Synthesis of Approaches to Estimating Global Marine Reservoirs of Plastic Pollution

Elucidating how much plastic debris by mass is contained in major reservoirs in the marine environment, and solving the mass balance, have long been knowledge gaps in the field. Our objective was to synthesize estimates of global marine reservoirs of plastic pollution to date, as well as the approaches used to generate these estimates. We identified a total of 22 global marine reservoir estimates across 14 studies, including 4 estimates of the coastlines reservoir spanning 0.049 to 2.06 million metric tonnes (MMT), 12 estimates of the ocean surface reservoir spanning 0.0027 to 4.9 MMT, one estimate of the ocean column reservoir (40-90 MMT), one estimate of the ocean floor reservoir (3-11 MMT), and four estimates of the ocean sediment reservoir spanning 3.05 to 905 MMT. We classified reservoir estimation approaches as data-driven or process-driven. Studies that used a data-driven approach based their reservoir estimates off of empirical data. The amount of environmental plastic data incorporated into data-driven estimates ranged from < 100 sample points to 10,000+ sample points. Studies that took a process-driven approach used mechanistic numerical models to estimate the mass of plastics in reservoirs. Interestingly, no two studies considered the same hydrodynamic processes, particle properties, and compartment-level processes in their model. Given the current state of knowledge, we discuss next steps that are necessary to further constrain estimates of global marine reservoirs of plastic pollution to achieve the ultimate goal of a mass balance.

Presentation Preference: Oral

Primary Presenter: Xia Zhu, Memorial University of Newfoundland (xzhu13@mun.ca)

Authors:

Xia Zhu, Memorial University of Newfoundland  (alice.zhu@mun.ca)

Kara Lavender Law, Sea Education Association  (klavender@sea.edu)

Matthew Hoffman, Rochester Institute of Technology  (matthew.j.hoffman@gmail.com)