College of Oceanography, Hohai University, Nanjing 210098, China.
College of Oceanography, Hohai University, Nanjing 210098, China.
Water Res. 2023 Oct 1;244:120493. doi: 10.1016/j.watres.2023.120493. Epub 2023 Aug 15.
Elucidating the mechanisms governing microplastic transport and spatial distribution in offshore waters is essential to microplastic control. However, current research on microplastic transport in the China Seas is largely restricted to small-scale investigations, which do not provide a comprehensive result. Therefore, in this study, we used the Regional Ocean Modeling System (ROMS) combined with the Lagrangian Transport (LTRANS v.2) model to investigate how microplastics are transported around the China Seas during different seasons and under climatological river discharge. Our findings showed that the microplastic pathways and spatial distributions exhibit marked seasonal variations controlled by circulation patterns in the China Seas, river discharge values, and the characteristics of the microplastic materials. Floating microplastics exhibited the longest transport distance in summer, when microplastics from the Pearl River could be transported up to 1375.8 km through the Tokara and Tsushima straits. The heavy pollution areas in summer were located in the South Yellow Sea and East China Sea, mainly resulting from the contribution of the Yangtze River (>66%). In autumn and winter, more than three-quarters of the microplastics beached off the south-central Chinese coast. In addition, simulating the vertical velocity of the water prolonged the time required for microplastics to reach the open ocean, thereby reducing the amount of microplastics entering the Pacific Ocean by 6% compared to the simulation without the vertical velocity of the water in summer. Microplastics with higher densities were generally transported shorter distances. The transmission distances of PET and PS were two orders of magnitude smaller than that of PE. This study enhances knowledge of the sources and fates of offshore microplastics and provides scientific support for offshore microplastic control.
阐明控制微塑料在近海水中迁移和空间分布的机制对于微塑料控制至关重要。然而，目前中国海的微塑料迁移研究主要局限于小规模调查，这些调查无法提供全面的结果。因此，在这项研究中，我们使用区域海洋模式系统（ROMS）结合拉格朗日输运（LTRANS v.2）模型，研究了在不同季节和气候河流排放条件下，微塑料如何在中国海周围迁移。我们的研究结果表明，微塑料的迁移路径和空间分布表现出明显的季节性变化，受中国海的环流模式、河流排放值和微塑料材料特性的控制。浮式微塑料在夏季的迁移距离最长，此时珠江的微塑料可以通过吐噶喇海峡和对马海峡输送到 1375.8 公里处。夏季重污染区位于南黄海和东海，主要是由长江的贡献（超过 66%）造成的。在秋季和冬季，超过四分之三的微塑料在华南海岸登陆。此外，模拟水的垂直速度延长了微塑料到达开阔海洋所需的时间，与夏季不考虑水的垂直速度的模拟相比，进入太平洋的微塑料减少了 6%。密度较高的微塑料通常迁移的距离较短。PET 和 PS 的传输距离比 PE 小两个数量级。这项研究提高了对近海微塑料来源和命运的认识，为近海微塑料控制提供了科学支持。
