Tying up Loose Ends of Microplastic Pollution in the Arctic: Distribution from the Sea Surface through the Water Column to Deep-Sea Sediments at the HAUSGARTEN Observatory

Abstract

Recent studies have shown that despite its remoteness, the Arctic region harbors some of the highest microplastic (MP) concentrations worldwide. Here, we present the results of a sampling campaign to assess the vertical distribution of MP particles (>11 μm) at five stations of the HAUSGARTEN observatory. Water column samples were taken with large volume pumps by filtering 218−561 L of seawater at two to four depth strata (near-surface, ∼300 m, ∼1000 m, and above seafloor), and sediment samples were taken with a multiple corer. MP concentrations in the water column ranged between 0 and 1287 N m −3 and in the sediment from 239 to 13 331 N kg −1 . Fourier transform infrared spectroscopy (FTIR) imaging with automated data analysis showed that polyamide (39%) and ethylenepropylene-diene rubber (23%) were the most abundant polymers within the water samples and polyethylene-chlorinated (31%) in sediments. MPs ≤ 25 μm accounted for more than half of the synthetic particles in every sample. The largest MP particle recorded was in the 200 μm size class. The concentrations of fibers were not reported, as fiber detection by FTIR imaging was not available at the time of analyses. Two-and three-dimensional simulations of particle transport trajectories suggest different pathways for certain polymer types. A positive correlation between MP size composition and particulate organic carbon indicates interactions with biological processes in the water column.

Pervasive distribution of polyester fibres in the Arctic Ocean is driven by Atlantic inputs

“…The prevalence of MP fibres 2,6,7 and polyester 4,6 in our samples is consistent with recent studies of near-surface water in the central Arctic Basin 2 and Hudson Bay and the eastern Canadian Arctic 8 , but contrasts observations of polymer composition in Arctic sea ice and ice floes where varnish (polymer used in coatings) 5,21 , and polyethylene and polypropylene fragments 5 were found to be abundant.…”

“…To account for any artifacts arising from microplastic contamination in our field samples, particles that were visually similar and present across multiple samples were removed from the final analysis. This conservative approach applied in previous research 4 resulted in a large number of particles excluded (a total 60%), but is validated by the similarity of our final estimates to others made for the region 2 . There were no differences among the microplastic contamination values on different cruises and vessels (ANOVA, p > 0.05).…”

“…icroplastics (MPs) have emerged as a significant global concern, having permeated the most remote reaches of the world [1][2][3][4] . MPs have been detected in Arctic pack ice 5 , seawater [6][7][8] and seafloor sediments 9 , but limited information exists on the mechanisms underlying their distribution and the scale of contamination.…”

Microplastics in Polar Samples

“…Furthermore, bulk water samples from HAUSGARTEN in the Fram Strait contained microplastics (>11 μm) in samples collected from the surface water to just above the seafloor (0-2500 m). Sample volumes ranged from 216 L to 561 L with microplastic concentrations ranging from 0 to 1287 particles per m 3 (Tekman et al 2020). Again, this study supports the transport of microplastic through the water column.…”

“…Mu et al (2019b) found a negative correlation between the microplastic concentration and depth of sample collection in the Chukchi Sea and Strait (range 0-68.73 items per kg dw), whereas concentrations in the Bering Sea and Strait ranged from 5.3 to 39.27 items per kg dw. In the Arctic deepsea observatory, HAUSGARTEN, five sites were investigated at depths from 271 to 5569 m (Tekman et al 2020); microplastic (>11 μm) concentrations were reported ranging from 239 to 13,331 particles per kg. Interestingly, the most commonly identified polymerschlorinated polyethylene (31%)has a density of 0.93-0.96 g/cm 3 which would normally float in seawater, suggesting that these particles sank following biofouling or other biological processes (van Sebille et al 2020).…”