Spatial Patterns of Plastic Debris along Estuarine Shorelines

TLDR

Human waste production generates vast amounts of plastic debris, both macro- and micro-sized fragments, posing a significant contamination problem. The study tests how wind and depositional regime influence spatial patterns of micro- and macro-plastic debris in the Tamar Estuary, UK. FT‑IR spectroscopy identified polymer types and densities, and the authors inferred that slow‑settling sediment and plastic particles are transported by water flow to low‑velocity deposition zones. Microplastics comprised 65 % of debris, mainly PVC, polyester, and polyamide, with higher concentrations at downwind sites; macroplastic distribution favored less dense items, while microplastic patterns were driven by density, and no link to clay proportion was found, demonstrating FT‑IR can map spatial debris patterns and identify downwind sinks.

Abstract

The human population generates vast quantities of waste material. Macro (>1 mm) and microscopic (<1 mm) fragments of plastic debris represent a substantial contamination problem. Here, we test hypotheses about the influence of wind and depositional regime on spatial patterns of micro- and macro-plastic debris within the Tamar Estuary, UK. Debris was identified to the type of polymer using Fourier-transform infrared spectroscopy (FT-IR) and categorized according to density. In terms of abundance, microplastic accounted for 65% of debris recorded and mainly comprised polyvinylchloride, polyester, and polyamide. Generally, there were greater quantities of plastic at downwind sites. For macroplastic, there were clear patterns of distribution for less dense items, while for microplastic debris, clear patterns were for denser material. Small particles of sediment and plastic are both likely to settle slowly from the water-column and are likely to be transported by the flow of water and be deposited in areas where the movements of water are slower. There was, however, no relationship between the abundance of microplastic and the proportion of clay in sediments from the strandline. These results illustrate how FT-IR spectroscopy can be used to identify the different types of plastic and in this case was used to indicate spatial patterns, demonstrating habitats that are downwind acting as potential sinks for the accumulation of debris.