Abstract. The molecular composition and structure of polar organic matters (POM) in particles emitted from various vessels and excavators were characterized using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS). POM was extracted by purified water and was discussed by elemental composition which was divided into three groups, namely CHO, CHON and S-containing compounds (CHONS and CHOS). The results showed that: (i) CHO (accounting for 49 % of total POM relative peak response) was the most abundant group for all tested off-road engines, followed by CHON (33 %) and CHOS (35 %) for diesel- and HFO (heavy fuel oil)-fueled off-road equipment, respectively. (ii) The abundance and structure of the CHON group in water extracts were different in terms of engine type and load. The fraction of relative peak response of CHON was highest for excavator emissions under the working mode compared to other modes (idling and moving). Furthermore, dinitrophenol and methyl dinitrophenol were the most abundant emission species for excavators with high rated speed, while nitronaphthol and methyl nitronaphthol were more important for low rated speed vessels. (iii) The composition and structure of S-containing compounds was directly influenced by fuel oil characteristics (sulfur content and aromatic ring), with much more condensed aromatic rings in S-containing compounds observed for HFO-fueled vessels, while more abundant aliphatic chains were observed in emissions from diesel equipment. Overall, higher fractions of condensed hydrocarbons and aromatic rings in POM emitted from vessels using HFO caused strong optical absorption capacity. And different structures existing in POM could provide a direction to qualitative and quantities the exact organic compounds as tracers to distinguish the emission from diesel or HFO- fueled off-road engines.
TG/DTG, FT-ICR Mass Spectrometry, and NMR Spectroscopy Study of Heavy Fuel Oil
