Abundance, Morphology and Diversity of Microplastics on Beaches in Northern Ireland

Microplastics pose a growing environmental threat across beaches globally. A first step in management is to assess their concentration in the natural environment and identify sources and transportation vectors. In this study microplastic abundance, morphologies, colourations, diversity and relationships with potential influencing variables were assessed for six different beaches along Northern Ireland’s north coast. Beaches with a range of anthropogenic pressures were sampled in summer and winter to evaluate sources and transportation mechanisms of microplastics. Significant differences were noted in microplastic abundances between urban and rural beaches (p=0.004), and between summer and winter (p=0.03). Fibres were the most abundant morphology (76.6%) and blue was the most common microplastic colouration (46.7%). Blue fibres were the most observed morphology/colouration combination (40.7%). Fibres correlated positively with river presence and storm water outlets, while fragments correlated with urbanisation. Microplastics were ubiquitous across all beaches regardless of beach rurality or season. Pollution risk (higher MP abundances and diversity) increased in summer and on urban beaches. Summer tourism, rivers and storm water outlets were identified as likely transportation vectors.