2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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6/06/2017 | 12:15 PM - 12:30 PM | THE STREAM FEASTS WHILE THE FOREST LEAKS: IN-STREAM AND WATERSHED RESPONSES TO A WHOLE WATERSHED ACID MITIGATION EXPERIMENT | 306A

THE STREAM FEASTS WHILE THE FOREST LEAKS: IN-STREAM AND WATERSHED RESPONSES TO A WHOLE WATERSHED ACID MITIGATION EXPERIMENT

Many headwater streams across the Northeast U.S. bear strong legacies of acid precipitation, despite long term declines in deposition. At Hubbard Brook, an experimental attempt to remediate decades of soil acidification successfully promoted forest growth and increased soil pH, but also generated dramatic increases in watershed nitrogen export. This experiment may provide an accelerated view into possible long-term trajectories of ecosystem recovery from acid precipitation. Here, we examine how the watershed acid remediation treatment has altered in-stream processing of nitrogen. We found that the treatment stream acted as a substantial net sink of nitrate during the growing season. During baseflow periods, nitrate flux declined by 15-55% along a 500m reach, despite a 2.4-fold increase in discharge over the same reach. By contrast, nitrate flux in the reference watershed increased monotonically with discharge. High nitrate export from the treatment watershed became more coupled to storm events, and denitrification potential increased threefold in treatment sediments. These results suggest that under ecosystem recovery from acid precipitation, aquatic ecosystems may act as substantial sinks of N, even as terrestrial ecosystems may become greater sources.

C22 Disturbance
C28 Land-Water Interfaces
C10 Biogeochemistry

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Presenters/Authors

Richard Marinos (), University of Waterloo, rmarinos@uwaterloo.ca;