Microplastic research has expanded rapidly, yet substantial methodological variability continues to limit comparability across sediment studies. To characterize current practice and identify priority areas for harmonization, we conducted a systematic literature review (SLR) of 3290 records, from which 37 sediment-focused studies (18 marine, 19 freshwater) met the inclusion criteria. Methods were analyzed using a Reproducible Analytical Pipelines (RAPs) framework encompassing sampling, preparation, detection, and polymer identification. Sampling approaches varied widely: grab samplers dominated (55% of marine and 42% of freshwater studies), while corers (28% and 16%) and manual tools (5% and 16%) were less frequently used. Lower size thresholds spanned <0.1-1mm, with <0.1 mm most common in marine studies (45%) and less so in freshwater systems (30%). Density separation was nearly universal (36 of 37 studies), with sodium chloride used in over 70% of workflows despite its limited ability to recover high-density polymers; denser media were employed in fewer than 25% of studies. Oxidative digestion was the dominant method for removing organic matter (81%). Polymer confirmation relied overwhelmingly on μFTIR (35 studies), whereas Raman spectroscopy appeared in only four studies, primarily for particles <0.1mm. Overall, the SLR reveals partial methodological convergence but persistent divergence in key analytical parameters, highlighting clear priorities for future harmonization efforts.
Jefroy et al. (2026) studied this question.