Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system

Retention of plastics in estuaries and storage in sediments likely contributes to the mass imbalance between the amount of ocean plastic debris and input from land. A sediment transport model, coupled with a hydrodynamic and wave model, was employed to analyze how microplastics of varying settling v...

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Main Authors: Emily Summers, Jiabi Du, Kyeong Park, Marcus Wharton, Karl Kaiser
Format: Article
Language:English
Published: Frontiers Media S.A. 2024-12-01
Series:Frontiers in Marine Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fmars.2024.1414459/full
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author Emily Summers
Emily Summers
Jiabi Du
Jiabi Du
Kyeong Park
Kyeong Park
Marcus Wharton
Marcus Wharton
Karl Kaiser
Karl Kaiser
author_facet Emily Summers
Emily Summers
Jiabi Du
Jiabi Du
Kyeong Park
Kyeong Park
Marcus Wharton
Marcus Wharton
Karl Kaiser
Karl Kaiser
author_sort Emily Summers
collection DOAJ
description Retention of plastics in estuaries and storage in sediments likely contributes to the mass imbalance between the amount of ocean plastic debris and input from land. A sediment transport model, coupled with a hydrodynamic and wave model, was employed to analyze how microplastics of varying settling velocities behave under non-storm conditions and during extreme storm events in Galveston Bay, USA. The model was informed by measured concentrations of microplastics in a main tributary (Buffalo Bayou), which flows through the highly populated Houston-metro area. Under non-storm conditions, concentrations of neutrally buoyant particles are highest near the source location. In contrast, negatively buoyant particles are highest near the bay mouth where bed shear stress, and thus the potential for erosion/resuspension, is highest. Simulation of Hurricane Harvey, an unpreceded 1000-year flood event, shows a drastic increase of overall microplastic levels in Galveston Bay, approximately 5x that of non-storm conditions, and an increase in corresponding flux of microplastics to the Gulf of Mexico. The differences are attributed both to increases in microplastic loading and erosion of microplastics from bed sediments during Harvey. Differences in concentration between storm and non-storm conditions are most clear in the upper bay, where shear stress is low under normal conditions but shows a significant increase during storms due to wave-enhanced stress. Following Harvey, negatively buoyant particles levels return to normal in less than a week, but neutrally buoyant particle concentrations remain elevated over several months. Use of a sediment transport model that simulates erosion/resuspension to understand particle behavior lends further understanding of processes of microplastics not explored through previous use of particle tracking models that do not account for erosion/resuspension. This is of upmost importance for simulation of negatively buoyant particles, which have more potential to interact with the sediment bed layer. Variation of critical shear stress for erosion, erosion rate, and use of a wave model, all show significant impacts on particle behavior. Future parameterization of microplastic behavior in sediments will enhance our understanding of estuarine retention and export ability.
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spelling doaj-art-7a1c60a1a1744cc18ff41a945406b4f32024-12-05T04:26:30ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452024-12-011110.3389/fmars.2024.14144591414459Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine systemEmily Summers0Emily Summers1Jiabi Du2Jiabi Du3Kyeong Park4Kyeong Park5Marcus Wharton6Marcus Wharton7Karl Kaiser8Karl Kaiser9Department of Oceanography, Texas A&M University, College Station, TX, United StatesDepartment of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX, United StatesDepartment of Oceanography, Texas A&M University, College Station, TX, United StatesDepartment of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX, United StatesDepartment of Oceanography, Texas A&M University, College Station, TX, United StatesDepartment of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX, United StatesDepartment of Oceanography, Texas A&M University, College Station, TX, United StatesDepartment of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX, United StatesDepartment of Oceanography, Texas A&M University, College Station, TX, United StatesDepartment of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX, United StatesRetention of plastics in estuaries and storage in sediments likely contributes to the mass imbalance between the amount of ocean plastic debris and input from land. A sediment transport model, coupled with a hydrodynamic and wave model, was employed to analyze how microplastics of varying settling velocities behave under non-storm conditions and during extreme storm events in Galveston Bay, USA. The model was informed by measured concentrations of microplastics in a main tributary (Buffalo Bayou), which flows through the highly populated Houston-metro area. Under non-storm conditions, concentrations of neutrally buoyant particles are highest near the source location. In contrast, negatively buoyant particles are highest near the bay mouth where bed shear stress, and thus the potential for erosion/resuspension, is highest. Simulation of Hurricane Harvey, an unpreceded 1000-year flood event, shows a drastic increase of overall microplastic levels in Galveston Bay, approximately 5x that of non-storm conditions, and an increase in corresponding flux of microplastics to the Gulf of Mexico. The differences are attributed both to increases in microplastic loading and erosion of microplastics from bed sediments during Harvey. Differences in concentration between storm and non-storm conditions are most clear in the upper bay, where shear stress is low under normal conditions but shows a significant increase during storms due to wave-enhanced stress. Following Harvey, negatively buoyant particles levels return to normal in less than a week, but neutrally buoyant particle concentrations remain elevated over several months. Use of a sediment transport model that simulates erosion/resuspension to understand particle behavior lends further understanding of processes of microplastics not explored through previous use of particle tracking models that do not account for erosion/resuspension. This is of upmost importance for simulation of negatively buoyant particles, which have more potential to interact with the sediment bed layer. Variation of critical shear stress for erosion, erosion rate, and use of a wave model, all show significant impacts on particle behavior. Future parameterization of microplastic behavior in sediments will enhance our understanding of estuarine retention and export ability.https://www.frontiersin.org/articles/10.3389/fmars.2024.1414459/fullmicroplastic transport pathwaysestuarine export abilityhurricanessettling velocitysediment transport model
spellingShingle Emily Summers
Emily Summers
Jiabi Du
Jiabi Du
Kyeong Park
Kyeong Park
Marcus Wharton
Marcus Wharton
Karl Kaiser
Karl Kaiser
Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system
Frontiers in Marine Science
microplastic transport pathways
estuarine export ability
hurricanes
settling velocity
sediment transport model
title Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system
title_full Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system
title_fullStr Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system
title_full_unstemmed Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system
title_short Importance of the water-sediment bed interactions in simulating microplastic particles in an estuarine system
title_sort importance of the water sediment bed interactions in simulating microplastic particles in an estuarine system
topic microplastic transport pathways
estuarine export ability
hurricanes
settling velocity
sediment transport model
url https://www.frontiersin.org/articles/10.3389/fmars.2024.1414459/full
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