144-7 Development of a Modified Submersible Pump System for Sampling Microplastic in Deep Groundwater Wells

Session: Microplastics in the Environment (Posters)

Poster Booth No.: 40

Presenting Author:

Rodrigo Villalpando-Vizcaino

Authors:

Villalpando-Vizcaino, Rodrigo¹, Larsen, Daniel², Baraza, Teresa³

(1) Center for Applied Earth Science and Engineering Research (CAESER), University of Memphis, Memphis, TN, USA, (2) Earth Sciences, University of Memphis, Memphis, TN, USA, (3) The WATER Institute, Saint Louis University, St. Louis, MO, USA; Department of Earth, Environmental, and Geospatial Science, Saint Louis University, Saint Louis, MO, USA,

Abstract:

Microplastics are widely acknowledged as persistent environmental contaminants. Commonly defined as plastic particles <5 millimeters, they are characterized by diverse physicochemical properties, sizes, shapes, colors, and origins. While studies have documented their presence across all environments, research on microplastics in groundwater remains limited despite the critical importance of this resource. Most existing studies have focused on high-conductivity systems such as fractured rock and karst aquifers, with research on sedimentary aquifers, particularly deeper, unconsolidated systems, still lacking. One of the main challenges in studying microplastics in groundwater is the need to collect large, representative water samples from wells. While low-volume methods such as bailers or glass jars are commonly used, research increasingly recommends sampling volumes >100 liters to reliably capture microplastic particles. Peristaltic or positive-displacement pumps were used successfully in some microplastic studies; however, they present notable limitations. These pumps rely on flexible plastic tubing to move water through compression and release, introducing the risk of contamination. More critically, their maximum theoretical suction lift is limited to 10.3 meters, restricting their use to shallow wells or to sampling casing water rather than from the screened interval. To address limitations, a stainless-steel submersible centrifugal impeller pump (Geotech Geosub 2) was modified for microplastic sampling in deeper wells. This pump can sample down to 60 meters using a single-stage impeller, is easy to clean, and allows for adjustable flow rates. Modifications included removing the screen intake mesh and increasing spacing between the impeller and intake screen to prevent clogging and particle loss. Laboratory recovery tests were performed in triplicate by pumping 5-liter filtered water samples spiked with 50 microplastics of different sizes and morphologies, through copper tubing and a new, low-cost, modular in-line metallic filtration apparatus equipped with 240 µm, 110 µm, and 30 µm filters. Once pumping was complete, filters were removed from the apparatus, transferred to clean petri dishes, and microplastics were quantified using stereo microscopy. Average recovery rates for different types of fibers, fragments, and films ranged from 70% to 100%, with some foam particles retained in the annular space due to their size. This modified pump and our filtration apparatus provide a practical and robust method for collecting large-volume samples from deeper, understudied aquifers, supporting future efforts to characterize microplastic distribution in groundwater.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9851

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