微塑料(MP)分布在世界各地的海洋中,是海洋污染的最大环境问题之一。在加的斯湾(GoC),国会议员遍布水柱,在海底,在商业海洋物种中积累,主要是由于主要河口的排放。这项研究的目的是分析运输途径,空间分布,以及基于密度和来源的MP在GoC中的积累区域。为此,将拉格朗日输运模型与高分辨率流体动力学模型耦合,并考虑了四个粒子源:CapeSanVicente,瓜迪亚纳河口,瓜达尔基维尔河口,加的斯湾/瓜达利特河。为了说明在GoC中检测到的塑料的多样性,使用了十种不同密度的颗粒,从低密度到高密度聚合物。这项研究表明,由于局部表面水流,很大一部分低密度MP积聚在其来源附近和水柱顶部几厘米内。瓜达基韦和瓜迪亚纳河口是GoC东部架子上低密度MP大量积累的主要贡献者,与以前的实地研究一致,这些河口是进入该地区的国会议员的主要来源,包括聚乙烯和聚丙烯。相比之下,加的斯湾/瓜达莱特河似乎是水柱最高米范围内近海水域低密度议员的主要来源,受局部中尺度特征的影响。瓜达尔基维尔河口似乎是高密度议员进入大陆架的主要来源,如聚苯乙烯,聚酰胺,和聚氯乙烯,其次是加的斯湾/瓜达利特河,在较小程度上,瓜迪亚纳河口.这些国会议员由于其较高的下沉率而在3.5至50m的深度附近积聚,但也可以通过深流运输到海上,沿着葡萄牙近海水域向北或向西离开GoC近海地区。
Microplastics (MPs) are distributed throughout the world oceans and represent one of the greatest environmental concerns of marine pollution. In the Gulf of Cadiz (GoC), MPs are found throughout the water column, on the seafloor, and accumulated within commercial marine species, primarily due to discharges from the main estuaries. The aim of this study was to analyse the transport pathways, spatial distribution, and accumulation regions of MPs in the GoC based on their density and source. For this, a Lagrangian transport model was coupled to a high-resolution hydrodynamic model and four particle sources were considered: Cape San Vicente, Guadiana Estuary, Guadalquivir Estuary, and Bay of Cadiz/Guadalete River. To account for the diversity of plastics detected in the GoC, particles with ten different densities were used, from low-density to high-density polymers. This study indicates that a significant proportion of low-density MPs accumulate near their sources and within the top few centimetres of the water column due to local surface currents. The Guadalquivir and Guadiana estuaries are the primary contributors to the high accumulation of low-density MPs on the GoC eastern shelf, consistent with previous field studies identifying these estuaries as the main sources of MPs into the region, including polyethylene and polypropylene. In contrast, the Bay of Cadiz/Guadalete River seems to be the primary source of low-density MPs in offshore waters within the uppermost meter of the water column, influenced by local mesoscale features. The Guadalquivir Estuary seems to be the main source of high-density MPs into the continental shelves, such as polystyrene, polyamide, and polyvinyl chloride, followed by the Bay of Cadiz/Guadalete River, and to a lesser extent, the Guadiana estuary. These MPs accumulate near their sources at depths of 3.5 to 50 m due to their high sinking rates, but can also be transported offshore by deep currents, either northwards along the Portuguese offshore waters or westwards off the GoC offshore region.