Non-methane hydrocarbon variability in Athens during wintertime: the role of traffic and heating
<p>Non-methane hydrocarbons (NMHCs) play an important role in atmospheric chemistry, contributing to ozone and secondary organic aerosol formation. They can also serve as tracers for various emission sources such as traffic, solvents, heating and vegetation. The current work presents, for t...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/16139/2018/acp-18-16139-2018.pdf |
| Summary: | <p>Non-methane hydrocarbons (NMHCs) play an important role in
atmospheric chemistry, contributing to ozone and secondary organic aerosol
formation. They can also serve as tracers for various emission sources such as
traffic, solvents, heating and vegetation. The current work presents, for the
first time to our knowledge, time-resolved data of NMHCs, from two to six
carbon atoms, for a period of 5 months (mid-October 2015 to
mid-February 2016) in the <q>greater Athens area</q> (GAA), Greece. The measured NMHC
levels are among the highest reported in the literature for the Mediterranean
area during winter months, and the majority of the compounds demonstrate a
remarkable day-to-day variability. Their levels increase by up to factor of
4 from autumn (October–November) to winter (December–February). Microscale
meteorological conditions, especially wind speed in combination with
the planetary boundary layer (PBL) height, seem to contribute significantly to the variability of NMHC
levels, with an increase of up to a factor of 10 under low wind speed ( < 3 m s<sup>−1</sup>) conditions; this reflects the impact of local sources rather than long-range
transport. All NMHCs demonstrated a pronounced bimodal, diurnal pattern with
a morning peak followed by a second peak before midnight. The amplitude of
both peaks gradually increased towards winter, in comparison to autumn, by
a factor of 3 to 6 and closely followed that of carbon monoxide (CO), which
indicates a contribution from sources other than traffic, e.g.,
domestic heating (fuel or wood burning). By comparing the NMHC diurnal
variability with that of black carbon (BC), its fractions associated with
wood burning (BC<sub>wb</sub>) and fossil fuel combustion
(BC<sub>ff</sub>), and with source profiles we conclude that the morning peak is attributed to
traffic while the night peak is mainly attributed to heating. With respect to the night peak, the
selected tracers and source profiles clearly indicate a contribution from both
traffic and domestic heating (fossil fuel and wood burning). NMHCs slopes
versus BC<sub>wb</sub> are similar when compared with those versus BC<sub>ff</sub>
(slight difference for ethylene), which indicates that NMHCs are most likely equally
produced by wood and oil fossil fuel burning.</p> |
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| ISSN: | 1680-7316 1680-7324 |