29 research outputs found
Mobile measurements of ship emissions in two harbour areas in Finland
Four measurement campaigns were performed in two
different environments – inside the harbour areas in the city centre of
Helsinki, and along the narrow shipping channel near the city of Turku,
Finland – using a mobile laboratory van during winter and summer conditions in 2010–2011. The
characteristics of gaseous (CO, CO2, SO2, NO, NO2,
NOx) and particulate (number and volume size distributions as
well as PM2.5) emissions for 11 ships regularly operating on the Baltic
Sea were studied to determine the emission parameters. The highest particle
concentrations were 1.5 × 106 and 1.6 × 105 cm−3 in
Helsinki and Turku, respectively, and the particle number size distributions
had two modes. The dominating mode peaked at 20–30 nm, and the
accumulation mode at 80–100 nm. The majority of the particle mass was
volatile, since after heating the sample to 265 °C, the particle
volume of the studied ship decreased by around 70%. The emission factors
for NOx varied in the range of 25–100 g (kg fuel)−1, for
SO2 in the range of 2.5–17.0 g (kg fuel)−1, for particle number in the range of
(0.32–2.26) × 1016 # (kg fuel)−1, and for
PM2.5 between 1.0–4.9 g (kg fuel)−1. The ships equipped with
SCR (selective catalytic reduction) had the lowest NOx emissions,
whereas the ships with DWI (direct water injection) and HAMs (humid air motors)
had the lowest SO2 emissions but the highest particulate emissions. For all
ships, the averaged fuel sulphur contents (FSCs) were less than 1% (by
mass) but none of them was below 0.1% which will be the new EU
directive starting 1 January 2015 in the SOx emission control
areas; this
indicates that ships operating on the Baltic Sea will face large challenges
Characterization and source identification of a fine particle episode in Finland
A strong long-range transported (LRT) fine particle (PM2.5) episode occurred from March 17–22, 2002 over large areas of Finland. Most of the LRT particle mass was in the submicrometre size fraction. The number of concentrations of 90–500 nm particles increased by a factor of 5.6 during the episode, but the concentrations of particles smaller than 90 nm decreased. This reduction of the smallest particles was caused by suppressed gas-to-particle conversion due to the vapour uptake of LRT particles. Individual particle analyses using SEM/EDX showed that the proportion of sulphur-rich particles rose strongly during the episode and that the relative weight percentage of potassium was unusually high in these particles. The median S/K ratios of S-rich particles were 2.1 at the beginning of the episode, 5.2 at the peak stage of the episode and 8.9 during the reference days. The high proportion of K is a clear indication of emissions from biomass burning, because K is a good tracer of biomass-burning aerosols. Trajectories and satellite detections of fire areas indicated that the main source of biomass-burning aerosols was large-scale agricultural field burning in the Baltic countries, Belarus, Ukraine and Russia. The higher S/K ratio of S-rich particles during the peak stage was obviously due to the increased proportion of fossil fuel-burning emissions in the LRT particle mass, since air masses arrived from the more polluted areas of Europe at that time. The concentrations of sulphate, total nitrate and total ammonium increased during the episode. Our results suggest that large-scale agricultural field burning may substantially affect PM2.5 concentrations under unfavourable meteorological conditions even at distances over 1000 km from the burning areas
Characterization of aerosol particle episodes in Finland caused by wildfires in Eastern Europe
We studied the sources, compositions and size
distributions of aerosol particles during long-range transport
(LRT) PM2.5 episodes which occurred on 12–15 August, 26–
28 August and 5–6 September 2002 in Finland. Backward
air mass trajectories, satellite detections of fire areas and dispersion
modelling results indicate that emissions from wild-
fires in Russia and other Eastern European countries arrived
in Finland during these episodes. Elemental analyses using
scanning electron microscopy (SEM) coupled with energy
dispersive X-ray microanalyses (EDX) showed that the proportions
of S-rich particles and agglomerates (agglomeration
was caused partly by the sampling method used) increased
during the episodes, and they contained elevated fractions
of K, indicating emissions from biomass burning. These
aerosols were mixed with S-rich emissions from fossil fuel
burning during transport since air masses came through polluted
areas of Europe. Minor amounts of coarse Ca-rich particles
were also brought by LRT during the episodes, and
they probably originated from wildfires and/or from Estonian
and Russian oil-shale-burning industrial areas. Ion chromatography
analysis showed that concentrations of sulphate
(SO2− 4 ), total nitrate (NO−3 +HNO3(g)) and total ammonium
(NH+4 +NH3(g)) increased during the episodes, but the ratio
of the total amount of these ions to PM10 concentration decreased,
indicating unusually high fractions of other chemical
components. Particle number size distribution measurements
with differential mobility particle sizer (DMPS) revealed
that concentrations of particles 90–500 nm increased during the episodes, while concentrations of particles smaller
than 90 nm decreased. The reduction of the smallest particles
was caused by suppressed new particle formation due to
vapour and molecular cluster uptake of LRT particles. Our
results show that emissions from wildfires in Russian and
other Eastern European countries deteriorated air quality of
very large areas, even at distances of over 1000 km from the
fire areas