Plastic litter pollution is one of the major concerns for the health of marine ecosystems worldwide. This pervasive form of pollution affects all oceans and seas and it's interacting with multiple levels of the marine food webs. In the European context, several pieces of legislation try to fight against this pervasive and ubiquitous form of pollution. Recently, EU Member States have agreed to a maximum threshold of litter items per coast length (20 items/100 m coastline). One major concern among stakeholders to reach this consensus was the transboundary litter, as measures need to be implemented in the country of origin. Henceforth, a solid method to estimate the amounts of the transboundary litter to a given Member State's coasts is needed. In this contribution, we use a combination of hydrodynamic and Lagrangian models for the Mediterranean Sea in order to understand the origin of coastal litter. Simulations show that the amount of transboundary litter in Mediterranean countries could be as large as 30% although both regional and seasonal differences could be significant.

塑料垃圾污染是全球海洋生态系统健康的主要问题之一。这种普遍的污染形式影响着所有海洋，并与海洋食物网的多个层次相互作用。在欧洲范围内，有几项立法试图对抗这种普遍存在的污染形式。最近，欧盟成员国已同意每个海岸长度的垃圾物品的最大阈值（20 件/100 米海岸线）。利益相关者达成这一共识的一个主要问题是跨界垃圾，因为需要在原产国实施措施。今后，需要一种可靠的方法来估计特定成员国海岸的跨界垃圾数量。在本次投稿中，我们结合了地中海的水动力模型和拉格朗日模型，以了解沿海垃圾的起源。模拟表明，地中海国家的跨界垃圾数量可能高达 30%，尽管区域和季节差异可能很大。