Premium
Vertical partitioning of nitrogen‐loss processes across the oxic‐anoxic interface of an oceanic oxygen minimum zone
Author(s) -
De Brabandere Loreto,
Canfield Don E.,
Dalsgaard Tage,
Friederich Gernot E.,
Revsbech Niels Peter,
Ulloa Osvaldo,
Thamdrup Bo
Publication year - 2014
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12255
Subject(s) - anammox , anoxic waters , denitrification , oxygen minimum zone , nitrate , environmental chemistry , nitrite , water column , biology , salinity , denitrifying bacteria , nitrogen , oceanography , ecology , chemistry , geology , organic chemistry , upwelling
Summary We investigated anammox, denitrification and dissimilatory reduction of nitrite to ammonium ( DNRA ) activity in the E astern T ropical S outh P acific oxygen minimum zone ( OMZ ) off northern C hile, at high‐depth resolution through the oxycline into the anoxic OMZ core. This was accompanied by high‐resolution nutrient and oxygen profiles to link changes in nitrogen transformation rates to physicochemical characteristics of the water column. Denitrification was detected at most depths, but anammox was the most active N 2 ‐producing process, while DNRA was not detectable. Anammox and denitrification were mainly active in the anoxic OMZ core while activity was low to not detectable in the oxycline, except in association with an intrusion of OMZ core water. This indicates that continuous exposure to even submicromolar oxygen levels inhibits the processes either directly or through nitrite limitation. Anammox activity did not peak at the oxic‐anoxic boundary but 20–50 m below matching the salinity maximum of the E quatorial S ubsurface W ater. This suggests that water history plays a major role for anammox activity possibly due to slow growth of anammox bacteria. Denitrification peaked deeper than anammox, likely reflecting a shift in the balance between this process and nitrate reduction to nitrite, governed by the relative availability of nitrate and nitrite.