# Per- and polyfluoroalkyl substances in waters associated with oil and gas development in the Denver Basin

## TL;DR

This study examines PFAS levels in water from oil and gas operations in the Denver Basin, finding low concentrations but highlighting potential environmental risks from reuse.

## Contribution

The study provides the first characterization of PFAS in produced water from the Denver Basin and identifies environmental redistribution risks.

## Key findings

- Total PFAS concentrations in produced water were below 35 ng/L, dominated by short-chain compounds.
- Most PFAS in hydraulic fracturing fluids originated from input water, not additives.
- Oxidation revealed undetected PFAS precursors, suggesting incomplete analysis.

## Abstract

Use of per- and polyfluoroalkyl substances (PFAS) in the petroleum industry could be a cause for concern due to the large volumes of produced water (PW) generated during oil and gas extraction, the reuse of these wastes in water-stressed regions, and adverse health outcomes related to PFAS exposures. However, PW PFAS characterization is nearly absent in the literature, and hydraulic fracturing (HF) chemical disclosures often omit the identities of additives as proprietary. Here we evaluate PFAS in PW samples from three petroleum wells in the Denver Basin during their first year of production. Total concentrations of targeted PFAS (Σ40PFAS) were < 35 ng/L in PW samples, with short-chain PFAS like perfluorobutanoic acid persisting throughout the sampled duration. Analysis of freshwater inputs for hydraulic fracturing (Σ40PFAS ~ 113 ng/L) and mixed fracture fluid (Σ40PFAS ~ 69 ng/L) indicated much of the targeted PFAS content was derived from the input water, and not from HF additives, however samples subjected to oxidation indicated the presence of PFAS precursors that would not be detected by targeted analysis. This study highlights that while PFAS content is low in the studied PWs, the potential for redistribution of PFAS in the environment may be a consideration for reuse applications.

The online version contains supplementary material available at 10.1038/s41598-025-33394-9.