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| Titel |
Atmospheric deposition as a source of carbon and nutrients to an alpine catchment of the Colorado Rocky Mountains |
| VerfasserIn |
N. Mladenov, M. W. Williams, S. K. Schmidt, K. Cawley |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 8 ; Nr. 9, no. 8 (2012-08-24), S.3337-3355 |
| Datensatznummer |
250007251
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| Publikation (Nr.) |
 copernicus.org/bg-9-3337-2012.pdf |
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| Zusammenfassung |
| Many alpine areas are experiencing deglaciation, biogeochemical changes
driven by temperature rise, and changes in atmospheric deposition. There is
mounting evidence that the water quality of alpine streams may be related to
these changes, including rising atmospheric deposition of carbon (C) and
nutrients. Given that barren alpine soils can be severely C limited,
atmospheric deposition sources may be an important source of C and nutrients
for these environments. We evaluated the magnitude of atmospheric deposition
of C and nutrients to an alpine site, the Green Lake 4 catchment in the
Colorado Rocky Mountains. Using a long-term dataset (2002–2010) of weekly
atmospheric wet deposition and snowpack chemistry, we found that volume
weighted mean dissolved organic carbon (DOC) concentrations were
1.12 ± 0.19 mg l−1, and weekly concentrations reached peaks as
high at 6–10 mg l−1 every summer. Total dissolved nitrogen
concentration also peaked in the summer, whereas total dissolved phosphorus
and calcium concentrations were highest in the spring. To investigate
potential sources of C in atmospheric deposition, we evaluated the chemical
quality of dissolved organic matter (DOM) and relationships between DOM and
other solutes in wet deposition. Relationships between DOC concentration,
fluorescence, and nitrate and sulfate concentrations suggest that pollutants
from nearby urban and agricultural sources and organic aerosols derived from
sub-alpine vegetation may influence high summer DOC wet deposition
concentrations. Interestingly, high DOC concentrations were also recorded
during "dust-in-snow" events in the spring, which may reflect an
association of DOM with dust. Detailed chemical and spectroscopic analyses
conducted for samples collected in 2010 revealed that the DOM in many late
spring and summer samples was less aromatic and polydisperse and of lower
molecular weight than that of winter and fall samples. Our C budget estimates
for the Green Lake 4 catchment illustrated that wet deposition
(9.9 kg C ha−1 yr−1) and dry deposition
(6.9 kg C ha−1 yr−1) were a combined input of approximately
17 kg C ha−1 yr−1, which could be as high as
24 kg C ha−1 yr−1 in high dust years. This atmospheric C input
approached the C input from microbial autotrophic production in barren soils.
Atmospheric wet and dry deposition also contributed
4.3 kg N ha−1 yr−1, 0.15 kg P ha−1 yr−1, and
2.7 kg Ca2+ ha−1 yr−1 to this alpine catchment. |
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