Medina Faull LE, Zaliznyak T, and Taylor GT. (2021) Assessing diversity, abundance, and mass of microplastics (~ 1–300 μm) in aquatic systems Limnology and Oceanography: Methods. doi: 10.1002/lom3.10430
Recent improvements in survey methods for microplastic (MP) pollution in natural waters have enabled quantification of MP particles < 300 μm in diameter. Historically, this putatively important size fraction of MP particles has not been sampled adequately, possibly leading to significant underestimations of plastic inventories in aquatic systems. Using Raman microspectroscopy coupled with three-dimensional (3D) spectral imaging, we developed a methodology to detect, identify, and quantify MPs retained on filters from discrete water samples. Raman spectral information enabled identification of plastic polymers in particles between 0.5 and 300 μm in diameter and generation of 3D chemical maps. This methodology provides accurate estimations of the smallest MP particles’ contributions to total MP mass in water samples, providing vital information for mass flux calculations of MPs in natural waters.
Example of a 3D chemical map of a PP particle produced by our Raman microspectroscopic volume mapping routine. (a) Reflected bright-field micrograph of a MP particle. (b) Representative Raman spectrum from the particle revealing diagnostic peaks (808 and 840 cm−1) for PP. (c) 3D chemical volume map of the particle based on distribution of a diagnostic PP Raman spectral peak (808 cm−1).
Example of a 3D chemical map of a PP particle produced by our Raman microspectroscopic volume mapping routine. (a) Reflected bright-field micrograph of a MP particle. (b) Representative Raman spectrum from the particle revealing diagnostic peaks (808 and 840 cm−1) for PP. (c) 3D chemical volume map of the particle based on distribution of a diagnostic PP Raman spectral peak (808 cm−1).
