摘要

对海洋累积塑料投入的估计数以亿吨表示，而海上漂浮的微塑料总质量则低于此数量级三个数量级。这种巨大的差距证明了我们对塑料的命运以及海洋中的变形和沉没的无知。当前的挑战之一包括识别和量化微尺度的塑料颗粒，小型微塑料（SMP，25-1000μm）。本研究的目的是调查海洋运动远征第七大陆期间北大西洋副热带环流海表面的SMP计数和质量密度。分离后，通过微傅里叶变换红外光谱表征SMP。微观弹性分布通过风力驱动的垂直混合校正模型建模，考虑单个颗粒特性（尺寸，形状和密度）。我们证明，与大型微塑料（LMP，1-5 mm）相比，SMP浮力显着降低，因此更容易垂直运输。未校正的LMP计数密度在13 000至174 000个km-2之间，并且是SMP的5至170倍。通过风力驱动的垂直混合校正，我们估计SMP比LMP丰富300至70 000倍。在校正后的重量方面进行讨论时，LMP密度在50到1 000 g km-2之间，SMP密度在5到14 000 g km-2之间。

Estimates of cumulative plastic inputs into the oceans are expressed in hundred million tons, whereas the total mass of microplastics afloat at sea is three orders of magnitude below this. This large gap is evidence of our ignorance about the fate of plastics, as well as transformations and sinks in the oceans. One of the current challenges consists of identifying and quantifying plastic particles at the microscale, the small microplastics (SMP, 25-1000 µm). The aim of the present study is to investigate SMP count and mass density at the sea surface in the North Atlantic subtropical gyre during the sea campaign Expedition 7th Continent. After isolation, SMP were characterized by micro-Fourier-transform infrared spectroscopy. Microplastic distribution was modeled by a wind-driven vertical mixing correction model taking into account individual particle properties (dimension, shape and density). We demonstrate that SMP buoyancy is significantly decreased compared to the large microplastics (LMP, 1-5 mm) and consequently more susceptible to vertical transport. The uncorrected LMP count density was between 13 000 and 174 000 pieces km-2, and was between 5 to 170 times more abundant for SMP. With a wind-driven vertical mixing correction, we estimated that SMP were 300 to 70 000 times more abundant than LMP. When discussing this in terms of weight after correction, LMP densities were between 50 to 1 000 g km-2, and SMP densities were between 5 and 14 000 g km-2.

https://www.ncbi.nlm.nih.gov/pubmed/30575384