Purpose

Microplastics have become a ubiquitous pollutant in marine, terrestrial and freshwater systems that seriously affects aquatic and terrestrial ecosystems. Common methods for analysing microplastic abundance in soil or sediments are based on destructive sampling or involve destructive sample processing. Thus, substantial information about local distribution of microplastics is inevitably lost.

Methods

Tomographic methods have been explored in our study as they can help to overcome this limitation because they allow the analysis of the sample structure while maintaining its integrity. However, this capability has not yet been exploited for detection of environmental microplastics. We present a bimodal 3D imaging approach capable to detect microplastics in soil or sediment cores non-destructively.

Results

In a first pilot study, we demonstrate the unique potential of neutrons to sense and localize microplastic particles in sandy sediment. The complementary application of X-rays allows mineral grains to be discriminated from microplastic particles. Additionally, it yields detailed information on the 3D surroundings of each microplastic particle, which supports its size and shape determination.

Conclusion

The procedure we developed is able to identify microplastic particles with diameters of approximately 1 mm in a sandy soil. It also allows characterisation of the shape of the microplastic particles as well as the microstructure of the soil and sediment sample as depositional background information. Transferring this approach to environmental samples presents the opportunity to gain insights of the exact distribution of microplastics as well as their past deposition, deterioration and translocation processes.

中文翻译：

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互补中子和X射线断层扫描技术无损检测和定位沙质沉积物中的微塑性颗粒

目的

微塑料已成为海洋，陆地和淡水系统中普遍存在的污染物，严重影响了水生和陆地生态系统。分析土壤或沉积物中微塑性丰度的常用方法是基于破坏性采样或涉及破坏性样品处理。因此，不可避免地会丢失有关微塑料局部分布的大量信息。

方法

层析成像方法在我们的研究中得到了探索，因为它们可以帮助克服这一局限性，因为它们可以在保持完整性的同时分析样品结构。但是，该功能尚未用于检测环境微塑料。我们提出了一种双峰3D成像方法，能够无损检测土壤或沉积物核心中的微塑性。

结果

在首次试点研究中，我们证明了中子在沙质沉积物中感测和定位微塑性颗粒的独特潜力。X射线的补充应用可以使矿物颗粒与微塑料颗粒区分开。此外，它还提供了有关每个微塑料颗粒3D周围环境的详细信息，这有助于确定其大小和形状。

结论

我们开发的程序能够识别沙土中直径约为1毫米的微塑性颗粒。它还可以表征微塑料颗粒的形状以及土壤和沉积物样品的微观结构，作为沉积背景信息。将这种方法转移到环境样品中提供了机会，可以深入了解微塑料的确切分布及其过去的沉积，劣化和易位过程。