Characterization of fleet emissions from ships through multi-individual determination of size-resolved particle emissions in a coastal area
2015
Westerlund, Jonathan | Hallquist, Mattias | Hallquist, Åsa M.
Shipping is becoming a major source of particulate air pollution in coastal cities. Here we describe the use of a stationary measurement site to characterize nanoparticle emissions (5.6–560 nm) from a large ship fleet (154 ships) in a harbor region of an emission control area (ECA) under real-world dilution conditions. Emission factors (EFs) are described with respect to particle number (PN), mass (PM), size and volatility. Automatic Identification System data were used to obtain information on ship class, direction, speed and acceleration. Cargo and passenger ships had similar average EFs: 2.79 ± 0.19 vs. 2.35 ± 0.20 × 1016 # (kg fuel)−1 and 2550 ± 170 vs. 2200 ± 130 mg (kg fuel)−1 respectively. The number size distributions for cargo and passenger ships were unimodal, peaking at ∼40 nm. Tug-boats and pilots emitted smaller particles with lower EFPN and EFPM. For emissions of non-volatile particles from cargo and passenger ships EFPM increased with decreasing speed and acceleration while the EFPN decreased. The size distributions of the non-volatile particles for all ships contained a large mode at ∼10 nm. This peak is believed to be formed during plume aging. A detailed understanding of size-resolved particle emissions from individual ships will be important in designing appropriate emission regulations for coastal areas.
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