TY - JOUR
T1 - Iron and manganese accumulation within the Eastern Tropical North Pacific oxygen deficient zone
AU - Bolster, Kenneth M.
AU - Heller, Maija I.
AU - Mulholland, Margaret R.
AU - Moffett, James W.
N1 - Funding Information:
The authors would like to thank the captains and crews of the R/V Thomas G. Thompson, the NOAA ship Ronald H. Brown, and the R/V Roger Revelle. We would also like to thank the chief scientists, Al Devol, and Gabrielle Rocap. We would additionally like to acknowledge Alejandro Arias, Peter Bernhardt, Alfonso Macías Tapia, Nicole Travis, Rachel Kelly, Shun-Chung Yang, Paulina Pinedo-Gonzalez, and Alexis Floback. Funding was provided by the University of Southern California, and the National Science Foundation [OCE-1459584, 1636332 to JWM and 1356056 to MRM at ODU].
Funding Information:
The authors would like to thank the captains and crews of the R/V Thomas G. Thompson, the NOAA ship Ronald H. Brown, and the R/V Roger Revelle. We would also like to thank the chief scientists, Al Devol, and Gabrielle Rocap. We would additionally like to acknowledge Alejandro Arias, Peter Bernhardt, Alfonso Macías Tapia, Nicole Travis, Rachel Kelly, Shun-Chung Yang, Paulina Pinedo-Gonzalez, and Alexis Floback. Funding was provided by the University of Southern California, and the National Science Foundation [OCE-1459584, 1636332 to JWM and 1356056 to MRM at ODU]. Trace metal data presented in this paper are available through the Biological and Chemical Oceanography Data Management Office (BCO-DMO), under dataset number 828183 (www.doi.org/10.26008/1912/bco-dmo.828183.1). Other data from the 2016 ETNP cruise are at https://www.bco-dmo.org/project/472492. The ETSP PCA was performed using publically available data from Schlitzer et al. (2018), Resing et al. (2015), and Cutter et al. (2018).
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/10/1
Y1 - 2022/10/1
N2 - The Eastern Tropical North Pacific (ETNP) contains the largest oxygen deficient zone (ODZ) in the modern ocean. We determined dissolved concentrations of Fe, Fe(II), and Mn from three cruises in the region. Similar to other reported ODZs, Fe(II) was highest in the depth range associated with the secondary nitrite maximum. The main source of this feature is likely lateral advection of water overlying reducing shelf sediments within a narrow density range centered on the potential density anomaly of 26.5 kg/m3. This density horizon is similar to the Eastern Tropical South Pacific (ETSP) and reflects the intersection of the same density range with a large fraction of the continental shelf bottom waters. We also observed subsurface maxima of dissolved Mn in this density range, in contrast to the ETSP. Deep waters were enriched in Fe within the ETNP, analogous to other eastern boundary upwelling systems as well as the Arabian Sea. We argue that in these systems, reducing conditions on the shelf and overlying water column facilitate a robust shelf to basin shuttle of Fe, moving Fe from the coastal margin to deep plumes. Mn is also transported offshore in the core of the ODZ, and the relationship between Fe(II), Mn, and nitrite is remarkably similar between the ETNP, ETSP, and Arabian Sea. The exception is that Mn supply from the Peruvian shelf is less pronounced than in the other two ODZs, potentially reflecting the absence of large rivers in the Peruvian system.
AB - The Eastern Tropical North Pacific (ETNP) contains the largest oxygen deficient zone (ODZ) in the modern ocean. We determined dissolved concentrations of Fe, Fe(II), and Mn from three cruises in the region. Similar to other reported ODZs, Fe(II) was highest in the depth range associated with the secondary nitrite maximum. The main source of this feature is likely lateral advection of water overlying reducing shelf sediments within a narrow density range centered on the potential density anomaly of 26.5 kg/m3. This density horizon is similar to the Eastern Tropical South Pacific (ETSP) and reflects the intersection of the same density range with a large fraction of the continental shelf bottom waters. We also observed subsurface maxima of dissolved Mn in this density range, in contrast to the ETSP. Deep waters were enriched in Fe within the ETNP, analogous to other eastern boundary upwelling systems as well as the Arabian Sea. We argue that in these systems, reducing conditions on the shelf and overlying water column facilitate a robust shelf to basin shuttle of Fe, moving Fe from the coastal margin to deep plumes. Mn is also transported offshore in the core of the ODZ, and the relationship between Fe(II), Mn, and nitrite is remarkably similar between the ETNP, ETSP, and Arabian Sea. The exception is that Mn supply from the Peruvian shelf is less pronounced than in the other two ODZs, potentially reflecting the absence of large rivers in the Peruvian system.
KW - Iron
KW - Margin
KW - Mexico
KW - Nitrogen
KW - Oxygen
KW - Redox
UR - http://www.scopus.com/inward/record.url?scp=85136498691&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2022.07.013
DO - 10.1016/j.gca.2022.07.013
M3 - Article
AN - SCOPUS:85136498691
VL - 334
SP - 259
EP - 272
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
SN - 0016-7037
ER -