Hot Spots of Nitrogen Cycling: A Regional Perspective
Abstract
Globally, the cycling of nitrogen is changing more rapidly than that of any other element cycle. The environmental consequences are diverse and large: human acceleration of the nitrogen cycle is arguably the most important aspect of global change to date. This acceleration has not been uniform over the surface of the earth, and the nitrogen cycle has been far more altered in some regions than in others. On average, human activity has at least doubled the availability of nitrogen on land and may also have altered rates of nitrogen fixation in the oceans. We present N budgets for watersheds in the eastern United States, Western Europe, and Eastern Asia, regions that are heavily impacted by human populations. We quantified anthropogenic inputs of N to each watershed from four sources: atmospheric deposition, application of nitrogenous fertilizers, biological nitrogen fixation, and net import or export of N in agricultural products (food and feedstocks). These inputs are compared to export of N from the watersheds in streamflow. Despite significant differences between these regions of the world, patterns relating human controlled N inputs to watershed exports are similar. Climate and runoff have important influences on this relationship. The greatest N inputs were observed in regions of Asia, which receive the highest deposition rates globally and have intensive and extensive agricultural practices. East Asia continues to see very rapid increases in population, agriculture, and industrial activity, and thus will continue to play a major role in the global nitrogen budget.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM...H51C10H
- Keywords:
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- 1803 Anthropogenic effects;
- 1860 Runoff and streamflow;
- 4845 Nutrients and nutrient cycling