Atmospheric Environment: X最新文献

Liquefied petroleum gas (LPG) is represented in the literature as a transport fuel with lower regulated and non-regulated emissions compared to petrol. For the purpose of this paper, real-world emissions measurements were performed on a random sample of four commonly operated passenger vehicles with higher mileage (over 200 thousand km) and on a new one. The aim is to compare the emission factors of particle-bound polycyclic aromatic hydrocarbons (PAHs) in dual-fuelled passenger cars running on LPG and petrol, or rather to compare the emission factors of the two fuel types. PAH concentrations are determined by gas chromatography based on the analysis of particles captured on a filter during isokinetic sampling of the exhaust gas during driving in real traffic. In terms of the sum of the 8 most hazardous PAHs analysed, LPG fuelling reduced the total (summary) emission factor of only two of the vehicles analysed, by 22% and 26% respectively compared to petrol. For the remaining vehicles, there was an increase in the total emission factor ranging from 4.4 to 68.8%. The results show that in terms of particle-bound PAHs, the benefit of LPG fuel in terms of vehicle emissions may not be so clear-cut in real-world tests and it depends very much on whether a suitable propulsion system is fitted to the vehicle, how it is set up and how the vehicle is serviced (i.e. the vehicle overall condition).

Aviation contributes to anthropogenic climate change mainly by contrails, CO₂ and NO_x emissions, whereof contrails are considered the largest single contributor to the radiative forcing from aviation. Powering aircraft with kerosene containing fewer or no-aromatics, i.e., “Sustainable Aviation Fuels” (SAF) or hydroprocessed, fossil-based kerosene, can significantly reduce contrail climate forcing. However, such kerosene is currently scarcely available. Moreover, less than 10 % of the flights worldwide cause more than 80 % of the contrail climate forcing. Hence, this study investigates a targeted allocation of paraffinic, i.e., aromatics-free kerosene to flights and flight segments with the highest contrail climate forcing, by calculating the resulting contrail energy forcing (in J) on 844 364 flight trajectories worldwide departing from five large European airports in 2019.

The contrail radiative forcing integrated over contrail evolution (i.e., contrail energy forcing [J]) is simulated for a reference fleet powered with conventional kerosene of 14.1 m - % hydrogen content. 5 % of overall kerosene demand assumed to be paraffinic kerosene with 15.3 m - % hydrogen content is allocated via a uniform, a flight-specific and a segment-specific approach. The uniform allocation assumes that all flights receive the same blend of 5 % paraffinic kerosene. The other cases target 100 % paraffinic kerosene either to flights or segments with highest contrail energy forcing. Compared to the reference, the results indicate a reduction on contrail energy forcing by 4 %, 36 % and 55 %, respectively. For market shares of paraffinic kerosene up to 30 %, a segment specific allocation appears advantageous compared to a flight specific allocation. However, they might require airport and aircraft modifications. Uncertainties in contrail climate benefits can be reduced by providing additional information on kerosene properties and accurate meteorological data. Overall, this study highlights robust potentials of paraffinic kerosene to significantly reduce the climate forcing from aviation.

South Africa remains an uncharted realm in terms of marine mobile emissions inventory and hence the impact of pollution from ships in coastal cities remains unknown. Such a void creates uncertainties about the extent of population exposure to pollution from ships, the health impact and economic value associated with the changes in policies for the port city of Durban.

This study was aimed at estimating the health and economic impact of marine mobile emissions and the health and economic benefits associated with improvement in air quality within the port city of Durban, which is under eThekwini municipality. The population exposure to particulate matter of less than 2.5 and 10 μm (PM_2.5 and PM₁₀) and sulphur dioxide (SO₂) from ships calling into Durban port were estimated using the AERMOD air dispersion model. The BenMAP modelling tool was then used to estimate the health impact and economic value of changes in emission of PM_2.5, PM₁₀ and SO₂ from ships visiting Durban port. The reduction in emissions from ships was due to the reduction in the sulphur content of fuel from 3.5% to 0.5% that was implemented by the International Maritime Organisation (IMO) on the 01^st of January 2020.

The results showed that PM_2.5 and PM₁₀ emissions reduced by 63% in 2020 compared to 2018, whilst SO₂ emissions reduced by 82% over the same period. The BenMAP results indicated that 49 premature mortalities were avoided in 2020 compared to 2018 since the IMO's forced reduction in sulphur content of fuel by 85% in 2020. These avoided cases on mortality were estimated a monetary value of R228 million using the World Bank’s 2016 estimates and R683 million using the USEPA Mean VSL estimate. Such monetary values were respectively equivalent to 0.05% and 0.2% of the eThekwini's GDP, which was estimated at R468 billion in 2016.

In the backdrop of persistent haze occurrences affecting Southeast Asia and Pakistan's environmental landscape, this study delves into an in-depth analysis of atmospheric Particulate Matter (PM2.5) during intense haze episodes prevalent in Lahore throughout October, November, and December 2019. Employing advanced analytical techniques encompassing Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), and Raman Spectroscopy (RS), this investigation meticulously scrutinized PM2.5 samples. The findings showcased substantial variability in PM2.5 concentrations, peaking notably in December within the range of 43.2–301 μgm⁻³, averaging 168 ± 88.3 μgm⁻³, whereas lower concentrations ranging from 30.9 to 268 μgm⁻³, with an average of 106 ± 66.1 μgm⁻³, were observed in October. These concentrations displayed correlations with meteorological parameters, demonstrating a direct association with relative humidity and varying relationships with temperature and wind speed. The maximal PM2.5 concentrations aligned with lower temperatures (19.1 °C), while higher temperatures (26.1 °C) coincided with the lowest concentrations, illustrating distinct relationships with relative humidity percentages and wind speeds. Advanced spectroscopic analyses (RS and XRD) confirmed the presence of various minerals and elements within PM2.5 samples, encompassing calcite, calcium aluminosilicate, hematite, barite, quartz, gypsum, organic carbon, and nineteen elements identified by EDX. Morphological evaluations unveiled diverse particle shapes, from round, pointed, and irregular to rod-like, and agglomerate structures. SEM investigations delineated distinctive groups of anthropogenic and geogenic particles, emphasizing emission sources such as automobile emissions, crop residue burning, biomass burning, construction activities, soil dust, and industrial emissions. This comprehensive study lays the groundwork for source apportionment, vital for understanding consequential impacts on climate, visibility, and human health, fostering future investigations in this domain.

Bottom-up modelling is used frequently to estimate emissions produced by seagoing vessels, and the accuracy of modelling is dependent on the data the model is trained with. Observational studies can be used to increase the model accuracy. Here we compared data from two measuring campaigns conducted on board ships that use Liquefied Natural Gas (LNG) as primary fuel in internal combustion engines (ICE) in a diesel-electric setup with values obtained from the Ship Traffic Emission Assessment Model (STEAM).

The power demand for propulsion calculated using Automatic Identification System (AIS) data matched observations reasonably. The root mean square error between the modelled and observed power demand was 759–914 kW (28.6–34.5%) for the measured ropax vessel and 1869–1916 kW (16.7–17.1%) for the large cruise vessel over four voyages while the ships were underway. The discrepancy is largely explained by the auxiliary power demand, which was 4 times higher on the large cruise vessel than the model prediction.

Using meteorological data to estimate the increase of resistance did not improve the goodness of fit between modelled and observed engine power demand. STEAM model's base-specific fuel consumption calculation method fits observed values reasonably when the engine load is over 50%, but ICEs used in constant speed mode have increased consumption at lower engine loads compared to variable speed ICEs.

The share of pilot fuel of total energy consumption was found to play a significant role in the emission factors for measured exhaust gas compounds. More accurate functions to model fuel consumption and emissions were derived using the observed data.

Plant leaves absorb some kinds of volatile organic compounds (VOCs) and can contribute to air purification, as revealed by recent exposure experiments conducted at environmentally realistic concentrations in ppb (v/v). However, the mechanisms underlying VOC absorption by plants remain unclear. In this study, we applied Fick's first law of diffusion to a VOC absorption model for plant leaves to account for the VOC diffusion process via stomata, air-liquid partitioning, partitioning into the plasma membrane, and metabolic conversion of the VOC in plant cells. The resistance and concentration of VOCs at individual sites were determined using previously reported absorption data for aliphatic aldehydes and ketones in three plant species and the leaf morphology parameters obtained from leaf cross-section micrographs. The highest resistance occurred at the metabolic site (r_met), suggesting that VOC metabolic capacity is the most influential factor in VOC absorption. The resistance of stomata (r_s) or plasma membrane (r_pl) was the second highest, depending on compound family. Using the absorption rate data of Q. acutissima, it is revealed that metabolic site resistance r_met for methyl vinyl ketone is affected by light intensity. Thus, our VOC absorption model can determine the most influential site in the absorption pathway both for different VOCs and plant species. Our model can contribute to the development of plant-based strategies for controlling air pollution.

Ammonia (NH₃) is an important pollutant, with serious negative environmental effects. With targets to reduce the total emissions at a United Kingdom level by 2030, it is important to quantify the emissions from contributing sectors to understand the current state for future mitigation strategies. The objective of this work was to establish an updated NH₃ emission factor for broiler production in Northern Ireland. NH₃ was measured on two identical broiler houses following the principles of the VERA 2.0 protocol across one year's production which encompassed at least six continuous measurement periods of a minimum of 24 h. The NH₃ emissions calculated during this work did not statistically differ between the site (P = 0.275) or house (P = 0.631). NH₃ emissions increased with progressing bird age (P < 0.001). NH₃ emissions were not influenced by outside environmental conditions. The current study updated the NH₃ emission factor for mechanically ventilated, confined broiler systems in Northern Ireland to 0.024 kg/bird place/year, 10.1 %TAN or 42.6 g/LU/d which is 29% lower in comparison to the previous the figure of 0.034 kg/bird place/year reported by The UK Ammonia Inventory.

In today's industrial landscape, energy management, process modification, and reduction of atmospheric concentrations of pollutants and safety risks have become paramount. This focus is driven by the need to address environmental concerns, economic efficiency, and the global energy and climate change crisis. In gas refineries, incinerators are widely used to convert deadly and environmentally polluting acid gases into less hazardous gases. Therefore, improving incinerator performance can significantly impact environmental, economic, and energy aspects. According to the results of an energy management study at the domestic gas processing plant, the acid gas incineration unit was identified as a significant energy use. Therefore, based on the effects of the performance of this incinerator from environmental and energy points of view, the mentioned unit was prioritized for modification in this work. For this purpose, incinerator performance was assessed using Promax simulation, and Hazard and Operability (HAZOP) analysis was employed to identify potential hazards. The simulations revealed that acid gas residence time was 0.81s, longer than the 0.6s initial design with the damper in place. This suggests damper removal is feasible. Removing the damper reduces residence time and lowers incinerator temperature, especially during startup. Therefore, temperature was considered as the keyword in the HAZOP study, and a number of recommendations were proposed to eliminate or mitigate the risks of system modification. Furthermore, the assistance of results obtained from energy management based on ISO 50001:2018 standards confirm improvements in energy efficiency and fuel consumption, which have positive economic and environmental impacts. Moreover, the study employs a Life Cycle Assessment (LCA) approach using SimaPro Software 9.5.0.1 and the CML-baseline method (Centrum voor Milieukunde Leiden) for environmental impact assessment. The results reveal that, across ten environmental impact categories, the modified project exhibits significantly reduced environmental impacts compared to its original state.