Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012
Abstract The eastern tropical North Pacific (ETNP) is a large region of anoxic water that hosts widespread water column N loss (denitrification). There is some disagreement about the long‐term trends of denitrification and anoxia and long‐term studies of water column denitrification within the anoxi...
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| Format: | Article |
| Language: | English |
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Wiley
2016-05-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1002/2016GL068871 |
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| author | Rachel E. A. Horak Wendi Ruef Bess B. Ward Allan H. Devol |
| author_facet | Rachel E. A. Horak Wendi Ruef Bess B. Ward Allan H. Devol |
| author_sort | Rachel E. A. Horak |
| collection | DOAJ |
| description | Abstract The eastern tropical North Pacific (ETNP) is a large region of anoxic water that hosts widespread water column N loss (denitrification). There is some disagreement about the long‐term trends of denitrification and anoxia and long‐term studies of water column denitrification within the anoxic zone are lacking. In this study, we compared ETNP water column nitrite, N*, and O2 data along the same transect for four studies ranging from 1972 to 2012. Anoxic water volume increased, and low‐oxygen conditions expanded into shallower isopycnals from 1972 to 2012. A geochemical marker for cumulative N loss indicates that denitrification was highest in 2012 and the upper oxygen‐deficient zone (ODZ) experienced the most change. Oxygen and N loss changes in the world's largest ODZ for 2012 could not be explained by the Pacific Decadal Oscillation, and decreased O2 in supply currents and increased wind‐driven upwelling are likely mechanisms contributing to increased N loss and anoxia. |
| format | Article |
| id | doaj-art-e62f76a205ef4500aaf08e507683cfe3 |
| institution | OA Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2016-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-e62f76a205ef4500aaf08e507683cfe32025-08-20T01:51:46ZengWileyGeophysical Research Letters0094-82761944-80072016-05-0143105252526010.1002/2016GL068871Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012Rachel E. A. Horak0Wendi Ruef1Bess B. Ward2Allan H. Devol3School of Oceanography University of Washington Seattle Washington USASchool of Oceanography University of Washington Seattle Washington USAGeosciences Department Princeton University Princeton New Jersey USASchool of Oceanography University of Washington Seattle Washington USAAbstract The eastern tropical North Pacific (ETNP) is a large region of anoxic water that hosts widespread water column N loss (denitrification). There is some disagreement about the long‐term trends of denitrification and anoxia and long‐term studies of water column denitrification within the anoxic zone are lacking. In this study, we compared ETNP water column nitrite, N*, and O2 data along the same transect for four studies ranging from 1972 to 2012. Anoxic water volume increased, and low‐oxygen conditions expanded into shallower isopycnals from 1972 to 2012. A geochemical marker for cumulative N loss indicates that denitrification was highest in 2012 and the upper oxygen‐deficient zone (ODZ) experienced the most change. Oxygen and N loss changes in the world's largest ODZ for 2012 could not be explained by the Pacific Decadal Oscillation, and decreased O2 in supply currents and increased wind‐driven upwelling are likely mechanisms contributing to increased N loss and anoxia.https://doi.org/10.1002/2016GL068871denitrificationnitrogen cycleanoxiaoxygen‐deficient zonedeoxygenation |
| spellingShingle | Rachel E. A. Horak Wendi Ruef Bess B. Ward Allan H. Devol Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012 Geophysical Research Letters denitrification nitrogen cycle anoxia oxygen‐deficient zone deoxygenation |
| title | Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012 |
| title_full | Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012 |
| title_fullStr | Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012 |
| title_full_unstemmed | Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012 |
| title_short | Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012 |
| title_sort | expansion of denitrification and anoxia in the eastern tropical north pacific from 1972 to 2012 |
| topic | denitrification nitrogen cycle anoxia oxygen‐deficient zone deoxygenation |
| url | https://doi.org/10.1002/2016GL068871 |
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