Particulate
matter (PM) emissions from ships are increasingly posing
health risks to population living along coastal areas. However, studies
on the characteristics of particulate emissions from ships fueled
with heavy fuel oil (HFO) are quite rare. In this paper, the characteristics
of the PM sampled from the exhaust of a low-speed two-stroke common-rail
marine diesel engine fueled with HFO are investigated at different
loads. The thermal/optical carbon analyzer was employed to discriminate
the elemental and organic carbons (EC and OC), the combustion-based
elemental analysis was performed to obtain the C/H ratio, and the
nuclear magnetic resonance spectrometer was used to analyze the molecular
structure of the sample. With increasing loads, the EC/OC and C/H
mass ratios and the mole ratio of polycyclic aromatic hydrocarbons
to aliphatic hydrocarbons increase. From transmission electron microscopy
images, noticeable changes in nanostructure, size, morphology, and
nanostructural parameters of soot particles were analyzed. Furthermore,
the elemental spatial distribution in soot particles was observed
by energy-dispersive X-ray spectroscopy mapping. The main elements
were detected by point-analyzed spectra. These results are believed
to be valuable references for hazard evaluation and building a strategy
of reducing particulate emissions from low-speed marine diesel engines.