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Testing the Use of Biofilms to Measure PFAS in the South Fork Palouse River: Final Report

Publication number Date Published
24-03-006May 2024
VIEW NOW Testing the Use of Biofilms to Measure PFAS in the South Fork Palouse River: Final Report (Number of pages: 52) (Publication Size: 10710KB)

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Author(s) Wong, S.
Description In August 2021, the Washington State Department of Ecology (Ecology) conducted a field study to test biofilms as a tool for measuring and identifying sources of per- and polyfluoroalkyl substances (PFAS) in the environment. Ecology chose the South Fork Palouse River watershed as the study area because high levels of PFAS have previously been documented in the river.

Ecology collected coinciding surface water and biofilm samples from 11 sites in the watershed during one sampling event. Ecology also collected sediment samples at a subset of four sites. Additionally, Ecology collected one influent and effluent sample from the Pullman Wastewater Treatment Plant (WWTP), which discharges effluent to the South Fork Palouse River.

PFAS were quantitatively detected in all 28 samples collected. Summed concentrations of 40 target analytes (total PFAS) were 13.4 – 118 ng/L in surface water, 0.11 – 3.6 ng/g in biofilm, and 0.27 – 5.4 ng/g in sediment samples. Ecology found the highest total PFAS concentrations downstream of the river’s confluence with Paradise Creek and in Paradise Creek (a WWTP-influenced water body). Total PFAS concentrations in effluent from the Pullman WWTP were higher than in the influent, primarily due to increases in perfluoroalkyl carboxylic acids. Ecology also found relatively high PFAS concentrations in the surface water, biofilm, and sediment in Missouri Flat Creek, which is not affected by WWTP effluent.

Ecology found that biofilm samples were useful in identifying at least three major conveyances of PFAS to the South Fork Palouse River: Paradise Creek, the Pullman WWTP, and Missouri Flat Creek. Ecology also found that PFAS partition differently in the surface water, biofilm, and sediment. For this study, collecting and analyzing multiple matrices seemed most effective in characterizing PFAS contamination and identifying potential sources in the South Fork Palouse watershed.
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Keywords South Fork Palouse River, Per- and polyfluoroalkyl substances (PFAS), wastewater treatment plant, perfluorooctane sulfonic acid (PFOS)
WATERSHED Water Resource Inventory Area 34 Palouse
DATA Environmental Information Management (EIM) #SWON0004


Quality Assurance Project Plan: Testing the Use of Biofilms to Measure PFAS in the South Fork Palouse River