PDF(Pubmed)
Abstract：
Microplastic particles move three-dimensionally through the ocean, but modeling studies often do not consider size-dependent vertical transport processes. In addition, microplastic fragmentation in ocean environments remains poorly understood, despite fragments making up the majority of microplastic pollution in terms of the number of particles and despite its potential role in mass removal. Here, we first investigate the role of particle size and density on the large-scale transport of microplastics in the Mediterranean Sea and next analyze how fragmentation may affect transport and mass loss of plastics. For progressively smaller particle sizes, microplastics are shown to be less likely to be beached and more likely to reach open water. Smaller particles also generally get mixed deeper, resulting in lower near-surface concentrations of small particles despite their higher total abundance. Microplastic fragmentation is shown to be dominated by beach-based fragmentation, with ocean-based fragmentation processes likely having negligible influence. However, fragmentation remains a slow process acting on decadal time scales and as such likely does not have a major influence on the large-scale distribution of microplastics and mass loss over periods less than 3 years.
摘要：
微塑料颗粒在海洋中三维移动，但是建模研究通常不考虑与尺寸相关的垂直运输过程。此外,海洋环境中的微塑料碎片仍然知之甚少，尽管就颗粒数量而言，碎片构成了微塑料污染的大部分，尽管它在质量去除中具有潜在的作用。这里,我们首先研究了粒径和密度在地中海微塑料大规模运输中的作用，然后分析了碎片如何影响塑料的运输和质量损失。对于逐渐变小的颗粒尺寸，微塑料被证明不太可能被搁浅，更有可能到达开阔水域。较小的颗粒通常也会混合得更深，导致较低的近表面浓度的小颗粒，尽管它们的总丰度较高。微塑料碎片被证明是以海滩为基础的碎片为主，基于海洋的破碎过程可能具有微不足道的影响。然而,碎片化仍然是一个缓慢的过程，作用于十年时间尺度，因此可能不会对微塑料的大规模分布和不到3年的质量损失产生重大影响。
