Atmospheric Environment: X最新文献

Microplastics are emitted to the environment from many sources, and transported via water, soil and air. The airborne component is less well studied and measurements often focus on particles larger than 10 μm, while smaller particles are worse from a health perspective and likely more abundant. Measurement studies do often not include tyre wear, which is a large source of microplastics in urban areas. To improve the understanding of the microplastics concentration in urban areas, simulations of emissions and concentrations of atmospheric tyre wear particles (TWP) over Stockholm are performed. The results show that TWP are ubiquitous in urban areas, with highest concentrations along busy highways and in poorly ventilated street canyons. Yearly average roof level concentrations of TWP-PM₁₀ range from 0.2 μg m⁻³ in areas with moderate traffic to 1.2 μg m⁻³ close to busy highways. Average yearly concentrations at three selected street canyons range from 0.7 to 1.1 μg m⁻³. The modelled concentrations correspond to 4–6% of the total measured PM₁₀ concentration. TWP emissions are expected to increase with increasing traffic in future, and possibly also with the increase in vehicle weight with electric vehicles and SUV:s.

The paper consolidates the role of conventional and stabilized N fertilizers used in coffee crop production in Brazil and their N₂O emissions in tropical systems. The experiment consisted of the combination of three fertilizers and five doses with four repetitions, totalling 60 experimental plots. The factors of the experiment were conventional urea (U), ammonium nitrate (AN), and urea + NBPT (U_NBPT), while the doses were 0, 150, 275, 400, and 525 kg ha⁻¹ year⁻¹ of N. The municipality is located in a region at 1100 m of altitude, 20°53′26.04″ S and 44°52′04.14″ W. A randomized block design with a 3 × 5 factorial scheme was used. This region, traditional in coffee production, has a tropical humid climate, classified as Cwa according to the Köppen scale, with temperate summer and dry winter. U_NBPT and the ammonium nitrate mitigated the N₂O emissions by 50.6% and 78.5%, respectively, in comparison to the conventional urea. High C stocks were found in the 1 m soil layer, from 117 to 162 t ha⁻¹ of organic C, indicating the importance of the soil as a C sink in coffee plantations. N stocks varied from 33 to 17 t ha⁻¹ of N but no differences among the treatments were found. Approximately 50% of soil C was in the 0–0.4 m layer as a consequence of the greater amount of plant biomass, nutrients, and biological activity. Soil C:N ratio in the entire layer varied from 4.2 to 9.2. Our results indicate that nitrification is the most predominant process of N₂O emissions. The standard EF proposed by the IPCC overestimates the N₂O emissions in the Brazilian coffee plantations and the emissions differ according to the N fertilizer technology. These coffee crop systems have an important ability to stock C and N in the soil.

Air pollution is one of the most important environmental problems in world cities. The main aims of this study were to characterize the spatio-temporal changes in the concentration of air pollutants in Tehran metropolis, Iran, in the last 6 years, identify the major sources of pollution, estimate the human health effects and economic costs, and recommendations for good practice. Hourly concentrations of standard air pollutants including PM₁₀, PM_2.5, NO₂, SO₂, CO and O₃ were collected from 21 air quality monitoring stations in Tehran from 2016 to 2021 and then, the air quality index (AQI) was calculated monthly and annually. The reached results indicated that AQI is relatively high in Tehran city and is above 100 (unhealthy for sensitive groups/unhealthy) on average on more than 20% (16.99–33.43%) of the days per year. According to the data, the highest and lowest percentages of clean days were observed in 2019 and 2021, respectively, with only 8.49% and 1.10%. Specifically, the highest concentrations of pollutants were observed in the autumn and winter seasons and during the months (by decreasing order) of December, November, and January. The produced annual emission rate of pollutants in Tehran city showed that approximately 84% are due to mobile sources while stationary sources correspond only to about 16%. The economic costs of the effects of air pollution on health were investigated and data showed that cardiovascular diseases > diabetes > lung cancer impose the highest costs to the health care system. Cardiovascular diseases accounted for the largest share of all premature deaths (26.28%) followed by stroke (10.46%), diabetes (3.77%), chronic obstructive pulmonary diseases (COPD) (3.21%), and lung, pharynx and bronchial cancer (2.28%). In addition, the share of air pollution in COPD was 34.2%, which is 31.98–39.2% more than the other ailments under investigation. Implementation of mitigation strategies in Tehran is urgently needed.

Identifying and quantifying the sources and clarifying the impacts of ultrafine particles (UFP) in the complicated urban environments are important for particle pollution control and UFP-climate interaction understanding. The previous studies have made notable contributions to these aspects and it is necessary to review the achievements. Here, the characteristics of traffic emissions and new particle formation (NPF) events/processes and their effects on urban UFP are summarized mainly based on the latest progresses. The constantly improved techniques of measuring UFP have played a vital role for knowing the sources and impacts of UFP. Meanwhile, the emissions inventories, dispersion models, and receptor models generally perform better when working together and using high resolution input and corrected algorithms. Besides, the interaction between UFP and climate is discussed mainly by linking radiation, cloud condensation nuclei, particle deposition, and the environmental conditions required for nucleation processes. Although for urban UFP, there are consensuses that traffic emissions and nucleation processes are two main sources and UFP and climate interact mainly via radiation and cloud condensation nuclei (CCN), there are many other crucial tasks for future and this work lists seven of them. They involve, scientifically, how much other sources such as industrial and regional sources mix with traffic emissions and nucleation processes in source contributions and how primary pollutants collaborate with UFP (aerosols) in aerosol-climate interactions; and engineeringly, how to improve the integration of the instruments and the instrument customization services according to actual situations. These progresses and future perspectives would help in more accurately quantifying the contributions of emissions and nucleation processes to UFP and better evaluating the impacts of UFP. Despite our efforts, knowledge on the main sources and impacts of urban UFP is limited and detailed solutions for the future tasks are missing here, which need joint efforts from UFP and related fields.

The quantification of gas emissions from waste storage and treatment ponds is an important problem. The objective of this study was to better understand the use of micrometeorological techniques for this purpose. Methane emissions were estimated from a large tailings pond (surface area >11 km²) at an oil sands mine site using datasets collected by different groups over a nine-month period. Emissions were calculated with eddy-covariance (EC) and inverse dispersion modelling (IDM) techniques. Three different IDM calculations were made using methane concentrations measured with either fixed-point sensors (IDM-LGR), a long-path laser (IDM-GL), or an unmanned aerial vehicle (IDM-UAV). Emissions were also estimated from a flux-chamber (FC) survey. Although the temporal overlap between the different datasets was limited, the results indicate substantial differences in emission-rate estimates. During a summer interval the EC, IDM-LGR, and IDM-GL estimates were 19%, 41%, and 56% of the FC-estimated rate, respectively. The overall ordering was EC ≈ IDM-UAV < IDM-LGR < IDM-GL < FC. Differences in the emission estimates appear to be explained by the physical location of the measurement footprints. The EC and IDM-UAV footprints were comparably small and confined to lower emitting areas of the pond, while the larger IDM-LGR and IDM-GL footprints included higher emitting areas. It would seem sensible to prefer the larger footprint IDM approaches for this large pond. However, the large IDM footprints necessitated a complicated analysis to remove the influence of an adjacent methane source in the calculations. This study illustrates the importance of understanding the footprint of micrometeorological techniques when quantifying emissions and the complications that arise when the footprint does not match the source area.

Tracer flux ratio (TFR) methodology performed downwind of 15 active oil and natural gas production sites in Ohio County, West Virginia sought to quantify air pollutant emissions over two weeks in April 2018. In coordination with a production company, sites were randomly selected depending on wind forecasts and nearby road access. Methane (CH₄), ethane (C₂H₆), and tracer gas compounds (acetylene and nitrous oxide) were measured via tunable infrared direct absorption spectroscopy. Ion signals attributed to benzene (C₆H₆) and other volatile gases (e.g., C₇ – C₉ aromatics) were measured via proton-transfer reaction time-of-flight mass spectrometry. Short-term whole facility emission rates for 12 sites are reported. Results from TFR were systematically higher than the sum of concurrent on-site full flow sampler measurements, though not all sources were assessed on-site in most cases. In downwind plumes, the mode of the C₂H₆:CH₄ molar ratio distribution for all sites was 0.2, which agreed with spot sample analysis from the site operator. Distribution of C₆H₆:CH₄ ratios was skew but values between 1 and 5 pptv ppbv^-1 were common. Additionally, the aromatic profile has been attributed to condensate storage tank emissions. Average ratios of C₇ – C₉ to C₆H₆ were similar to other literature values reported for natural gas wells.

Fused filament fabrication (FFF) is a material extrusion-based technique often used in desktop 3D printers. Polymeric filaments are melted and are extruded through a heated nozzle to form a 3D object in layers. The extruder temperature is therefore a key parameter for a successful print job but also one of the main emission driving factors as harmful pollutants (e.g., ultrafine particles) are formed by thermal polymer degradation. The awareness of potential health risks has increased the number of emission studies in the past years. However, studies usually refer their calculated emission data to the printer set extruder temperature for comparison purposes. In this study, we used a thermocouple and an infrared camera to measure the actual extruder temperature and found significant temperature deviations to the displayed set temperature among printer models. Our result shows that printing the same filament feedstocks with three different printer models and with identical printer set temperature resulted in a variation in particle emission of around two orders of magnitude. A temperature adjustment has reduced the variation to approx. one order of magnitude. Thus, it is necessary to refer the measured emission data to the actual extruder temperature as it poses a more accurate comparison parameter for evaluation of the indoor air quality in user scenarios or for health risk assessments.

This study investigated the variation of particle number (PN), morphological features and nano structural parameters of particulate matter (PM) from a China Ⅵ GDI engine under different working conditions, oxidation temperatures, and aerodynamic diameters. The results showed that, particles with a diameter less than 10 nm or 23 nm accounted for 40–65% and 68–94% of total PN respectively. Engine speed has a larger effect on PN emissions with the diameter less than 10 nm. PM emitted from the GDI engine were mainly consisted of primary particles with a diameter of 12–72 nm. Primary particles were composed of numerous graphite fringes with a length of 0.1–1.8 nm, tortuosity of 1.10–2.65, and separation distance of 0.2–1.6 nm. The boundaries of primary particles became vague, the fringe tortuosity and separation distance decreased with the progress of oxidation. Particles in larger aerodynamic diameters were more likely to form cluster-like PM in micromorphology. PM accumulated by particles with an aerodynamic diameter of 52.1 nm had larger fractal dimension, smaller fringe length, higher fringe tortuosity, and greater fringe separation distance, and was more easily be oxidized.

Polyoxymethylene Dimethyl Ether (PODE_n) is a promising diesel additive that can reduce particulate matter (PM) emission effectively, yet the changes in chemical and physical characteristics of PM emissions due to the application of PODE_n-diesel blended fuel remain largely unexplored. This laboratory study investigates the effects of PODE₃–diesel blended fuels (10, 20, and 30 vol% of PODE₃ mixed with diesel, denoted as P10, P20, and P30, respectively) on diesel engine emissions at 30% and 60% engine loads. Black carbon (BC) and organic aerosol (OA) were characterized in real time by a combination of a soot-particle aerosol mass spectrometer (SP-AMS) and a seven-wavelength aethalometer. Our results show that PODE₃ can significantly reduce both OA and BC emissions at both engine loads, with P20 producing the largest total PM mass reductions (>84%). The changes in the contribution of refractory oxygenated fragments to BC mass (i.e., C₃O₂⁺/C₃⁺ and C₃O⁺/C₃⁺) indicate that PODE₃ can reduce the functionality of soot surface/nanostructure. This is the first work showing that PODE₃ can affect the mixing state of BC and OA in diesel engine exhaust. Increasing PODE₃ blended volume can reduce the total fraction contribution of particle types that were composed of notably amounts of BC by mass. Furthermore, clustering analysis of single-particle data can identify two OA-dominated particle classes that were dominated by hydrocarbon fragments (C_xH_y⁺), and one of them had higher signal contribution from high molecular weight compounds. Lastly, the absorption Ångström exponent of BC (AAE_BC) can be enhanced with PODE₃ blended volume for both engine loads, and brown carbon (i.e., a light absorbing fraction of OA) can contribute up to ∼5% to the total aerosol absorption at the wavelength of 370 nm. Overall, this work provides insights into the potential impacts of PODE_n blended fuel application on the chemical and optical properties of BC and OA emitted from diesel engine combustion.