Full size microplastics in crab and fish collected from the mangrove wetland of Beibu Gulf: Evidences from Raman Tweezers (1–20 μm) and spectroscopy (20–5000 μm)

Highlights: • Raman Tweezers were firstly used to detect small MPs in organisms from mangrove. • The proportion of small MPs cannot be negligible in organisms from mangrove. • Fiber is the main shape of the full-size MPs detected in organisms. • Total abundance of full-size MPs in GITs was higher than that of gills in organisms. Microplastic pollution in organisms is a growing environmental concern worldwide. Current methods to identify microplastics (MPs) are subject to the limitations of analytical techniques, and there is no full-scale method to measure MPs in organisms. In this study, Raman Tweezers and spectroscopy methods were combined and applied to identify MPs in organisms within the size range of 1–5000 μm. The abundance of small MPs (1–20 μm) was measured in crab (0.39–2.83 items/individual) and fish (0.35–3.22 items/individual). Most MPs were transparent in color and pellet shape. The proportion of small MPs (1–20 μm) was 35.77%, and analysis revealed the non-inclusion of this fraction will induce large deviations in the overall measurement. The large MPs (20–5000 μm) were identified in crab and fish with abundances ranging from 0.74–4.96 items/individual and 0.72–5.39 items/individual, respectively. Mainly fiber shape items were detected, the dominant particle size ranged from 20 to 100 μm, and most MPs were white. Polyethylene (PE) and polyethylene terephthalate (PET) were the main types of MPs polymers detected. Our study fills the gap to provide a new method to detect MPs in organisms below 20 μm, facilitating study of the migration and transformation of small MPs in the environment.