Date of Award

Spring 5-2022

Document Type


Degree Name

Master of Science (MS)


Ocean & Earth Sciences


Ocean and Earth Sciences

Committee Director

Hans-Peter Plag

Committee Member

John M. Klinck

Committee Member

Cesar A. Pinto

Committee Member

Hannah R. Torres


As plastic becomes a ubiquitous part of society, its growth outpaces waste disposal infrastructure and enters the environment as physical and chemical pollution. Plastic can also erode during the use cycle and reach the environment without any chance of being arrested by collection efforts. Plastic is a hazard to many parts of the earth’s life support system but there are many knowledge gaps regarding the processes by which plastic moves through the use cycle and environment. In particular, the ocean is generally regarded as a sink for plastic out of which it is difficult to escape, but plastic can sink into the benthic zone reaching a deeper and more permanent sink and affecting a different environment. Little is known about the rate plastic moves from the surface to the benthic zone, the time it spends on the surface, and the quantity already in the benthic zone. To address these knowledge gaps, a stock and flow model was constructed using FORTRAN to simulate as much of the plastic use, disposal, and pollution cycle as was feasibly possible. The constructed model allowed for a complex use of Residence Time Distributions (RTDs), with plastic exiting a stock at variable rates and percentages based on the quantity of plastic entering the stock. This model was then cross-referenced with real data on surface ocean plastic, plastic waste, and other known quantities to check the accuracy of the simulation. Once it was determined that the model’s derived values for quantities that have been accurately measured in real life were within acceptable margins, the model’s values for the RTDs of plastic in the ocean were deemed reasonable. The model was also used to project plastic pollution into the future using several different scenarios to obtain estimates on future plastic production and pollution as well as the effects of RTDs on various stocks in the model. The model produced in this research could be scaled to different regions by changing the production value of the plastic entering the model and the plastic use quantities and waste disposal methods and rates.


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Included in

Oceanography Commons