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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/50190

Title: Impact of glacial/interglacial sea level change on the ocean nitrogen cycle
Authors: Haojia Ren
Daniel M. Sigman
Alfredo Martínez-García
Robert F. Anderson
Min-Te Chen
Ana Christina Ravelo
Marietta Straub
George T. F. Wong
Gerald H. Haug
Contributors: 國立臺灣海洋大學:應用地球科學研究所
Date: 2017-08
Issue Date: 2018-09-20T02:36:20Z
Publisher: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Abstract: Abstract: The continental shelves are the most biologically dynamic regions of the ocean, and they are extensive worldwide, especially in the western North Pacific. Their area has varied dramatically over the glacial/interglacial cycles of the last million years, but the effects of this variation on ocean biological and chemical processes remain poorly understood. Conversion of nitrate to N2 by denitrification in sediments accounts for half or more of the removal of biologically available nitrogen (“fixed N”) from the ocean. The emergence of continental shelves during ice ages and their flooding during interglacials have been hypothesized to drive changes in sedimentary denitrification. Denitrification leads to the occurrence of phosphorus-bearing, N-depleted surface waters, which encourages N2 fixation, the dominant N input to the ocean. An 860,000-y record of foraminifera shell-bound N isotopes from the South China Sea indicates that N2 fixation covaried with sea level. The N2 fixation changes are best explained as a response to changes in regional excess phosphorus supply due to sea level-driven variations in shallow sediment denitrification associated with the cyclic drowning and emergence of the continental shelves. This hypothesis is consistent with a glacial ocean that hosted globally lower rates of fixed N input and loss and a longer residence time for oceanic fixed N—a “sluggish” ocean N budget during ice ages. In addition, this work provides a clear sign of sea level-driven glacial/interglacial oscillations in biogeochemical fluxes at and near the ocean margins, with implications for coastal organisms and ecosystems.
Relation: 114(33) pp.E6759-E6766
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/50190
Appears in Collections:[應用地球科學研究所] 期刊論文

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