First multi-compartment approach to microplastics in an urbanized estuary of Argentina: The case of Magallana gigas.

This study assesses MP in water, sediment, gills, and digestive tract of the oyster Magallana gigas in three Bahía Blanca estuary sites, Argentina, using, Pollution Load Index (PLI) and SEM/EDX (Scanning Electron Microscopy with Energy-dispersive X-ray spectroscopy) and FTIR (Fourier-transform infrared spectroscopy) techniques. A total of 51 MPs were detected in water (mean: 16 items L) and 126 in sediments (mean: 1399 items Kg) with no significant differences between sites. In oysters, 186 MPs were found, with no significant differences in the MPs load between gills (mean: 2.41 items g w.w), digestive tract (2.06 ± 2 items g w.w), and the total tissues. Transparent fiber MPs were predominant, with cellulose, polyamides, polyethylene terephthalate and polyethylene being common polymers. SEM/EDX showed Si, Fe, Cl, Na, Ti, Al, K, Ca and suspended particulate matter on MP surfaces. The PLI indicated a low-risk level for estuary bivalves and water, suggesting minimal MPs impact.