Abundance and distribution of large microplastics (1-5 mm) within beach sediments at the Po River Delta, northeast Italy

Abstract

Coastal areas are especially prone to plastic debris, being subjected to various land- and sea-based sources. Nevertheless, knowledge about microplastic distribution on beaches is limited, as studies focused either on high tide lines, specific items, or relied on visual identification. Beaches exhibit several accumulation zones and microplastic deposition depends on particle properties. We thus studied microplastic distribution (1-5 mm), including various types and shapes, among three driftlines at three beaches within the Po River Delta. Particles were analyzed using ATR-FTIR spectroscopy. Abundances ranged from 2.92 (± 4.86 SD) to 23.30 (± 45.43 SD) microplastics per kilogram dry weight between the beaches. The accumulation of microplastics among driftlines showed no consistent pattern, besides expanded polystyrene tending to accumulate backshore. We observed that accumulation hotspots within a single driftline can disrupt a general observed accumulation pattern. Thus, microplastic monitoring guidelines should further include protocols for the handling of accumulation hotspots within datasets.

Keywords: ATR-FTIR; Beach sediment; Microplastics; Monitoring; Po River Delta; Small-scale distribution.