Abstract：
Polystyrene foam is widely used due to its lightweight, impact resistance, and excellent thermal insulation properties. Meanwhile, weak adhesion between beads in polystyrene foam leads to fragmentation, generating a substantial amount of microplastics (<5 mm). Such polystyrene foam debris littered on beaches diminishes the aesthetic value of coastal areas, negatively impacting tourism. Due to its density lower than other plastics, polystyrene foam macroplastics float on the sea surface and, thus, they are significantly influenced by wind drag during oceanic transport. In contrast, polystyrene foam microplastics drifting beneath the sea surface are carried mostly by ocean currents. These properties of polystyrene foam macroplastics and microplastics hinder the elucidation of their transport, distribution, and fate in nature, despite their potential to adversely impact marine ecosystems. To elucidate the generation, transport, and fragmentation processes of polystyrene foam ocean plastics, we conducted concurrent visual observations and surface net towing from seven training vessels around Japan during 2014-2020. Overall, the abundances of polystyrene foam ocean plastics were higher in the Sea of Japan than in the North Pacific south of Japan. The average abundances of polystyrene foam microplastics and macroplastics were 0.33 pieces/m3 and 0.45 pieces/km, respectively, over the entire sea area around Japan. In the Sea of Japan, the peak abundances of polystyrene foam macroplastics occurred in upstream of the Tsushima Current, while the peak for microplastics occurred downstream, suggesting that continuous fragmentation occurred during transport between the two peaks. Backward-in-time particle tracking model experiments suggested that the sources of polystyrene foam macroplastics observed in the Sea of Japan included aquaculture buoys and styrene debris beached around the Tsushima Strait. The present study demonstrated that reducing the release of polystyrene foam aquaculture floats will likely diminish the abundance of ocean plastics in the Sea of Japan.
摘要：
聚苯乙烯泡沫由于其轻质而被广泛使用,耐冲击性,和优良的隔热性能。同时,聚苯乙烯泡沫中珠子之间的弱粘附会导致碎裂，产生大量的微塑料（<5毫米）。这种聚苯乙烯泡沫碎片散落在海滩上，削弱了沿海地区的美学价值，对旅游业产生负面影响。由于其密度低于其他塑料，聚苯乙烯泡沫大塑料漂浮在海面上，因此，在海洋运输过程中，它们受到风阻力的显著影响。相比之下,漂浮在海面下的聚苯乙烯泡沫微塑料主要由洋流携带。聚苯乙烯泡沫大塑料和微塑料的这些特性阻碍了它们运输的阐明，分布，自然界中的命运，尽管它们有可能对海洋生态系统产生不利影响。为了阐明这一代人，运输,和聚苯乙烯泡沫海洋塑料的破碎过程，我们在2014-2020年期间对日本各地的7艘训练船进行了同时的视觉观察和水面网拖曳.总的来说,日本海的聚苯乙烯泡沫海洋塑料的丰度高于日本南部的北太平洋。聚苯乙烯泡沫微塑料和大型塑料的平均丰度为0.33片/m3和0.45片/km，分别,在日本周围的整个海域。在日本海,聚苯乙烯泡沫塑料的峰值丰度发生在对马水流的上游，虽然微塑料的峰值出现在下游，表明在两个峰之间的运输过程中发生了连续的碎裂。时间落后的粒子跟踪模型实验表明，在日本海中观察到的聚苯乙烯泡沫宏观塑料的来源包括水产养殖浮标和对马海峡周围搁浅的苯乙烯碎片。本研究表明，减少聚苯乙烯泡沫水产养殖浮标的释放可能会减少日本海中海洋塑料的丰度。
