Ship plumes in the Baltic Sea Sulfur Emission Control Area: chemical characterization and contribution to coastal aerosol concentrations

Summary, in English

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 2913 and 3720 ngm􀀀3 to PM0:5,
188 and 3419 ngm􀀀3 to PM0:15, and 1:210:57 and
1:110:61 μgm􀀀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
3:51:7 ngm􀀀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.