Nicolas Marchand

Recent changes in elemental particulate matter (PMel., or sum of individual elements analysed) concentrations and composition from road traffic and shipping call for an updated assessment. High-time-resolution PMel. measurements at three strategically selected Barcelona sites urban background (UBG), traffic (TRF), and harbour (HARB), enabled source- and element-specific assessment of urban air quality. Positive Matrix Factorization (PMF) was applied independently to PM10-el. and/or PM2.5-el. at each site. The high-resolution measurements captured short-term pollution episodes and distinguished local from regional/secondary sources. Compared with UBG, the hotspots (TRF, HARB) were enriched in anthropogenic (Fe, Cu, Zn, Ba, Cr, Mn, Pb, Ni, V) and crustal elements (Si, Ca, Ti, Fe). Sources of regional origin contributed 40–70% of PM10-el. and PM2.5-el. across all sites. Transport-relsated increments were substantial: Brake and Tyre-road wear contributions at TRF were >3-times higher than at UBG, and 1-h shipping plumes at HARB increased PM2.5-el. concentrations by ~1.2 µg m−3 (~26–40-times) relative to UBG. The multisite approach improved source apportionment by reducing the misattribution of ship-related S to Regional at the inland sites. The findings highlight the need for targeted mitigation strategies addressing both traffic and coastal shipping emissions.

The contributions and evolution of fine elemental particulate matter (PM) sources were investigated in the Marseille–Fos basin (south of France) based on a 1-year-long (January–December 2023) study using online X-ray fluorescence (Xact) PM1 measurements. The region's intense anthropogenic activity and complex meteorological conditions make it an ideal case study for fine aerosol characterization. Given the limited information available on fine elemental sources in the area, a dual-site approach was implemented, combining an urban background site (MRS-LCP) and an industrial site (FOS) to distinguish between regional and local emission influences. Source apportionment was conducted using a rolling positive matrix factorization (PMF) method, implemented via the Source Finder Professional (SoFi) toolkit. Several tests were carried out to determine optimal rolling PMF parameters. Eventually, a 21 d rolling-window configuration was selected, resolving nine factors at FOS and eight at MRS-LCP, with seven similar factors detected at both sites. Among them, three were attributed to secondary aerosols, including sulfur photooxidation leading to sulfate-rich aerosols (S-rich factor) and the formation of halogenated reactive particulate species (Cl-rich and Br-rich factors). Additionally, biomass-burning-, shipping-, and dust-related factors were identified at both locations. In contrast, three industrial factors (steel industry, Zn-industrial, Pb-industrial) were detected at FOS, while only the steel industry factor appeared at MRS-LCP, suggesting downwind transport of industrial plumes from Fos-sur-Mer to Marseille under mistral- and thermal-breeze regimes. Furthermore, the comparison of the dynamic rolling PMF approach to static PMF analysis demonstrated higher dissimilarities across factors profiles, reflecting an enhanced ability of rolling PMF to capture seasonal variability in aerosol sources. Overall, this study highlights the dominant anthropogenic imprint on submicron PM elements and the effectiveness of dynamic source apportionment in complex coastal–industrial environments.

This study presents the first nationwide phenomenological analysis of submicron organic aerosol (OA) sources in France, based on highly time‑resolved Aerosol Chemical Speciation Monitor (ACSM) measurements collected at 12 (sub)urban sites over one to seven years. A harmonized rolling Positive Matrix Factorization (PMF) approach was applied, ensuring consistent constraints and criteria across all datasets. The methodology enabled the identification of major OA sources, including primary OA (POA) factors such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), and cooking-like OA (COA), which together accounted for approximately 33% of the OA mass. Secondary or aged OA was represented by oxygenated OA (OOA), which dominated OA at all sites and was further separated into Less Oxidized (LO-OOA) and More Oxidized OOA (MO-OOA). Additional site-specific OA factors were also resolved, including a mixed shipping/industrial OA factor in Marseille Longchamp and an amine-related OA factor in Strasbourg and Creil.Strong seasonality was observed for POA, particularly BBOA, which increased substantially during winter due to residential heating. LO-OOA correlated with BBOA in winter, highlighting the important contribution of biomass combustion to wintertime air quality degradation across France, while summer LO-OOA was mainly associated with biogenic precursors. Comparison with the CHIMERE chemical transport model revealed systematic biases in simulated OA components, underscoring the value of this unique long-term dataset for improving OA representation. These findings are highly relevant for various applications, including epidemiological studies and near-real-time source apportionment. They also offer observational insights for improving air quality, providing valuable information to policymakers for proposing effective mitigation strategies.

Contributions and evolution of fine elemental particulate matter (PM) sources were investigated in the Marseille-Fos basin (South of France) based on a 1 year-long (January–December 2023) study using on-line x-ray fluorescence (Xact) PM₁ measurements. The region's intense anthropogenic activity and complex meteorological conditions make it an ideal case study for fine aerosol characterization. Given the limited information available on fine elemental sources in the area, a dual-site approach was implemented, combining an urban background site (MRS-LCP) and an industrial site (FOS) to distinguish between regional and local emission influences. Source apportionment was conducted using a rolling Positive Matrix Factorization (PMF) method, implemented via the Source Finder Professional (SoFi) toolkit. Several tests were carried out to determine optimal rolling PMF parameters. Eventually, a 21-day rolling window configuration was selected, resolving nine factors at FOS and eight at MRS-LCP, with seven similar factors detected at both sites. Among them, three were attributed to secondary aerosols, including sulfur photooxidation leading to sulfate-rich aerosols (S-rich factor) and the formation of halogenated reactive particulate species (Cl-rich and Br-rich factors). Additionally, biomass burning, shipping, and dust related factors were identified at both locations. In contrast, three industrial factors (Steel Industry, Zn-Industrial, Pb-Industrial) were detected at FOS, while only the Steel Industry factor appeared at MRS-LCP, suggesting downwind transport of industrial plumes from Fos-sur-Mer to Marseille under Mistral and thermal breeze regimes. Furthermore, the comparison of dynamic rolling PMF approach to static PMF analysis, demonstrated higher dissimilarities across factors profiles, reflecting enhanced ability of Rolling PMF to capture seasonal variability in aerosol sources. Overall, this study highlights the dominant anthropogenic imprint on submicron PM elements and the effectiveness of dynamic source apportionment in complex coastal-industrial environments.

Atmospheric particulate matter (PM), a public health concern worldwide, is at present regulated according to its mass concentration¹. However, it is increasingly thought that mass concentration may not fully capture the physicochemical properties of PM linked to its health impact². Consequently, it has been suggested to further investigate the adequacy of this metric as an unequivocal indicator of PM health effects^3,4,5. The new European regulation on air quality introduced oxidative potential (OP) as a recommended parameter to be monitored at supersites¹, to explore further deciphering information about PM reactivity and health impacts^6,7. Here we use a database of almost 11,500 OP measurements from 43 locations across parts of Europe that were analysed with the two most commonly used OP assays⁸, OP^AA and OP^DTT, with a standardized protocol^9,10. We find high spatial variability of OP across Europe, strongly influenced by site type, such as urban or rural. Accounting for OP alongside PM mass suggests that further improvements in urban air quality may require consideration, particularly near roads, where volumetric OP of PM₁₀ exceeds background levels by a factor of 2.4 to 3.1, depending on the assay used. Analysis of mitigation strategies shows that traffic is a key source to target for effectively reducing OP in cities, whereas comprehensive reductions in PM from both traffic and biomass burning are required to also meet World Health Organization mass guidelines. Although the epidemiological evidence for OP health impacts is still evolving^2,8, our findings may help inform the interpretation of future work.

A summertime field campaign was conducted in Marseille, one of the major cruise and ferry ports in the Mediterranean, to provide comprehensive analysis of in-port ship emissions. High-temporal-resolution data were simultaneously collected from two monitoring stations deployed in the port area to examine the composition in both the gas and the particulate phases. More than 350 individual plumes were captured from a variety of ships and operational phases. Gaseous emissions are predominantly composed of NO_x (86 %) and CO (12 %), with SO₂ and CH₄ each accounting for about 1 %. Although non-methane volatile organic compounds (NMVOCs) make up less than 0.1 % of the gaseous phase, they can be as high as 10 % under specific operational conditions. Submicron particles (PM₁) are mainly composed of organics (75 %), black carbon (21 %), and sulfate (4 %) that is not balanced with ammonium. Among the ship-related characteristics investigated, the operational phase is the most influential, with a 3-fold increase in submicron particle (PM₁) emissions, along with higher relative contributions of black carbon (BC) and sulfate and the detection of vanadium, nickel, and iron during manoeuvring/navigation compared to at berth. Pollutant levels in the port are higher than those found at the urban background site, with average concentrations of NO_x, PM₁, and particle numbers up to twice as high in the port. Analysis of the maximum concentrations reveals that pollutants such as SO₂ and trace metals, including vanadium and nickel, are 2 to 10 times higher in the port area. This study provides robust support for enhancing source apportionment and emission inventories, both of which are crucial for assessing air, health, and climate impacts of shipping.

Brown carbon (BrC) is a fraction of organic aerosol (OA) that absorbs radiation in the ultraviolet and short visible wavelengths. Its contribution to radiative forcing is uncertain due to limited knowledge of its imaginary refractive index (k). This study investigates the variability of k for OA from wildfires, residential, shipping, and traffic emission sources over Europe. The Multiscale Online Nonhydrostatic Atmosphere Chemistry (MONARCH) model simulated OA concentrations and source contributions, feeding an offline optical tool to constrain k values at 370 nm. The model was evaluated against OA mass concentrations from aerosol chemical speciation monitors (ACSMs) and filter sample measurements, as well as aerosol light absorption measurements at 370 nm derived from an Aethalometer™ from 12 sites across Europe. Results show that MONARCH captures the OA temporal variability across environments (regional, suburban, and urban background). Residential emissions are a major OA source in colder months, while secondary organic aerosol (SOA) dominates in warmer periods. Traffic is a minor primary OA contributor. Biomass and coal combustion significantly influence OA absorption, with shipping emissions also notable near harbors. Optimizing k values at 370 nm revealed significant variability in OA light absorption, influenced by emission sources and environmental conditions. Derived k values for biomass burning (0.03 to 0.13), residential (0.008 to 0.13), shipping (0.005 to 0.08), and traffic (0.005 to 0.07) sources improved model representation of OA absorption compared to a constant k. Introducing such emission source-specific constraints is an innovative approach to enhance OA absorption in atmospheric models.

A summertime field campaign was conducted in Marseille, one of the major cruise and ferry ports in the Mediterranean to provide comprehensive analysis of in-port ship emissions. High-temporal-resolution data were simultaneously collected from two monitoring stations deployed in port area to examine the composition in both gas and particulate phases. More than 350 individual plumes were captured from a variety of ships and operational phases. Gaseous emissions are predominantly composed of NO_x (86 %) and CO (12 %), with SO₂ and CH₄ each accounting for about 1 %. Although NMVOCs make up less than 0.1 % of the gaseous phase, they can be as high as 10% under specific operational conditions. Submicron particles (PM₁) are mainly composed of organics (75 %), black carbon (21 %), and sulphate (4 %) not balanced with ammonium. Among the ship-related characteristics investigated, the operational phase is the most influential with a threefold increase on PM₁ emissions, along with higher relative contributions of BC and sulphate, and detection of vanadium, nickel, and iron during “manoeuvring/navigation” compared to “at berth”. Pollutant levels in the port are higher than those found at the urban background site, with average concentrations of NOx, PM₁, and particle number (PN) up to twice as high. Analysis of the maximum concentrations reveals pollutants such as SO₂ and metals, including Vanadium and Nickel, are 2 to 10 times higher in the port area. This study provides robust support for enhancing source apportionment and emission inventories, both of which are crucial for assessing air, health, and climate impacts of shipping.