Particulate δ15N in laminated marine sediments as a proxy for mixing between the California Undercurrent and the California Current: A proof of concept
Particulate δ15N in laminated marine sediments as a proxy for mixing between the California Undercurrent and the California Current: A proof of concept
复制标题
DOI：
10.1002/2014gl061993
复制
发表时间：
2015-01
影响因子：
5.2
通讯作者：
Caitlin E. Tems;W. Berelson;M. Prokopenko
中科院分区：
文献类型：
--
作者：
Caitlin E. Tems;W. Berelson;M. Prokopenko
沿海海洋层状沉积物中颗粒δ15N的测量为水柱中反硝化强度的波动提供了一个高分辨率的代理。在热带北太平洋东部的氧最小带，这种反硝化信号被加利福尼亚潜流向北输送，从而成为海洋环流的示踪剂。通过比较南加州（圣莫尼卡盆地）温跃层的盐度，以及南部（佩斯卡德罗斜坡）和北部（圣莫尼卡盆地）同龄沉积物中δ15Nsed的差异，证实了这一点。该参数Δδ15Nsed的趋势与1900年至1990年太平洋年代际涛动（PDO）的相位变化有关。我们假设Δδ15Nsed在暖PDO阶段的下降是由于加利福尼亚潜流从热带北太平洋东部向北输送富含15N的硝酸盐的加强。1990年以后对这一趋势的偏离表明环流和/或加利福尼亚海流水体养分生物地球化学最近发生了变化。
The measurements of particulate δ15N in coastal marine laminated sediments provide a high‐resolution proxy for fluctuations in the intensity of denitrification in the water column. In the eastern tropical North Pacific oxygen minimum zone, this denitrification signal is transported northward by the California Undercurrent, thus serving as a tracer of ocean circulation. This is verified through comparisons between salinity in the thermocline off Southern California (Santa Monica Basin) and the difference between δ15Nsed within age equivalent sediments from a southern (Pescadero Slope) and northern (Santa Monica Basin) site. Trends in this parameter, Δδ15Nsed, relate to Pacific Decadal Oscillation (PDO) phase changes between 1900 and 1990. We hypothesize that the decline in Δδ15Nsed during warm PDO phases is due to a strengthening of the California Undercurrent transporting 15N‐enriched nitrate from the eastern tropical North Pacific northward. The deviation from this trend after 1990 suggests recent changes in circulation and/or California Current water nutrient biogeochemistry.