TY - JOUR
T1 - All about nitrite
T2 - exploring nitrite sources and sinks in the eastern tropical North Pacific oxygen minimum zone
AU - Tracey, John C.
AU - Babbin, Andrew R.
AU - Wallace, Elizabeth
AU - Sun, Xin
AU - Durussel, Katherine L.
AU - Frey, Claudia
AU - Martocello, Donald E.
AU - Tamasi, Tyler
AU - Oleynik, Sergey
AU - Ward, Bess B.
N1 - Funding Information:
We would like to acknowledge the crew and scientists of the R/V Sally Ride and the R/V Falkor for logistical and scientific support during our 2018 cruises. We thank Amal Jayakumar for providing amoA and nirS gene abundances for the RDA and PCA analyses. We thank Emilio Robledo-Garcia for assistance using the LUMOS instrument for the oxidation gradient experiments. We thank Matthias Spieler for supporting reduction rate measurements in Basel. We thank Patrick Boduch for his aid in reviewing graphics before submission. We also acknowledge the Schmidt Ocean Institute for providing R/V Falkor ship time to Andrew R. Babbin. We thank the Simons Foundation and National Science Foundation for supporting Andrew R. Babbin, Tyler Tamasi, and Donald E. Martocello III, via the Simons Foundation grant no. 622065 and NSF grant nos. OCE-2138890 and OCE-2142998, as well as Bess B. Ward, Claudia Frey, John C. Tracey, and Xin Sun, via NSF grant no. OCE-1657663.
Funding Information:
This research has been supported by the Schmidt Ocean Institute (grant no. Solving Microbial Mysteries with Autonomous Technology), the Simons Foundation (grant no. 622065), and the NSF Directorate for Geosciences (grant nos. OCE-2138890, OCE-2142998, and OCE-1657663).
Publisher Copyright:
© 2023 Copernicus GmbH. All rights reserved.
PY - 2023/6/30
Y1 - 2023/6/30
N2 - Oxygen minimum zones (OMZs), due to their large volumes of perennially deoxygenated waters, are critical regions for understanding how the interplay between anaerobic and aerobic nitrogen (N) cycling microbial pathways affects the marine N budget. Here, we present a suite of measurements of the most significant OMZ N cycling rates, which all involve nitrite (NO2-) as a product, reactant, or intermediate, in the eastern tropical North Pacific (ETNP) OMZ. These measurements and comparisons to data from previously published OMZ cruises present additional evidence that NO3- reduction is the predominant OMZ N flux, followed by NO2- oxidation back to NO3-. The combined rates of both of these N recycling processes were observed to be much greater (up to nearly 200 times) than the combined rates of the N loss processes of anammox and denitrification, especially in waters near the anoxic-oxic interface. We also show that NO2- oxidation can occur when O2 is maintained near 1 nM by a continuous-purge system, NO2- oxidation and O2 measurements that further strengthen the case for truly anaerobic NO2- oxidation. We also evaluate the possibility that NO2- dismutation provides the oxidative power for anaerobic NO2- oxidation. The partitioning of N loss between anammox and denitrification differed widely from stoichiometric predictions of at most 29 % anammox; in fact, N loss rates at many depths were entirely due to anammox. Our new NO3- reduction, NO2- oxidation, dismutation, and N loss data shed light on many open questions in OMZ N cycling research, especially the possibility of truly anaerobic NO2- oxidation.
AB - Oxygen minimum zones (OMZs), due to their large volumes of perennially deoxygenated waters, are critical regions for understanding how the interplay between anaerobic and aerobic nitrogen (N) cycling microbial pathways affects the marine N budget. Here, we present a suite of measurements of the most significant OMZ N cycling rates, which all involve nitrite (NO2-) as a product, reactant, or intermediate, in the eastern tropical North Pacific (ETNP) OMZ. These measurements and comparisons to data from previously published OMZ cruises present additional evidence that NO3- reduction is the predominant OMZ N flux, followed by NO2- oxidation back to NO3-. The combined rates of both of these N recycling processes were observed to be much greater (up to nearly 200 times) than the combined rates of the N loss processes of anammox and denitrification, especially in waters near the anoxic-oxic interface. We also show that NO2- oxidation can occur when O2 is maintained near 1 nM by a continuous-purge system, NO2- oxidation and O2 measurements that further strengthen the case for truly anaerobic NO2- oxidation. We also evaluate the possibility that NO2- dismutation provides the oxidative power for anaerobic NO2- oxidation. The partitioning of N loss between anammox and denitrification differed widely from stoichiometric predictions of at most 29 % anammox; in fact, N loss rates at many depths were entirely due to anammox. Our new NO3- reduction, NO2- oxidation, dismutation, and N loss data shed light on many open questions in OMZ N cycling research, especially the possibility of truly anaerobic NO2- oxidation.
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UR - http://www.scopus.com/inward/citedby.url?scp=85163934761&partnerID=8YFLogxK
U2 - 10.5194/bg-20-2499-2023
DO - 10.5194/bg-20-2499-2023
M3 - Article
AN - SCOPUS:85163934761
SN - 1726-4170
VL - 20
SP - 2499
EP - 2523
JO - Biogeosciences
JF - Biogeosciences
IS - 12
ER -