Tag: Thanh-Binh Duong

by Thanh-Binh Duong

Faculty Mentor: Dr. Tyler Frankel

Nanoplastics (NPs), defined as plastic particles < 0.1 mm, have become an emerging concern in aquatic environments due to their multiple pathways of entry into rivers and streams. NPs may originate from the manufactured beads for personal care products as well as the from the fragmentation of larger plastic items. Due to their small size they are easily ingested by aquatic organisms, resulting in detrimental health effects such as digestive tract obstructions, feeding debilitation, and energy depletion. Due to their physiochemical attributes, NPs have also been shown to sorb and mobilize organic pollutants such as pesticides, suggesting that interactions between these two types of pollutants may result in an altered biological response compared to the effects of each individual contaminant. This study assessed the potential synergistic or antagonistic effects of polyethylene nanoparticles and the organochlorine pesticide methoxychlor on the viability and mobility of Daphnia magna. Adult D. magna were exposed to either 1) virgin 10-20µm polyethylene pellets, 2) methoxychlor, or 3) various combinations of the same pellet and methoxychlor concentrations for 48 hours or 7 days using a static exposure method. Mortality and paralysis were assessed per 24 hours of exposure. Mobility was assessed after 24 hours of exposure. To assess mobility, individuals were recorded in a light-controlled behavioral chamber for 3 minutes. Footage was analyzed using ToxTrac to quantify mobile speed, acceleration, and distance traveled. While this project is currently ongoing, we expect to find a significant difference in mobility parameters and mortality rates when exposed to the combination of polyethylene pellets and methoxychlor compared to the effects from each contaminant alone. Thus far, few studies have examined the ability of NPs to influence the toxicity of organochlorine pesticides in aquatic invertebrates. This study will help explicate the impacts of plastic pollution on aquatic biota in freshwater systems.

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by Thanh-Binh Duong

Faculty Mentor: Dr. Ben Kisila

The Chesapeake Bay is a large estuary located along the east coast of the United States, with numerous wastewater treatment plants (WWTP) located throughout its basin. This area supports a vast diversity of aquatic biota and provides for numerous communities throughout the eastern United States. While effluent from WWTPs has been identified as a major contributor to microplastic pollution, little research has been conducted to examine microplastic contamination in the Chesapeake Bay watershed areas surrounding these effluent streams. Microplastics are unique in that their size (<5mm) enables ease of ingestion by aquatic organisms, causing adverse health effects such as energy depletion and digestive tract obstructions. MPs may also biomagnify throughout trophic levels, ultimately posing a threat to human health due to unintended consumption. In this study, the presence of microplastics in major rivers in the lower basin of the Chesapeake Bay, USA was examined. Water samples and sediment samples were collected in the Potomac and Rappahannock river upstream, midstream, and downstream of WWTP outfall sites via dip sampling and grab sampling, respectively. Sediment samples were treated with a wet peroxide oxidation using Fenton’s reagent to digest natural organic matter and sodium chloride to separate MPs from the sample. Surface water samples were filtered by vacuum filtration to separate suspended particles from water. Presence, type, and quantity of MPs were assessed using light microscopy. While this project is currently ongoing, we expect to find that MPs are more abundant in samples collected at WWTP outfall locations rather than locations upstream or downstream from those sites. The results of this study will provide novel information regarding the presence, distribution, and concentrations of MPs in water and sediment samples from several areas of the Chesapeake Bay watershed due to inputs from WWTP effluent.

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