Quantifying primary and secondary humic-like substances in urban aerosol based on emission source characterization and a source-oriented air quality model
<p>Humic-like substances (HULIS) are a mixture of high-molecular-weight, water-soluble organic compounds that are widely distributed in atmospheric aerosol. Their sources are rarely studied quantitatively. Biomass burning is generally accepted as a major primary source of ambient humic-like su...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/2327/2019/acp-19-2327-2019.pdf |
| Summary: | <p>Humic-like substances (HULIS) are a mixture of high-molecular-weight,
water-soluble organic compounds that are widely distributed in atmospheric
aerosol. Their sources are rarely studied quantitatively. Biomass burning is
generally accepted as a major primary source of ambient humic-like substances
(HULIS) with additional secondary material formed in the atmosphere. However,
the present study provides direct evidence that residential coal burning is
also a significant source of ambient HULIS, especially in the heating season
in northern China based on source measurements, ambient sampling and
analysis, and apportionment with source-oriented CMAQ modeling. Emission
tests show that residential coal combustion produces 5 % to 24 % of the
emitted organic carbon (OC) as HULIS carbon (HULISc). Estimation of primary
emissions of HULIS in Beijing indicated that residential biofuel and coal
burning contribute about 70 % and 25 % of annual primary HULIS,
respectively. Vehicle exhaust, industry, and power plant contributions are
negligible. The average concentration of ambient HULIS in PM<span class="inline-formula"><sub>2.5</sub></span> was
7.5 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span>
in urban Beijing and HULIS exhibited obvious seasonal variations
with the highest concentrations in winter. HULISc accounts for 7.2 % of
PM<span class="inline-formula"><sub>2.5</sub></span> mass, 24.5 % of OC, and 59.5 % of water-soluble organic carbon. HULIS
are found to correlate well with <span class="inline-formula">K<sup>+</sup></span>, <span class="inline-formula">Cl<sup>−</sup></span>, sulfate, and
secondary organic aerosol, suggesting its sources include biomass burning,
coal combustion, and secondary aerosol formation. Source apportionment based
on CMAQ modeling shows residential biofuel and coal burning and secondary
formation are important sources of ambient HULIS, contributing 47.1 %,
15.1 %, and 38.9 %, respectively.</p> |
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| ISSN: | 1680-7316 1680-7324 |