Is wind a good proxy for floating microplastics? A case study in Galway Bay, Ireland

, Frias João, Lyashevska Olga, Haleigh Joyce, Pagter Elena, Nash Roisin.

According to a recent report, floating microplastic debris at the ocean's surface represent approximately 1% of all plastics found in the environment, while 99% are thought to either be deposited at along coastlines or at the bottom of the ocean. This exploratory research work conducted on Galway Bay, a coastal bay located in the Northeast Atlantic Ocean, assesses the density of floating microplastics and the potential influence of wind in their dispersal. Twenty manta trawl samples retrieved a total of 1182 microplastics from a total surface seawater volume of 2039.86 m3. The average microplastic density (0.56 ± 0.33 MP m‑3), which mainly comprised fibres (n=1017), followed by fragments (n=148), fishing line (n=9), beads (n=3), films (n=2) and foams (n=2). This study reports for the first time primary microplastics (microbeads) floating in Irish coastal waters, which could probably result from personal care items, although source it is not obvious. Black was the predominant microplastic colour, followed by blue and red. This exploratory study provides a snapshot of microplastics density in Galway Bay where the results show no obvious pattern of microplastic distribution based solely on wind speed and direction. Therefore, oceanic currents, like other authors suggest, seem to play a more influential role on surface microplastic distribution. Although the abundance of microplastic densities is slightly higher than similar bays around the world, they are in the same order of magnitude. This work highlights that microplastics in surface waters are a multifaceted issue which requires multiple sample collection points for coastal monitoring in order to reflect the area being sampled and ensuring a more holistic approach.

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