Neodymium budget in the Mediterranean Sea: evaluating the role of atmospheric dusts using a high-resolution dynamical-biogeochemical model

Author:

Ayache MohamedORCID,Dutay Jean-ClaudeORCID,Tachikawa Kazuyo,Arsouze Thomas,Jeandel Catherine

Abstract

Abstract. The relative importance of river solid discharge, deposited sediment remobilisation, and atmospheric dust as sources of neodymium (Nd) to the ocean is the subject of ongoing debate, the magnitudes of these fluxes being associated with a significant uncertainty. The Mediterranean basin is a specific basin; it receives a vast amount of emissions from different sources and is surrounded by continental margins, with a significant input of dust as compared to the global ocean. Furthermore, it is largely impacted by the Atlantic water inflow via the Strait of Gibraltar. Here, we present the first simulation of dissolved Nd concentration ([Nd]) and Nd isotopic composition (εNd) using a high-resolution regional model (NEMO/MED12/PISCES) with an explicit representation of all Nd inputs, and the internal cycle, i.e. the interactions between the particulate and dissolved phases. The high resolution of the oceanic model (at 1/12∘), essential to the simulation of a realistic Mediterranean circulation in present-day conditions, gives a unique opportunity to better apprehend the processes governing the Nd distribution in the marine environment. The model succeeds in simulating the main features of εNd and produces a realistic distribution of [Nd] in the Mediterranean Sea. We estimated the boundary exchange (BE, which represents the transfer of elements from the margin to the sea and their removal by scavenging) flux at 89.43 × 106 g(Nd) yr−1, representing ∼84.4 % of the total external Nd source to the Mediterranean basin. The river discharge provided 3.66 × 106 g(Nd) yr−1, or 3.5 % of the total Nd flow into the Mediterranean. The flux of Nd from partially dissolved atmospheric dusts was estimated at 5.2 × 106 g(Nd) yr−1, representing 5 % of the total Nd input, and 7.62 × 106 g(Nd) yr−1 comes from the Atlantic across the Strait of Gibraltar, i.e. 7.1 % of the total Nd input. The total quantity of Nd in the Mediterranean Sea was estimated to 7.28 × 109 g(Nd); this leads to a new calculated Nd residence time of ∼68 year. This work highlights that the impact of river discharge on [Nd] is localised near the catchments of the main rivers. In contrast, the atmospheric dust input has a basin-wide influence, correcting for a too-radiogenic εNd when only the BE input is considered and improving the agreement of simulated dissolved Nd concentration with field data. This work also suggests that εNd is sensitive to the spatial distribution of Nd in the atmospheric dust, and that the parameterisation of the vertical cycling (scavenging/remineralisation) considerably constrains the ability of the model to simulate the vertical profile of εNd.

Publisher

Copernicus GmbH

Subject

Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3