Date of Graduation

5-2026

Document Type

Thesis

Degree Name

Bachelor of Science in Biological Engineering

Degree Level

Undergraduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Brian Haggard

Committee Member

Julian Fairey

Second Committee Member

Kenrick Hardaway

Abstract

The class of chemicals known as Per- and Polyfluoroalkyl Substances (PFAS) are believed to be widespread in the natural environment, but the full extent of PFAS prevalence is not well understood, particularly in karst springs. The objectives of this study were to (1) collect water samples from Cave Springs and Withrow Springs, Northwest Arkansas, (2) measure for concentrations of 40 PFAS compounds using EPA Method 1633, and (3) compare differences in PFAS concentrations and discuss potential sources of PFAS for each spring. Each spring was sampled on September 29, 2025, October 13, 2025, and November 10, 2025, and water samples were frozen and sent to a contract lab for testing. Total PFAS (ΣPFAS) was calculated as the sum of concentrations of each PFAS present at a site. 15 PFAS were reliably estimated concentration above the minimum detection limit (MDL) and method blank at Cave Springs, while 11 PFAS were reliably estimated at concentrations above the MDL and method blank at Withrow Springs. The PFAS measured at the greatest concentrations at Cave Springs were PFBA, PFBS, PFOS, and PFOA. The PFAS measured at the greatest concentrations at Withrow Springs were PFBA, PFPeA, PFOS, and PFOA. Mean ΣPFAS was 8.45 ng/L at Cave Springs and 2.82 ng/L at Withrow Springs. Mean ΣPFAS (one tailed t-test, P = 0.038) and eight individual PFAS (one tailed t-test, P ≤ 0.045) were significantly greater at Cave Springs than at Withrow Springs. The occurrence of PFAS was greater at Cave Springs than at Withrow Springs likely due to land use differences within their recharge zones. Testing at additional springs around the region and across different weather conditions is needed to further understand the scope of PFAS presence in karst springs in Northwest Arkansas.

Keywords

PFAS; karst; water quality; springs

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