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| Titel |
Trends and drivers of ozone human health and vegetation impact metrics from UK EMEP supersite measurements (1990–2013) |
| VerfasserIn |
C. S. Malley, M. R. Heal, G. Mills, C. F. Braban |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 8 ; Nr. 15, no. 8 (2015-04-16), S.4025-4042 |
| Datensatznummer |
250119649
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| Publikation (Nr.) |
 copernicus.org/acp-15-4025-2015.pdf |
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| Zusammenfassung |
Analyses have been undertaken of the spatial and temporal trends and drivers
of the distributions of ground-level O3 concentrations associated with
potential impacts on human health and vegetation using measurements at the
two UK European Monitoring and Evaluation Program (EMEP) supersites of Harwell and Auchencorth. These two sites provide
representation of rural O3 over the wider geographic areas of
south-east England and northern UK respectively. The O3 exposures
associated with health and vegetation impacts were quantified respectively
by the SOMO10 and SOMO35 metrics and by the flux-based PODY metrics
for wheat, potato, beech and Scots pine. Statistical analyses of measured
O3 and NOx concentrations were supplemented by analyses of
meteorological data and NOx emissions along air-mass back trajectories.
The findings highlight the differing responses of impact metrics to the
decreasing contribution of regional O3 episodes in determining O3
concentrations at Harwell between 1990 and 2013, associated with European
NOx emission reductions. An improvement in human health-relevant
O3 exposure observed when calculated by SOMO35, which decreased
significantly, was not observed when quantified by SOMO10. The decrease in
SOMO35 is driven by decreases in regionally produced O3 which makes a
larger contribution to SOMO35 than to SOMO10. For the O3 vegetation
impacts at Harwell, no significant trend was observed for the PODY
metrics of the four species, in contrast to the decreasing trend in
vegetation-relevant O3 exposure perceived when calculated using the
crop AOT40 metric. The decreases in regional O3 production have not
decreased PODY as climatic and plant conditions reduced stomatal
conductance and uptake of O3 during regional O3 production.
Ozone concentrations at Auchencorth (2007–2013) were more influenced by
hemispheric background concentrations than at Harwell. For health-related
O3 exposures this resulted in lower SOMO35 but similar SOMO10 compared
with Harwell; for vegetation PODY values, this resulted in greater
impacts at Auchencorth for vegetation types with lower exceedance ("Y")
thresholds and longer growing seasons (i.e. beech and Scots pine).
Additionally, during periods influenced by regional O3 production, a
greater prevalence of plant conditions which enhance O3 uptake (such as
higher soil water potential) at Auchencorth compared to Harwell resulted in
exacerbation of vegetation impacts at Auchencorth, despite being further
from O3 precursor emission sources.
These analyses indicate that quantifications of future improvement in
health-relevant O3 exposure achievable from pan-European O3
mitigation strategies are highly dependent on the choice of O3
concentration cut-off threshold, and reduction in potential health impact
associated with more modest O3 concentrations requires reductions in
O3 precursors on a larger (hemispheric) spatial scale. Additionally,
while further reduction in regional O3 is more likely to decrease
O3 vegetation impacts within the spatial domain of Auchencorth compared
to Harwell, larger reductions in vegetation impact could be
achieved across the UK from reduction of hemispheric background O3
concentrations. |
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