1,2,2,1,1- 1University of Florence, Department of Chemistry, Sesto F.no, Italy
- 2ENEA- Laboratorio Modelli e Misure per la Qualità dell'Aria ed Osservazioni Climatiche
Several papers in the last decades demonstrate the strong impact of aerosol emitted by ships in harbors, coastal regions, and also in the central Mediterranean Sea (e.g. Viana et al., 2014; Becagli et al., 2017).
The ship aerosol is characterized by high concentrations of sulphate and metals (V and Ni) and has been shown to affect the radiation field and to produce adverse health effects.
In the Mediterranean region, high sulphate levels (often exceeding 10 µg/m3), allowed to characterize this region as one of the areas worldwide strongly influenced by the negative radiative forcing induced by the sulphate.
A review of five ship aerosol modeling studies finds a mean radiative forcing at the top of the atmosphere of +0.12±0.03 W/m2 (Gettelman et al., 2024), essentially induced by changes in the cloud properties. Although the estimated radiative forcing expected from changes in ship aerosol is not large, its effect is highly nonlinear (i.e., if aerosols emitted into polluted air have much less effect on clouds than aerosols emitted into a pristine atmosphere), and the decreased ship emissions may have a large effect on Earth’s albedo.
This works aims to investigate the effect of the implementation of the International Maritime Organization (IMO) 2020 regulation leading to a decrease of sulfur concentration in the marine fuels down to 0.5%, on PM10 composition in central Mediterranean Sea. PM10 was sampled at Lampedusa by sequential aerosol sampler (Gemini Dadolab srl) equipped with PM10 and PTS sampling heads. PM10 was measured by gravimetry and analyzed for ions and metals content as reported in Becagli et al. (2012 and 2017). Several interesting conclusions cand be drawn from the comparison of sulphate, V, and Ni concentrations obtained before and after 2020.
The sulphate concentration has been observed to decrease by factor 2 in summer. The decrease is smaller than that observed in the eastern Mediterranean, where it was reduced by almost a factor of 4 since 90’s (Urdiales-Flores et al., 2023). This significant decrease in sulphate is considered as one of the main drivers of the rapid warming of the Mediterranean compared to the rest of the world (Urdiales-Flores et al., 2023).
A remarkably higher reduction in concentration is observed for V and Ni. The concentration of these metals decreases by a factor of about 5. Moreover, V ad Ni solubility shows a strong reduction with respect to data prior to 2020, becoming similar to that measured on crustal samples. Also, the V/Ni ratio of ship aerosol (soluble fraction) becomes close to 2, a value similar to that of mineral aerosol.
In previous studies (e.g., Becagli et al., 2012) values of V>8 ng/m3 coupled with the value of V/Ni ratio in the range 3-3.5 were used as a tracers for identifying ship-emitted particles. The present analysis shows that these criteria, are no more valid for present day measurements.
Viana et al. 2014. DOI: 10.1016/j.atmosenv.2014.03.046
Becagli et al. 2017. DOI: 10.5194/acp-17-2067-2017
Gettelman et al., 2024. DOI: 10.1029/2024gl109077.
Becagli et al. 2012. DOI: 10.5194/acp-12-3479-2012
Urdiales-Flores et al. 2023. DOI: 10.1038/s41612-023-00423-1
How to cite: Becagli, S., di Sarra, A., Di Iorio, T., Meloni, D., Monteleone, F., Quarratesi, G., Severi, M., Sferlazzo, D., and Traversi, R.: New evidence on the impact of ship emission in central Mediterranean Sea as a consequence of the sulfur reduction in heavy fuel oil, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6034, https://doi.org/10.5194/egusphere-egu26-6034, 2026.
