An Ocean of Plastic

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November 30, 2021 by Helen Hill

Story by Helen Hill for MITgcm

Researchers at Nanjing University, China, and Scripps Institution of Oceanography, USA, use MITgcm to help understand where​ COVID-related trash will likely end up within the world’s oceans.

Using a​ hybrid MITgcm-plastic model​ they have developed, researchers Yiming Peng, Peipei Wu, and Yanxu Zhang (Nanking Univ.), together with Amina Schartup (Scripps) have been projecting the likely footprint of plastic waste release ​into the global ocean ​caused by COVID-19 with the goal of predicting dispersal of excess trash arising due to modified behaviors associated with the ongoing coronavirus pandemic. Their work appears in the PNAS.

“​Plastic waste causes harm to marine life and has ​become a ​cause for major global environmental concern,” explains Graduate student and lead author Yiming Peng. “COVID, however, has exacerbated the problem, triggering increased ​demand for​ single-use plastic.”

While suspected to be large, the ​absolute ​magnitude and​ ultimate fate of pandemic-associated mismanaged plastic waste ​can only be estimated. ​Based on an extensive literature review, the inventory compiled by the paper’s authors suggests that (as of August 2021) more than eight million tons of pandemic-associated plastic waste had been generated, with in excess of ​twenty thousand tons released into the global ocean; ​an amount ​representing just over one percent of global total riverine plastic discharge.

To ​try to understand where this excess plastic will end up, ​the team used the​Nanjing University MITgcm-Plastic model (NJU-MP)​, which combines MITgcm with add-on packages coding for the physical, chemical, and environmental behaviors of advected plastic in a marine environment.

“NJU-MP​ ​is based on a 2​ ​x​ ​2.5-degree resolution global implementation of MITgcm​”, says ​co-author Yanxu Zhang, one of the model’s designers. “We used forcing fields ​taken ​from IGSM model output (1860-2100), (Monier et al. 2018), initializing with zero plastic concentrations,​ ​and using point sources at river mouths.​”​

​”​The plastic part ​of NPU-MP ​is an augmented​ tracer advection model.,” Zhang explains. “​Tracers ​representing plastic particles with different chemical compositions and sizes exhibit different transport characteristics in response to the ocean circulation. Vertically, ​particles ​can move either up or down depending on their density, and the model also includes a component representing surface wind drag, depending on the fraction of ​the ​particle exposed above the waterline.​”​ ​ Other biogeochemical processes​ included in the model, ​are​ biofouling and defouling (attachment or detachment of plankton on ​the plastic’s ​surfaces), sinking to the sediment, capture by beaches, degradation by solar radiation, and fragmentation from larger pieces to smaller ones.​

Using their source estimates to guide ​​input​ profiles, the model projects that​ within as little as three years the spatial distribution of the discharge ​evolves ​ rapidly with a significant portion of plastic debris washing up on beaches and ​collecting on the ​seabed as well as the subsequent formation of a circumpolar plastic accumulation zone in the Arctic.

“​Our estimates suggest more than eight million tons of pandemic-associated plastic waste had​ been generated globally​ by August 2021, with more than ​twenty-five thousand​ tons ​having ​entered​ the global ocean,” ​says​ Yiming Peng,​ the studies lead author. “​Our modeling work demonstrates how this ​poses a long-lasting problem for the ocean environment ​with, in particular,​ accumulation​ on beaches and ​in ​coastal sediments.”

The team’s analysis finds plastic from medical waste generated by hospitals dwarfs the contribution from ​eg ​personal protective equipment or the increase in online-shopping packaging ​material​ and lends specific weight to​​ ​improving​ medical waste management in pandemic epicenters, especially in developing countries. Peng says,​”​We find hospital waste represents the bulk of the global discharge (73%), and most of the global discharge is from Asia (72%), which calls for better management of medical waste in ​particular in those areas​.”

To find out more about this work contact Yanxu

Story image: Pixabay

This Month’s Featured Publication

Other New Publications this Month:

Maryam R. Al-Shehhi, Hajoon Song, Jeffery Scott, and John Marshall (2021), Water mass transformation and overturning circulation in the Arabian Gulf, Water mass transformation and overturning circulation in the Arabian Gulf, Journal of Physical Oceanography, doi: 10.1175/JPO-D-20-0249.1

Hayley Beltz et al (2021), Exploring the Effects of Active Magnetic Drag in a GCM of the Ultra-Hot Jupiter WASP-76b, arXiv:2109.13371 [astro-ph.EP]

Bishnu, Siddhartha (2021), Time-Stepping Methods for Partial Differential Equations and Ocean Models, Doctoral Dissertation
The Florida State University, ProQuest Dissertations Publishing, 2021. 28542729.

Haihong Guo and Michael A. Spall (2021), Topographic Influences on the Wind-driven Exchange Between Marginal Seas and the Open Ocean, Journal of Physical Oceanography, doi: 10.1175/JPO-D-21-0058.1

Antoine Hochet, Thierry Huck, Olivier Arzel, Florian Sévellec, Alain de Verdière. Energy transfers
between multidecadal and turbulent variability. Journal of Climate, American Meteorological Society,
In press. ffhal-03390256f

Reiner Jung, Sven Gundlach, and Wilhelm Hasselbring (2021), CP-DSL: Supporting Configuration and Parametrization of Ocean Models with UVic (2.9) and MITgcm (67w), Geosci. Model Dev. Discuss. doi: 10.5194/gmd-2021-311

Lee, H., Moon, BK., Jung, HC. et al. (2021), Development of the UKESM-TOPAZ Earth System Model (Version 1.0) and Preliminary Evaluation of its Biogeochemical Simulations, doi: 10.1007/s13143-021-00263-0

Song Li (2021), The Ocean Submesoscale: Kinetic Energy
Conversion and Adjoint Modelling, Doctoral Dissertation University of Hamburg, Germany

Lu, X., Li, G., Yang, B. et al (2021), StreamFlow: a visual analysis system for 2D streamlines based on workflow mining technique, Journal of Visualization, doi: 10.1007/s12650-021-00795-7

Ali Mashayek, Jonathan Gula, Lois Baker, Alberto Naveira Garabato, Laura Cimoli, James Riley (2021), Mountains to climb: on the role of seamounts in upwelling of deep ocean waters, Research Square in Review for Nature Portfolio

Mouyen, M., Plateaux, R., Kunz, A., Steer, P., and Longuevergne, L. (2021), LAPS v1.0.0: Lagrangian Advection of Particles at Sea, a Matlab program to simulate the displacement of particles in the ocean, Geosci. Model Dev. Discuss., doi: 10.5194/gmd-2021-233

David R. Munday, Xiaoming Zhai, James Harle, Andrew C. Coward, A.J. George Nurser (2021), Relative vs. absolute wind stress in a circumpolar model of the Southern Ocean, Ocean Modelling, doi: 10.1016/j.ocemod.2021.101891

Mucaza, Muveno Pascoal Elias (2021), Complicating factors in hydraulic jumps: the effects of earth’s rotation, Master Thesis , University of Western Ontario,

Yiming Peng et al, (2021), Plastic waste release caused by COVID-19 and its fate in the global ocean, PNAS, doi: 10.1073/pnas.2111530118

Oliver, S. E., Cartis, C., Kriest, I., Tett, S. F. B., and Khatiwala, S. (2021), A derivative-free optimisation method for global ocean biogeochemical models, Geosci. Model Dev. Discuss., doi: 10.5194/gmd-2021-175

Roberta Sciascia, Katell Guizien, Marcello Gatimu Magaldi (2021), Guidelines for larval dispersal simulations: flow field representation versus biological traits, ffhal-03365790ff

Callum J. Shakespeare, Angus H. Gibson, Andrew McC. Hogg, Scott D. Bachman, Shane R. Keating, Nick Velzeboer (2021), A New Open Source Implementation of Lagrangian Filtering: A Method to Identify Internal Waves in High-Resolution Simulations, Journal of Advances in Modeling Earth Systems, doi: 10.1029/2021MS002616

Clément Soufflet, Francois Lott, Bruno Deremble (2021), Mountain waves produced by a stratified shear flow with a boundary layer. Part III: Trapped lee waves and horizontal momentum transport, Journal of the Atmospheric Sciences, ffhal-03365418f

Strobach, E., Molod, A., Barahona, D., Trayanov, A., Menemenlis, D., and Forget, G. (2021), Earth System Model Parameter Adjustment Using a Green’s Functions Approach, Geosci. Model Dev. Discuss. doi: 10.5194/gmd-2021-251

Trossman, D. S., Whalen, C. B., Haine, T. W. N., Waterhouse, A. F., Nguyen, A. T., Bigdeli, A., Mazloff, M., and Heimbach, P. (2021), Tracer and observationally-derived constraints on diapycnal diffusivities in an ocean state estimate, Ocean Sci. Discuss, doi: 10.5194/os-2021-87

Pengcheng Wang, Natacha B. Bernier, Keith R. Thompson, Tsubasa Kodaira (2021), Evaluation of a global total water level model in the presence of radiational S2 tide, Ocean Modelling, doi: 10.1016/j.ocemod.2021.101893

Yifan Zhou et al (2021), HST/WFC3 Complete Phase-resolved Spectroscopy of White Dwarf-Brown Dwarf Binaries WD 0137 and EPIC 2122, arXiv:2110.10162 [astro-ph.SR]

Do you have news about research using MITgcm? We are looking for contributions to these pages. If you have an interesting MITgcm project (ocean, atmosphere, sea-ice, physics, biology or otherwise) that you want to tell people about, get in touch. To make a post, contact Helen