Marine Plastic Pollution in Waters around Australia: Characteristics, Concentrations, and Pathways

Abstract

Plastics represent the vast majority of human-made debris present in the oceans. However, their characteristics, accumulation zones, and transport pathways remain poorly assessed. We characterised and estimated the concentration of marine plastics in waters around Australia using surface net tows, and inferred their potential pathways using particle-tracking models and real drifter trajectories. The 839 marine plastics recorded were predominantly small fragments (“microplastics”, median length = 2.8 mm, mean length = 4.9 mm) resulting from the breakdown of larger objects made of polyethylene and polypropylene (e.g. packaging and fishing items). Mean sea surface plastic concentration was 4256.4 pieces km−2, and after incorporating the effect of vertical wind mixing, this value increased to 8966.3 pieces km−2. These plastics appear to be associated with a wide range of ocean currents that connect the sampled sites to their international and domestic sources, including populated areas of Australia's east coast. This study shows that plastic contamination levels in surface waters of Australia are similar to those in the Caribbean Sea and Gulf of Maine, but considerably lower than those found in the subtropical gyres and Mediterranean Sea. Microplastics such as the ones described here have the potential to affect organisms ranging from megafauna to small fish and zooplankton.

Global Distribution, Composition and Abundance of Marine Litter

“…Most surveys focused on specific oceanic regions and habitats, such as coastal areas, regional seas, gyres or the poles (Thompson et al 2004, Collignon et al 2012Rios and Moore 2007). Concentrations of microplastics at sea vary from thousands to hundreds of thousands of particles km −2 and latest reports suggest that microplastic pollution has spread throughout the world's oceans from the water column (Lattin et al 2010;Cole et al 2011) to sediments even of the deep sea (Moore et al 2001b;Law et al 2010;Claessens et al 2011;Cole et al 2011;Collignon et al 2012;Erikssen et al 2014;Reisser et al 2013;van Cauwenberghe et al 2013;Fischer et al 2015). Recently, microplastics were also recorded from Arctic sea ice in densities two orders of magnitude higher than those previously reported from highly contaminated surface waters, such as those of the Pacific gyre (Obbard et al 2014).…”

Combining Litter Observations with a Regional Ocean Model to Identify Sources and Sinks of Floating Debris in a Semi-enclosed Basin: The Adriatic Sea

“…While global and country-specific production, consumption, and disposal rates of plastic are available (Lebreton et al, 2012;Hardesty et al, 2015;Jambeck et al, 2015;Liubartseva et al, 2016), reliable estimates of the spatial and temporal distributions of plastic sources are lacking (Reisser et al, 2013). As a result, modeling studies often assume population-dependent, timeinvariant AMD input (Lebreton et al, 2012;Liubartseva et al, 2016) or use spatially uniform initial positions (Yoon et al, 2010;Mansui et al, 2015).…”

“…Identifying sources and sinks of AMD can assist resource managers maximize the effectiveness of prevention and response efforts by providing scientific support to the implementation of public policies. While progress has been made, most relevant studies either relied on observations of beached AMD (Yoon et al, 2010;Kako et al, 2011Kako et al, , 2014Neumann et al, 2014), made assumptions about the amount of AMD as well as its temporal and/or spatial distributions (Lebreton et al, 2012;Critchell et al, 2015;Mansui et al, 2015;Liubartseva et al, 2016), or used coarse resolution velocity data and/or idealized surface currents (Aliani and Molcard, 2003;Maximenko et al, 2012;van Sebille et al, 2012;Reisser et al, 2013;Isobe et al, 2014). Such studies have identified the physical processes relevant to the transport and accumulation of debris, however, the efficacy of models in aiding management efforts depends strongly on the assumptions applied in the particle tracking scheme (Critchell and Lambrechts, 2016) as well as the resolution and accuracy of the underlying velocity field (Putman and He, 2013).…”

Plastic Pollution Patterns in Offshore, Nearshore and Estuarine Waters: A Case Study from Perth, Western Australia

“…This denomination is followed herein. As plastics fragment into smaller pieces over time, smaller SMPs are suspected to have spent longer time at sea than their larger counter parts or complete items Reisser et al, 2013;Cózar et al, 2014). Primary microplastics (PMPs) on the other hand, are polymer products that have been intentionally produced in the nominal size range of ≤5 mm, such as cosmetic microbeads, some pre-production pellets, and synthetic sandblasting media (Cole et al, 2011).…”

“…Primary microplastics (PMPs) on the other hand, are polymer products that have been intentionally produced in the nominal size range of ≤5 mm, such as cosmetic microbeads, some pre-production pellets, and synthetic sandblasting media (Cole et al, 2011). SMPs are often the most dominant type of plastic found in marine environments (Shaw and Day, 1994;Morét-Ferguson et al, 2010;Reisser et al, 2013). Therefore, another rationale why increases of microplastic concentrations in oceanic surface waters over time have not been recorded yet, is due to nano-fragmentation to size ranges below current limits of detection (Andrady, 2011).…”