Local and remote forcing on the interannual variations of the sedimentary δ15N in Santa Barbara Basin during the past 80 years
Local and remote forcing on the interannual variations of the sedimentary δ15N in Santa Barbara Basin during the past 80 years
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近80年来圣巴巴拉盆地沉积层δ15N年际变化的局地和远程强迫
DOI：
10.3389/fmars.2022.982051
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发表时间：
2022-09
影响因子：
3.7
通讯作者：
Misra Satabdi
中科院分区：
文献类型：
--
作者：
Xu Hanyue;Li Da-Wei;Li Hong-Chun;Zhao Meixun;Berelson William M.;Jin Gui’e;Li Li;Misra Satabdi
圣巴巴拉盆地（SBB）沉积物氮同位素（δ 15 N sed）大多被解释为热带北太平洋东部（ETNP）中层水反硝化过程的记录。然而，关于SBB中δ 15 N sed信号的来源和控制机制仍存在争议。对2019年从SBB采集的46 cm沉积物柱样（SBB-190629）进行了包括δ 15 N sed，总有机碳（TOC），总氮（TN），C/N比和海洋生物标志物在内的多替代分析。岩心年龄测定采用纹孔计数和210 Pb测年方法，显示沉积历史为1938-2019 CE，沉积速率为0.564 cm/年。结果表明，δ 15 Nsed记录（0.25年分辨率）的变化范围为6.24‰ ~ 7.43‰，受局地强迫和远海强迫的共同影响。SBB δ 15 N sed特征的长期变化表现为1940 ~ 1980年代末总体呈下降趋势，1980~2000年为低值，之后呈上升趋势，反映了热带信风强度引起的ETNP反硝化作用的变化。我们的研究结果还揭示了一系列的突然的年度到多年的变化，叠加在上述的长期变化。通过使用SBB-190629的平均δ 15 N（Δ δ 15 N）的偏差减去ETNP的Δ δ 15 N，获得SBB本地δ 15 N信号（Δ δ 15 N SBB）。Δδ 15 N SBB记录与SBB底层水的氧化还原敏感性指标（Re/Mo比值和C29甾烷醇/甾烯醇比值）以及基于C/N比值混合模型计算的海洋OC含量的对比结果表明，Δδ 15 N SBB主要受底层水反硝化作用的控制，而底层水反硝化作用是由上升流强度和海洋生产力的变化引起的。由于各种气候因素（例如，厄尔尼诺-南方涛动（ENSO）、太平洋年代际涛动（PDO）和北太平洋涡旋涛动（NPGO）等气候因子在不同时间尺度上对SBB的上升流强度（进而对海洋生产力和反硝化作用）有不同的影响，综合气候因子对SBB反硝化作用的影响具有时间依赖性。
Sedimentary nitrogen isotope (δ 15 N sed ) in Santa Barbara Basin (SBB) has been mostly interpreted as the record of the eastern tropical North Pacific (ETNP) intermediate water denitrification process. Nevertheless, debate remains regarding sources and control mechanisms of δ 15 N sed signal in SBB. Multi-proxy analyses including δ 15 N sed , total organic carbon (TOC), total nitrogen (TN), C/N ratio, and marine biomarkers were performed on a 46-cm sediment core (SBB-190629) collected from SBB in 2019. The core was dated with varve counting and 210 Pb dating method, showing a depositional history of 1938–2019 CE with a sedimentation rate of 0.564 cm/year. The findings show that the δ 15 N sed record (at ~0.25-year resolution) ranges from 6.24‰ to 7.43‰, which was affected by both local and remote forcing. The long-term variations of the SBB δ 15 N sed signature show a general decreasing trend from 1940 to the late 1980s, low values during 1980~2000, and an increase afterward, which is thought to reflect changes in ETNP denitrification induced by the strength of tropical trade winds. Our results also reveal a series of abrupt annual to multiannual changes, superimposed on the long-term variation mentioned above. The SBB local δ 15 N signal (Δδ 15 N SBB ) is accessed by using the deviation from the mean δ 15 N (Δδ 15 N) of SBB-190629 to subtract the Δδ 15 N of the ETNP. The Δδ 15 N SBB record compares well with redox-sensitive proxies (Re/Mo ratio and C 29 stanol/stenol ratio) from the SBB bottom water and with the OC marine content calculated based on the C/N ratio mixing model, indicating that the Δδ 15 N SBB is mainly controlled by bottom water denitrification, which was induced by the change of upwelling intensity and marine productivity. Since various climatic factors (e.g., El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North Pacific Gyre Oscillation (NPGO)) have different impacts on the upwelling intensity (hence the marine productivity and denitrification) in SBB on different timescales, the influence of combined climatic factors on SBB denitrification is time dependent.
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影响因子：
5.2
作者：
Caitlin E. Tems;W. Berelson;M. Prokopenko
通讯作者：
Caitlin E. Tems;W. Berelson;M. Prokopenko
影响因子：
3.7
作者：
D. Sigman;Rebecca S. Robinson;Angela N. Knapp;A. Geen;D. McCorkle;Jay A. Brandes;R. Thunell
通讯作者：
D. Sigman;Rebecca S. Robinson;Angela N. Knapp;A. Geen;D. McCorkle;Jay A. Brandes;R. Thunell
影响因子：
5.2
作者：
R. Thunell;A. B. Kepple
通讯作者：
R. Thunell;A. B. Kepple
影响因子：
6.5
作者：
R. Rosenfeld;L. Hellman
通讯作者：
R. Rosenfeld;L. Hellman
影响因子：
3
作者：
Meyers, PA
通讯作者：
Meyers, PA