Kooi Merel, Nes Egbert H van, Scheffer Marten, Koelmans Albert A
Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University & Research , P.O. Box 47, 6700 AA Wageningen, The Netherlands.
Wageningen Marine Research, P.O. Box 68, 1970 AB IJmuiden, The Netherlands.
Environ Sci Technol. 2017 Jul 18;51(14):7963-7971. doi: 10.1021/acs.est.6b04702. Epub 2017 Jun 29.
Recent studies suggest size-selective removal of small plastic particles from the ocean surface, an observation that remains unexplained. We studied one of the hypotheses regarding this size-selective removal: the formation of a biofilm on the microplastics (biofouling). We developed the first theoretical model that is capable of simulating the effect of biofouling on the fate of microplastic. The model is based on settling, biofilm growth, and ocean depth profiles for light, water density, temperature, salinity, and viscosity. Using realistic parameters, the model simulates the vertical transport of small microplastic particles over time, and predicts that the particles either float, sink to the ocean floor, or oscillate vertically, depending on the size and density of the particle. The predicted size-dependent vertical movement of microplastic particles results in a maximum concentration at intermediate depths. Consequently, relatively low abundances of small particles are predicted at the ocean surface, while at the same time these small particles may never reach the ocean floor. Our results hint at the fate of "lost" plastic in the ocean, and provide a start for predicting risks of exposure to microplastics for potentially vulnerable species living at these depths.
近期研究表明，海洋表面存在对小塑料颗粒进行尺寸选择性清除的现象，这一观察结果仍无法得到解释。我们研究了关于这种尺寸选择性清除的一种假设：微塑料上生物膜的形成（生物污损）。我们开发了首个能够模拟生物污损对微塑料归宿影响的理论模型。该模型基于沉降、生物膜生长以及光、水密度、温度、盐度和粘度的海洋深度剖面。利用实际参数，该模型模拟了小尺寸微塑料颗粒随时间的垂直输运，并预测这些颗粒会根据其大小和密度要么漂浮、要么沉入海底、要么进行垂直振荡。预测的微塑料颗粒与尺寸相关的垂直运动导致在中间深度出现最大浓度。因此，预计海洋表面小颗粒的丰度相对较低，而与此同时这些小颗粒可能永远不会到达海底。我们的研究结果暗示了海洋中“失踪”塑料的归宿，并为预测生活在这些深度的潜在脆弱物种接触微塑料的风险提供了开端。
