Dynamics and early post-tsunami evolution of floating marine debris near Fukushima Daiichi
Dynamics and early post-tsunami evolution of floating marine debris near Fukushima Daiichi
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DOI：
10.1038/ngeo2975
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发表时间：
2017-08-01
影响因子：
18.3
通讯作者：
Tamura, Hitoshi
中科院分区：
文献类型：
--
作者：
Matthews, John Philip;Ostrovsky, Lev;Tamura, Hitoshi
2011年3月11日东北冲地震引发的毁灭性海啸在福岛第一核电站引发了一场危机，冲垮了海堤防御工事。在撤退时，海啸将松散的碎片和残骸带向大海，并将浮力物质编织成广泛的羽状物。对这些和其他许多东北海啸沉积的命运的广泛担忧促使人们尝试模拟碎片在更广泛的太平洋上的扩散。然而，局部扰动的风场和波浪场、活跃的朗缪尔环流和电流诱导的磨损的影响决定了大型漂浮聚团的复杂和鲜为人知的形态。在这里，我们展示了海啸后福岛第一核电站附近海洋垃圾羽流的早期演变也是由发生在相对平静(较低表面粗糙度)水域上方的近地表风场改造形成的，水面上覆盖着来自石油和其他污染物的表层薄膜。高空间分辨率卫星跟踪显示，这些区域内的漂浮碎片运动速度快于预期，羽流演化活跃，而对低阻力、覆盖薄膜的表面上的湍流气流进行的数值模拟通常预测厘米高度的风速以每秒米的速度增强，这足以解释观察到的碎片速度的增加。风的重组可能会刺激生物和人为来源的漂浮物在全球海洋表面粗糙度高度可变的情况下扩散。
The devastating tsunami triggered by the Tohoku-Oki earthquake of 11 March 2011 caused a crisis at the Fukushima Daiichi nuclear power station where it overtopped the seawall defences. On retreating, the tsunami carried loose debris and wreckage seaward and marshalled buoyant material into extensive plumes. Widespread concern over the fate of these and numerous other Tohoku tsunami depositions prompted attempts to simulate debris dispersion throughout the wider Pacific. However, the effects of locally perturbed wind and wave fields, active Langmuir circulation and current-induced attrition determine a complex and poorly understood morphology for large floating agglomerations. Here we show that the early post-tsunami evolution of marine-debris plumes near Fukushima Daiichi was also shaped by near-surface wind modifications that took place above relatively calm (lower surface roughness) waters covered by surface films derived from oil and other contaminants. High-spatial-resolution satellite tracking reveals faster-than-expected floating-debris motions and invigorated plume evolution within these regions, while numerical modelling of turbulent air flow over the low-drag, film-covered surface predicts typically metre-per-second wind strengthening at centimetric heights, sufficient to explain the observed debris-speed increases. Wind restructuring probably stimulates the dispersion of flotsam from both biological and anthropogenic sources throughout a global ocean of highly variable surface roughness.