van de Flierdt Tina, Griffiths Alexander M, Lambelet Myriam, Little Susan H, Stichel Torben, Wilson David J
Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Philos Trans A Math Phys Eng Sci. 2016 Nov 28;374(2081). doi: 10.1098/rsta.2015.0293.
The neodymium (Nd) isotopic composition of seawater has been used extensively to reconstruct ocean circulation on a variety of time scales. However, dissolved neodymium concentrations and isotopes do not always behave conservatively, and quantitative deconvolution of this non-conservative component can be used to detect trace metal inputs and isotopic exchange at ocean-sediment interfaces. In order to facilitate such comparisons for historical datasets, we here provide an extended global database for Nd isotopes and concentrations in the context of hydrography and nutrients. Since 2010, combined datasets for a large range of trace elements and isotopes are collected on international GEOTRACES section cruises, alongside classical nutrient and hydrography measurements. Here, we take a first step towards exploiting these datasets by comparing high-resolution Nd sections for the western and eastern North Atlantic in the context of hydrography, nutrients and aluminium (Al) concentrations. Evaluating those data in tracer-tracer space reveals that North Atlantic seawater Nd isotopes and concentrations generally follow the patterns of advection, as do Al concentrations. Deviations from water mass mixing are observed locally, associated with the addition or removal of trace metals in benthic nepheloid layers, exchange with ocean margins (i.e. boundary exchange) and/or exchange with particulate phases (i.e. reversible scavenging). We emphasize that the complexity of some of the new datasets cautions against a quantitative interpretation of individual palaeo Nd isotope records, and indicates the importance of spatial reconstructions for a more balanced approach to deciphering past ocean changes.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.
海水的钕（Nd）同位素组成已被广泛用于重建各种时间尺度上的海洋环流。然而，溶解态钕的浓度和同位素并不总是保守的，对这种非保守成分进行定量反褶积可用于检测海洋 - 沉积物界面处的痕量金属输入和同位素交换。为了便于对历史数据集进行此类比较，我们在此提供一个扩展的全球数据库，涵盖水文和营养背景下的钕同位素及浓度。自2010年以来，在国际GEOTRACES断面航次中收集了大量微量元素和同位素的综合数据集，同时还进行了经典的营养和水文测量。在此，我们通过在水文、营养和铝（Al）浓度背景下比较北大西洋西部和东部的高分辨率钕断面，朝着利用这些数据集迈出了第一步。在示踪剂 - 示踪剂空间中评估这些数据表明，北大西洋海水的钕同位素和浓度通常遵循平流模式，铝浓度也是如此。在局部观察到与水团混合的偏差，这与底栖 nepheloid 层中痕量金属的添加或去除、与海洋边缘的交换（即边界交换）和/或与颗粒相的交换（即可逆清除）有关。我们强调，一些新数据集的复杂性提醒人们不要对单个古钕同位素记录进行定量解释，并表明空间重建对于更全面地解读过去海洋变化的重要性。本文是主题为“海洋微量元素化学的生物和气候影响”的特刊的一部分。
