cover period, the average soil CO2 emission rate (25.39 μmol·m−2·s−1) was 5.1 times higher than that of the uncovered Lei bamboo forest (5.02 μmol·m−2·s−1) during the same period. Thicker husk layers (25 cm and 35 cm) corresponded to higher soil CO2 emission rates, with significant differences noted among the thicknesses. When the soil was moist to 10 cm, the CO2 emission rate was highest (62.51 μmol·m−2·s−1); moisture to 15 cm and 20 cm resulted in significantly lower emission rates. Chicken manure produced the highest peak CO2 emissions in the third week, at 70.64 μmol·m−2·s−1, while straw cake and wheat ash reached their peaks in the fifth week, at 66.56 μmol·m−2·s−1 and 57.58 μmol·m−2·s−1, respectively. The interactions between the three factors (heating materials, husk layer thickness, and moisture levels) significantly affected the soil CO2 emission rates. By optimally configuring these factors, CO2 emissions can be regulated. This study recommends using wheat ash or straw cake as heating materials, combined with a 25 cm husk layer thickness, and moistening the soil to 15 cm before covering. This approach effectively reduces the peak and total soil CO2 emissions while ensuring suitable soil temperatures for the growth of bamboo shoots in spring. This research provides a scientific basis for the environmental management of bamboo forests, aiding in the optimization of covering measures to achieve low-carbon and sustainable bamboo management.

N2O Generation, Key Influencing Factors, and Emission Reduction Strategies of A2O Process in Municipal Wastewater Treatment Plant

To achieve non-carbon dioxide greenhouse gas emission reduction and control in municipal wastewater treatment plants （WWTPs）, this study conducted one-year long-term monitoring of nitrous oxide （N2O） in the anaerobic-anoxic-aerobic （A2O） process of a large-scale municipal wastewater treatment plant in Beijing. The experimental results showed that the anaerobic and anoxic zones of the A2O process could effectively remove dissolved N2O contained in the return sludge, while the aerobic zone was the main area for N2O generation and emission, and its generation pathway may have been dominated by ammonia oxidizing bacteria （AOB） denitrification. A significant difference was observed between winter and summer N2O production, and the difference in the average N2O release flux was up to 7.6 times, and the average monthly N2O emission in winter was 32.75 kg, which was significantly higher than that in summer （6.06 kg）. The accumulation of nitrite （NO2--N） and the concentration of dissolved oxygen （DO） had a significant impact on N2O production. Therefore, to achieve N2O reduction in the A2O process, the concentration of NO2--N in the aerobic zone should be controlled below 0.40 mg·L-1 in winter and 0.10 mg·L-1 in summer, while the DO concentration should be maintained above 1.2 mg·L-1.

Earthquakes Have Accelerated the Carbon Dioxide Emission Rate of Soils on the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau (QTP) has an extensive frozen soil distribution and intense geological tectonic activity. Our surveys reveal that Qinghai-Tibet Plateau earthquakes can not only damage infrastructure but also significantly impact carbon dioxide emissions. Fissures created by earthquakes expose deep, frozen soils to the air and, in turn, accelerate soil carbon emissions. We measured average soil carbon emission rates of 968.53 g CO2 m-2·a-1 on the fissure sidewall and 514.79 g CO2 m-2·a-1 at the fissure bottom. We estimated that the total soil carbon emission flux from fissures caused by M ≥ 6.9 earthquakes on the Qinghai-Tibet Plateau from 326 B.C. to 2022 is 1.83 × 1012 g CO2 a-1; this value is equivalent to 0.51% ~ 1.48% and 2.34% ~ 5.14% of the increased annual average carbon sink resulting from the national ecological restoration projects targeting forest protection and grassland conservation in China, respectively. These earthquake fissures thus increased the soil carbon emission rate by 0.71 g CO2 m-2·a-1 and significantly increased the total carbon emissions. This finding shows that repairing earthquake fissures could play a very important role in coping with global climate change.

Extreme value theory analysis of high emitter trends across four US cities from 1995 to 2021.

Extreme value theory provides a direct means to characterize the distribution of high emitters within a vehicle fleet and calculate statistical confidence intervals for comparisons. Defining a "high emitter" as the maximum emitter in a random sample of N vehicles implies in the limit of large N that high emitters follow an extreme value distribution, comprised of three distinct domains. The analysis of over twenty years of roadside remote sensing emissions measurements in Chicago, Denver, Los Angeles and Tulsa reveals clear differences between gasoline vehicle high emitter distributions across pollutants (hydrocarbons (HC), carbon monoxide (CO) and nitric oxide (NO)), but very similar behavior across the four cities. As Federal emissions regulations became more stringent, HC and CO high emitters evolved from distributions bounded by the stoichiometric limits of HC and CO formation in an engine to progressively longer tailed distributions. In contrast, NO high emitter distributions have changed little over this time period. These distinct behaviors likely reflect differences in the failure mechanisms leading to high HC, CO, versus NO emissions. Whereas average HC, CO and NO fleet emissions fell dramatically over these two plus decades by factors of about 4, 6 and 7, respectively, mean high emitter emissions declined by less than half of these. The paper examines in detail similarities and differences in high emitter distributions versus pollutant, city and vehicle type, how these changed over a period of roughly twenty years and the policy implications that can be drawn.

Summer CH4 ebullition strongly determines year-round greenhouse gas emissions from agricultural ditches despite frequent dredging.

Recent studies indicate that greenhouse gas (GHG) emissions from agricultural drainage ditches can be significant on a per-unit area basis, but spatiotemporal investigations are still limited. Additionally, the impact of dredging - a common management in such environments - on ditch GHG emissions is largely unknown. This study presents year-round GHG emissions from nine ditches on a dairy farm in the center of the Netherlands, where each year, approximately half of the ditches are dredged in alternating cycles. We measured monthly diffusive fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), along with ebullitive CH4 emissions, supplemented by diel flux measurements (i.e., 24-h measurements) conducted in summer and winter. Our findings indicate that while diffusive GHG fluxes exhibited low spatiotemporal variation, ebullitive CH4 emissions were significantly higher during warmer periods and marginally elevated at ditch intersections. CH4 ebullition was the dominant pathway of ditch GHG emissions, accounting for 58% of the total annual emissions, followed by CO2 (39%), and N2O (3%). Approximately 80% of the total CH4 emissions occurred through ebullition during spring and summer. The average CH4 emission factor estimated for our ditches (574kgha-1 year-1) is ∼40% higher than the Tier-1 value suggested by the IPCC for ditches on mineral soils (416kgha-1 year-1). Based on two 24-h measurement campaigns, we concluded that neglecting nighttime diffusive CO2 and CH4 emissions may lead to inaccurate estimates of annual ditch GHG emissions, with ∼12% underestimation in this study. Although dredging led to subtle increases in water-to-atmosphere GHG emissions immediately after the activity, it reduced overall annual GHG emissions by ∼35%. This study highlights the importance of CH4 ebullition and of capturing diel cycles of diffusive emissions to accurately assess ditch GHG emissions and underscores the importance of considering seasonal variations and dredging practices when budgeting ditch GHG emissions.

Synthesis of a Novel Derivative Containing Phosphaphenanthrene and Phenyl Propargyl Ether Groups Toward Enhanced Flame Retardance and Mechanical Properties of Epoxy Resin

ABSTRACTTo achieve effective flame retardancy and improved toughness in epoxy resin (EP) without compromising strength and modulus, a new derivative containing phosphaphenanthrene and phenyl propyl ether groups (HPMD) has been developed and used as an additive. The structure of HPMD has been fully characterized, and the properties of HPMD and modified EP have been thoroughly studied. The phenyl propyl ether group in HPMD can undergo Claisen type rearrangement to form benzopyran during heat treatment and subsequently polymerize by curing via the CC bond in the benzopyran. The unique rigid and flexible structures of HPMD allow it to disperse in the EP matrix through melting. Dynamic mechanical analysis suggests that HPMD has a high degree of interpenetration in the EP matrix, resulting in a single‐phase structure for the epoxy resins containing HPMD. Notably, incorporating only 4 wt% HPMD content into the polymer matrix yields a flame‐retarded, toughened, and strengthened EP. EP containing 4 wt% HPMD (EP4; phosphorus content of only 0.33%) displays a limiting oxygen index value of 31.1% and exhibits a UL94 V‐0 rating. Compared with that of EP, the combustion of EP4 exhibits a decrease in the peak of heat release rate, maximum average heat rate emission, average heat release rate, and total heat release, along with an increase in the char yield, further indicating that HPMD effectively retards the combustion of EP. Moreover, EP4 displays improvements in tensile strength, elongation at break, flexural strength, flexural modulus, and impact strength of 18.4%, 9.7%, 14.9%, 19.1%, and 26.7%, respectively, compared with unmodified EP. Analysis of HPMD's flame‐retardant action suggests that it exhibits flame‐retardant activity simultaneously in the gas and condensed phases. Significant progress has been demonstrated toward the development of a meltable epoxy resin additive that combines flame‐retardant, toughening, and strengthening functions while avoiding phase separation from the epoxy resin.

Carbon Footprint of Milk Processing—Case Study of Polish Dairy

Sustainable milk processing is essential to minimize negative environmental impacts. The purpose of this study was to determine the carbon footprint (CF) of the production of milk products in an industrial plant in Poland. Annual production and technological processes were analyzed, and relevant parameters were determined, as well as the method of data collection according to the chosen method of analysis and the developed database. It was found that each process is a source of greenhouse gas (GHG) emissions and affects the CF of the product. The total carbon footprint of the production of milk products was 0.367 kgCO2eq/kg. The average GHG emissions associated with production came mainly from indirect emissions (electricity consumption) and accounted for 50% of the total emissions. The determined relationship between the CF and monthly production volume also allows production planning in the context of sustainability. An increase in the monthly production volume by about 12% results in a reduction in the carbon footprint by about 18%. Decarbonization of dairies is possible through the use of renewable energy sources. Determining the CF of milk processing is the first step toward reducing GHG emissions, improving the sustainability of the sector and aligning with global trends and regulations.

Carbon Footprint of Electricity Produced in the Russian Federation

Energy generation makes a significant contribution to greenhouse gas emission. The carbon footprint of electricity significantly affects the total carbon footprint of a wide variety of products, which is especially relevant for energy-intensive industries (aluminum, platinum, carbon fiber-reinforced plastics, etc.) and hydrogen energy. The carbon footprint of aluminum, produced in Russia is 8.0–15.0 kg CO2-eq./kg. It is lower than the actual carbon footprint of aluminum produced in other countries due to the lower carbon intensity of Russian grid electricity in comparison with the world average. The carbon footprint of hydrogen, produced by photovoltaic modules with electricity consumption from the Russian national electricity grid is 16.6 kg CO2-eq./kg, while the world average carbon footprint of photovoltaic hydrogen is 18.1 kg CO2-eq./kg. The average carbon footprint of electricity generated and consumed in Russia ranges from 310 to 634 g CO2-eq./kWh. This paper analyzes methodological approaches to determining grid emission factors for Russian electricity. It has been established that different principles of spatial division of the Russian energy system can be used to determine grid emission factors (national average grid emission factor, grid emission factors for the integrated energy system, grid emission factors for price and non-price zones of the wholesale electricity market).

Interaction of Straw Mulching and Nitrogen Fertilization on Ammonia Volatilization from Oilseed Rape–Maize Rotation System in Sloping Farmland in Southwestern China

Ammonia (NH3) volatilization caused by urea application has negative implications for human health, environmental quality, and the value of nitrogen fertilizers. It remains to be investigated how management strategies should be adopted to not only reduce NH3 volatilization but also improve nitrogen use efficiency (NUE) in the agriculture industry at present. Hence, a two-year field trial, including subplots, was conducted to simultaneously evaluate the effects of mulching treatments (NM: non-mulching; SM: straw mulching) and different fertilizer treatments (U: urea; U + NBPT: urea plus 1% N-(n-butyl) thiophosphoric triamide; U + CRU: the mixture of urea and controlled-release urea at a 3:7 ratio; U + OF: urea plus commercial organic fertilizer at a 3:7 ratio) on NH3 volatilization, crop production, and NUE in an oilseed rape–maize rotation system in the sloping farmland of purple soil in southwestern China between 2021 and 2023. Compared with NM + U, NH3 volatilization losses under the NM + U + NBPT, NM + U + CRU, and NM + U + OF treatments decreased, on average, by 64.13%, 17.39%, and 15.09% during the oilseed rape growing season but by 64.01%, 11.67%, and 10.13% during the maize growing season, respectively. An average increase in NH3 volatilization of 35.65% for the straw-mulching treatment was recorded during the oilseed rape season, while during the maize season, this parameter showed an increase of 10.69%, in comparison to NM + U. With the combination of urea with NBPT, CRU, and organic fertilizer, contrastingly, a reduction in NH3 volatilization was achieved under the SM + U + NBPT, SM + U + CRU, and SM + U + OF treatments. When compared with NM + U, the difference in the NUE between the NM + U + NBPT, NM + U + CRU, and NM + U + OF treatments was not significant in the oilseed rape season. The NUE was around 4.27% higher under NM + U + NBPT during the maize season (p < 0.05). Compared with NM + U, under the NM + U + NBPT, NM + U + CRU, and NM + U + OF treatments, consistently lower values of yield-scaled NH3 volatilization were noted: 13.15–65.66% in the oilseed rape season and 10.34–67.27% in the maize season. Furthermore, SM + U, SM + U + NBPT, SM + U + CRU, and SM + U + OF showed average annual emission factors (AEFs) of 14.01%, 5.81%, 12.14%, and 11.64%, respectively. Overall, straw mulching, along with the application of the mixture of NBPT and urea, was found to be the optimal strategy to effectively reduce the NH3 emissions in the purple soil areas of southern China.

Designing a sector-coupled European energy system robust to 60 years of historical weather data

As energy systems transform to rely on renewable energy and electrification to mitigate climate change, they encounter stronger year-to-year variability in energy supply and demand. Yet, most infrastructure planning relies on a single weather year, risking a potential lack of robustness. In this paper, we optimize capacity layouts for a European energy system under net-zero CO2 emissions for 62 different weather years. Subsequently, we fix the layouts and optimize their operation in every other weather year to assess resource adequacy and CO2 emissions. Our analysis shows a variation of ± 10% in total system costs across weather years. Layouts designed for years with compound weather events prove more robust, achieving resource adequacy of 99.9% and net-negative CO2 emissions of −0.5% per year relative to 1990 levels. CO2-emitting backup generation regulated by a CO2 tax offers a cost-effective measure to enhance robustness. It increases emissions only marginally, keeping average emissions below 1% of 1990 levels over all layouts. Our findings underscore the need for policymakers and energy stakeholders to account for interannual weather variability in future infrastructure planning.

Is a dedicated bus lane operationally and environmentally beneficial? A case study in Beijing

ABSTRACT In 2023, Beijing adjusted dedicated bus lane (DBL) policies, allowing private car access during specific periods to improve road transport efficiency. This study proposes a comprehensive method to assess the operational and environmental impact of DBL adjustments. Traffic volumes are estimated using a localized traffic fundamental diagram model based on large-scale floating car speed data, while vehicle emissions are quantified employing a high-resolution road network emission inventory. Results show over 20% increased traffic volumes and 10% higher average speed on DBLs in central Beijing. Extended to regional road network, the adjustments enhance expressway capacity and improve traffic efficiency on main and minor arterial roads. While total emissions on expressways increase due to heightened traffic volumes, average vehicular emission intensities in urban areas decrease because of smoother traffic flow. These findings could provide valuable insights for decision-makers with the information needed to target reasonable DBL policies in metropolitan regions.

Satellite-Based Monitoring of Methane Emissions from China's Rice Hub.

Rice cultivation is one of the major anthropogenic methane sources in China and globally. However, accurately quantifying regional rice methane emissions is often challenging due to highly heterogeneous emission fluxes and limited measurement data. This study attempts to address this issue by quantifying regional methane emissions from rice cultivation with a high-resolution inversion of satellite methane observations from the Tropospheric Monitoring Instrument (TROPOMI). We apply the method to the largest rice-producing province (Heilongjiang) in China for 2021. Our satellite-based estimation finds a rice methane emission of 0.85 (0.69-1.03) Tg a-1 from the province or an average emission factor of 22.0 (17.8-26.6) g m-2 a-1 when normalized by rice paddy areas. The satellite-based analysis reveals a 2 to 4 times lower bias in widely used global and national inventories, which lack up-to-date regional information. The inversion reduces the uncertainty of regional rice emissions by 73% relative to bottom-up estimates based on field flux measurements. The satellite inversion also shows that the highest rice methane emissions occur in June during the tillering stage of rice, decreasing toward ripening, indicating that the predominant water management practice in the region involves drainage and intermittent flooding after initial flooding. Process-based modeling further suggests that this practice can lead to a reduction of methane emissions by more than 50% compared to continuous flooding of rice paddies and natural wetlands.

The Influence of Polylactic Acid Filament Moisture Content on Dust Emissions in 3D Printing Process.

This paper presents the results of a study on the effect of moisture content in polylactic acid (PLA) filaments on dust emissions during incremental manufacturing. The tests were conducted in a customised chamber using a standard 3D printer, and Plantower PMS3003 sensors were used to monitor air quality by measuring PM1, PM2.5 and PM10 concentrations. The filament humidity levels tested were 0.18%, 0.61% and 0.83%. The results show that a higher moisture content in the filament significantly increases dust emissions. For dry filaments (0.18% humidity), the average dust emissions ranged from 159 to 378 µg/m3. Slightly humid filaments (0.61%) produced higher emissions, with averages between 59 and 905 µg/m3, with one outlier reaching up to 1610 µg/m3. For very humid filaments (0.83%), the highest average emissions were observed, ranging from 57 to 325 µg/m3, along with greater variability (standard deviation up to 198). These findings highlight that increased filament humidity correlates with elevated dust emissions and greater instability in emission levels, raising potential health concerns during 3D printing.

Air Pollution Measurement and Dispersion Simulation Using Remote and In Situ Monitoring Technologies in an Industrial Complex in Busan, South Korea.

Rapid industrialization and the influx of human resources have led to the establishment of industrial complexes near urban areas, exposing residents to various air pollutants. This has led to a decline in air quality, impacting neighboring residential areas adversely, which highlights the urgent need to monitor air pollution in these areas. Recent advancements in technology, such as Solar Occultation Flux (SOF) and Sky Differential Optical Absorption Spectroscopy (SkyDOAS) used as remote sensing techniques and mobile extraction Fourier Transform Infrared Spectrometry (MeFTIR) used as an in situ technique, now offer enhanced precision in estimating the pollutant emission flux and identifying primary sources. In a comprehensive study conducted in 2020 in the Sinpyeong Jangrim Industrial Complex in Busan City, South Korea, a mobile laboratory equipped with SOF, SkyDOAS, and MeFTIR technologies was employed to approximate the emission flux of total alkanes, sulfur dioxide (SO2), nitrogen dioxide (NO2), formaldehyde (HCHO), and methane (CH4). Using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) diffusion model, pollutant dispersion to residential areas was simulated. The highest average daily emission flux was observed for total alkanes, with values of 69.9 ± 71.6 kg/h and 84.1 ± 85.8 kg/h in zones S1 and S2 of the Sinpyeong Jangrim Industrial Complex, respectively. This is primarily due to the prevalence of metal manufacturing and mechanical equipment industries in the area. The HYSPLIT diffusion model confirmed elevated pollution levels in residential areas located southeast of the industrial complex, underscoring the influence of the dominant northwesterly wind direction and wind speed on pollutant dispersion. This highlights the urgent need for targeted interventions to address and mitigate air pollution in downwind residential areas. The total annual emission fluxes were estimated at 399,984 kg/yr and 398,944 kg/yr for zones S1 and S2, respectively. A comparison with the Pollutant Release and Transfer Registers (PRTRs) survey system revealed that the total annual emission fluxes in this study were approximately 24.3 and 4.9 times higher than those reported by PRTRs. This indicates a significant underestimation of the impact of small businesses on local air quality, which was not accounted for in the PRTR survey system.