Surface water plastics in the Eastern Arctic

Published: 17 February 2021| Version 1 | DOI: 10.17632/ypck7kw694.1
Contributor:
Max Liboiron

Description

This study finds an average of 0.018 plastic particles/m2 in surface waters near the capital city of Iqaluit in Tasiujarjuaq (Frobisher Bay), Nunavut (0.014 particles/m2), and in the Labrador Sea close to Qaqortoq and Narsaq in southwest Greenland (0.026 particles/m2). While a comparison with other studies shows the abundance of plastics in the study area holds with a broad increase in plastic abundance in the north compared to the south, within and across study areas, latitude does not appear to be a significant factor in plastic abundance. Moreover, some characteristics of recovered plastics such as morphology and colour support local origins, while others support long range transport. Research moving forward should consider relative scales in spatial trends of plastic abundance. Samples for this study were collected in 2018 by a team of settler, non-Inuit authors using a Manta surface water trawl with a net mesh size of 335μm, and each trawl was conducted for 30 minutes. The cut off size for this data set is 425μm. Sample collection sites were designed to answer two specific questions. First, whether burned plastics that might have originated in the Iqaluit landfill were moving from land into Tasiujarjuaq, a local hypothesis. Sampling locations in Tasiujarjuaq are grouped close to Iqaluit and further in the bay to test that hypothesis. Secondly, the site in southwest Greenland was used as a comparison to determine whether the abundance and types of plastics in Tasiujarjuaq (both near Iqaluit and farther into the bay) were markedly different than those of a location in another current but at a similar latitude. This sample collection design this provides a snapshot of plastic profiles in key locations, and is limited to wider generalizations given its relatively low sample size (see the section below on statistical power), and that samples were collected in the late summer months rather than across multiple seasons. This data was used for the publication: "Abundance and types of plastic pollution in surface waters in the Eastern Arctic (Inuit Nunangat) and the case for reconciliation science" (2021). More information about the data is available there, and/or by contacting Max Liboiron mliboiron@mun.ca

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Researchers used a Manta surface water trawl with a net mesh size of 335μm, and each trawl was conducted for 30 minutes. A flowmeter was attached to the trawl and distance traveled was recorded to determine the amount of water sampled. Entire cod ends containing samples were placed in sample bags with 20mL of hydrogen peroxide (3%) for storage and frozen at -20 °C for later laboratory analysis. Contamination samples were taken each day from mittens, gloves, scarfs, toques, jackets, and other fabrics of all personnel in contact with the trawl. Samples were transferred from the freezer to a bleach solution for 18-20 hours to discolour any organics to aid in identifying plastics. Once bleached, samples were sieved to eliminate items smaller than 425μm. This size cut off was chosen to align with existing plastic monitoring occurring in Nunatsiavut, another region of Inuit Nunangat, and because this size allows accurate visual identification (Song et al. 2015), a more accessible method for future comparisons (Government of Canada 2018). We visually examined sieve contents using a stereo microscope (Olympus SZ61, model SZ2-ILST) with a magnification range of 0.5–12x. Suspected plastics were extracted from the sample and placed into folded filter paper to dry for a minimum of 4 days, until a consistent weight was observed. After the drying period, suspected plastics were re-examined under the microscope to further confirm plastic identification. Visually confirmed plastics were classified based on morphology, color, size class, and whether and what types of erosion were present, including burning and melting . Mass, length, width, and height of plastics were also recorded. Plastics were classified as microplastics (<5mm), mesoplastics (5-20mm) or macroplastics (>20mm) following other studies in the region for comparability (Baak et al. 2020; Avery-Gomm et al. 2018). Plastics were transferred into labeled scintillation jars for storage and then glass slides for fourier-transform infrared (FTIR) polymer analysis. To eliminate contamination plastics from our analysis, sample plastics were compared with those in blanks from both the lab and the ship and any plastics in our sample that were identical to those in the control were eliminated. Criteria for elimination included identical: color, thickness, and “kinkiness” (shape characteristics) for microplastics, and color, morphology, and erosion patterns for non-microplastics such as paint chips or ropes