Evidence from diatom‐bound nitrogen isotopes for subarctic Pacific stratification during the last ice age and a link to North Pacific denitrification changes

Brunelle, Brigitte G.; Sigman, Daniel M.; Cook, M. S.; Keigwin, Lloyd D; Haug, Gerald H.; Plessen, Birgit; Schettler, Georg; Jaccard, Samuel L.

doi:10.1029/2005pa001205

Cited by 132 publications

(240 citation statements)

References 126 publications

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“…These changes do not necessarily match those in the Okhotsk and Bering adjacent seas [Sato et al, 2002;Brunelle et al, 2007]. Vertical mixing of oligotrophic surface water with nutrient-enriched waters from below is most important.…”

Section: Discussionmentioning

confidence: 99%

“…ka (170 cm bsf; i.e., during final H1), right near the end of IRD deposition. This rise occurred >2000 years later than in the northwest Pacific and only little prior to a ''green sediment layer'' and opal-based productivity peak in the Bering Sea (Core JPC17; Brunelle et al [2007]), where productivity changes may also be controlled by variations in the Aleutian Current. Sedimentation rates at MD02-2489 culminated at 50 cm/1000 years (Figures 3b and S4b), as compared to 15-30 cm/1000 years during earlier and later periods.…”

Section: Termination I In the Northeastern Pacific (Core Md02-2489)mentioning

confidence: 98%

“…Thus the maxima are coeval with pronounced minima in planktic productivity (and in relative nutrient utilization; Galbraith et al [2008]), and on the other hand with prominent preservation spikes of CaCO 3 , for reasons not properly understood, but in harmony with caveats discussed by Plewa et al [2006]. In contrast to Site 882, a Holocene maximum of biogenic Ba in the Bering Sea (Core JPC 17; Brunelle et al [2007]) slightly precedes that of biogenic opal, but clearly lags behind a deglacial CaCO 3 maximum near 15 cal. ka.…”

Section: Standard Series Of Productivity Events Over Termination Imentioning

confidence: 98%

“…High nutrients in surface and/or subsurface waters, in turn, are reflected by lowered d 13 C values in shell calcite of subpolar planktic foraminifera; these values depend on their dominant habitats [Simstich et al, 2002]. High d 15 N values of organic matter may record increased surface water nutrient utilization [Galbraith et al, 2008;Brunelle et al, 2007]. Sediment records of variations in surface water temperature (SST), transport of ice-rafted debris (IRD), and the epibenthic d 13 C record of bottom water ventilation provide complementary evidence of contemporary paleoceanographic regimes.…”

Section: Introductionmentioning

confidence: 99%

“…Further records were established for the Okhotsk adjacent sea (e.g., PC1, Figure 1) Figure 1. Locations of ODP Site 882 and Marion Dufresne (MD) sites MD01-2416 and MD02-2489 on Emperor and Patton Seamounts and of cores JPC17 in the Bering Sea [Brunelle et al, 2007] and PC1 in the Sea of Okhotsk [Sato et al, 2002]. Bold contour line delineates 100-m water depth, and dark areas outline glacial ice sheets.…”

Section: Introductionmentioning

confidence: 99%

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Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

Gebhardt¹,

Sarnthein²,

et al. 2008

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[1] Our study addresses fundamental questions of the mode and timing of orbital and millennial-scale changes in the meridional overturning circulation (MOC) of the subarctic North Pacific. Particular concerns are the vertical mixing, the present and past abundance of nutrients in surface waters despite strong stratification, and the North Pacific-North Atlantic seesaw of oscillations in sea surface temperature (SST). We do this by generating and interpreting multiple records for glacial terminations I-V down two long piston cores, one each from the western and eastern subarctic Pacific. Chlorins and biogenic opal are proxies for surface water productivity; d 13 C of epibenthic foraminifera is a record of deepwater ventilation; and the d 13 C of N. pachyderma sin. is a tracer of nutrients in subsurface waters that extend up to the sea surface during times of vertical mixing. The degree of mixing is traced by pairing SST and d 18 O records of planktic surface and subsurface (pycnocline) dwellers. Tight age control is deduced from a suite of age-calibrated 14 C plateau boundaries for Termination I and benthic d 18 O and geomagnetic events for the last 800 ka. Carbon 14 paleoreservoir ages record the ages of surface and deep waters to uncover short-term changes in MOC over Termination I. We have defined a standard sequence of short-term productivity events for Termination I, also evident during terminations II to V and subsequent interglacials over the last 450 ka. The peak glacial regime of stable stratification and low productivity terminated, together with the end of ice rafting and melting, near 17 ka, $2000 years after the onset of Termination I. Pulses of vertical mixing and incursion of warm surface waters from the subtropics followed. Convected young water masses finally penetrated down to 3600-m water depth at 17.0 to less than 14.5 ka, significantly improving bottom water ventilation through the late deglacial and earliest interglacial. Mixing with upwelled nutrients from the pycnocline induced short-term maxima in algal production of chlorins and biogenic opal near 17-15 and 15-12 ka, respectively. Deglacial meltwater incursions in the Aleutian Current and silica input from North American rivers also promoted East Pacific productivity after 15.5 ka. Productivity decreased during the late deglacial and early interglacial, coeval with an exceptional peak in CaCO 3 preservation caused by both low organic flux and well-ventilated deepwater. Subsequently, low salinity and cool surface waters and in turn, stratification were gradually restored. A second, opaldominated productivity maximum marked the ends of interglacials. The deglacial pulses of vertical mixing around 17-11 ka imply an important contribution of the North Pacific to the coeval release of oceanic CO 2 into the atmosphere and support the east-west seesaw model of climate change.Citation: Gebhardt, H., M. Sarnthein, P. M. Grootes, T. Kiefer, H. Kuehn, F. Schmieder, and U. Röhl (2008), Paleonutrient and productivity records from the subarctic North ...

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Section: Discussionmentioning

confidence: 99%

Section: Termination I In the Northeastern Pacific (Core Md02-2489)mentioning

confidence: 98%

Section: Standard Series Of Productivity Events Over Termination Imentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

Gebhardt¹,

Sarnthein²,

et al. 2008

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Time-transgressive North Atlantic productivity changes upon Northern Hemisphere glaciation

et al. 2013

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Marine biological export productivity declined in high‐latitude regions in the North Pacific and Southern Ocean 2.7 million years ago, in parallel with the intensification of Northern Hemisphere glaciation. Here we present data from the North Atlantic, which show a similar but time‐transgressive pattern of high‐latitude productivity decline from 3.3 to 2.5 Ma, with productivity decreasing first at 69°N, hundreds of thousands of years before it declined at 58°N. We propose that the cumulative data are best explained by an equatorward migration of the westerly winds, which caused a southward shift in the zone of Ekman divergence and upwelling‐associated major nutrient supply over this time interval. We suggest that a similar equatorward migration of the westerly winds may also help explain the productivity changes observed in other high‐latitude regions, particularly the Southern Ocean. At 2.7 Ma, equatorial and temperate Atlantic sites began to show orbitally paced productivity pulses, consistent with a shoaling and meridional contraction of the nutrient‐poor “warm sphere” that characterizes the low latitude upper ocean. This timing coincides with observed productivity changes in Southern Ocean, consistent with previous findings that the Southern Ocean exerts a strong influence on the fertility of the low‐latitude Atlantic. Finally, we propose that the unique basin geometry of the North Atlantic caused deep water formation in this region to remain relatively stable despite equatorward migration of winds and ocean fronts.

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Response of the Bering Sea to 11‐year solar irradiance cycles during the Bølling‐Allerød

Katsuki

Itaki

Khim

et al. 2014

Geophysical Research Letters

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Previous studies find decadal climate variability possibly related to solar activity, although the details regarding the feedback with the ocean environment and ecosystem remain unknown. Here, we explore the feedback system of solar irradiance change during the Bølling-Allerød period, based on laminated sediments in the northern Bering Sea. During this period, well-ventilated water was restricted to the upper intermediate layer, and oxygen-poor lower intermediate water preserved the laminated sediment. An 11-year cycle of diatom and radiolarian flux peaks was identified from the laminated interval. Increased fresh meltwater input and early sea-ice retreat in spring under the solar irradiance maximum follow the positive phase of Arctic Oscillation which impacted the primary production and volume of upper intermediate water production in the following winter. Strength of this 11 year solar irradiance effect might be further regulated by the pressure patterns of Pacific decadal oscillation and/or El Niño-Southern Oscillation variability.

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Evidence from diatom‐bound nitrogen isotopes for subarctic Pacific stratification during the last ice age and a link to North Pacific denitrification changes

Cited by 132 publications

References 126 publications

Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

Time-transgressive North Atlantic productivity changes upon Northern Hemisphere glaciation

Response of the Bering Sea to 11‐year solar irradiance cycles during the Bølling‐Allerød

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