Assessment of Microplastic in the Western Irish Sea Gyre: From Surface to Sediment

Abstract:

Up to 236 thousand tonnes of microplastic are estimated to be in the ocean’s surface water yet high-resolution data sets from physical observations in shelf seas and oceans are scarce. Macro-scale gyres are known accumulation zones of plastic however, meso-scale, seasonal gyres are less discussed in the literature. In some cases, the proximity of these gyres to the coast, as well as the timescales over which they form, could give an interesting insight into extent of microplastic contamination in a particular region, as well as the wider hydrodynamics of the gyre itself. Data of microplastic contamination in much of the Irish Sea (a generally energetic semi-enclosed shelf sea system) is yet to be published, the details of which could be of interest to the communities of the highly populated coastlines in the region.

Details of a field campaign through the Western Irish Sea Gyre aiming to resolve spatial variability of microplastic in surface, sub-surface and seabed sediments will be presented. Over 200 surface, sub-surface and seabed samples were collected aboard the Bangor University’s School of Ocean Science’s RV Prince Madog during July 2020 using trongo nets, niskin bottles and a box corer. Researchers collecting data visually identified microplastic particles in the surface water of the gyre, but more detailed analysis is now needed. The samples will be analysed for microplastic extent, mass and composition using LD-IR and sediments dated using radioactive Pb²¹⁰.

Being able to understand and quantify current microplastic contamination within the Western Irish Sea Gyre will lay the foundations for research into microplastic contamination at larger scales within the Irish Sea, and provide much needed data for the validation of regional microplastic dispersal models.