Assessing Microplastic Pollution in the Hudson River Before and After CSO-Linked Rainfall Events

Presented by Roberto Lopez

Introduction

• The Hudson River is at increased risk of pollution due to stormwater runoff and combined sewer overflows in urban communities (New York Sea Grant, 2024)
• Microplastics are now found everywhere in our rivers and oceans, posing a serious threat to aquatic life and human health (PolyGone Systems, 2024)

(Olympian Water Testing, 2024)

Introduction

• Microplastics come from clothes, packaging, cosmetics, and broken plastic, and can end up in animals and our food (Rutgers University, 2021)
• Smaller microplastics in the Hudson may be older and more worn down from the river’s strong currents (Fahrenfeld, 2021)
• Hudson River marshes trap a lot of microplastics in their sediment, more than in the river or streams nearby (Polgar & Randall, 2018)

Review of Literature

Plastic bottles were the most commonly found item during shoreline cleanups along the Hudson River, indicating significant plastic pollution

The Hudson River sends 300 million microfibers into the Atlantic daily, with no strong link to treatment plants or population density

(Riverkeeper, 2019)

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(Miller et al., 2017)

(Riverkeeper, 2019)

Statement of Purpose/Hypothesis

Rainfall events associated with combined sewer overflows lead to a measurable increase in microplastic concentration in the Hudson River at the Yonkers waterfront.

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To quantify the impact of combined sewer overflow (CSO)-linked rainfall events on microplastic concentrations in the Hudson River at the Yonkers waterfront, addressing the gap in understanding how CSOs contribute to microplastic pollution in urban rivers.

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Hypothesis

Purpose

Intended Methods: Step 1

Sampling Strategy and Study Site

• Water samples will be collected from the Yonkers waterfront at the Center for the Urban River at Beczak
• Located near a known Combined Sewer Overflow outlet
• Samples taken from the river’s surface using clean collection bottles

Intended Methods: Step 2

Sample Frequency + Environmental Conditions

• Sampling will occur twice a week: after rainfall and during dry weather
• Temperature, water clarity, and flow rate will be noted
• Each sample will be labeled with date, time, weather conditions, and tide level

Intended Methods: Step 3

Procedure/Tools for Microplastic Collection

• Collected water samples will be filtered using a fine mesh sieve to capture microplastics
• In the lab, particles will be examined under a dissecting microscope
• Microplastics will be sorted by type and color

(D'Hont et al., 2021)

Intended Methods: Step 4

Data Organization + Analysis Plan

• Results will be recorded in a spreadsheet for comparison across sampling dates
• Bar graphs and tables will be used to visualize differences between conditions
• Samples will be grouped into post-rainfall and dry-weather categories

(Ross et al., 2023)

Intended Methods: Other Studies

Data Organization + Analysis Plan

• Rainfall increased microplastic levels, highlighting the impact of stormwater and CSOs
• Downstream sites show greater accumulation, likely due to urban runoff and CSOs

Ravit et al., 2017

Expected Results

• Microplastic levels at the Yonkers waterfront will be higher after rainfall linked to CSO events
• Dry-weather samples will show lower microplastic concentrations
• Larger particles may be found after storms; smaller particles during dry days due to settling
• Results will show how rain events worsen pollution

Expected Results

• Seasonal variation may affect results: warmer months could increase plastic breakdown.
• Microplastic shapes and types may reflect local human activity
• Tide level and water flow might influence concentration in samples

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Expected Results:

Other Studies

• Microplastic levels were higher near CSO outfalls and after rain in the Lower Hudson River Estuary, about 70% were plastic fragments (Hudson River Park Study, 2019)
• Fish in the Hudson River were found with ingested plastic, especially near wastewater discharge sites (Cornell University, 2016).

(Hudson River Park Study, 2019)

Discussion: Summary and Significance

• This study expects to show a clear relationship between rainfall and microplastic spikes due to CSOs
• Could help strengthen policies on stormwater and wastewater management
• Results could highlight the need for better plastic waste handling in urban areas

Discussion: Summary and Significance

Limitations:

• Limited sample size and duration.
• Only one location studied.
• Weather-dependent; hard to predict storm timing.

Future Research:

• Expand study to more CSO sites along the Hudson.
• Use finer filtration to detect smaller particles.
• Study biological impacts on local fish or sediment-dwelling organisms.

Discussion

• This study expects to show that rainfall and CSO events raise microplastic levels in the Hudson River at the Yonkers waterfront.
• Understanding these patterns can inform better stormwater and plastic waste policies to protect river ecosystems and public health.
• These results highlight preventable pollution linked to urban infrastructure.

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• Cornell University. Hudson River Plastic Pollution and Fish Ingestion Study. 2016.
• D’Hont, Anouk, et al. “Microplastic Types: Shape and Color.” Dropping the Microbead, 2021, www.researchgate.net.
• Fahrenfeld, Nicole. “Aging and Degradation of Microplastics in the Hudson River.” Rutgers University, 2021.
• Hudson River Park. Microplastics Research in the Lower Hudson Estuary. 2019, www.hudsonriverpark.org.
• Miller, Eric, et al. “Microplastics in the Hudson River.” Environmental Pollution, vol. 224, 2017, pp. 103–110.
• New York Sea Grant. “Hudson River Microplastic Sampling and Remediation Program.” NYSG, 2024, www.nyseagrant.org.
• Olympian Water Testing. “How Dirty Is the Hudson River?” 2024, www.olympianwatertesting.com/how-dirty-is-the-hudson-river/.
• Polgar, T. T., and C. Randall. “Microplastic Content in Hudson River Sediment and Surface Water.” Hudson River Foundation, 2018.
• PolyGone Systems. “Tracking and Filtering Microplastics in Urban Waterways.” 2024, www.polygone.systems.
• Ravit, Beth, et al. “Microplastics in Urban New Jersey Freshwaters: Distribution, Chemical Identification, and Biological Effects.” Environmental Engineering Science, vol. 34, no. 1, 2017.
• Riverkeeper. “Plastic Pollution in the Hudson: Cleanup Data from Riverkeeper Sweep 2019.” Riverkeeper, 2019, www.riverkeeper.org.
• Ross, M. S., et al. “Estimated Discharge of Microplastics via Urban Stormwater during Individual Rain Events.” Communications Earth & Environment, vol. 4, no. 1, 2023, https://doi.org/10.1038/s43247-023-00691-y.
• Rutgers University. “Microplastics in the Hudson River: What They Are and Where They Come From.” Rutgers Department of Environmental Sciences, 2021.

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References