The abundance and distribution of microplastics in estuaries have been barely documented, and generally without accounting for the vertical structure in the water column. This study presents the very first data on the occurrence and distribution of microplastics in the Adour Estuary, SW France. The experimental data set was complemented by numerical simulations to gain understanding of the behaviour of suspended microplastics. Microplastics were found throughout the water column with a mean abundance of 1.13 part/m³. Films and fragments were the most abundant types of particles collected. Numerical simulations demonstrated that vertical distribution of microplastics in the water column is highly dependent on particle characteristics and on the local hydrodynamics. The main trend is that neutrally-buoyant microplastics are easily flushed out while heavier microplastics are prone to entrapment in the estuary, in particular under low discharge conditions. The present study suggest that estuaries could be a sink of microplastics.

仅有很少文献记录了河口中微塑料的含量和分布，并且通常没有考虑水柱中的垂直结构。这项研究提供了法国西南部阿杜尔河口微塑料的发生和分布的第一批​​数据。通过数值模拟对实验数据集进行补充，以了解悬浮微塑料的行为。在整个水柱中发现了微塑料，平均丰度为1.13份/ m ³。薄膜和碎片是收集到的最丰富的颗粒类型。数值模拟表明，微塑料在水柱中的垂直分布高度依赖于颗粒特性和局部流体动力学。主要趋势是，中性浮力的微塑料很容易被冲出，而较重的微塑料则容易在河口滞留，特别是在低排放条件下。本研究表明，河口可能是微塑料的汇。