Measurement report: A one-year study to estimate maritime contributions to PM₁₀ in a coastal area in Northern France

Abstract. This work is focused on filling the lack of knowledge associated with natural and anthropogenic marine emissions on PM₁₀ concentrations in Northern France. For this purpose, a one-year measurement and sampling campaign for PM₁₀ has been performed at a French coastal site situated in front of the Straits of Dover. The characterization of PM₁₀ samples was performed considering major and trace elements, water-soluble ions, organic carbon (OC), elemental carbon (EC), and organic markers of biomass burning and primary biogenic emissions. Furthermore, the source apportionment of PM₁₀ was achieved using the constrained weighted-non-negative matrix factorization (CW-NMF) model. The annual average PM₁₀ was 24.3 µg/m³ with six species contributing to 69 % of its mass (NO₃-, OC, SO₄^2-, Cl^-, Na⁺, and NH₄⁺). The source apportionment of PM₁₀ led to the identification of 10 sources. Fresh and aged sea-salts contributed to 37 % of PM₁₀, while secondary nitrate and sulfate contributed 41 %, biomass burning 10 %, and Heavy Fuel Oil (HFO) combustion from shipping emissions contributed 5 %, on yearly averages. Additionally, monthly evolution of the sources’ contribution evidenced different behaviors with high contributions of secondary nitrate and biomass burning during winter. In the summer season, 10 times higher concentrations for HFO combustion (July compared to January) and the predominance of aged sea-salts versus fresh sea-salts were observed. Constant weighted trajectories showed that the sources contributing to more than 80 % of PM₁₀ at Cape Gris-Nez are of regional and/or long-range origins with the North Sea and the English Channel as hotspots for natural and anthropogenic marine emissions and Belgium, the Netherlands, and the West of Germany as hotspots for secondary inorganic aerosols.