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| Titel |
Evaluating the effects of China's pollution controls on inter-annual trends and uncertainties of atmospheric mercury emissions |
| VerfasserIn |
Y. Zhao, H. Zhong, J. Zhang, C. P. Nielsen |
| 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 (2015-04-29), S.4317-4337 |
| Datensatznummer |
250119667
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| Publikation (Nr.) |
 copernicus.org/acp-15-4317-2015.pdf |
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| Zusammenfassung |
| China's anthropogenic emissions of atmospheric mercury (Hg) are effectively
constrained by national air pollution control and energy efficiency policies.
In this study, improved methods, based on available data from domestic field
measurements, are developed to quantify the benefits of Hg abatement by
various emission control measures. Those measures include increased use of
(1) flue gas desulfurization (FGD) and selective catalyst reduction (SCR)
systems in power generation; (2) precalciner kilns with fabric filters (FF)
in cement production; (3) mechanized coking ovens with electrostatic
precipitators (ESP) in iron and steel production; and (4) advanced production
technologies in nonferrous metal smelting. Investigation reveals declining
trends in emission factors for each of these sources, which together drive a
much slower growth of total Hg emissions than the growth of China's energy
consumption and economy, from 679 metric tons (t) in 2005 to 750 t in 2012.
In particular, estimated emissions from the above-mentioned four source types
declined 3% from 2005 to 2012, which can be attributed to expanded
deployment of technologies with higher energy efficiencies and air pollutant
removal rates. Emissions from other anthropogenic sources are estimated to
increase by 22% during the period. The species shares of total Hg
emissions have been stable in recent years, with mass fractions of around 55,
39, and 6% for gaseous elemental Hg (Hg0), reactive gaseous mercury
(Hg2+), and particle-bound mercury (Hgp), respectively. The
higher estimate of total Hg emissions than previous inventories is supported
by limited simulation of atmospheric chemistry and transport. With improved
implementation of emission controls and energy saving, a 23% reduction
in annual Hg emissions from 2012 to 2030, to below 600 t, is expected at the
most. While growth in Hg emissions has been gradually constrained,
uncertainties quantified by Monte Carlo simulation for recent years have
increased, particularly for the power sector and particular industrial
sources. The uncertainty (expressed as 95% confidence intervals) of Hg
emissions from coal-fired power plants, for example, increased from
−48–+73% in 2005 to −50–+89% in 2012. This is attributed
mainly to increased penetration of advanced manufacturing and pollutant
control technologies; the unclear operational status and relatively small
sample sizes of field measurements of those processes have resulted in lower
but highly varied emission factors. To reduce uncertainty and further confirm
the benefits of pollution control and energy polices, therefore, systematic
investigation of specific Hg pollution sources is recommended. The
variability of temporal trends and spatial distributions of Hg emissions
needs to be better tracked during the ongoing dramatic changes in China's
economy, energy use, and air pollution status. |
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