Ammonium, a key intermediate nutrient, is typically low to undetectable on the Oregon coast, particularly as active upwelling delivers high onshore flow of ammonium‐poor waters. However, during bloom and post‐bloom conditions large ammonium concentrations and uptake rates have been described. High‐frequency
Denitrification in the anoxic sediments of the Santa Barbara Basin has been well documented in the historic and modern record, but the regulation of and frequency with which denitrification occurs in the overlying water column are less understood. Since 2004, the magnitude and speciation of redox active nitrogen species in bottom waters have changed markedly. Most notable are periods of decreased nitrate and increased nitrite concentrations. Here we examine these changes in nitrogen cycling as recorded by the stable isotopes of dissolved nitrate from 2010–2016. When compared to previous studies, our data identify an increase in water column denitrification in the bottom waters of the basin. Observations from inside the basin as well as data from the wider California Current Ecosystem implicate a long‐term trend of decreasing oxygen concentrations as the driver for these observed changes, with ramifications for local benthic communities and regional nitrogen loss.
more » « less- Award ID(s):
- 1637632
- NSF-PAR ID:
- 10453927
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 46
- Issue:
- 12
- ISSN:
- 0094-8276
- Page Range / eLocation ID:
- p. 6786-6795
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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