Recent Increases in Water Column Denitrification in the Seasonally Suboxic Bottom Waters of the Santa Barbara Basin
Journal
Geophysical Research Letters
Journal Volume
46
Journal Issue
12
Start Page
6786
End Page
6795
ISSN
0094-8276
1944-8007
Date Issued
2019-06-28
Author(s)
Abstract
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.
Subjects
California
California Current
Pacific Ocean
Santa Barbara Basin
Anoxic sediments
Ionization of gases
Nitrates
Nitrogen
Redox reactions
Benthic communities
Long-term trend
Nitrogen cycling
Nitrogen species
Overlying water
Oxygen concentrations
Stable isotopes
anoxic conditions
benthos
bottom water
concentration (composition)
denitrification
nitrogen cycle
suboxic conditions
water column
Denitrification
SDGs
Publisher
American Geophysical Union (AGU)
Type
journal article