Details

Autor(en) / Beteiligte

• Horak, Rachel E. A.
• Ruef, Wendi
• Ward, Bess B.
• Devol, Allan H.

Titel

Expansion of denitrification and anoxia in the eastern tropical North Pacific from 1972 to 2012

Ist Teil von

• Geophysical research letters, 2016-05, Vol.43 (10), p.5252-5260

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• 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. Key Points Cumulative nitrogen loss in eastern tropical North Pacific was highest in 2012 Low‐O2 conditions in the ETNP have gradually expanded into shallower isopycnals, and anoxic water has expanded vertically Increased denitrification and anoxia may be explained by increased wind‐driven upwelling