DOI: 10.1002/2015GB005277
Scopus记录号: 2-s2.0-84973138125
论文题名: Heavy silicon isotopic composition of silicic acid and biogenic silica in Arctic waters over the Beaufort shelf and the Canada Basin
作者: Varela D ; E ; , Brzezinski M ; A ; , Beucher C ; P ; , Jones J ; L ; , Giesbrecht K ; E ; , Lansard B ; , Mucci A
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2016
卷: 30, 期: 6 起始页码: 804
结束页码: 824
语种: 英语
英文关键词: Arctic
; biogenic silica
; diatoms
; isotopes
; silicic acid
; silicon
Scopus关键词: biogenic material
; deep water
; diatom
; global ocean
; halocline
; isotopic fractionation
; pelagic environment
; sea ice
; silica
; silicic acid
; silicon
; suspended particulate matter
; vertical profile
; water mass
; Arctic Ocean
; Atlantic Ocean
; Beaufort Sea
; Beaufort Shelf
; Canada
; Canada Basin
; Mackenzie River [Northwest Territories]
; Northwest Territories
; Pacific Ocean
; Bacillariophyta
英文摘要: The silicon isotopic composition of silicic acid (δ30Si(OH)4) and biogenic silica (δ30Si-bSiO2) were measured for the first time in marine Arctic waters from the Mackenzie River delta to the deep Canada Basin in the late summer of 2009. In the upper 100 m of the water column, δ30Si(OH)4 signals (+1.82‰ to +3.08‰) were negatively correlated with the relative contribution of Mackenzie River water. The biogenic Si isotope fractionation factor estimated using an open system model, 30ε = −0.97 ± 0.17‰, agrees well with laboratory and global-ocean estimates. Nevertheless, the δ30Si dynamics of this region may be better represented by closed system isotope models that yield lower values of 30ε, between −0.33‰ and −0.41‰, depending on how the contribution of sea-ice diatoms is incorporated. In the upper 400 m, δ30Si-bSiO2 values were among the heaviest ever measured in marine suspended bSiO2 (+2.03‰ to +3.51‰). A positive correlation between δ30Si-bSiO2 and sea-ice cover implies that heavy signals can result from isotopically heavy sea-ice diatoms introduced to pelagic assemblages. Below the surface bSiO2 production zone, the δ30Si(OH)4 distribution followed that of major water masses. Vertical δ30Si(OH)4 profiles showed a minimum (average of +1.84 ± 0.10‰) in the upper halocline (125–200 m) composed of modified Pacific water and heavier average values (+2.04 ± 0.11‰) in Atlantic water (300–500 m deep). In the Canada Basin Deep Water (below 2000 m), δ30Si(OH)4 averaged +1.88 ± 0.12‰, which represents the most positive value ever measured anywhere in the deep ocean. Since most Si(OH)4 enters the Arctic from shallow depths in the Atlantic Ocean, heavy deep Arctic δ30Si(OH)4 signals likely reflect the influx of relatively heavy intermediate Atlantic waters. A box model simulation of the global marine δ30Si(OH)4 distribution successfully reproduced the observed patterns, with the δ30Si(OH)4 of the simulated deep Arctic Ocean being the heaviest of all deep-ocean basins. ©2016. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77845
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Biology, University of Victoria, Victoria, BC, Canada; School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada; Marine Science Institute, University of California, Santa Barbara, CA, United States; Department of Ecology Evolution and Marine Biology, University of California, Santa Barbara, CA, United States; GEOTOP and Department of Earth and Planetary Sciences, McGill University, Montréal, QC, Canada; Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
Recommended Citation:
Varela D,E,, Brzezinski M,et al. Heavy silicon isotopic composition of silicic acid and biogenic silica in Arctic waters over the Beaufort shelf and the Canada Basin[J]. Global Biogeochemical Cycles,2016-01-01,30(6)