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| Titel |
Atmospheric wet and dry deposition of trace elements at 10 sites in Northern China |
| VerfasserIn |
Y. P. Pan, Y. S. Wang |
| 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. 2 ; Nr. 15, no. 2 (2015-01-28), S.951-972 |
| Datensatznummer |
250119349
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| Publikation (Nr.) |
 copernicus.org/acp-15-951-2015.pdf |
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| Zusammenfassung |
Atmospheric deposition is considered to be a major process that removes
pollutants from the atmosphere and an important source of nutrients and
contaminants for ecosystems. Trace elements (TEs), especially toxic metals
deposited on plants and into soil or water, can cause substantial damage to
the environment and human health due to their transfer and accumulation in
food chains. Despite public concerns, quantitative knowledge of metal
deposition from the atmosphere to ecosystems remains scarce. To advance our
understanding of the spatiotemporal variations in the magnitudes, pathways,
compositions and impacts of atmospherically deposited TEs, precipitation
(rain and snow) and dry-deposited particles were collected simultaneously at
10 sites in Northern China from December 2007 to November 2010.
The measurements showed that the wet and dry depositions of TEs in the
target areas were orders of magnitude higher than previous observations
within and outside China, generating great concern over the potential risks.
The spatial distribution of the total (wet plus dry) deposition flux was
consistent with that of the dry deposition, with a significant decrease from
industrial and urban areas to suburban, agricultural and rural sites, while
the wet deposition exhibited less spatial variation. In addition, the
seasonal variation of wet deposition was also different from that of dry
deposition, although they were both governed by the precipitation and
emission patterns.
For the majority of TEs that exist as coarse particles, dry deposition
dominated the total flux at each site. This was not the case for potassium,
nickel, arsenic, lead, zinc, cadmium, selenium, silver and thallium, for
which the relative importance between wet and dry deposition fluxes varied
by site. Whether wet deposition is the major atmospheric cleansing mechanism
for the TEs depends on the size distribution of the particles.
We found that atmospheric inputs of copper, lead, zinc, cadmium, arsenic and
selenium were of the same magnitude as their increases in the topsoil of
agricultural systems. At a background forest site in Northern China, the
total deposition flux of lead observed in this study (14.1 mg m−2 yr−1) was twice that of the critical load calculated for temperate
forest ecosystems in Europe. These findings provide baseline data needed for
future targeting policies to protect various ecosystems from long-term heavy
metal input via atmospheric deposition. |
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