Detection of microplastic pollution in top soils using optical reflectance spectroscopy from the ultraviolet to shortwave infrared: a review

Environmental pollution by microplastic (MP) particles is a global issue. So far, the majority of publications have focused on the presence of MPs in aquatic environments; however, more recently, other elements of the ecosystem, including soil, have also begun to be studied. Optical reflectance spectroscopy methods are increasingly being used to detect the presence and estimate the concentration of MPs. Among these methods, field and laboratory spectral measurements are relatively cost-effective and quick. Other methods based on analyzing radiation reflected from particles include hyperspectral imaging systems and the use of satellite imagery. Existing publications demonstrate that the adopted methodology enables the identification and differentiation of particles made of various plastic types in different soil samples. However, there is a need for further research, primarily focused on developing comprehensive spectral reference libraries of different plastic types and soil types, with particular emphasis on variations in optical reflectance caused by color of plastic, sample concentration, degree of fragmentation, and other factors.