Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast
<p>The chemical composition of aerosols is of particular importance to assess their interactions with radiation, clouds and trace gases in the atmosphere and consequently their effects on air quality and the regional climate. In this study, we present the results of the first long-term dataset...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/20/15811/2020/acp-20-15811-2020.pdf |
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| author | D. Klopper P. Formenti A. Namwoonde M. Cazaunau S. Chevaillier A. Feron C. Gaimoz P. Hease F. Lahmidi C. Mirande-Bret S. Triquet Z. Zeng S. J. Piketh |
| author_facet | D. Klopper P. Formenti A. Namwoonde M. Cazaunau S. Chevaillier A. Feron C. Gaimoz P. Hease F. Lahmidi C. Mirande-Bret S. Triquet Z. Zeng S. J. Piketh |
| author_sort | D. Klopper |
| collection | DOAJ |
| description | <p>The chemical composition of aerosols is of particular importance to assess
their interactions with radiation, clouds and trace gases in the atmosphere and consequently their effects on air quality and the regional climate. In
this study, we present the results of the first long-term dataset of the
aerosol chemical composition at an observatory on the coast of Namibia,
facing the south-eastern Atlantic Ocean. Aerosol samples in the mass fraction of particles smaller than 10 <span class="inline-formula">µ</span>m in aerodynamic diameter (PM<span class="inline-formula"><sub>10</sub></span>) were
collected during 26 weeks between 2016 and 2017 at the ground-based Henties
Bay Aerosol Observatory (HBAO; 22<span class="inline-formula"><sup>∘</sup></span>6<span class="inline-formula"><sup>′</sup></span> S, 14<span class="inline-formula"><sup>∘</sup></span>30<span class="inline-formula"><sup>′</sup></span> E; 30 m above mean sea level). The resulting 385 filter samples were analysed by
X-ray fluorescence and ion chromatography for 24 inorganic elements and 15 water-soluble ions.</p>
<p>Statistical analysis by positive matrix factorisation (PMF) identified five major components, <i>sea salt</i> (mass concentration: <span class="inline-formula">74.7±1.9 <i>%</i></span>), <i>mineral dust</i> (<span class="inline-formula">15.7±1.4 <i>%</i></span>,), <i>ammonium</i> <i>neutralised</i> (<span class="inline-formula">6.1±0.7 <i>%</i></span>), <i>fugitive dust</i> (<span class="inline-formula">2.6±0.2 <i>%</i></span>) and <i>industry</i> (<span class="inline-formula">0.9±0.7 <i>%</i></span>). While the contribution of sea salt aerosol was persistent, as the
dominant wind direction was south-westerly and westerly from the open ocean,
the occurrence of mineral dust was episodic and coincided with high wind
speeds from the south-south-east and the north-north-west, along the coastline. Concentrations of heavy metals measured at HBAO were higher than
reported in the literature from measurements over the open ocean. V, Cd, Pb
and Nd were attributed to fugitive dust emitted from bare surfaces or mining
activities. As, Zn, Cu, Ni and Sr were attributed to the combustion of
heavy oils in commercial ship traffic across the Cape of Good Hope sea route, power generation, smelting and other industrial activities in the
greater region. Fluoride concentrations up to 25 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span> were
measured, as in heavily polluted areas in China. This is surprising and a worrisome result that has profound health implications and deserves further
investigation. Although no clear signature for biomass burning could be
determined, the PMF <i>ammonium-neutralised</i> component was described by a mixture of aerosols typically emitted by biomass burning, but also by other biogenic activities.
Episodic contributions with moderate correlations between NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ad57fe4a8dcf7ebabf2d1e48d90b5292"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-15811-2020-ie00001.svg" width="9pt" height="16pt" src="acp-20-15811-2020-ie00001.png"/></svg:svg></span></span>,
nss-SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="9def59c1763723bf85d4c029a1ebd14e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-15811-2020-ie00002.svg" width="13pt" height="17pt" src="acp-20-15811-2020-ie00002.png"/></svg:svg></span></span> (higher than 2 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup>)</span> and nss-K<span class="inline-formula"><sup>+</sup></span> were observed, further indicative of the potential for an episodic source of
biomass burning.</p>
<p>Sea salt accounted for up to 57 % of the measured mass concentrations of
SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="49798bc14746e7788afe38c7f4bc425f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-15811-2020-ie00003.svg" width="13pt" height="17pt" src="acp-20-15811-2020-ie00003.png"/></svg:svg></span></span>, and the non-sea salt fraction was contributed mainly by the <i>ammonium-neutralised</i> component and small contributions from the <i>mineral dust </i>component. The marine biogenic
contribution to the <i>ammonium-neutralised</i> component is attributed to efficient oxidation in the moist marine atmosphere of sulfur-containing gas phase emitted by marine phytoplankton in the fertile waters offshore in the Benguela Upwelling
System.</p>
<p>The data presented in this paper provide the first ever information on the temporal variability of aerosol<span id="page15812"/> concentrations in the Namibian marine
boundary layer. This data also provide context for intensive observations in
the area.</p> |
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| spelling | doaj.art-4ddf20dc6c2e45a0b078a8bd3bc9b92a2022-12-21T18:00:13ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242020-12-0120158111583310.5194/acp-20-15811-2020Chemical composition and source apportionment of atmospheric aerosols on the Namibian coastD. Klopper0P. Formenti1A. Namwoonde2M. Cazaunau3S. Chevaillier4A. Feron5C. Gaimoz6P. Hease7F. Lahmidi8C. Mirande-Bret9S. Triquet10Z. Zeng11S. J. Piketh12Unit for Environmental Science and Management, School of Geo and Spatial Science, North-West University, Potchefstroom, South AfricaLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceSam Nujoma Marine and Coastal Resources Research Centre (SANUMARC), University of Namibia, Henties Bay, NamibiaLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceUnit for Environmental Science and Management, School of Geo and Spatial Science, North-West University, Potchefstroom, South Africa<p>The chemical composition of aerosols is of particular importance to assess their interactions with radiation, clouds and trace gases in the atmosphere and consequently their effects on air quality and the regional climate. In this study, we present the results of the first long-term dataset of the aerosol chemical composition at an observatory on the coast of Namibia, facing the south-eastern Atlantic Ocean. Aerosol samples in the mass fraction of particles smaller than 10 <span class="inline-formula">µ</span>m in aerodynamic diameter (PM<span class="inline-formula"><sub>10</sub></span>) were collected during 26 weeks between 2016 and 2017 at the ground-based Henties Bay Aerosol Observatory (HBAO; 22<span class="inline-formula"><sup>∘</sup></span>6<span class="inline-formula"><sup>′</sup></span> S, 14<span class="inline-formula"><sup>∘</sup></span>30<span class="inline-formula"><sup>′</sup></span> E; 30 m above mean sea level). The resulting 385 filter samples were analysed by X-ray fluorescence and ion chromatography for 24 inorganic elements and 15 water-soluble ions.</p> <p>Statistical analysis by positive matrix factorisation (PMF) identified five major components, <i>sea salt</i> (mass concentration: <span class="inline-formula">74.7±1.9 <i>%</i></span>), <i>mineral dust</i> (<span class="inline-formula">15.7±1.4 <i>%</i></span>,), <i>ammonium</i> <i>neutralised</i> (<span class="inline-formula">6.1±0.7 <i>%</i></span>), <i>fugitive dust</i> (<span class="inline-formula">2.6±0.2 <i>%</i></span>) and <i>industry</i> (<span class="inline-formula">0.9±0.7 <i>%</i></span>). While the contribution of sea salt aerosol was persistent, as the dominant wind direction was south-westerly and westerly from the open ocean, the occurrence of mineral dust was episodic and coincided with high wind speeds from the south-south-east and the north-north-west, along the coastline. Concentrations of heavy metals measured at HBAO were higher than reported in the literature from measurements over the open ocean. V, Cd, Pb and Nd were attributed to fugitive dust emitted from bare surfaces or mining activities. As, Zn, Cu, Ni and Sr were attributed to the combustion of heavy oils in commercial ship traffic across the Cape of Good Hope sea route, power generation, smelting and other industrial activities in the greater region. Fluoride concentrations up to 25 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span> were measured, as in heavily polluted areas in China. This is surprising and a worrisome result that has profound health implications and deserves further investigation. Although no clear signature for biomass burning could be determined, the PMF <i>ammonium-neutralised</i> component was described by a mixture of aerosols typically emitted by biomass burning, but also by other biogenic activities. Episodic contributions with moderate correlations between NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ad57fe4a8dcf7ebabf2d1e48d90b5292"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-15811-2020-ie00001.svg" width="9pt" height="16pt" src="acp-20-15811-2020-ie00001.png"/></svg:svg></span></span>, nss-SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="9def59c1763723bf85d4c029a1ebd14e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-15811-2020-ie00002.svg" width="13pt" height="17pt" src="acp-20-15811-2020-ie00002.png"/></svg:svg></span></span> (higher than 2 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup>)</span> and nss-K<span class="inline-formula"><sup>+</sup></span> were observed, further indicative of the potential for an episodic source of biomass burning.</p> <p>Sea salt accounted for up to 57 % of the measured mass concentrations of SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="49798bc14746e7788afe38c7f4bc425f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-15811-2020-ie00003.svg" width="13pt" height="17pt" src="acp-20-15811-2020-ie00003.png"/></svg:svg></span></span>, and the non-sea salt fraction was contributed mainly by the <i>ammonium-neutralised</i> component and small contributions from the <i>mineral dust </i>component. The marine biogenic contribution to the <i>ammonium-neutralised</i> component is attributed to efficient oxidation in the moist marine atmosphere of sulfur-containing gas phase emitted by marine phytoplankton in the fertile waters offshore in the Benguela Upwelling System.</p> <p>The data presented in this paper provide the first ever information on the temporal variability of aerosol<span id="page15812"/> concentrations in the Namibian marine boundary layer. This data also provide context for intensive observations in the area.</p>https://acp.copernicus.org/articles/20/15811/2020/acp-20-15811-2020.pdf |
| spellingShingle | D. Klopper P. Formenti A. Namwoonde M. Cazaunau S. Chevaillier A. Feron C. Gaimoz P. Hease F. Lahmidi C. Mirande-Bret S. Triquet Z. Zeng S. J. Piketh Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast Atmospheric Chemistry and Physics |
| title | Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast |
| title_full | Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast |
| title_fullStr | Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast |
| title_full_unstemmed | Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast |
| title_short | Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast |
| title_sort | chemical composition and source apportionment of atmospheric aerosols on the namibian coast |
| url | https://acp.copernicus.org/articles/20/15811/2020/acp-20-15811-2020.pdf |
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