Abstract The abundance and distribution of plastic debris in natural waters is largely unknown due to limited comprehensive monitoring. Here, optical properties of dry and wet marine-harvested plastic debris were quantified to explore the feasibility of plastic debris optical remote sensing in the natural environment. We measured the spectral reflectance of microplastics ( 5 mm) washed ashore along the USA west coast and virgin plastic pellets over a wavelength range from 350 to 2500 nm. Compared to the spectral variability of multi-colored dry macroplastics, the measured dry marine-harvested microplastic reflectance spectra could be represented as a single bulk average spectrum with notable absorption features at ~ 931, 1215, 1417 and 1732 nm. The wet marine-harvested microplastics had similar spectral features to the dry microplastics but the magnitude was lower over the measured spectrum. When spectrally matched to the reference library of typical dry virgin pellets, the mean dry marine-harvested microplastics reflectance had moderate similarities to low-density polyethylene, polyethylene terephthalate, polypropylene and polymethyl methacrylate. This composition was consistent with the subset sampled with the Fourier Transform Infrared (FTIR) spectrometer and what has been reported globally. The absorption features at 1215 and 1732 nm were observable through an intervening atmosphere and used to map the distributions of synthetic hydrocarbons at a landfill and on man-made structures from airborne visible-infrared imaging spectrometer (AVIRIS) imagery, indicating the potential to remotely sense dry washed ashore and land-origin plastics. These same absorption features were identifiable on wet marine-harvested microplastics, but the ability to conduct remote sensing of microplastics at the ocean surface layer will require more detailed radiative transfer analysis and development of high signal-to-noise sensors. The spectral measurements presented here provide a foundation for such advances towards remote detection of plastics from various platforms.

中文翻译：

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使用从海洋收获的大塑料和微塑料中识别出的短波红外吸收特征进行合成碳氢化合物检测的航空遥感案例研究

摘要 由于综合监测有限，天然水域中塑料碎片的丰度和分布在很大程度上是未知的。在这里，量化了干湿海洋收获塑料碎片的光学特性，以探索塑料碎片光学遥感在自然环境中的可行性。我们测量了沿美国西海岸冲上岸的微塑料 (5 毫米) 和原始塑料颗粒在 350 到 2500 纳米波长范围内的光谱反射率。与多色干大塑料的光谱变异性相比，测量的干海洋收获微塑料反射光谱可以表示为单个整体平均光谱，在 ~ 931、1215、1417 和 1732 nm 处具有显着的吸收特征。从海洋中收获的湿微塑料与干微塑料具有相似的光谱特征，但在测量光谱中幅度较低。当与典型干燥原始颗粒的参考库进行光谱匹配时，平均干燥的海洋收获微塑料反射率与低密度聚乙烯、聚对苯二甲酸乙二醇酯、聚丙烯和聚甲基丙烯酸甲酯具有中等相似性。这种成分与傅里叶变换红外 (FTIR) 光谱仪采样的子集以及全球报道的内容一致。1215 和 1732 nm 处的吸收特征可通过介入大气观察到，并用于从机载可见红外成像光谱仪 (AVIRIS) 图像绘制垃圾填埋场和人造结构上合成碳氢化合物的分布图，表明有可能遥感干洗上岸和陆源塑料。这些相同的吸收特征在湿的海洋收获的微塑料上是可识别的，但在海洋表层对微塑料进行遥感的能力需要更详细的辐射传输分析和高信噪比传感器的开发。此处介绍的光谱测量为从各种平台远程检测塑料提供了此类进展的基础。