Decadal to centennial fluctuations in the intensity of the eastern tropical North Pacific oxygen minimum zone during the last 1200 years. (31st August 2016)

• Record Type: Journal Article
• Authors: Tems, Caitlin E.; Berelson, William M.; Thunell, Robert; Tappa, Eric; Xu, Xiaomei; Khider, Deborah; Lund, Steve; González‐Yajimovich, Oscar; Hamann, Yvonne
• Is Part Of: Paleoceanography. Volume 31:Number 8(2016)
• Page Start: 1138
• Page End: 1151
• Publication Date: 2016-08-31
• Subjects: eastern tropical North Pacific oxygen minimum zone -- Gulf of California -- N isotopes -- denitrification -- Pacific Decadal Oscillation -- solar forcing; Paleoceanography -- Periodicals; 551.46
• DOI: 10.1002/2015PA002904
• Languages: English
• ISSNs: 0883-8305

Abstract

Abstract: Oxygen minimum zones (OMZs), located below highly productive marine regions, are sites of microbially mediated denitrification and biogeochemical cycling that have global significance. The intensity of OMZs fluctuates naturally; however, the degree of these fluctuations and a comprehensive understanding of the factors that drive these fluctuations on decadal to centennial time scales is lacking. Our high‐resolution (near‐annual) record of δ 15 Nsed from laminated sediments at the Pescadero Slope in the Gulf of California (eastern tropical North Pacific) fluctuates between maximum values of 10.5‰ and minimum values of 8.0‰ over the past 1200 years. An analysis of the relationship between δ 15 NO3 − and [O2 ] in the water column suggests that the observed range of δ 15 Nsed values is equivalent to an approximately 8 µ M fluctuation in O2 content and that these changes can occur in less than 25 years. Our findings show that the OMZ typically intensifies quickly and contracts gradually; the average rate of OMZ intensification (−0.24 µ M O2 /yr) is twice as fast as the rate of OMZ reoxygenation. Spectral analyses of the δ 15 Nsed record and Br/Cl counts, with the latter are used as a proxy for organic carbon preservation, suggest that the Pacific Decadal Oscillation and the Suess (deVries) solar cycle (solar irradiance) may influence the intensity of the OMZ and carbon production/export during the late Holocene. Coherence between δ 15 Nsed and weight percent organic carbon also suggests that similar mechanisms influence both OMZ fluctuations and variation in organic carbon production/export. Key Points: Oxygen minimum zone intensity in Gulf of California during late Holocene interpreted from δ 15 Nsed Late Holocene is characterized by rapid OMZ intensification followed by more gradual reoxygenation OMZ strength and organic carbon productivity/export related to Pacific Decadal Oscillation and solar cycles