Sterl Miriam F, Delandmeter Philippe, van Sebille Erik
Institute for Marine and Atmospheric Research Utrecht University Utrecht The Netherlands.
J Geophys Res Oceans. 2020 Feb;125(2):e2019JC015583. doi: 10.1029/2019JC015583. Epub 2020 Jan 29.
Floating plastic debris is an increasing source of pollution in the world's oceans. Numerical simulations using models of ocean currents give insight into the transport and distribution of microplastics in the oceans, but most simulations do not account for the oscillating flow caused by global barotropic tides. Here, we investigate the influence of barotropic tidal currents on the transport and accumulation of floating microplastics, by numerically simulating the advection of virtual plastic particles released all over the world's oceans and tracking these for 13 years. We use geostrophic and surface Ekman currents from GlobCurrent and the currents caused by the four main tidal constituents (M , S , K , and O ) from the FES model. We analyze the differences between the simulations with and without the barotropic tidal currents included, focusing on the open ocean. In each of the simulations, we see that microplastic accumulates in regions in the subtropical gyres, which is in agreement with observations. The formation and location of these accumulation regions remain unaffected by the barotropic tidal currents. However, there are a number of coastal regions where we see differences when the barotropic tidal currents are included. Due to uncertainties of the model in coastal regions, further investigation is required in order to draw conclusions in these areas. Our results suggest that, in the global open ocean, barotropic tidal currents have little impact on the transport and accumulation of floating microplastic and can thus be neglected in simulations aimed at studying microplastic transport in the open ocean.
漂浮的塑料碎片是全球海洋中日益严重的污染源。利用洋流模型进行的数值模拟有助于深入了解海洋中微塑料的输运和分布情况，但大多数模拟并未考虑全球正压潮汐引起的振荡流。在此，我们通过对全球海洋中释放的虚拟塑料颗粒的平流进行数值模拟，并对其进行13年的追踪，来研究正压潮流对漂浮微塑料输运和积累的影响。我们使用了GlobCurrent提供的地转流和表面埃克曼流，以及FES模型中由四个主要潮汐成分（M、S、K和O）引起的海流。我们分析了包含和不包含正压潮流的模拟之间的差异，重点关注开阔海洋。在每个模拟中，我们都看到微塑料在亚热带环流区域积累，这与观测结果一致。这些积累区域的形成和位置不受正压潮流的影响。然而，在一些沿海地区，当考虑正压潮流时，我们发现了差异。由于沿海地区模型存在不确定性，需要进一步研究才能在这些地区得出结论。我们的结果表明，在全球开阔海洋中，正压潮流对漂浮微塑料的输运和积累影响很小，因此在旨在研究开阔海洋中微塑料输运的模拟中可以忽略不计。
