Impacts of Ship Emissions on Regional Air Quality in the Post-DECA Era: A Case Study of the Yangtze River Basin.

Spatiotemporal Characterization of Ship Emissions in the Yangtze River Delta Region: Insights from High-Resolution AIS Data

Bottom-up ship emission inventories derived from Automatic Identification System (AIS) data are normally reported on kilometre-scale grids, which merge port waters that perform very different functions. Working with an AIS-based STEAM inventory for the Yangtze River Delta (YRD), we ask a question that gridded inventories rarely separate: are the cells where ships accumulate time the same cells where they emit? To answer it, we define the Static–Dynamic Ratio (SDR), the ratio of hotelling (auxiliary-engine) to propulsion (main-engine) emissions within a cell, and use it to classify YRD waters without recourse to external port charts. Hotelling-dominated cells occupy 17.7% of the sea area and accumulate 59.3% of all ship-hours, a ship-hour density seven times that of transit-dominated fairways, yet they carry only 22.4% of NOx. A vessel at anchor emits about one-eighth as much NOx per hour as one under way, and the two effects nearly cancel. The cancellation is species dependent: low-load correction factors are steeper for sulfur and particulate species than for NOx, so hotelling zones reach relative SO2 and PM2.5 densities of 1.21 and 1.09 against 0.89 for NOx. Coarsening the same activity field from 100 m to 1 km drops the share held by the busiest 1% of cells from 70% to 50%, showing how kilometre grids manufacture apparent continuity along shipping lanes. Activity hotspots are therefore not emission hotspots, and anchorage-targeted measures such as shore power are best justified by particulate and sulfur exposure near populated coasts rather than by their share of the regional NOx burden.

Bottom-up assessment of atmospheric emissions from service vessels in the Port of Mohammedia (Morocco) and their potential onshore atmospheric transport

Atmospheric Emissions from Maritime Activities: Evidence from the Port of Casablanca

Port-related maritime emissions constitute a significant source of urban air pollution and greenhouse gas emissions, particularly in rapidly developing coastal cities. Within this context, the present study quantifies ship-related emissions at the Port of Casablanca, Morocco’s largest and most strategically important port, and evaluates their associated environmental and socio-economic impacts. A bottom-up methodology was applied to estimate emissions from vessel operations between 2017 and 2021. The inventory integrates vessel characteristics, engine specifications, operational load factors, emission factors, and the duration of maneuvering and hotelling phases to estimate emissions of CO2, SO2, NOx, CO, NMVOCs, PM, PM10, and PM2.5. The emission inventory was subsequently coupled with damage cost factors to assess the external costs associated with shipping emissions. The obtained results demonstrate that CO2 was the dominant emitted pollutant, representing approximately 97% of total emissions, whereas NOx and SO2 accounted for 2% and 1%, respectively. Bulk carriers emerged as the principal emission source (44%), followed by container vessels (36%), with the highest emission levels observed during 2018–2019, coinciding with increased port operations. Furthermore, the integration of emission inventories with damage cost factors demonstrated that NOx, although emitted in much smaller quantities than CO2, exerts a disproportionately higher environmental and societal burden due to its impacts on public health and ecosystem quality. This study provides one of the first integrated bottom-up emission inventories and external cost assessments for a Moroccan port. The proposed framework supports evidence-based decision-making for sustainable port management and demonstrates the need for emission reduction strategies that simultaneously address climate change and air quality objectives.

Synergy Between Air Pollution and Carbon Emissions of On-Road Mobile Sources, Evidence from a Typical Southwestern Region in China

The transport sector has emerged as a significant source of greenhouse gases and airborne pollutants. However, few studies have carried out a comprehensive assessment of the synergistic benefits between air pollutant and carbon emission reductions that account for the unique regional characteristics of individual provinces. In this study, we establish nonlinear prediction models for future activity levels of on-road mobile sources by integrating economic and demographic drivers. We then dynamically quantify the co-benefits of simultaneous air pollutant and CO2 abatement under diverse mitigation scenarios. Environmental tax rates and carbon trading prices are combined with conventional elasticity coefficients and coordinate-based methodologies to convert emission cuts into economic advantages. The results show that under the most optimistic scenario, 47.86% of the CO2 emissions could be mitigated, while emissions of NOX may increase by 60.49% in the absence of mitigation strategies (BAU scenario). Marginal CO2 emissions under the ELC scenario indicates a peak around 2027. Elasticity coefficients for all pollutants gradually converge toward 1, indicating that more stringent mitigation efforts enhance co-benefits. Findings in this study could provide essential insights for the co-management of CO2 and air pollutants from road mobile sources in Guangxi and other key regions along the Belt and Road Initiative.

The Impact of Pilot Policies for New Energy Vehicles on Pollutant Emissions in Prefecture-level Cities

Against the backdrop of the "Dual Carbon" goals, transportation electrification serves as a critical low-carbon technical pathway to optimize urban energy structures and cut mobile-source air pollution. To quantitatively assess the environmental techno-economic performance of new energy vehicle (NEV) pilot promotion policies, this paper adopts panel data of 282 prefecture-level and above cities in China from 2014 to 2024, and conducts empirical estimation via the PSM-DID model, transmission pathway test, and multi-dimensional heterogeneity grouping. The results indicate that NEV pilot policies can significantly reduce urban PM₂.₅ and NOₓ emission levels, and the net policy effect remains robust after parallel trend and placebo tests. NEV ownership acts as the core transmission carrier of emission reduction dividends, with the substitution of fuel vehicles contributing 48.91% of total emission cuts. The emission reduction performance of the policies presents prominent differentiation across spatial location, city scale and industrial structure, where megacities, eastern cities and service-dominated cities achieve better low-carbon technology penetration effects. Such disparities stem from unbalanced local supporting policies, charging infrastructure and industrial market foundations. From a techno-economic optimization perspective, differentiated promotion schemes are proposed to provide quantitative support for local governments to formulate targeted NEV support policies and advance collaborative pollution reduction in the transportation sector. Keywords: New energy vehicles, Pilot policy, Pollutant emission reduction, PSM-DID, Low-carbon techno-economy, Prefecture-level panel.

Spatiotemporal Emission Characteristics and Driving Factors of Air Pollutants and CO2 from Aircraft at Airports: A Case Study in China

With the rapid expansion of China’s civil aviation industry, airport aircraft emissions have raised growing environmental concerns, making it imperative to clarify their emission characteristics and driving mechanisms. In this study, 10 major civil aviation airports in Shandong Province, a highly representative airport cluster in China, were selected to investigate the characteristics of aviation emissions using actual flight activity data from 2023. Our results show that the total emissions of HC, CO, NOx, SO2, PM, and CO2 from the airport aircraft were 144.6, 1890.4, 2571.8, 358.7, 18.2, and 584,822 tons, respectively, with NOx and CO being the dominant air pollutants. The taxiing phase was identified as the largest contributor to total emissions, and the B737-800 emerged as the largest emission-contributing aircraft type. Moreover, our results reveal that airport aircraft emissions exhibited spatiotemporal heterogeneity. These emissions peaked in July and August, but displayed low levels during wintertime. Spatially, these aviation emissions were predominantly concentrated in eastern Shandong Province, and Qingdao and Jinan cities were the top two contributors, jointly contributing more than 66% of the total emissions. This study further indicates that this spatiotemporal heterogeneity was primarily attributed to air passenger throughput, aircraft movements, and GDP. Our findings can be extended to other provinces in China and provide a scientific basis for the future mitigation of aviation emissions at airports across China.