A large contribution of methylsiloxanes to particulate matter from ship emissions. (July 2022)

• Record Type: Journal Article
• Authors: Yao, Peng; Chianese, Elena; Kairys, Norbertas; Holzinger, Rupert; Materić, Dušan; Sirignano, Carmina; Riccio, Angelo; Ni, Haiyan; Huang, Ru-Jin; Dusek, Ulrike
• Is Part Of: Environment international. Volume 165(2022)
• Publication Date: 2022-07
• Subjects: Methylsiloxane -- Ship emissions -- Organic aerosol -- Mass spectrometry -- 13C analysis -- Lubricating oil; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2022.107324
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Highlights: Methylsiloxanes were identified in aerosols emitted by a ship. The natural abundance of silicon isotopes can be used to identify methylsiloxanes in high resolution mass spectrometry. Particulate-phase methylsiloxanes were mainly emitted near the harbor under inefficient combustion conditions. Considerably lower methylsiloxane emissions were observed under cruise conditions. Abstract: The chemical and stable carbon isotopic composition of the organic aerosol particles (OA) emitted by a shuttle passenger ship between mainland Naples and island Capri in Italy were investigated. Various methylsiloxanes and derivatives were found in particulate ship emissions for the first time, as identified in the mass spectra of a thermal desorption – proton transfer reaction – mass spectrometer (TD-PTR-MS) based on the natural abundance of silicon isotopes. Large contributions of methylsiloxanes to OA (up to 59.3%) were found under inefficient combustion conditions, and considerably lower methylsiloxane emissions were observed under cruise conditions (1.2% of OA). Furthermore, the stable carbon isotopic composition can provide a fingerprint for methylsiloxanes, as they have low δ 13 C values in the range of −44.91‰ ± 4.29‰. The occurrence of methylsiloxanes was therefore further supported by low δ 13 C values of particulate organic carbon (OC), ranging from −34.7‰ to −39.4‰, when carbon fractions of methylsiloxanes in OC were high. The δ 13 C values of OC increased up to around −26.7‰ under cruise conditions, when carbon fractions of methylsiloxanes in OC were low. Overall, the δ 13 C value of OC decreased linearly with increasing carbon fraction of methylsiloxanes in OC, and the slope is consistent with a mixture of methylsiloxanes and fuel combustion products. The methylsiloxanes in ship emissions may come from engine lubricants.