Chemical characterization of exhaust emissions from selected canadian marine vessels: the case of trace metals and lanthanoids.

Abstract

This paper reports the chemical composition of exhaust emissions from the main engines of five ocean going cargo vessels, as they traveled in Canadian waters. The emission factors (EFs) of PM2.5 and SO2 for vessels tested on various intermediate fuel oils (IFO), ranged from 0.4 to 2.2 g kW(-1) hr(-1) and 4.7 to 10.3 g kW(-1) hr(-1), respectively, and were mainly dependent on the content of sulfur in the fuel. Average NOx, CO, and CO2 EFs for these tests were 12.7, 0.45, and 618 g kW(-1) hr(-1), respectively and were generally below benchmark values commonly used by regulatory agencies. The composition of PM2.5 was dominated by hydrated sulfates, organic carbon and trace metals which accounted for 80-97% of total PM2.5 mass. A substantial decrease of measured emission factors for PM2.5 and SO2 was observed when the fuel was changed from IFO to marine diesel oil (MDO), in one of the tested vessels. The main component of PM2.5 in this case was organic carbon accounting for 65% of PM2.5 mass. In addition to commonly reported pollutants, this study presents EFs of the lanthanoid elements and showed that their distribution patterns in ship-exhaust PM2.5 were very similar to the PM2.5 emitted by oil refining facilities. Hence, using La:Ce:V tertiary diagrams and La/V ratios is necessary to distinguish ship plumes from primary emissions related to accidental and/or routine operation of oil-refining industry.