State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; University of Chinese Academy of Sciences, Beijing, 100039, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
Chemosphere. 2019 May;222:856-864. doi: 10.1016/j.chemosphere.2019.02.015. Epub 2019 Feb 6.
Plastic pollution has been increasingly reported in both marine environment and inland waters, but their fate is not well understood. Several studies have showed that the surface of plastic debris can be colonized by microbes, leading to the sinking of floating plastic debris in marine environment. In this work, development of biofilm on polypropylene sheet (squares with a side length of 5 and 10 mm) and their buoyancy changes were studied in a freshwater lake in four seasons. Results showed that biofilm development have different growth rate and distinct algae composition in different seasons, which are mainly related to the difference in temperature, nutrient levels, and suspend solids in lake water. Biofilm development was much quicker on small plastics in all seasons. At the end of the experiment, all plastics lost buoyancy in summer while only a small portion lost buoyance in other seasons. Sinking of the floating plastics can be attributed to the development of biofilm and the trapped minerals. Our results demonstrated that biofilm development can cause the sinking of floating plastics in fresh lakes but the time required to lose buoyance can differ seasonally. Floating plastics will remain in water for a longer time in cold season but sink in a short time in warm season. Future research is required to determine the influence of plastic types and shapes, and quantitative relation between environmental variables and the sinking behavior of the fouled plastics should be established for a better prediction of their fate in the freshwater environment.
塑料污染在海洋环境和内陆水域中都有越来越多的报道，但它们的命运还没有得到很好的理解。几项研究表明，塑料碎片的表面可以被微生物定殖，导致海洋环境中漂浮的塑料碎片下沉。在这项工作中，研究了在四个季节的一个淡水湖中，聚丙烯片（边长为 5 和 10 毫米的正方形）上生物膜的发展及其浮力变化。结果表明，生物膜的发展在不同季节具有不同的生长速度和明显不同的藻类组成，这主要与温度、营养水平和湖水悬浮物的差异有关。在所有季节，小塑料上的生物膜发展都更快。实验结束时，所有塑料在夏季都失去了浮力，而在其他季节只有一小部分失去了浮力。漂浮塑料的下沉可归因于生物膜的发展和被困矿物质。我们的结果表明，生物膜的发展会导致淡水湖中漂浮塑料下沉，但失去浮力所需的时间可能因季节而异。在寒冷季节，漂浮塑料将在水中停留更长时间，但在温暖季节会迅速下沉。未来需要研究不同类型和形状的塑料以及环境变量与污染塑料下沉行为之间的定量关系，以更好地预测它们在淡水环境中的命运。
