Abstract
Abstract. Studies of detailed chemical compositions in particles with different size ranges emitted from ships are in serious shortage. In this study, size-segregated distributions and characteristics of particle mass, organic carbon (OC), elemental carbon (EC), 16 EPA polycyclic aromatic hydrocarbons (PAHs) and 25 n-alkanes measured aboard 12 different vessels in China are presented. The results showed the following. (1) More than half of the total particle mass, OC, EC, PAHs and n-alkanes were concentrated in fine particles with aerodynamic diameter (Dp) < 1.1 µm for most of the tested ships. The relative contributions of OC, EC, PAH and alkanes to the size-segregated particle mass are decreasing with the increase in particle size. However, different types of ships showed quite different particle-size-dependent chemical compositions. (2) In fine particles, the OC and EC were the dominant components, while in coarse particles, OC and EC only accounted for very small proportions. With the increase in particle size, the OC / EC ratios first decreased and then increased, having the lowest values for particle sizes between 0.43 and 1.1 µm. (3) Out of the four OC fragments and three EC fragments obtained in thermal–optical analysis, OC1, OC2 and OC3 were the dominant OC fragments for all the tested ships, while EC1 and EC2 were the main EC fragments for ships running on heavy fuel oil (HFO) and marine-diesel fuel, respectively; different OC and EC fragments presented different distributions in different particle sizes. (4) The four-stroke low-power diesel fishing boat (4-LDF) had much higher PAH emission ratios than the four-stroke high-power marine-diesel vessel (4-HMV) and two-stroke high-power heavy-fuel-oil vessel (2-HHV) in fine particles, and 2-HHV had the lowest values. (5) PAHs and n-alkanes showed different profile patterns for different types of ships and also between different particle-size bins, which meant that the particle size should be considered when source apportionment is conducted. It is also noteworthy from the results in this study that the smaller the particle size, the more toxic the particle was, especially for the fishing boats in China.
Highlights
Particulate matter (PM) emitted from ships has significant impacts on human health and air quality (Schröder et al, 2017; Liu et al, 2016; Oeder et al, 2015; Viana et al, 2014)
We focused on the particle mass size distribution of the tested ships
The findings were in line with the previous studies which reported that the mass distributions of ship emissions were dominated by accumulation-mode and/or coarse-mode particles (Moldanová et al, 2009, 2013; Murphy et al, 2009)
Summary
Particulate matter (PM) emitted from ships has significant impacts on human health and air quality (Schröder et al, 2017; Liu et al, 2016; Oeder et al, 2015; Viana et al, 2014). PM emitted from ships in harbor cities or areas accounts for non-ignorable proportions of primary PM2.5 (Gregoris et al, 2016; Zhao et al, 2013; Agrawal et al, 2009) This fraction can reach up to 17 %–30 % if the contribution of shipping emissions to secondary particles is considered, too (Pandolfi et al, 2011; Liu et al, 2017). As important components, water-soluble ions such as SO24−, NO−3 , NH+4 , Cl− and Na+ are routinely studied due to their unique emission characteristics in PM of ships, different from other sources (Sippula et al, 2014; Moldanová et al, 2013, 2009; Agrawal et al, 2008). Because a large number of particles emitted from ships are very small (< 0.1 μm), which may have significant impacts on cloud formation (Fridell et al, 2008), particle number concentrations, for ultrafine particles, have gained more and more attention in recent years
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