Abstract. In coastal areas, there is increased concern about
emissions from shipping activities and the associated impact on air quality.
We have assessed the ship aerosol properties and the contribution to coastal
particulate matter (PM) and nitrogen dioxide (NO2) levels by measuring
ship plumes in ambient conditions at a site in southern Sweden, within a
Sulfur Emission Control Area. Measurements took place during a summer and a
winter campaign, 10 km downwind of a major shipping lane. Individual ships
showed large variability in contribution to total particle mass, organics,
sulfate, and NO2. The average emission contribution of the shipping
lane was 29±13 and 37±20 ng m−3 to PM0.5, 18±8 and 34±19 ng m−3 to PM0.15, and 1.21±0.57 and
1.11±0.61 µg m−3 to NO2, during winter and summer, respectively. Sulfate and organics dominated the particle mass and most
plumes contained undetectable amounts of equivalent black carbon (eBC). The
average eBC contribution was 3.5±1.7 ng m−3 and the absorption
Ångström exponent was close to 1. Simulated ageing of the ship
aerosols using an oxidation flow reactor showed that on a few occasions,
there was an increase in sulfate and organic mass after photochemical
processing of the plumes. However, most plumes did not produce measurable
amounts of secondary PM upon simulated ageing.
Discussion on the proposed area of an international ship emission control area in China
