Microplastics in the Arctic Ocean
A view of the Arctic Ocean during the AO16 expedition. Photo credit: La Daana K. Kanhai.
The Arctic Ocean is the smallest ocean on planet earth. Due to its remote location, it has often been regarded as being a pristine ecosystem. Yet, plastics can enter this polar ecosystem via oceanic currents, freshwater influx, bio-transport, atmospheric deposition and localized anthropogenic activities. Within the past five years, studies started emerging in the published literature about the presence of microplastics in the Arctic Ocean.
A portion of my PhD research (2016 - 2018) was focused on addressing the existing knowledge gap regarding plastics in Polar Regions. During the Arctic Ocean 2016 (AO16) expedition and under the supervision of Dr. Katarina Gardfeldt, I sampled the various environmental compartments (surface waters, sub-surface waters, deep sea sediments, sea ice) of the Arctic Ocean for microplastics.
AO16 Expedition: Multi-national collaboration
The AO16 expedition took place between August 8th - September 20th 2016. For 6 weeks, various teams sampled the different environmental compartments of the Arctic Ocean. On August 21st 2016, icebreaker Oden reached the North Pole with a multi-national team. The AO16 expedition was one that fostered collaborative scientific research. Photo credit: Lars Lehnert.
Sub-surface waters (single depth)
Sub-surface Arctic waters at a single depth were pumped via the bow water system of icebreaker Oden, filtered and samples were analysed for microplastics.
Sub-surface waters (multiple depths)
Traditionally, sampling of oceanic waters for microplastics has focused on surface waters with a few studies utilizing the underway or bow water systems of research vessels to sample waters down to a depth of approximately 15 m. During the AO16 expedition, we utilized the CTD rosette sampler to sample sub-surface waters between depths of 8 - 4400 m. This was done in order to determine whether microplastics were present in water column of the Arctic Central Basin.
Deep sea sediments
Deep sea sediments from several locations in the Arctic Central Basin were also sampled, potential microplastics were isolated using density separation and the particles were analysed.
Arctic sea ice
In 2014, it was first suggested that Arctic sea ice could act as a sink and a source for microplastics (Obbard et al. 2014). Subsequently, it was also suggested that Arctic sea ice can function as a transport medium for microplastics (Peeken et al. 2018). Building on previous research, our team sampled sea ice and seawater at multiple locations in the Arctic Ocean during the AO16 expedition. Our findings corroborate those of previous studies and indicate that sea ice functions as a temporary sink, secondary source and a transport medium for microplastics in the Arctic Ocean.
Visual identification
Visual identification is a key step in the isolation of potential microplastics from the various samples. At this stage, there is no information about the polymer composition of the suspected microplastics.
Polymer identification
Although there are many different analytical techniques that may be used to confirm the polymer type of the suspected microplastics, I utilized Fourier Transform Infrared (FT-IR) Spectroscopy to analyse the polymer composition of all suspected microplastics.
The Arctic Ocean is an indescribably beautiful place. For someone who grew up on a Caribbean island, I was simply captivated! It is my sincere hope that those who come after me will be able to witness the beauty of the Arctic. Photo credit: La Daana K. Kanhai.