Microplastic Contamination and Geochemical Tracers in the Goro Lagoon Ecosystem: Pathways, Fate, and Biota Interactions

This study investigates microplastic pollution pathways and fate in the Goro Lagoon (NW Adriatic Sea), integrating geochemical and stable isotope analyses across sediments, lagoon waters, and bivalve mollusks (Ruditapes philippinarum) to trace contaminant dispersion and bioaccumulation. We developed a validated protocol for microplastic extraction from complex, organic-rich matrices: alkaline H₂O₂/NaOH digestion, oil separation exploiting the lipophilic properties of plastics, Nile Red staining, and stereomicroscopic quantification under blue light with ImageJ for size distribution. Microplastics were ubiquitous, with the highest abundances found in sediments and biota, indicating widespread environmental contamination. Complementary ICP-MS (32 trace/major elements), EA-IRMS (δ¹³C, δ¹⁵N, %C/%N; δ¹⁸O in shells), and XRF analyses revealed distinct chemical and isotopic signatures across matrices, reflecting local environmental gradients and stressors. These patterns highlight microplastic hotspots linked to sediment-water exchanges and bivalve uptake within lagoon dynamics. These findings underscore microplastics as persistent marine pollutants interacting with coastal geochemistry and biota, supporting sustainable shellfish management and advancing monitoring protocols for pollution assessment.