Ship emissions amplify soluble iron in PM2.5 in a typical coastal port in North China.

The maritime sector is a significant contributor to greenhouse gases and air pollutant emissions, accounting for approximately 3% of global CO 2 emissions in 2018, a figure expected to rise to 17% by 2050. To address these challenges, the authorities put forward initiatives for reducing emissions through technical and operational strategies. Accurate emissions estimation is critical for evaluating the impact of these measures and technologies on emissions reductions. The main method used in the EU for maritime emissions inventorying and projections is the European Monitoring and Evaluation Programme/European Environment Agency (EMEP/EEA) air pollutant emission inventory guidebook methodology. This study identifies key limitations in the current European shipping guidebook methodology, which has not been updated since 2010, and proposes enhancements improving accuracy and relevance. Utilizing a dataset of around 15,000 vessels trading in European ports, the analysis reveals the need to expand ship categories from nine to nineteen to reflect the current fleet profile. The study proposes updates to technical and operational parameters, like main and auxiliary engine specifications, speed profiles, engine loads and operational phase durations. The inclusion of the anchorage phase in emissions calculations is also recommended to address emissions near port areas. Validation against MRV-reported emissions demonstrates that the recommended approach reduces CO 2 estimation deviations from 52.1% to 12.3% compared to the original methodology, with improvements for other harmful air pollutants. Such updates will assist stakeholders in devising better targeted emissions reduction strategies and align the European guidebook with advancements in maritime technologies and operational practices. • Fleet in European ports during 2022: 15,000 ships analyzed • Proposed ship categories for introduction in methodology expanded from 9 to 19 • Updates reduce CO 2 deviations from 52.1% to 12.3% compared to official database • Anchorage phase inclusion in emission calculations is recommended • Better estimates of climate-relevant and air pollutant emissions

This study examines the relationship between ship traffic and ambient air pollutant concentrations in Quintero Bay, Chile, an industrial coastal area characterized by intense port activity. The analysis integrates air quality measurements from the national monitoring network (SINCA) with vessel movement data derived from the AIS, combined with advanced time–frequency analysis techniques. Unlike traditional emission inventories, which aim to quantify emissions at the source, SINCA provides real-time ambient pollutant concentrations expressed in µg/m 3 and ppb. Therefore, the objective of this study is not to directly estimate ship emissions, but to evaluate how variations in maritime activity co-vary with observed pollutant levels at air quality monitoring stations. The investigation focuses on pollutants commonly associated with shipping activities, including PM 10 and PM 2.5 , NO x , SO 2 , and CO. A detailed characterization of the vessel fleet operating in the study area was performed using both static and dynamic AIS data. This included ship type classification, estimation of main engine power based on gross-tonnage models, and calculation of engine load distributions derived from AIS-reported vessel speeds. Although these parameters allow the estimation of emission factors, the present work emphasizes identifying temporal associations between ship movements and ambient pollutant concentrations rather than quantifying emissions. Additionally, pollution roses and Conditional Probability Functions (CPF) were used to evaluate the directional origin of high-concentration episodes in relation to prevailing wind conditions. The results show that several episodes of elevated NO x , SO 2 , and PM 10 concentrations exhibit significant coherence with ship activity, particularly at daily time scales influenced by local meteorology. Among the analyzed pollutants, PM 10 displays the strongest and most recurrent association with maritime traffic, highlighting the influence of port operations on air quality in Quintero Bay.

Maritime transport is a major contributor to greenhouse gas (GHG) emissions, and ports play a critical role in shaping regional and national decarbonization pathways. This study develops a comprehensive framework to quantify both offshore and onshore GHG emissions associated with port activities and applies it to the Vancouver Fraser Port Authority (VFPA), the largest maritime gateway of Canada. Using the port area ship emission model, fuel emission factors, life cycle assessment (LCA), and scenario forecasting, the analysis integrates emissions from ocean-going vessels, port authority operations, and non-port authority transport activities from 2020 to 2024 and extends forecasting for 2030 and 2050. Results show that total annual emissions from 2020 to 2024 ranged from 899 to 1,012 kilotonnes of CO₂e, with offshore maritime activity consistently accounting for over 50% of total emissions. Shore power expansion reduced offshore emissions by 20.1% between 2021 and 2022. Three emission scenarios for 2030 and 2050 demonstrate that aggressive adoption of renewable biodiesel, vessel speed reduction, and electrification operations can decrease total emissions by up to 86% by 2050 relative to 2024 levels. The findings highlight the critical role of fuel transitions, port electrification, and policy-supported incentives in accelerating decarbonization. The framework provides a replicable methodological basis for global port emission mitigation planning.

The liner shipping industry is thriving in the low-carbon transition, and optimizing operational strategies for liquefied natural gas (LNG) dual-fuel ships has become a research hotspot. This research examines the impacts of the carbon tax, emission control area (ECA) policies, fuel price discounts and methane slip rate on fuel management strategies. Firstly, to reduce liner operating costs and adhere to ECA policies, this study develops a basic optimization model. Further, the model is extended to take into account the impact of fuel price discounts. Secondly, by linearizing multiple nonlinear terms, the operational strategies are obtained. Thirdly, taking a real vessel sailing between the Far East and Northwest Europe as a case study, this study identifies the ports for LNG and very low sulfur fuel oil (VLSFO) bunkering, determines the bunkering amounts and calculates the planned speeds. Furthermore, sensitivity analyses are conducted on fuel price difference, carbon tax rate and methane slip rate. Results show that fuel price difference, carbon tax rate, methane slip rate and fuel price discount exert a significant impact on ship operational decisions. To ensure the effectiveness of maritime decarbonization regulations, authorities should monitor ship engines with high methane slip rates. This study offers important references for shipping enterprises to meet ship emission policies and simultaneously cut operational costs.

Fine particulate matter (PM2.5) is the leading environmental risk factor for premature mortality. Although mass concentrations of PM2.5 have declined in the past decade, the unequal toxicity in different sources remains overlooked in air-quality management. Here, we integrated source-specific toxicities of PM2.5, derived from field measurements and cellular assays, with high-resolution emission inventories to conduct health-oriented source apportionment in the Yangtze River Delta (YRD). The average of toxicity-adjusted population-weighted PM2.5 exposure was high in central and northern Anhui and along the Yangtze River, approximately 6.6 times that of Zhejiang and Shanghai. Residential solid fuel combustion was the dominant contributor to PM2.5 toxicity, especially in winter (74.4%, 95% CI: [62.9%, 85.9%]). The toxicity contribution of residential combustion was negatively correlated with city-level income (r = -0.83; p < 0.0001). Targeting residential emissions effectively reduced relative toxicity-adjusted risks in low-income regions, and the costs for reducing a unit of toxicity-adjusted PM2.5 were 2.7% of those for industrial emission control. Ship emission abatement might yield optimal cost-health benefits in coastal areas based on relative ranking under assumed marginal costs. Our findings, based on in vitro cellular toxicity, highlighted controlling residential and ship emissions, providing insights into tailored air-quality policies and regional health equity.

Process analysis of the impacts of ship emissions on PM2.5 and O3 in the Yangtze River Delta, China.

Pathways and geographical patterns of international shipping CO2 emissions in the future.

Abstract. Non-dust emissions have been increasingly recognized as important contributors to atmospheric iron (Fe), influencing marine productivity through enhanced bioavailable Fe inputs. However, accurately quantifying the contributions and spatiotemporal variability of non-dust sources remains challenging due to relatively low time-resolution of traditional filter-based analytical methods. In this study, the contributions of non-dust emissions to atmospheric total and soluble Fe in the Northwest Pacific were quantified based on online measurements from three ship-based observation campaigns in 2021–2022. A Positive Matrix Factorization (PMF) model was applied for source apportionment. Results showed non-dust emissions were notable contributors to atmospheric total Fe, representing 24 %–41 % of total Fe in PM10 and 30 %–56 % in PM2.5 samples across different cruise legs. Importantly, their contributions to soluble Fe were significantly higher, reaching 88 %–97 % in PM10 and 85 %–98 % in PM2.5 samples. Among non-dust sources, land anthropogenic emissions contributed substantially to both total and soluble Fe, whereas ship emission contributed a small portion to total Fe but was a major source of soluble Fe, particularly in summer, when its contribution reached 79 % of soluble Fe in PM10 samples in coastal regions. Additionally, Fe from non-dust sources exhibited stronger spatial variability than dust source. The concentrations of land anthropogenic Fe differed by 3–5 times between coastal and open-ocean areas during the same cruises, while ship-derived Fe varied by an order of magnitude or more. This study offers critical observational evidence to advance understanding of how diverse emission sources shape atmospheric composition in Asian continental outflow regions.

Abstract. Maritime transport exerts a substantial influence on local air quality, particularly in port cities. Ship emissions are recognized as major contributors to air pollution, with comparable magnitude to those of road transport. This study, conducted in 2021 in Toulon, a port city on the French Mediterranean coast, assessed ship emissions one year after the implementation of IMO2020 sulfur regulations. Emission factors (EFs) were determined for key pollutants such as SO2, NOx, CO, NO, CH4 and particulate matter (PM), including black carbon (BC), organics (Org), sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), and polycyclic aromatic hydrocarbons (PAHs), as well as the particle number concentration (PN). The IMO2020 regulation led to a marked reduction in sulfur-related emissions, whereas pollutants such as BC, Org, and PAHs remained at pre-regulation levels. Positive Matrix Factorization (PMF) analysis of PM1 organic aerosol (OA) measured by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was used to investigate shipping contribution to local air quality. PMF successfully distinguished between road and marine transport emissions, revealing a shipping contribution to the total OA of 11.2 %. Eight factors were resolved: three shipping-related OA, a Hydrocarbon-like OA (HOA), a Cooking-like OA (COA), an Oxidized Hydrocarbon-like OA (OxHOA), a Less Oxidized OA (LOOA), and a More Oxidized OA (MOOA). Shipping and HOA factors were the dominant contributors to ultrafine particles, accounting together for 51.9 % of the alkylated PAHs (APAHs). These findings highlight the persistent influence of shipping emissions in port areas and demonstrate the effectiveness of advanced source apportionment methods to improve emission monitoring strategies, particularly as the Mediterranean region prepares for the implementation of Emission Control Area (ECA) regulations in 2025.

The vanadium/nickel (V/Ni) ratio has long served as a chemical fingerprint of shipping emissions, typically exhibiting values around 3. Also, over the past two decades, the progressive implementation of the International Maritime Organization (IMO) fuel sulfur content (FSC) regulations has driven major shifts in both fuel characteristics and compliance technologies. The widespread adoption of desulfurized marine fuels has markedly decreased average V/Ni ratios in coastal environments (to ∼1), whereas the continued use of heavy fuel oil (HFO) with exhaust gas cleaning systems (scrubbers) appears to maintain pre-IMO values. Compiling two decades of V/Ni data from ship emission studies, this work assesses temporal and technological trends to evaluate the robustness of this ratio as a diagnostic marker. The results show a global decrease in V/Ni ratios driven by fuel desulfurization with residual variability reflecting fuel type, sampling context, and industrial influence. Overall, the V/Ni ratio is a relevant tracer of shipping emissions in coastal areas and a potential indicator of scrubber operation in an evolving regulatory landscape.

The maritime sector's transition toward decarbonization cannot occur in isolation, rather it will be tied to broader transformations in energy, economic, and societal systems. Yet, most existing studies often overlook this integrated perspective, focusing primarily on sector-specific strategies without considering broader societal changes and energy availability on a global scale. To address this gap, this study integrates the MariTeam ship emission model into the MESSAGEix-GLOBIOM integrated assessment framework. Through this approach, we assess how climate scenarios may influence the maritime sector's trajectory toward achieving net-zero emissions by 2050, in line with the International Maritime Organization (IMO) targets. Our findings indicate that action before 2030 is crucial and it can be achieved through combining four key solutions:improvements in energy efficiency, biofuels, liquefied hydrogen, and ammonia. Furthermore, the results suggest that the maritime sector could have access to enough renewables to achieve substantial emissions reductions with increase in final product costs ranging from 2 to 30% (interquartile range) with variations across products and regions. On average, cost increases are estimated at 10.2% for Global North countries and 13.3% for Global South countries. This analysis highlights the urgency and scale of transformation required for the maritime industry to meet the IMO's net-zero ambitions and align with broader global sustainability goals.

Understanding the mechanisms of coastal PM2.5 formation driven by land-sea breeze recirculation and ship emissions.

Comparative analysis of atmospheric trace elements pollution in Beijing and Haikou: Sources, transport and local emissions.

How will arctic shipping emissions evolve? A spatiotemporal topology-aware transformer approach

Particulate Matter (PM) is a type of air pollution that poses risks to human health, the environment, and property. Among the various PM types, PM10 is particularly significant, as it acts as a vector for numerous hazardous trace elements that can negatively impact human health and the ecosystem. Identifying potential sources of PM10 and quantifying their impact on ambient concentrations is crucial for developing efficient control strategies to meet threshold values. Receptor modeling, which identifies sources using chemical species information derived from PM samples, has been widely used for source apportionment. In this study, PM10 samples were collected over three periods (April, May, and June 2021), each lasting 16 days, using semi-automatic dust sampling systems at two sites in Biga, Canakkale, Turkiye. The relative contributions of different source types were quantified using EPA PMF (Positive Matrix Factorization) based on 35 elements comprising PM10. As a result of the analysis, five source types were identified: crustal elements/limestone/calcite quarry (64.9%), coal-fired power plants (11.2%), metal industry (9%), sea salt and ship emissions (8.5%), and road traffic emissions and road dust (6.3%). The distribution of source contributions aligned with the locations of identified sources in the region.

Global maritime transport carries nearly four-fifths of world merchandise trade and is a significant source of greenhouse gas (GHG) emissions. With the GHG reduction strategies from the International Maritime Organization (IMO), the EU’s inclusion of shipping in the Emissions Trading System and the introduction of fuel GHG-intensity standards, there is an urgent need for prediction frameworks that are more robust, transparent and adaptable to evolving policy landscapes. Drawing on a structured search of the Web of Science Core Collection for the period 2020–2024, this review synthesises 1,012 peer-reviewed studies on global shipping emissions, decarbonisation measures and AI-enabled modelling. It first compares conventional approaches—fuel-based top-down inventories, AIS-driven bottom-up models and statistical or machine learning techniques—highlighting their respective strengths and limitations in terms of spatial and temporal resolution, data requirements and policy relevance. It then examines the emerging capabilities of large language models (LLMs) in knowledge integration, code generation and tool orchestration, and proposes five LLM-enabled paradigms for shipping emissions prediction, including multi-source information extraction, model orchestration, scenario construction and intelligent compliance auditing. Key technical and governance challenges are discussed, such as data quality and confidentiality, physical consistency, explainability and the environmental footprint of AI. The study argues that coupling LLMs with physics-based and data-driven models can enhance the flexibility and policy relevance of shipping emissions prediction, while a clearly defined research agenda is needed to ensure their responsible and effective use in supporting the decarbonisation of maritime transport.

Abstract. Coastal wetlands serve as critical sinks for both carbon and nitrogen within regional ecosystems, playing an essential role in mitigating atmospheric greenhouse gases and nutrient enrichment. This study integrates high-resolution wetland type data, ship emission inventories, and regional nitrogen deposition simulations to quantify nitrogen inputs to East Asian coastal wetlands from the perspective of source–sink coupling. Firstly, atmospheric nitrogen deposition fluxes in coastal wetland areas of East Asia were simulated and evaluated using an air quality model. Nitrogen deposition fluxes were spatially coupled with classified wetland maps. Net primary productivity (NPP) was estimated using a modified light-use efficiency model, incorporating solar radiation and the fraction of photosynthetically active radiation (FPAR) from remote sensing. Carbon sequestration and oxygen release were then quantified using stoichiometric relationships based on NPP. The results indicate that total nitrogen deposition across East Asian coastal wetlands follows a general gradient of “high in the south, low in the north” and “strong in urban-industrial clusters, weak in remote coastal zones.” On average, ship emissions contribute 10.13 % and 15.22 % to NO3--N and NH4+-N deposition, respectively, while their contribution to gaseous NH3-N is negligible. Among wetland types, salt marshes receive the highest nitrogen input per unit area (654.99 mg NO3--N m−2 yr−1), although tidal flats dominate total regional nitrogen input due to their extensive spatial coverage. Dry and wet deposition exhibit significant seasonal variation: wet deposition consistently prevails during the spring and summer months due to frequent rainfall, while dry deposition becomes increasingly prominent in autumn and winter. For instance, in the Korean Peninsula (KP), the wet-dry gap in nitrate deposition reaches 0.17 g N m−2 yr−1, while the Yangtze River Delta (YRD) exhibits relatively balanced ammonium inputs (dry-wet difference of only 0.05 g N m−2 yr−1). Carbon sequestration capacity shows strong spatial and temporal coupling with nitrogen deposition. Mangrove forests exhibit the highest annual NPP (∼ 776.16 g C m−2 yr−1 in summer), supported by high FPAR and solar radiation (1749.29 MJ m−2), followed by salt marshes and tidal flats. Seasonal patterns reveal a summer peak in carbon uptake across all wetland types, with mangrove NPP in summer being two times higher than winter values. Nitrogen deposition primarily enhances carbon sequestration during warm seasons; for instance, in the mangroves of the Pearl River Delta (PRD), nitrogen inputs increase summer carbon sequestration by 6.85 g C m−2, while the effect is negligible in winter (&lt;0.06 %) or in nitrogen-saturated regions. These findings provide a scientific foundation for understanding how coastal ecosystems respond to anthropogenic activities and long-range nitrogen transport. Furthermore, the results serve as an important reference for wetland conservation, nitrogen cycle management, and the development of regional carbon neutrality strategies.

This study presents a first-of-its-kind investigation into retrofitting domestic vessels with a novel hybrid system integrating a Solid Oxide Fuel Cell (SOFC) and an Internal Combustion Engine (ICE). Using a Lake Ferry and an Island Ferry as case studies, three power-sharing scenarios (10–20% SOFC contribution) were examined for cruise and port operations. The results show that increasing the SOFC power share enhances overall system efficiency, reducing daily fuel energy consumption by up to 9% while achieving SOFC efficiencies of 58–60% in port. The design analysis confirms the physical retrofit feasibility for both vessels, with all scenarios occupying 72–92% of available machinery space. However, increasing the SOFC share from 10% to 15–20% raised total system weight by 10–20% and volume by 12–27%. Economically, the system demonstrates strong viability for high-utilization vessels, with Levelized Cost of Energy (LCOE) values of 236–248 EUR/MWh, while the sensitivity analysis highlights the SOFC capital cost as the dominant economic driver. Environmentally, the hybrid system achieves annual CO2 reductions of 46–51% and NOx reductions of 51–62% compared to conventional diesel systems, with zero NOx emissions in port. The SOFC-ICE hybrid system proves to be a robust transitional pathway for maritime decarbonization, particularly for vessels with significant port-side operating hours.

Shipping is a high-energy-intensive sector and a major source of climate-relevant and harmful air pollutant emissions. In response to growing environmental concerns, the sector has been subject to increasingly stringent regulations, promoting the uptake of alternative fuels and emission control technologies. Accurate and diverse emission factors (EFs) are critical for quantifying shipping’s contribution to current emission inventories and projecting future developments under different policy scenarios. This study advances the development of load-dependent EFs for ships by incorporating alternative fuels, biofuels and emission control technologies. The methodology combines statistical analysis of data from an extensive literature review with newly acquired on-board emission measurements, including two-stroke propulsion engines and four-stroke auxiliary units. To ensure broad applicability, the updated EFs are expressed as functions of engine load and are categorized by engine and fuel type, covering conventional marine fuels, liquified natural gas, methanol, ammonia and biofuels. The results provide improved resolution of shipping emissions and insights into the role of emission control technologies, supporting robust, up-to-date emission models and inventories. This work contributes to the development of effective strategies for sustainable maritime transport and supports both policymakers and industry stakeholders in their decarbonization efforts.