Aix Marseille Univ, CNRS, LCE, Marseille, France.
Université Clermont Auvergne, CNRS, UMR 6296, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF), 8 Avenue Blaise Pascal, TSA 60026, CS 60026, 63178, Aubière, Cedex, France.
Environ Pollut. 2021 Jul 1;280:116949. doi: 10.1016/j.envpol.2021.116949. Epub 2021 Mar 17.
Plastic debris in the marine environment are the subject of an extensive literature. According to studies dedicated to the determination of plastic litter abundance and to the characterisation of degradation and fragmentation processes, models were used to estimate the global plastic debris abundance and to simulate their transfer and distribution. Despite these efforts, there is still missing plastic in the models used as areas exist where plastic abundance is less than that estimated. In parallel, microplastics presence in the atmosphere and in remote areas was confirmed suggesting long range atmospheric transport. Potentially addressing both these issues, recent literature suggests that microplastics (MPs) and nanoplastics (NPs) can be transferred from the marine environment to the atmosphere via the bursting of air bubbles at the sea surface. Nevertheless, to date there is no direct evidence of this transfer. In this study, we evaluate plastic particles transfer as a function of MPs/NPs characteristics and water composition by simulating the bubble bursting phenomenon in a laboratory reactor. Size distribution of transferred particles were recorded, and their plastic nature was confirmed using electron microscopy. Results show that under tested conditions, the transfer is possible but limited to particles smaller than 1 μm. The influence of the presence of proxies of components of the sea surface microlayer in the water was evaluated showing a higher particle transfer rate in the presence of a surfactant (sodium dodecyl sulfate) and no significant effect of polysaccharides (xanthan gum and dextran). The surface state of the particles can alter their behaviour in the aqueous phase and thus their transfer to the atmosphere. The effect of bubble size was also evaluated showing a higher transfer rate with the smaller bubble size. In addition, experiments performed with grounded polyethylene (PE) samples showed higher transfer for UV-aged PE than for pristine PE.
海洋环境中的塑料碎片是大量文献的主题。根据专门用于确定塑料垃圾丰度和表征降解和碎片化过程的研究，使用模型来估计全球塑料碎片丰度并模拟其转移和分布。尽管做出了这些努力，但模型中仍存在缺失的塑料，因为存在塑料丰度低于估计值的区域。与此同时，大气中和偏远地区存在微塑料的情况得到了证实，这表明存在长距离大气传输。最近的文献表明，微塑料 (MPs) 和纳米塑料 (NPs) 可以通过海面气泡爆裂从海洋环境转移到大气中，从而可能解决这两个问题。然而，迄今为止，没有直接证据表明存在这种转移。在这项研究中，我们通过在实验室反应器中模拟气泡爆裂现象，评估了作为 MPs/NPs 特性和水成分函数的塑料颗粒转移。记录了转移颗粒的大小分布，并使用电子显微镜确认了它们的塑料性质。结果表明，在测试条件下，转移是可能的，但仅限于小于 1μm 的颗粒。评估了海表微层成分的代表物质在水中存在的影响，结果表明，在存在表面活性剂（十二烷基硫酸钠）的情况下，颗粒转移率更高，而多糖（黄原胶和葡聚糖）没有显著影响。颗粒表面状态会改变其在水相中的行为，从而影响其向大气中的转移。还评估了气泡大小的影响，结果表明较小的气泡尺寸具有更高的转移率。此外，用研磨后的聚乙烯 (PE) 样品进行的实验表明，经紫外线老化的 PE 比原始 PE 的转移率更高。
