Supplementary material to "Source apportionment and impact of long-range transport on carbonaceous aerosol particles in Central Germany during HCCT-2010"

Abstract. Marine aerosol particles are an important part of the natural aerosol systems and might have a significant impact on the global climate and biological cycle. It is widely accepted that truly pristine marine conditions are difficult to find over the ocean. However, the influence of continental and anthropogenic emissions on the marine boundary layer (MBL) aerosol is still less understood and non-quantitative, causing uncertainties in the estimation of the climate effect of marine aerosols. This study presents a detailed chemical characterization of the MBL aerosol as well as the source apportionment of the organic aerosol (OA) composition. The data set covers the Atlantic Ocean from 53∘ N to 53∘ S, based on four open-ocean cruises in 2011 and 2012. The aerosol particle composition was measured with a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), which indicated that sub-micrometer aerosol particles over the Atlantic Ocean are mainly composed of sulfates (50 % of the particle mass concentration), organics (21 %) and sea salt (12 %). OA has been apportioned into five factors, including three factors linked to marine sources and two with continental and/or anthropogenic origins. The marine oxygenated OA (MOOA, 16 % of the total OA mass) and marine nitrogen-containing OA (MNOA, 16 %) are identified as marine secondary products with gaseous biogenic precursors dimethyl sulfide (DMS) or amines. Marine hydrocarbon-like OA (MHOA, 19 %) was attributed to the primary emissions from the Atlantic Ocean. The factor for the anthropogenic oxygenated OA (Anth-OOA, 19 %) is related to continental long-range transport. Represented by the combustion oxygenated OA (Comb-OOA), aged combustion emissions from maritime traffic and wild fires in Africa contributed, on average, a large fraction to the total OA mass (30 %). This study provides the important finding that long-range transport was found to contribute averagely 49 % of the submicron OA mass over the Atlantic Ocean. This is almost equal to that from marine sources (51 %). Furthermore, a detailed latitudinal distribution of OA source contributions showed that DMS oxidation contributed markedly to the OA over the South Atlantic during spring, while continental-related long-range transport largely influenced the marine atmosphere near Europe and western and central Africa (15∘ N to 15∘ S). In addition, supported by a solid correlation between marine tracer methanesulfonic acid (MSA) and the DMS-oxidation OA (MOOA, R2>0.85), this study suggests that the DMS-related secondary organic aerosol (SOA) over the Atlantic Ocean could be estimated by MSA and a scaling factor of 1.79, especially in spring.

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Source apportionment and impact of long-range transport on carbonaceous aerosol particles in central Germany during HCCT-2010

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-3667-2021 ◽

2021 ◽

Vol 21 (5) ◽

pp. 3667-3684

Author(s):

Laurent Poulain ◽

Benjamin Fahlbusch ◽

Gerald Spindler ◽

Konrad Müller ◽

Dominik van Pinxteren ◽

...

Keyword(s):

Black Carbon ◽

Long Range ◽

Biomass Burning ◽

Mass Concentration ◽

Carbonaceous Aerosol ◽

Long Range Transport ◽

Air Masses ◽

Central Germany ◽

Range Transport ◽

Local Emissions

Abstract. The identification of different sources of the carbonaceous aerosol (organics and black carbon) was investigated at a mountain forest site located in central Germany from September to October 2010 to characterize incoming air masses during the Hill Cap Cloud Thuringia 2010 (HCCT-2010) experiment. The near-PM1 chemical composition, as measured by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), was dominated by organic aerosol (OA; 41 %) followed by sulfate (19 %) and nitrate (18 %). Source apportionment of the OA fraction was performed using the multilinear engine (ME-2) approach, resulting in the identification of the following five factors: hydrocarbon-like OA (HOA; 3 % of OA mass), biomass burning OA (BBOA; 13 %), semi-volatile-like OA (SV-OOA; 19 %), and two oxygenated OA (OOA) factors. The more oxidized OOA (MO-OOA, 28 %) was interpreted as being influenced by aged, polluted continental air masses, whereas the less oxidized OOA (LO-OOA, 37 %) was found to be more linked to aged biogenic sources. Equivalent black carbon (eBC), measured by a multi-angle absorption photometer (MAAP) represented 10 % of the total particulate matter (PM). The eBC was clearly associated with HOA, BBOA, and MO-OOA factors (all together R2=0.83). Therefore, eBC's contribution to each factor was achieved using a multi-linear regression model. More than half of the eBC (52 %) was associated with long-range transport (i.e., MO-OOA), whereas liquid fuel eBC (35 %) and biomass burning eBC (13 %) were associated with local emissions, leading to a complete apportionment of the carbonaceous aerosol. The separation between local and transported eBC was well supported by the mass size distribution of elemental carbon (EC) from Berner impactor samples. Air masses with the strongest marine influence, based on back trajectory analysis, corresponded with a low particle mass concentration (6.4–7.5 µg m−3) and organic fraction (≈30 %). However, they also had the largest contribution of primary OA (HOA ≈ 4 % and BBOA 15 %–20 %), which was associated with local emissions. Continental air masses had the highest mass concentration (11.4–12.6 µg m−3), and a larger fraction of oxygenated OA (≈45 %) indicated highly processed OA. The present results emphasize the key role played by long-range transport processes not only in the OA fraction but also in the eBC mass concentration and the importance of improving our knowledge on the identification of eBC sources.

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Source apportionment and impact of long-range transport on carbonaceous aerosol particles in Central Germany during HCCT-2010

10.5194/acp-2020-626 ◽

2020 ◽

Author(s):

Laurent Poulain ◽

Benjamin Fahlbusch ◽

Gerald Spindler ◽

Konrad Müller ◽

Dominik van Pinxteren ◽

...

Keyword(s):

Black Carbon ◽

Long Range ◽

Biomass Burning ◽

Mass Concentration ◽

Carbonaceous Aerosol ◽

Long Range Transport ◽

Air Masses ◽

Central Germany ◽

Range Transport ◽

Local Emissions

Abstract. The identification of different sources of the carbonaceous aerosol (organics and black carbon) was investigated at a mountain forest site located in central Germany from September to October 2010 to characterize incoming air masses during the Hill Cap Cloud Thuringia 2010 (HCCT-2010) experiment. The near-PM1 chemical composition, as measured by an Aerosol Mass Spectrometer (HR-ToF-AMS), was dominated by organics (OA, 41 %), followed by sulfate (19 %) and nitrate (18 %). Source apportionment of the OA fraction was performed using the Multilinear Engine approach (ME-2), resulting in the identification of five factors: Hydrocarbon-like OA (HOA, 3 % of OA mass), biomass burning OA (BBOA, 13 %), semi-volatile-like OA (SVOOA, 19 %), and two oxygenated OA (OOA) factors. The more-oxidized OOA (MO-OOA, 28 %) was interpreted as being influenced by aged polluted continental air masses, whereas the less-oxidized OOA (LO-OOA, 37 %) was found to be more linked to aged biogenic sources. Equivalent black carbon (eBC) measured by a multi-angle absorption photometer, MAAP, represented 10 % of the total PM. The eBC was clearly associated with the three factors HOA, BBOA, and MO-OOA (all together R2 = 0.83). Therefore, eBC's contribution to each factor was achieved using a multi-linear regression model. More than half of the eBC (52 %) was associated with long-range transport (i.e. MO-OOA), whereas liquid fuel eBC (35 %) and biomass burning eBC (13 %) were associated with local emissions leading to a complete apportionment of the carbonaceous aerosol. The separation between local and transported eBC was well supported by the mass size distribution of elemental carbon (EC) from Berner-impactor samples. Air masses with the strongest marine influence based on back trajectory analysis corresponded with a low particle mass concentration (6.4–7.5 µg m−3) and organic fraction (&approx; 30 %). However, they also had the largest contribution of primary OA (HOA &approx; 4 % and BBOA 15–20 %), which was associated with local emissions. Continental air masses had the highest mass concentration (11.4–12.6 µg m−3) and a larger fraction of oxygenated OA (&approx; 45 %) indicated highly processed OA. The present results emphasize the key role played by long-range transport processes not only on the OA fraction but also on the eBC mass concentration and the importance of improving our knowledge on the identification of eBC sources.

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