Microplastic and nanoplastic debris left behind by a plastic water tank subjected to a mimicked bushfire

Little is known about the catastrophic bushfire from a micro-pollution point of view, and there is also very limited understanding of the emerging contamination of microplastics and nanoplastics. Upon exposure to fire, plastic items, such as water tanks, may release a substantial quantity of microplastics and nanoplastics, as characterized in this study through the analysis of residual debris. Using Raman imaging with the scanning pixel size down to 100 nm × 100 nm, we over-scan the sample surface to collect a hyperspectral matrix. In order to map and convert the scanning hyperspectral matrix to an image, we compare and advance the chemometrics of algorithms, including logic and principal component analysis (PCA), to extract the weak signal of microplastics and particularly nanoplastics, which enables us to directly visualize the different degrees of burning. By doing so, we can identify the microplastics and nanoplastics down to ˜100 nm, which means that we can break through the diffraction limit of the laser which is ˜296 nm (λ/2NA) to capture nanoplastics. Using statistical analysis, we estimate that 1.4–4.7 million micro- and nanoplastics per cm2 can be left behind by the mimicked-bushfire-burned plastic tank. This study suggests that bushfire can accelerate the release of micro- and nanoplastics in the environment. This study not only contributes essential insights into the micro-pollution consequences of fire burning but also underscores the urgency of addressing this understudied aspect to inform environmental conservation strategies and public health measures.