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Riverine nitrogen export from the continents to the coasts

Riverine nitrogen export from the continents to the coasts We present an overview of riverine nitrogen flux calculations that were prepared for the International Nitrogen Initiative's current global assessment of nitrogen cycles: past, present, and future (Galloway et al., 2004). We quantified anthropogenic and natural inputs of reactive nitrogen (N) to terrestrial landscapes and the associated riverine N fluxes. Anthropogenic inputs include fossil‐fuel derived atmospheric deposition, fixation in cultivated croplands, fertilizer use, and the net import in human food and animal feedstuffs. Natural inputs include natural biological N fixation in forests and other noncultivated vegetated lands, and fixation by lightning. We use an empirical model relating total N inputs per landscape area to the total flux of N discharged in rivers based on watershed data from contrasting ecosystems spanning multiple spatial scales. With this approach, we simulate riverine N loads to the coastal zone and to inland waters from the continents. Globally, rivers exported about 59 Tg N yr−1, with 11 Tg N yr−1 transported to dry lands and inland receiving waters, and 48 Tg N yr−1 transported to the coastal zone. Rates of riverine N loss vary greatly among the continents, reflecting the regional differences in population and the associated anthropogenic N inputs. We compare our estimates to other approaches that have been reported in the literature. Our work provides an understanding of the sources of N to landscapes and the associated N fluxes in rivers, and highlights how anthropogenic activities impact N cycling around the world. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Global Biogeochemical Cycles Wiley

Riverine nitrogen export from the continents to the coasts

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References (50)

Publisher
Wiley
Copyright
Copyright © 2006 by the American Geophysical Union.
ISSN
0886-6236
eISSN
1944-9224
DOI
10.1029/2005GB002537
Publisher site
See Article on Publisher Site

Abstract

We present an overview of riverine nitrogen flux calculations that were prepared for the International Nitrogen Initiative's current global assessment of nitrogen cycles: past, present, and future (Galloway et al., 2004). We quantified anthropogenic and natural inputs of reactive nitrogen (N) to terrestrial landscapes and the associated riverine N fluxes. Anthropogenic inputs include fossil‐fuel derived atmospheric deposition, fixation in cultivated croplands, fertilizer use, and the net import in human food and animal feedstuffs. Natural inputs include natural biological N fixation in forests and other noncultivated vegetated lands, and fixation by lightning. We use an empirical model relating total N inputs per landscape area to the total flux of N discharged in rivers based on watershed data from contrasting ecosystems spanning multiple spatial scales. With this approach, we simulate riverine N loads to the coastal zone and to inland waters from the continents. Globally, rivers exported about 59 Tg N yr−1, with 11 Tg N yr−1 transported to dry lands and inland receiving waters, and 48 Tg N yr−1 transported to the coastal zone. Rates of riverine N loss vary greatly among the continents, reflecting the regional differences in population and the associated anthropogenic N inputs. We compare our estimates to other approaches that have been reported in the literature. Our work provides an understanding of the sources of N to landscapes and the associated N fluxes in rivers, and highlights how anthropogenic activities impact N cycling around the world.

Journal

Global Biogeochemical Cycles – Wiley

Published: Mar 1, 2006

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