Minnesota Sea Grant-supported master's student, Samantha McClung, will be presenting her master's defense, titled "Observations and Source Apportionment of Targeted Per- and Polyfluoroalkyl Substances in Wet Deposition and their Importance to Secluded Lake Sediments."
McClung is an M.S. Candidate in the water resources science graduate program at the University of Minnesota.
This hybrid event is free and open to the public. Registration is not required.
When
Friday, May 30, 2025
10:00 - 11:00 a.m. CT
Location
This event will be held virtually via Zoom and in-person at:
Swenson Civil Engineering Building, room 265
1405 University Dr.
Duluth, MN 55812
Presentation Abstract
Per- and poly-fluoroalkyl substances (PFAS) are a group of persistent organic pollutants that have been observed in environmental media (e.g., sediments, surface water, ice) in remote areas suggesting the importance of atmospheric transport, transformation, and deposition of PFAS as a pathway into surface hydrologic systems. Freshwater lakes with large surface areas could be markedly impacted by atmospheric PFAS through precipitation (i.e., wet deposition).
To investigate wet-deposited PFAS in the Great Lakes region, weekly wet deposition samples were collected at five National Atmospheric Deposition Program National Trends Network sites in Michigan and Minnesota and analyzed for 33 PFAS. Annual flux of measured PFAS ranged from 835 to 1507 ng m-2 year-1. Perfluorocarboxylic acids (PFCA) were the dominant (> 90%) PFAS observed, but spatial and temporal variations of non-dominant PFAS highlight the value of long-term, high frequency sampling.
Source apportionment of PFAS in wet deposition was conducted using positive matrix factorization and identified four unique PFAS source profiles (i.e., precursor degradation, long-chain PFCAs, a baseline atmospheric PFAS signature, and industrial emissions). The factors that accounted for most wet-deposited PFAS were precursor degradation (37%) and atmospheric baseline (37%), while the long-chain PFCAs and industrial emissions factors each accounted for less than 17% of the total mass flux of PFAS. To constrain the influence of wet-deposited PFAS on lake sediments, a sediment core from a remote lake with primarily atmospheric inputs was age-dated and analyzed for 37 PFAS.
The wet deposition and lake sediments had similar compositional profiles of PFAS, favoring PFCAs, but annual fluxes of individual PFAS varied indicating physical removal/enrichment mechanisms and/or additional sources of PFAS. Overall, these observations highlight the impact physicochemical characteristics have on the fate and transport of PFAS in the atmosphere and lake sediments.
Event Organizer
This event is organized by the conservation sciences graduate program at the University of Minnesota.
Contact
Alex Frie, research and fellowship coordinator, Minnesota Sea Grant. [email protected].
Image credit: UMPR.