College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
Science and Technology Resource Coordination Center of Hanzhong, Hanzhong, Shaanxi 723000, PR China.
Sci Total Environ. 2022 Aug 1;832:154962. doi: 10.1016/j.scitotenv.2022.154962. Epub 2022 Apr 1.
In freshwater ecosystems, microplastics (MPs) are commonly found in reservoirs. However, limited information is available on the distribution of MPs in the reservoirs. In this study, we investigated the horizontal and vertical distribution characteristics of MPs in the Guanyingyan reservoir (the upper reaches of the Yangtze River, China) after impoundment and the influence of free-floating plant residues on the distribution of MPs. Results indicated that the MPs abundance in the horizontal distribution of the reservoir decreased significantly while the distance from the dam increased. The abundance of MPs in shoreline waters (average: 8.45 items L) was significantly higher than that in central waters (average: 4.80 items L). As for the vertical distribution, the percentages of fibers in the three water layers (surface, intermediate, and deep) have less variation when compared to other types of MPs. Besides, MPs who are less than 0.5 mm in size are the majority. With deeper underwater, there would be more MPs with particles smaller than 200 μm in size. At the same time, there would be fewer MPs with particles ranging from 200 to 500 μm in size. PS, PP, and PE are the main polymer types of surface water, while PVC, PE, and PET are the common type in deep water. In shoreline water, the dry weight of floating plant residues showed a positive correlation with microplastic abundance in different layers. As above said, this study confirmed that MPs in reservoirs after impoundment would tend to accumulate in the front section of the reservoir and the shoreline water. Besides, free-floating plant residues would accumulate in reservoirs, resulting in the sinking of MPs.
在淡水生态系统中，微塑料（MPs）通常存在于水库中。然而，关于水库中 MPs 的分布情况，目前的信息有限。在这项研究中，我们调查了蓄水后观音岩水库（中国长江上游）的 MPs 水平和垂直分布特征，以及自由漂浮植物残体对 MPs 分布的影响。结果表明，随着与大坝距离的增加，水库水平分布中 MPs 的丰度显著降低。岸线水域（平均：8.45 个/升）中 MPs 的丰度明显高于中心水域（平均：4.80 个/升）。就垂直分布而言，与其他类型的 MPs 相比，三个水层（表层、中层和深层）中的纤维比例变化较小。此外，粒径小于 0.5 毫米的 MPs 占多数。随着水下深度的增加，粒径小于 200μm 的 MPs 会越多，而粒径在 200-500μm 之间的 MPs 会越少。同时，PS、PP 和 PE 是表层水的主要聚合物类型，而 PVC、PE 和 PET 是深水的常见类型。在岸线水域，漂浮植物残体的干重与不同层位微塑料丰度呈正相关。如前所述，本研究证实，蓄水后的水库中 MPs 会倾向于在水库前段和岸线水域积累。此外，自由漂浮的植物残体会在水库中积累，导致 MPs 下沉。
