DOI: 10.1002/2017JC013527
Scopus记录号: 2-s2.0-85042586148
论文题名: Isotopic Evidence for the Evolution of Subsurface Nitrate in the Western Equatorial Pacific
作者: Lehmann N. ; Granger J. ; Kienast M. ; Brown K.S. ; Rafter P.A. ; Martínez-Méndez G. ; Mohtadi M.
刊名: Journal of Geophysical Research: Oceans
ISSN: 21699275
出版年: 2018
卷: 123, 期: 3 起始页码: 1684
结束页码: 1707
语种: 英语
英文关键词: nitrogen cycle
; nutrient dynamics
; stable isotopes
; Western Equatorial Pacific
Scopus关键词: dissolved inorganic carbon
; equatorial dynamics
; isotopic analysis
; nitrate
; nitrogen fixation
; nitrogen isotope
; nutrient dynamics
; organic matter
; oxygen isotope
; remineralization
; stable isotope
; subsurface flow
; thermocline
; Pacific Ocean
; Pacific Ocean (Equatorial)
; Pacific Ocean (South)
; Pacific Ocean (West)
英文摘要: Subsurface waters from both hemispheres converge in the Western Equatorial Pacific (WEP), some of which form the Equatorial Undercurrent (EUC) that influences equatorial Pacific productivity across the basin. Measurements of nitrogen (N) and oxygen (O) isotope ratios in nitrate (δ15NNO3 and δ18ONO3), the isotope ratios of dissolved inorganic carbon (δ13CDIC), and complementary biogeochemical tracers reveal that northern and southern WEP waters have distinct biogeochemical histories. Organic matter remineralization plays an important role in setting the nutrient characteristics on both sides of the WEP. However, remineralization in the northern WEP contributes a larger concentration of the nutrients, consistent with the older “age” of northern thermocline-depth and intermediate-depth waters. Remineralization introduces a relatively low δ15NNO3 to northern waters, suggesting the production of sinking organic matter by N2 fixation at the surface—consistent with the notion that N2 fixation is quantitatively important in the North Pacific. In contrast, remineralization contributes elevated δ15NNO3 to the southern WEP thermocline, which we hypothesize to derive from the vertical flux of high-δ15N material at the southern edge of the equatorial upwelling. This signal potentially masks any imprint of N2 fixation from South Pacific waters. The observations further suggest that the intrusion of high δ15NNO3 and δ18ONO3 waters from the eastern margins is more prominent in the northern than southern WEP. Together, these north-south differences enable the examination of the hemispheric inputs to the EUC, which appear to derive predominantly from southern hemisphere waters. © 2018. 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/114339
Appears in Collections: 气候减缓与适应
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作者单位: Department of Oceanography, Dalhousie University, Halifax, NS, Canada; Department of Marine Sciences, University of Connecticut, Groton, CT, United States; Departments of Biomedical Engineering, Physics, Chemical and Biomedical Engineering, and Marine Sciences, University of Connecticut, Storrs, CT, United States; Department of Earth System Science, University of California, Irvine, CA, United States; MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
Recommended Citation:
Lehmann N.,Granger J.,Kienast M.,et al. Isotopic Evidence for the Evolution of Subsurface Nitrate in the Western Equatorial Pacific[J]. Journal of Geophysical Research: Oceans,2018-01-01,123(3)