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Titel |
Isotopic identification of nitrogen hotspots across natural terrestrial ecosystems |
VerfasserIn |
E. Bai, B. Z. Houlton, Y. P. Wang |
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 (2012-08-23), S.3287-3304 |
Datensatznummer |
250007248
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Publikation (Nr.) |
copernicus.org/bg-9-3287-2012.pdf |
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Zusammenfassung |
Nitrogen (N) influences local biological processes, ecosystem productivity,
the composition of the atmospheric-climate system, and the human endeavour
as a whole. Here we use natural variations in N isotopes, coupled with two
models, to trace global pathways of N loss from the land to the water and
atmosphere. We show that denitrification accounts for approximately 35 %
of total N losses from the natural soil, with NO, N2O, and N2
fluxes equal to 15.7 ± 4.7 Tg N yr−1, 10.2 ± 3.0 Tg N yr−1,
and 21.0 ± 6.1 Tg N yr−1, respectively. Our analysis
points to tropical regions as the major "hotspot" of nitrogen export from
the terrestrial biosphere, accounting for 71 % of global N losses from
the natural land surface. The poorly studied Congo Basin is further
identified as one of the major natural sources of atmospheric N2O.
Extra-tropical areas, by contrast, lose a greater fraction of N via leaching
pathways (~77 % of total N losses) than do tropical biomes, likely
contributing to N limitations of CO2 uptake at higher latitudes. Our
results provide an independent constraint on global models of the N cycle
among different regions of the unfertilized biosphere. |
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