Microplastics are widely dispersed throughout the marine environment. An understanding of the distribution and accumulation of this form of pollution is crucial for gauging environmental risk. Presented here is the first record of plastic contamination, in the 5 mm–250 μm size range, of Irish continental shelf sediments. Sixty-two microplastics were recovered from 10 of 11 stations using box cores. 97% of recovered microplastics were found to reside shallower than 2.5 cm sediment depth, with the area of highest microplastic concentration being the water-sediment interface and top 0.5 cm of sediments (66%). Microplastics were not found deeper than 3.5 ± 0.5 cm. These findings demonstrate that microplastic contamination is ubiquitous within superficial sediments and bottom water along the western Irish continental shelf. Results highlight that cores need to be at least 4–5 cm deep to quantify the standing stock of microplastics within marine sediments. All recovered microplastics were classified as secondary microplastics as they appear to be remnants of larger items; fibres being the principal form of microplastic pollution (85%), followed by broken fragments (15%). The range of polymer types, colours and physical forms recovered suggests a variety of sources. Further research is needed to understand the mechanisms influencing microplastic transport, deposition, resuspension and subsequent interactions with biota.

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Litter and microplastic assessments are being carried out worldwide. Arctic ecosystems are no exception and plastic pollution is high on the Arctic Council’s agenda. Water and sediment have been identified as two of the priority compartments for monitoring plastics under the Arctic Monitoring and Assessment Programme (AMAP). Recommendations for monitoring both compartments are presented in this publication. Alone, such samples can provide information on presence, fate, and potential impacts to ecosystems. Together, the quantification of microplastics in sediment and water from the same region produce a three-dimensional picture of plastics, not only a snapshot of floating or buoyant plastics in the surface water or water column but also a picture of the plastics reaching the shoreline or benthic sediments, in lakes, rivers, and the ocean. Assessment methodologies must be adapted to the ecosystems of interest to generate reliable data. In its current form, published data on plastic pollution in the Arctic is sporadic and collected using a wide spectrum of methods which limits the extent to which data can be compared. A harmonised and coordinated effort is needed to gather data on plastic pollution for the Pan-Arctic. Such information will aid in identifying priority regions and focusing mitigation efforts.

<p>Most relative sea level (RSL) curves in Norway have been solidly constructed using sea-level index points (SLIPs) from isolation basins. Many of these curves show RSL falling at a slow and steady rate to modern sea level during the late Holocene, despite a lack of SLIPs younger than ca. 2000 years. Tide gauge records from southern and western Norway indicate that RSL may have been rising since they were installed (ca. 100 years ago), while the few RSL curves with one or two SLIPs younger than 2000 years BP hint that rates of sea-level fall accelerated during this period. This study aims to close the gap between palaeo and instrumental data by generating late Holocene SLIPs from low-elevation and intertidal basins in southwestern Norway. Geochemical analyses of the sediment cores from all the studied areas thus far suggests that marine influence has been increasing in recent centuries, possibly due to rates of eustatic sea level rise overtaking residual glacioisostatic adjustment (ca. 1-2 mm/yr) from the Last Glacial Maximum. Anecdotal evidence from local residents of Egersund, with family histories and records of past storm levels going back to the 1800s, confirm this. Discrete storm layers consisting of shell fragments in one salt marsh at the back of a sheltered intertidal basin, however, may be overprinting any subtle trends in recent RSL rise. Full results of multi-proxy analyses of 8 cores from four salt marshes and protected, intertidal basins with bedrock sills will be presented from the southwestern corner of Norway.</p>

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