Surface nitrate utilization in the Bering Sea since 180 ka BP : insight from sedimentary nitrogen isotopes.

Riethdorf, Jan-Rainer, Thibodeau, Benoit, Ikehara, D., Nürnberg, Dirk , Max, L., Tiedemann, Ralf and Yokoyama, Y. (2016) Surface nitrate utilization in the Bering Sea since 180 ka BP : insight from sedimentary nitrogen isotopes. Open Access Deep-Sea Research Part II-Topical Studies in Oceanography, 125 . pp. 163-176. DOI 10.1016/j.dsr2.2015.03.007.

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Supplementary data:

Abstract

We present high-resolution records of sedimentary nitrogen (δ15Nbulk) and carbon isotope ratios (δ13Cbulk) from piston core SO201-2-85KL located in the western Bering Sea. The records reflect changes in surface nitrate utilization and terrestrial organic matter contribution in submillennial resolution that span the last 180 kyr. The δ15Nbulk record is characterized by a minimum during the penultimate interglacial indicating low nitrate utilization (~62–80%) despite the relatively high export production inferred from opal concentrations along with a significant reduction in the terrestrial organic matter fraction (mterr). This suggests that the consumption of the nitrate pool at our site was incomplete and even more reduced than today (~84%). δ15Nbulk increases from Marine Isotope Stage (MIS) 5.4 and culminates during the Last Glacial Maximum, which indicates that nitrate utilization in the Bering Sea was raised during cold intervals (MIS 5.4, 5.2, 4) and almost complete during MIS 3 and 2 (~93–100%). This is in agreement with previous hypotheses suggesting that stronger glacial stratification reduced the nutrient supply from the subeuphotic zone, thereby increasing the iron-to-nutrient ratio and therefore the nitrate utilization in the mixed surface layer. Large variations in δ15Nbulk were also recorded from 180 to 130 ka BP (MIS 6), indicating a potential link to insolation and sea-level forcing and its related feedbacks. Millennial-scale oscillations were observed in δ15Nbulk and δ13Cbulk that might be related to Greenland interstadials.

Document Type: Article
Additional Information: WOS:000375739800015
Keywords: Bering Sea; Quaternary; Nitrogen isotopes; Nitrate utilization
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
AWI
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.dsr2.2015.03.007
ISSN: 0967-0645
Projects: Laptev Sea System, Transdrift, KALMAR
Expeditions/Models/Experiments:
Date Deposited: 27 Feb 2015 08:20
Last Modified: 01 Feb 2019 15:15
URI: http://oceanrep.geomar.de/id/eprint/27677

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