Long-Term Changes in Watershed Retention of Nitrogen: Its Causes and AquaticConsequences

摘要

The paper has two primary purposes: first, to establish how watersheds andsurface waters are likely to change as the impacts of nitrogen (N) deposition become more severe; and second, to present the accumulated evidence, primarily from the eastern United States, that otherwise undisturbed watersheds are currently showing impacts from elevated N deposition, and that the severity of these impacts corresponds to the historical levels of N deposition that the various sites have experienced. The focus on watersheds that are undisturbed, other than by elevated rates of deposition, is important, as other disturbances (especially tree harvesting) can have significant and long-lived effects on N cycling; eliminating other potential sources of disruption to the N cycle allows us to narrow the field of stresses that might be contributing to the effects the authors observe.