Abstract
Within the past decade, an alarm was raised about microplastics in the remote and seemingly pristine Arctic Ocean. To gain further insight about the issue, microplastic abundance, distribution and composition in sea ice cores (n = 25) and waters underlying ice floes (n = 22) were assessed in the Arctic Central Basin (ACB). Potential microplastics were visually isolated and subsequently analysed using Fourier Transform Infrared (FT-IR) Spectroscopy. Microplastic abundance in surface waters underlying ice floes (0–18 particles m−3) were orders of magnitude lower than microplastic concentrations in sea ice cores (2–17 particles L−1). No consistent pattern was apparent in the vertical distribution of microplastics within sea ice cores. Backward drift trajectories estimated that cores possibly originated from the Siberian shelves, western Arctic and central Arctic. Knowledge about microplastics in environmental compartments of the Arctic Ocean is important in assessing the potential threats posed by microplastics to polar organisms.
Highlights
Within the past decade, microplastic pollution emerged as an issue of concern in the Arctic Ocean due to the discovery of these contaminants in its sea ice[1,2], surface and sub-surface waters[3,4,5,6,7,8], deep sea sediments[9,10,11], biota[4,6,12,13] and mostly recently its snow[14]
Microplastic concentrations in sea ice (estimations based on extrapolations from 25 sea ice cores, (2 × 103) to (1.7 × 104) particles m−3) were orders of magnitude higher than those reported for seawater beneath ice floes (0–18 particles m−3)
Analytical techniques employed in the present study led to the exclusion of particles
Summary
Microplastic pollution emerged as an issue of concern in the Arctic Ocean due to the discovery of these contaminants in its sea ice[1,2], surface and sub-surface waters[3,4,5,6,7,8], deep sea sediments[9,10,11], biota[4,6,12,13] and mostly recently its snow[14]. In the context of a changing climate, projections for Arctic sea ice include decreasing sea ice extent, reductions in sea ice thickness (less multi-year ice), alterations in the rate of sea ice drift, intensified melting of sea ice in the marginal zones and interruption of its Transpolar Drift[28,31,32,33] These changing conditions will inevitably influence the dynamics of contaminant fate and transport in the Arctic Ocean, especially if the contaminants of interest are capable of being entrapped within, transported and subsequently released by sea ice. Given that the 18 Arctic Large Marine Ecosystems (LMEs) support a diverse array of marine life[34] and sea ice provides a range of microhabitats for numerous species[35,36,37], an understanding of microplastic contamination in sea ice and surface waters of the Arctic Ocean is vitally important. The specific objectives of this study were to (i) provide a more spatially comprehensive assessment of microplastic concentration and composition in sea ice cores from the Arctic Ocean, (ii) assess the vertical distribution of microplastics in entire sea ice cores, (iii) estimate backward drift trajectories and identify source areas of sampled sea ice cores and (iv) assess microplastic abundance, distribution and composition in surface waters (beneath ice floes) in the Arctic Ocean
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