Document Type

Article

Publication Date

2021

DOI

10.1029/2020JG005826

Publication Title

Journal of Geophysical Research: Biogeosciences

Volume

126

Issue

5

Pages

1-18

Abstract

Excessive nutrient inputs from land, particularly nitrogen (N), have been found to increase the occurrence of hypoxia and harmful algal blooms in coastal ecosystems. To identify the main contributors of increased N loading and evaluate the efficacy of water pollution control policies, it is essential to quantify and attribute the long‐term changes in riverine N export. Here, we use a state‐of‐the‐art terrestrial–aquatic interface model to examine how multiple environmental factors may have affected N export from the Chesapeake Bay watershed since 1900. These factors include changes in climate, carbon dioxide, land use, and N inputs (i.e., atmospheric N deposition, animal manure, synthetic N fertilizer use, and wastewater discharge). Our results estimated that ammonium (NH4+) and nitrate (NO3) export increased substantially (66% for NH4+ and 123% for NO3) from the 1900s to the 1990s and then declined (32% for NH4+ and 14% for NO3) since 2000. The temporal trend of dissolved organic nitrogen (DON) export paralleled that of dissolved inorganic N, while particulate organic nitrogen export was relatively constant during 1900–2015. Precipitation was the primary driver of interannual variability in N export to the Bay. Wastewater discharge explained most of the long‐term change in riverine NH4+ and DON fluxes from 1900 to 2015. The changes in atmospheric deposition, wastewater, and synthetic fertilizer were responsible for the trend of riverine NO3. In light of our model‐based attribution analysis, terrestrial non‐point source nutrient management will play an important role in achieving water quality goals.

Comments

An edited version of this paper was published by AGU. © 2021 American Geophysical Union.

"AGU allows authors to deposit their journal articles if the version is the final published citable version of record, the AGU copyright statement is clearly visible on the posting, and the posting is made 6 months after official publication by the AGU."

To view the publisher's open abstract, go to https://doi.org/10.1029/2020JG005826

Original Publication Citation

Pan, S., Bian, Z., Tian, H., Yao, Y., Najjar, R. G., Friedrichs, M. A. M., . . . Zhang, B. (2021). Impacts of multiple environmental changes on long‐term nitrogen loading from the Chesapeake Bay watershed. Journal of Geophysical Research: Biogeosciences, 126(5), Article e2020JG005826, 1-18. https://doi.org/10.1029/2020JG005826.

ORCID

0000-0001-6710-4371 (Hofmann)

Available for download on Saturday, October 16, 2021

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