Detailing the distribution of past and future plastic debris in the marine environment has become a pressing challenge. Plastic pollution poses a potential threat to marine organisms and the marine environment as a whole. Previous studies using Lagrangian particle models have identified five garbage patches within subtropical ocean gyres, with the possibility of a sixth garbage patch within the Barents Sea. We present the first coarse resolution three-dimensional plastic distribution model to use an Eulerian approach. It considers seven plastic components, three of them buoyant and four nonbuoyant, based upon real world plastic types. Our control results support the observations of positively buoyant plastic accumulations within the five garbage patches. However, there is no evidence of a sixth garbage patch in the Barents Sea. Meanwhile, our simulations reveal a previously unreported accumulation of plastic in the Gulf of Guinea. The negatively buoyant plastic tends to accumulate within the deepest regions of the sea floor, loosely following the bathymetry. In two further experiments, we introduce idealized plastic removal rates to simulate the proportion of plastics that are sequestered within sediments once they reach the sea floor. The results of the simulations show that substantial quantities of plastic debris are subject to vertical transport in the ocean and are therefore present throughout the water column as well as on the sea floor. A final experiment, focusing on neutrally buoyant plastics, shows the potentially ubiquitous presence of small microplastics and nanoplastics in the water column. Plain Language SummaryDetailing the distribution of past and future plastic debris in the ocean has become a pressing challenge. Plastic pollution poses a potential threat to marine organisms and the marine environment as a whole. The use of numerical modeling has identified five garbage patches, with the possibility of a sixth garbage patch in the Arctic. However, these models have focused on plastics that float on or near the sea surface and do not consider the plastics which sink or are drawn down once they enter the ocean. We present the first plastic distribution model, which includes both floating and sinking plastics and looks at the distribution of these plastics throughout the water column. Both types of plastics are present throughout the water column, with the floating plastics mainly collecting within the five previously identified garbage patches and the sinking plastics gathering within the deepest areas of the seafloor. Simulations including a crude mechanism by which plastics are removed into the seafloor "sediments," reveal wide-spread areas of the seafloor, which may host large amounts of plastic debris. An experiment with neutrally buoyant plastic tracers that mimics the behavior of microplastics and nanoplastics shows these plastics to be present at all depths globally.

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

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-

No abstract

No abstract