Woce Radiocarbon IV: Pacific Ocean Results; P10, P13N, P14C, P18, P19 &amp; S4P

Key, Robert M.; Quay, Paul D.; Schlosser, Peter; McNichol, Ann P.; Reden, KF von; Schneider, Robert J.; Elder, Kathryn; Stuiver, Minze; Östlund, H. Göte

doi:10.1017/s0033822200064845

Cited by 62 publications

(56 citation statements)

References 43 publications

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“…The three rows, from top to bottom, are ∆ b−p , the difference between the 14 C age of benthic and planktonic foraminifera (panels a-c); t v , the apparent ventilation age of subsurface water, taking into account change in atmospheric ∆ 14 C (panels d-f); and ∆ 14 C 0 −∆ 14 C sw , the difference between ∆ 14 C of subsurface water and surface water (panels g-i). For comparison to the modern ocean, on each panel, the solid grey profile is the average North Pacific ∆ 14 C from the WOCE dataset (Key et al, 2002). In panels g-i, the dashed grey profile is the modern ∆ 14 C profile, corrected for the higher amount of 14 C in the ocean-atmosphere system for each time slice.…”

Section: Lithologymentioning

confidence: 99%

“…For reference, I plot ∆ b−p with a profile of mean North Pacific ∆ 14 C from the WOCE dataset (Key et al, 2002). This profile includes stations from 0 N to 55 N. The modern ∆ 14 C profile is converted to apparent age using Equation A.1.…”

Section: Future Directionsmentioning

confidence: 99%

“…Plotted here is ∆ b−p , the difference between the 14 C age in ky (using the true half life) of benthics and planktonics. The average North Pacific ∆ 14 C profile from the WOCE dataset (Key et al, 2002) is converted to apparent age with Equation A.1. The right-hand edge of the shaded region is the apparent age profile minus 400 y (the mean apparent age of surface water), and the left-hand edge of the shaded region is the apparent age profile minus 800 y (a hypothetical apparent age of surface water in an upwelling region).…”

Section: Future Directionsmentioning

confidence: 99%

“…In Figure A-4, I plot ∆ 14 C 0 −∆ 14 C sw for the three time slices. For reference, I plot in the solid grey curve the Key et al (2002) profile of ∆ 14 C, where the R (400 y) is subtracted so that the curve is relative to the mean pre-industrial, pre-nuclear surface ocean.…”

Section: Future Directionsmentioning

confidence: 99%

“…Plotted here is ∆ 14 C 0 −∆ 14 C sw , the difference between the estimated ∆ 14 C of water in which the benthic foraminifera grew and the mean surface ocean ∆ 14 C at that time. The solid grey line is the mean North Pacific ∆ 14 C profile from the WOCE dataset minus the ∆ 14 C of a mean PIPN surface ocean where R = 400 y (∆ 14 C sw = −49.6 ) (Key et al, 2002). The dashed grey line is the same profile, but where the 14 C age everywhere in the ocean was decreased by exactly the apparent age of the mean surface water for that time period.…”

Section: Future Directionsmentioning

confidence: 99%

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The paleoceanography of the Bering Sea during the last glacial cycle

Cook¹

2006

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In this thesis, I present high-resolution stable-isotope and planktonic-fauna records from Bering Sea sediment cores, spanning the time period from 50,000 years ago to the present. During Marine Isotope Stage 3 (MIS3) at 30-20 ky BP (kiloyears before present) in a core from 1467 m water depth near Umnak Plateau, there were episodic occurrences of diagenetic carbonate minerals with very low δ 13 C (−22.4 ), high δ 18 O (6.5 ), and high [Mg]/ [Ca], which seem associated with sulfate reduction of organic matter and possibly anaerobic oxidation of methane. The episodes lasted less than 1000 years and were spaced about 1000 years apart. During MIS3 at 55-20 ky BP in a core from 2209 m water depth on Bowers Ridge, N. pachyderma (s.) and Uvigerina δ 18 O and δ 13 C show no coherent variability on millennial time scales.Bering Sea sediments are dysoxic or laminated during the deglaciation. A high sedimentation rate core (200 cm/ky) from 1132 m on the Bering Slope is laminated during the Bølling warm phase,Ållerød warm phase, and early Holocene, where the ages of lithological transitions agree with the ages of those climate events in Greenland (GISP2) to well within the uncertainty of the age models. The subsurface distribution of radiocarbon was estimated from a compilation of published and unpublished North Pacific benthic-planktonic 14 C measurements (475-2700 m water depth). There was no consistent change in 14 C profiles between the present and the Last Glacial Maximum, Bølling-Ållerød, or the Younger Dryas cold phase. N. pachyderma (s.) δ 18 O in the Bering Slope core decreases rapidly (in less than 220 y) by 0.7-0.8 at the onset of the Bølling and the end of the Younger Dryas. These isotopic shifts are accompanied by transient decreases in the relative abundance of N. pachyderma (s.), suggesting that the isotopic events are transient warmings and sustained freshenings.

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Section: Lithologymentioning

confidence: 99%

Section: Future Directionsmentioning

confidence: 99%

Section: Future Directionsmentioning

confidence: 99%

Section: Future Directionsmentioning

confidence: 99%

Section: Future Directionsmentioning

confidence: 99%

See 3 more Smart Citations

The paleoceanography of the Bering Sea during the last glacial cycle

Cook¹

2006

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Radiocarbon profiles of the NW Pacific from the LGM and deglaciation: Evaluating ventilation metrics and the effect of uncertain surface reservoir ages

Cook

Keigwin

2015

Paleoceanography

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During the last deglaciation, the ventilation of the subarctic Pacific is hypothesized to have changed dramatically, including the rejuvenation of a poorly ventilated abyssal water mass that filled the deep ocean, and fluctuations in the strength of North Pacific intermediate and deep water formation at millennial timescales. Foraminiferal radiocarbon reconstructions of past ventilation changes in the Pacific are valuable but are hampered by poor carbonate preservation, low sediment accumulation rates, bias from bioturbation, and poorly constrained past surface reservoir age. In this study, we present paired benthic-planktonic radiocarbon measurements from the Okhotsk Sea and Emperor Seamounts. We take advantage of large contemporaneous peaks in benthic abundances from the last glacial maximum, Bolling-Allerod (BA), and early Holocene to produce time slices of radiocarbon from 1 to 4 km water depth. We explore the impact of uncertain surface reservoir age and evaluate several approaches to quantifying past ocean radiocarbon distribution using our NW Pacific data and a compilation of published data from the North Pacific. Both the calendar age and the absolute value of an ocean radiocarbon estimate depend on the assumed surface reservoir age. But for a time slice from a small geographical area with radiocarbon-independent stratigraphic correlation between cores, the shape of a water column profile is independent of surface reservoir age. The NW Pacific profiles are similar in shape to the compilation profiles for the entire North Pacific, which suggests that deglacial surface reservoir age changes across the N Pacific did not diverge dramatically across the areas sampled. The Last Glacial Maximum (LGM) profile >2 km spans a wide range of values, ranging from values similar to today to lower than today. However, by the BA the profile has a similar shape to today. Ultimately, local surface reservoir ages, end-member water mass composition, and mixing ratios must each be constrained before a radiocarbon activity reconstruction can be used to confidently infer ventilation changes.

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Allochthonous sources and dynamic cycling of ocean dissolved organic carbon revealed by carbon isotopes

Zigah

McNichol

et al. 2017

Geophysical Research Letters

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We present concentration and isotopic profiles of total, size, and polarity fractionated dissolved organic carbon (DOC) from Station ALOHA (A Long‐term Oligotrophic Habitat Assessment), an oligotrophic site in the North Pacific Ocean. The data show that, between the surface and 3500 m, low molecular weight (LMW) hydrophilic DOC, LMW hydrophobic DOC, and high molecular weight (HMW) DOC constitute 22–33%, 45–52%, and 23–35% of DOC, respectively. LMW hydrophilic DOC is more isotopically depleted (δ13C of −23.9‰ to −31.5‰ and Δ14C of −304‰ to −795‰; mean age of 2850 to 15000 years) than the LMW hydrophobic DOC (δ13C of −22‰ to −23‰ and Δ14C of −270‰ to −568‰; 2470 to 6680 years) and HMW DOC (δ13C of ~−21‰ and Δ14C of −24‰ to −294‰; 135–2700 years). Our analyses suggest that a large fraction of DOC may be derived from allochthonous sources such as terrestrial and hydrothermal DOC and cycle on much longer time scales of >10000 years or enter the ocean as preaged carbon.

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Woce Radiocarbon IV: Pacific Ocean Results; P10, P13N, P14C, P18, P19 & S4P

Cited by 62 publications

References 43 publications

The paleoceanography of the Bering Sea during the last glacial cycle

The paleoceanography of the Bering Sea during the last glacial cycle

Radiocarbon profiles of the NW Pacific from the LGM and deglaciation: Evaluating ventilation metrics and the effect of uncertain surface reservoir ages

Allochthonous sources and dynamic cycling of ocean dissolved organic carbon revealed by carbon isotopes

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