LIBS-Based Detection and Preliminary Classification of Microplastic Signatures in Soil Samples.

Contamination of terrestrial systems by microplastics (MPs) has become a critical environmental hazard, but detection of such contaminants in a complex soil system is a challenge for conventional analytical techniques. This research aims to assess the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for the detection and differentiation of different types of microplastics, including HDPE, LDPE, PP, PS, and PVC, dispersed in the soil of Al Najaf, Iraq. Soil samples were collected from different functional zones, namely, Industrial, Commercial, Agricultural, Residential, and Roadside, at the surface level and 30 cm depth. Detection was done by measuring the intensity of the C/H ratio, where the Carbon emission line was fixed at 247.86 nm, and the Hydrogen emission line was fixed at 388.47 nm, and the results were compared with the atomic spectra given in the NIST database. The results showed a strong relationship between different types of polymers and different functional zones, where the industrial zone was showed spectral signatures most consistent with HDPE, the roadside was showed a predominance of PS spectral fingerprints, and the agricultural zone showed consistency in PVC vertical distribution. Although the residential prediction was in favor of LDPE, the empirical results pointed towards PET and PVC, which was due to the effect of synthetic fibers and debris. The conclusion of the research was that the proposed method of LIBS, which uses the ratio method, may help reduce the influence of the background matrix interferences of carbonate-rich and gypsiferous soils, thereby providing a cost-effective and rapid solution for the environmental analysis of the diffusion of microplastics in arid terrestrial environments.