2 research outputs found
Spatial Variation of Aerosol Chemical Composition and Organic Components Identified by Positive Matrix Factorization in the Barcelona Region
The
spatial distribution of PM<sub>1</sub> components in the Barcelona
metropolitan area was investigated using on-road mobile measurements
of atmospheric particle- and gas-phase compounds during the DAURE
campaign in March 2009. Positive matrix factorization (PMF) applied
to organic aerosol (OA) data yielded 5 factors: hydrocarbon-like OA
(HOA), cooking OA (COA), biomass burning OA (BBOA), and low volatility
and semivolatile oxygenated OA (LV-OOA and SV-OOA). The area under
investigation (∼500 km<sup>2</sup>) was divided into six zones
(city center, harbor, industrial area, precoastal depression, 2 mountain
ranges) for measurements and data analysis. Mean zonal OA concentrations
are 4.9–9.5 μg m<sup>–3</sup>. The area is heavily
impacted by local primary emissions (HOA 14–38%, COA 10–18%,
BBOA 10–12% of OA); concentrations of traffic-related components,
especially black carbon, are biased high due to the on-road nature
of the measurements. The formation of secondary OA adds more than
half of the OA burden outside the city center (SV-OOA 14–40%,
LV-OOA 17–42% of OA). A case study of one measurement drive
from the shore to the precoastal mountain range furthest downwind
of the city center indicates the importance of nonfossil over anthropogenic
secondary OA based on OA/CO
Trends in Chemical Composition of Global and Regional Population-Weighted Fine Particulate Matter Estimated for 25 Years
We
interpret in situ and satellite observations with a chemical transport
model (GEOS-Chem, downscaled to 0.1° × 0.1°) to understand
global trends in population-weighted mean chemical composition of
fine particulate matter (PM<sub>2.5</sub>). Trends in observed and
simulated population-weighted mean PM<sub>2.5</sub> composition over
1989–2013 are highly consistent for PM<sub>2.5</sub> (−2.4
vs −2.4%/yr), secondary inorganic aerosols (−4.3 vs
−4.1%/yr), organic aerosols (OA, −3.6 vs −3.0%/yr)
and black carbon (−4.3 vs −3.9%/yr) over North America,
as well as for sulfate (−4.7 vs −5.8%/yr) over Europe.
Simulated trends over 1998–2013 also have overlapping 95% confidence
intervals with satellite-derived trends in population-weighted mean
PM<sub>2.5</sub> for 20 of 21 global regions. Over 1989–2013,
most (79%) of the simulated increase in global population-weighted
mean PM<sub>2.5</sub> of 0.28 μg m<sup>–3</sup>yr<sup>–1</sup> is explained by significantly (<i>p</i> < 0.05) increasing OA (0.10 μg m<sup>–3</sup>yr<sup>–1</sup>), nitrate (0.05 μg m<sup>–3</sup>yr<sup>–1</sup>), sulfate (0.04 μg m<sup>–3</sup>yr<sup>–1</sup>), and ammonium (0.03 μg m<sup>–3</sup>yr<sup>–1</sup>). These four components predominantly drive
trends in population-weighted mean PM<sub>2.5</sub> over populous
regions of South Asia (0.94 μg m<sup>–3</sup>yr<sup>–1</sup>), East Asia (0.66 μg m<sup>–3</sup>yr<sup>–1</sup>), Western Europe (−0.47 μg m<sup>–3</sup>yr<sup>–1</sup>), and North America (−0.32 μg m<sup>–3</sup>yr<sup>–1</sup>). Trends in area-weighted mean
and population-weighted mean PM<sub>2.5</sub> composition differ significantly