Measurement report: Emission factors and organic aerosol source apportionment of shipping emissions in the coastal city of Toulon, France

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.