Characterization of PM2.5-bound polycyclic aromatic hydrocarbons and their derivatives (nitro-and oxy-PAHs) emissions from two ship engines under different operating conditions

Emissions from ship exhaust have been recognized as an important source of air pollution in coastal areas. To investigate the impacts of engine type, fuel and operating conditions on polycyclic aromatic compounds (PACs) emissions, particle matter (PM2.5) samples emitted from an inland-river bulk freighter (BF) using marine diesel oil (MDO) and an ocean-going passenger vessel (PV) using heavy fuel oil (HFO) were collected under five operation conditions (preheating, leaving, cruising, entering and berthing). The concentrations of 17 polycyclic aromatic hydrocarbons (PAHs), 12 nitro-PAHs (NPAH5) and 4 oxygenated-PAHs species were determined. The concentrations of Sigma PAHs, Sigma NPAHs and Sigma OPAHs measured on the BF and PV exhausts ranged from 1.95 to 417 mu g/m(3), 86.5 to 6.89 x 10(3) ng/m(3) and 2.00-102 mu g/m(3), respectively. Both ships showed a high proportion of four-ring PAHs, while the BF had more three-ring PAHs (34.00-7038%) and the PV had more five-ring PAHs (30.02-35.95%). The calculation of indicatory PACs are able to increase the precision of source appointment. The emission factors (EFs) of PACs under maneuvering (including preheating, leaving, entering and berthing) was much higher than those under cruising, which might be due to the engine load, fuel consumption, and secondary reactions. Compared with HFO, combustion with MDO decreased the power-based Sigma PAH EFs by 82-99%, power-based Sigma NPAH EFs by 86-98%, and power-based Sigma PAHs EFs by 50-82%. These data highlight the importance of quantifying and monitoring ship emissions in close proximity to port area, and are useful for enhancing the relevant databases and improving the accuracy of ship emission inventories. (C) 2019 Elsevier Ltd. All rights reserved.