Modeling the Accumulation and Transport of Microplastics by Sea Ice

Abstract

Marine plastic pollution was first documented in the 1970s but has gained attention and popularity both within the scientific community and with the general public over the past decade. Despite public awareness of the issues associated with plastic pollution and a societal shift toward a reduction in single-use plastics, global plastic production reached 359 million tonnes in 2018 (PlasticsEurope, 2019), of which between 4.8 and 12.7 million tonnes are thought to enter the marine environment (Jambeck et al., 2015). Floating marine plastic pollution is estimated at around 250,000 tonnes, although this is thought to only reflect around 1% of the total amount of plastic that has entered the marine environment over the past 60-70 years and much of the "missing" plastic may be within the water column and within marine sediments (Mountford & Morales Maqueda, 2019; van Sebille et al., 2020). Both empirical data and the use of numerical modeling have shown that plastics have pervaded remote regions of the world's oceans, from deep sea sediments (Courtene

Microplastics in the Weddell Sea (Antarctica): A Forensic Approach for Discrimination between Environmental and Vessel-Induced Microplastics

“…For the region east of the Antarctic Peninsula, a recently published model suggests that this region might be shielded from MP pollution by the Peninsula itself. 20 Our findings partially support this assumption for MP in surface waters east of the Antarctic Peninsula. Average MP concentrations found in our samples that were collected in the region that was predicted to be shielded from MP pollution by the model were comparably low, yet, with an average of 0.004 MP m −3 , concentrations are still an order of magnitude higher than predicted.…”

“…Seawater close to the freezing point is exposed; new sea ice is formed and advected away from the coast as it forms . Recent studies showed that sea ice incorporates MP and acts like a seasonal MP sink. ,, It might be possible that in polynyas, buoyant MP are incorporated in newly forming sea ice, removing MP from the water surface in these areas. For the region east of the Antarctic Peninsula, a recently published model suggests that this region might be shielded from MP pollution by the Peninsula itself .…”

“…RV Polarstern ’s ballast water exchange was conducted before crossing 60°S, yet the location was still south of the ACC boundary (Figure B). Once released south of the ACC, MP are likely to remain trapped in Antarctic waters, , highlighting the importance of discharging potentially contaminated ballast water before crossing the ACC. However, even if released north of the ACC, there remains the possibility that drifting items are transported southward by surface eddies and storm-driven surface waves. , …”

“…Yet, it was shown that the ACC is not as impermeable as previously thought , and human activities, including tourism, fisheries, and research are increasing. − In the Ross Sea, potential MP emission from research stations was evidenced, , while shipping was identified as a MP source along the West Antarctic Peninsula . Once present in waters south of the ACC, MP may become trapped and accumulate in the Antarctic marine environment. ,, Highly variable MP concentrations found in Antarctic waters − ,, and the fact that most studies south of 60°S are focusing on the Ross Sea ,, and the West Antarctic Peninsula ,,, highlight that knowledge is still patchy and the problem of MP pollution in Antarctica is not well understood. Further studies on the occurrence and distribution of MP in the Southern Ocean, especially for less investigated areas, are crucial to evaluate which areas are vulnerable to MP pollution and accumulation, as well as identifying possible MP sources.…”

“…10 Once present in waters south of the ACC, MP may become trapped and accumulate in the Antarctic marine environment. 10,19,20 Highly variable MP concentrations found in Antarctic waters [9][10][11]21,22 and the fact that most studies south of 60°S are focusing on the Ross Sea 9,18,23 and the West Antarctic Peninsula 10,21,24,25 highlight that knowledge is still patchy and the problem of MP pollution in Antarctica is not well understood. Further studies on the occurrence and distribution of MP in the Southern Ocean, especially for less investigated areas, are crucial to evaluate which areas are vulnerable to MP pollution and accumulation, as well as identifying possible MP sources.…”