Dust-deposited lithogenic particles in the iron cycle in the tropical and subtropical Atlantic, link to model results in NetCDF format@en

Lithogenic material deposited as dust is one of the major sources of trace metals to the ocean, particularly in the tropical and subtropical Atlantic. On the other hand, it can also act as a scavenging surface for iron. Here we studied this double role of lithogenic material in the marine iron cycle by adding a new scheme for describing particle dynamics into a global biogeochemistry and ecosystem model including particle aggregation and disaggregation of two particle size classes as well as scavenging on both organic and lithogenic particles. Considering the additional scavenging of iron on lithogenic particles, the modelled dissolved iron concentration is reduced significantly in the tropical and subtropical Atlantic, bringing the model much closer to observations. This underlines the necessity to consider the double role of dust particles as iron source and sink in studies on the marine iron cycle in high dust regions and with changing dust fluxes.以粉尘形式沉降的岩源物质（lithogenic material）是海洋微量金属的主要来源之一，尤其在热带和亚热带大西洋海域。另一方面，该物质亦可充当铁的清除载体。本研究通过在全球生物地球化学与生态系统模型中新增一套颗粒物动力学描述方案，探究了岩源物质在海洋铁循环中的双重作用；该方案涵盖两类粒径颗粒物的聚集与解聚过程，以及有机颗粒物与岩源颗粒物上的铁清除过程。考虑到岩源颗粒物对铁的额外清除作用，热带和亚热带大西洋海域的模拟溶解铁浓度显著降低，令模型结果更贴近实测数据。这一结果凸显了在高粉尘区域及粉尘通量变化的海洋铁循环研究中，必须将粉尘颗粒作为铁的源与汇的双重作用纳入考量。