2 Advances in characterizing groundwater, surface water, and their interactions
This session focuses on characterizing groundwater, surface water, and their interactions through fieldwork, modeling, and data synthesis. We welcome submissions addressing flow, transport, water quality, and water levels under both typical and extreme conditions.
Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 25
Simulating vertical vadose zone PFAS transport at Maine agricultural biosolid spreading sites.
Paper number: 2-1
Program: Technical Sessions
Time: 8:05 AM – 8:25 AM
Authors
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Andrew CollinsUnited States Geological Survey, Bangor, ME
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Rachel SchattmanSchool of Food and Agriculture, University of Maine, Orono, ME
Abstract
Per- and polyfluoroalkyl substances (PFAS) have been documented in groundwater and soils across New England. These substances leach from biosolids, applied as fertilizer to agricultural and other lands, resulting in soil and groundwater contamination. As a result, PFAS may affect surface water and groundwater quality and accumulate in agricultural products. Potential trends in groundwater PFAS concentrations over time and the persistence of PFAS in the vadose zone at Maine biosolid application sites are simulated using recently published one-dimensional vadose zone transport models (PFAS-LEACH Tier 3-4 and related software), focusing on the federally regulated compounds perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The PFAS-LEACH model utilizes a range of inputs (e.g. infiltration rates, water-table depth, soil texture, PFAS surface tension) to predict groundwater PFAS concentration, PFAS soil residence time, and soil concentration profiles. Our simulations use a soil testing and analytical chemistry dataset for known PFAS contamination sites compiled by the Maine Department of Environmental Protection (MEDEP) between 2022 and 2024 to parameterize models. In this presentation we: 1) compare PFAS concentrations in the MEDEP dataset with simulation results to predict the persistence of PFOA and PFOS in soil and groundwater at several Maine sites and 2) assess the sensitivity of simulated groundwater concentrations to poorly constrained model input parameters. Preliminary models, initialized with measured PFOA and PFOS soil concentrations, simulate groundwater concentrations that are within an order of magnitude of measured concentrations, typically underpredicting measured concentrations. Simulated groundwater PFOA concentrations leached from the overlying soil column exceed current regulatory limits for PFOA for 10 to 50 years.
Geological Society of America Abstracts with Programs. Vol. 58, No. 2
doi: 10.1130/abs/2026NE-411357
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