Trends, composition, and sources of carbonaceous aerosol at the Birkenes Observatory, northern Europe, 2001-2018
Artikel i vetenskaplig tidskrift, 2021

We present 18 years (2001-2018) of aerosol measurements, including organic and elemental carbon (OC and EC), organic tracers (levoglucosan, arabitol, mannitol, trehalose, glucose, and 2-methyltetrols), trace elements, and ions, at the Birkenes Observatory (southern Norway) - a site representative of the northern European region. The OC=EC (2001-2018) and the levoglucosan (2008-2018) time series are the longest in Europe, with OC=EC available for the PM10, PM2:5 (fine), and PM10-2:5 (coarse) size fractions, providing the opportunity for a nearly 2-decade-long assessment. Using positive matrix factorization (PMF), we identify seven carbonaceous aerosol sources at Birkenes: mineraldust- dominated aerosol (MIN), traffic/industry-like aerosol (TRA/IND), short-range-transported biogenic secondary organic aerosol (BSOASRT), primary biological aerosol particles (PBAP), biomass burning aerosol (BB), ammoniumnitrate- dominated aerosol (NH4NO3), and (one low carbon fraction) sea salt aerosol (SS). We observed significant (p < 0:05), large decreases in EC in PM10 (-3:9%yr-1) and PM2:5 (-4:2%yr-1) and a smaller decline in levoglucosan (-2:8%yr-1), suggesting that OC=EC from traffic and industry is decreasing, whereas the abatement of OC=EC from biomass burning has been slightly less successful. EC abatement with respect to anthropogenic sources is further supported by decreasing EC fractions in PM2:5 (-3:9%yr-1) and PM10 (-4:5%yr-1). PMF apportioned 72% of EC to fossil fuel sources; this was further supported by PMF applied to absorption photometer data, which yielded a two-factor solution with a low aerosol ngstr m exponent (AAED0.93) fraction, assumed to be equivalent black carbon from fossil fuel combustion (eBCFF), contributing 78% to eBC mass. The higher AAE fraction (AAED2.04) is likely eBC from BB (eBCBB). Source-receptor model calculations (FLEXPART) showed that continental Europe and western Russia were the main source regions of both elevated eBCBB and eBCFF. Dominating biogenic sources explain why there was no downward trend for OC. A relative increase in the OC fraction in PM2:5 (C3:2%yr-1) and PM10 (C2:4%yr-1) underscores the importance of biogenic sources at Birkenes (BSOA and PBAP), which were higher in the vegetative season and dominated both fine (53 %) and coarse (78 %) OC. Furthermore, 77 %-91% of OC in PM2:5, PM10-2:5, and PM10 was attributed to biogenic sources in summer vs. 22 %- 37% in winter. The coarse fraction had the highest share of biogenic sources regardless of season and was dominated by PBAP, except in winter. Our results show a shift in the aerosol composition at Birkenes and, thus, also in the relative source contributions. The need for diverse offline and online carbonaceous aerosol speciation to understand carbonaceous aerosol sources, including their seasonal, annual, and long-term variability, has been demonstrated.


Karl Espen Yttri

Norsk institutt for luftforskning (NILU)

Francesco Canonaco

Datalystica Ltd.

Paul Scherrer Institut

S. Eckhardt

Norsk institutt for luftforskning (NILU)

Nikolaos Evangeliou

Norsk institutt for luftforskning (NILU)

Markus Fiebig

Norsk institutt for luftforskning (NILU)

Hans Gundersen

Norsk institutt for luftforskning (NILU)

Anne Gunn Hjellbrekke

Norsk institutt for luftforskning (NILU)

Cathrine Lund Myhre

Norsk institutt for luftforskning (NILU)

Stephen Matthew Platt

Norsk institutt for luftforskning (NILU)

A.S.H. Prevot

Paul Scherrer Institut

David Simpson

Meteorologisk institutt

Chalmers, Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys

S. Solberg

Norsk institutt for luftforskning (NILU)

J. D. Surratt

The University of North Carolina System

K. Torseth

Norsk institutt for luftforskning (NILU)

Hilde Uggerud

Norsk institutt for luftforskning (NILU)

Marit Vadset

Norsk institutt for luftforskning (NILU)

Xin Wan

Chinese Academy of Sciences

Wenche Aas

Norsk institutt for luftforskning (NILU)

Atmospheric Chemistry and Physics

1680-7316 (ISSN) 1680-7324 (eISSN)

Vol. 21 9 7149-7170


Meteorologi och atmosfärforskning

Annan geovetenskap och miljövetenskap




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