Nowadays it is widely known that pollution by microplastics (MP) at the open ocean covers immense areas. Buoyant plastics tend to accumulate in areas of convergence at the sea surface such as subtropical gyres, while non-buoyant plastics accumulate at the seafloor. However, previous studies have revealed that the total amount of plastic in the different oceans is not well correlated with the concentrations measured at the sea surface and the sea floor, evidencing a significant amount of missing plastic in the oceans. This deviation could be related to an underestimation of the role played by small fragments of plastic and fibers in the oceans. Furthermore, microplastic fragments with a density lower than the density of seawater have been gathered hundreds of meters below the sea surface in the Pacific Ocean due to their size and shape.

The main objective of this study is to carry out, for the first time, an equivalent analysis along the water column for the Atlantic Ocean. In that sense, a total number of 51 samples were collected during four different oceanographic cruises between February and December 2019, from the sea surface down to 1150 m depth at the open ocean waters of the Canary Islands region (Spain). For each sample, 72 l of seawater were filtered on board with a mesh size of 100 μm, where the presence of microplastics has been clearly observed. Our results reveal the presence of microplastics at least up to 1150 m depth, at the Northeastern Atlantic Subtropical Gyre with noticeable seasonal differences. The spatial distribution of these small fragments and fibers at the water column is mainly related to the oceanic dynamics and mesoscale convective flows, overcoming the MP motion induced by their own buoyancy.

Moreover, these microplastics have being transported by the ocean dynamics as passive drifters.

如今，众所周知的是，公海中的微塑料（MP）污染覆盖了很多地区。漂浮性塑料倾向于聚集在海表层的汇合区域，例如亚热带回旋，而非漂浮性塑料则聚集在海底。但是，先前的研究表明，不同海洋中塑料的总量与在海面和海床测得的浓度并没有很好的相关性，这表明海洋中大量丢失了塑料。这种偏差可能与低估海洋中的塑料和纤维小碎片所起的作用有关。此外，由于其大小和形状，密度低于海水密度的微塑料碎片在太平洋海面以下数百米处被收集。

这项研究的主要目的是首次对大西洋沿水域进行等效分析。从这个意义上讲，在2019年2月至12月之间的四次不同的海洋航行中，从加纳利群岛地区（西班牙）的开放海域到海面直至1150 m的深度共采集了51个样本。对于每个样品，在船上以100μm筛孔尺寸过滤72升海水，其中清楚地观察到微塑料的存在。我们的研究结果表明，在东北大西洋亚热带回旋带中至少存在深度达1150 m的微塑料，并且存在明显的季节差异。这些小碎片和纤维在水柱处的空间分布主要与海洋动力学和中尺度对流有关，

而且，这些微塑料已被海洋动力学作为被动漂流器运输。