PFAS Source Attribution Investigation Using Air Dispersion Modeling, Fingerprinting, and Environmental Forensics
Project Overview
This environmental forensic investigation evaluated the historical release, environmental transport, deposition, and source attribution of per- and polyfluoroalkyl substances (PFAS) originating from long-term industrial operations. The investigation integrated historical operational records, air dispersion modeling, environmental chemistry, hydrogeology, groundwater investigations, soil sampling, PFAS fingerprinting, statistical analysis, geographic information systems (GIS), and quantitative exposure assessment to determine whether historical industrial activities contributed to PFAS contamination identified in surrounding environmental media. Multiple independent scientific disciplines were synthesized to reconstruct historical contaminant releases, evaluate environmental transport mechanisms, and assess the relationship between historical operations and off-site PFAS detections.
A principal objective of the investigation involved reconstructing historical PFAS release mechanisms occurring over several decades. Historical engineering records, aerial photography, satellite imagery, operational documents, waste management practices, environmental investigations, and regulatory records were evaluated to characterize changes in facility operations through time and identify potential mechanisms capable of releasing PFAS into the surrounding environment. Historical site reconstruction incorporated multiple generations of aerial imagery and GIS analysis to document changes in disposal areas, operational footprints, transportation corridors, and surface conditions relevant to environmental release and contaminant transport. These historical reconstructions provided the foundation for developing representative source terms used in subsequent environmental modeling.
Atmospheric transport represented a major component of the investigation. Historical source terms were developed using engineering records, operational histories, particulate emission inventories, historical facility layouts, and reconstructed land-use conditions. EPA-approved AERMOD air dispersion modeling was used to estimate long-term atmospheric transport and deposition of PFAS-containing particulate matter under multiple historical operating scenarios. Sensitivity analyses evaluated alternative historical facility configurations, emission assumptions, meteorological conditions, and source geometries to determine the influence of historical operational changes on predicted deposition patterns. Independent modeling scenarios consistently demonstrated similar spatial deposition trends despite differences in source assumptions, providing additional confidence in the robustness of the reconstructed environmental transport analysis.
The investigation further integrated PFAS fingerprinting and multivariate statistical analyses to evaluate source attribution. Chemical fingerprints obtained from environmental samples were compared using multiple statistical similarity techniques, including compositional analyses and pattern recognition methods, to evaluate relationships among onsite materials, groundwater, soil, and off-site environmental samples. Rather than relying upon individual PFAS concentrations alone, the investigation evaluated the relative distribution of numerous PFAS compounds to determine whether observed environmental signatures were consistent with a common historical source. Fingerprinting analyses were further integrated with hydrogeologic information, soil investigations, groundwater monitoring, atmospheric deposition modeling, and historical operational records to strengthen source attribution using multiple independent lines of scientific evidence.
The investigation was conducted using accepted principles of environmental chemistry, atmospheric science, contaminant fate and transport, air dispersion modeling, hydrogeology, GIS analysis, PFAS fingerprinting, analytical chemistry, statistics, exposure science, and environmental forensics. Rather than relying upon a single environmental dataset or individual analytical technique, the evaluation synthesized historical records, engineering documentation, atmospheric modeling, environmental sampling, fingerprinting analyses, statistical evaluations, hydrogeologic information, and regulatory guidance into a multidisciplinary weight-of-evidence framework. This integrated scientific methodology provides a technically robust approach for reconstructing historical PFAS releases, identifying environmental transport pathways, evaluating contaminant fate, and supporting scientifically defensible source attribution.
Chemicals of Concern
This investigation evaluated a broad suite of per- and polyfluoroalkyl substances (PFAS) associated with historical industrial operations, with particular emphasis on perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and fluorochemical precursor compounds capable of transforming into persistent terminal PFAS. The investigation integrated environmental chemistry, atmospheric science, hydrogeology, analytical chemistry, contaminant fate and transport, toxicology, and environmental forensics to characterize historical releases, environmental transformation, atmospheric deposition, groundwater migration, and long-term environmental persistence. Rather than evaluating individual compounds independently, the investigation assessed the collective environmental behavior of multiple PFAS compounds using chemical fingerprinting, statistical analysis, historical manufacturing information, and environmental monitoring data.
Perfluorooctane sulfonate (PFOS) represented one of the principal contaminants evaluated because it was associated with historical industrial surfactant formulations used during manufacturing operations. Historical engineering documentation, product information, operational records, environmental sampling, and analytical chemistry were reviewed to characterize PFOS occurrence within facility soils, groundwater, and surrounding environmental media. Particular emphasis was placed on understanding the environmental persistence of PFOS, its strong affinity for particulate matter, and its potential transport through airborne dust, contaminated fill materials, and groundwater. These characteristics made PFOS a critical component of both the atmospheric transport analysis and the environmental fingerprinting evaluation.
Perfluorooctanoic acid (PFOA) was similarly evaluated because it represented both a historically detected environmental contaminant and an unintended byproduct associated with fluorochemical manufacturing processes. Historical manufacturing information, environmental monitoring, engineering records, and published scientific literature were reviewed to characterize PFOA occurrence within environmental media and to evaluate its contribution to long-term soil and groundwater contamination. Atmospheric deposition modeling, environmental sampling, and groundwater investigations were integrated to evaluate the distribution of PFOA across the study area and to compare modeled deposition patterns with independently measured environmental concentrations. These multiple lines of evidence strengthened interpretation of historical PFOA transport and environmental persistence.
The investigation also evaluated fluorochemical precursor compounds capable of degrading into terminal PFAS such as PFOS. Environmental chemistry assessments examined transformation pathways, environmental persistence, precursor degradation, and changes in PFAS composition over time. Because precursor compounds may undergo environmental transformation following release, fingerprinting analyses considered both precursor compounds and terminal degradation products when evaluating historical source attribution. Incorporating environmental transformation processes allowed chemical fingerprints to be interpreted within the context of long-term environmental weathering rather than assuming that all compounds remain chemically unchanged following release.
An additional focus of the investigation involved evaluating PFAS associated with contaminated particulate matter generated during historical industrial operations. Environmental chemistry and particulate transport evaluations examined the interaction between PFAS and suspended soil particles, aggregate materials, road dust, and other particulate sources capable of becoming airborne through industrial activities and vehicle traffic. Engineering evaluations quantified particulate generation from unpaved roads, aggregate handling, material transfer operations, and dust suppression activities, while atmospheric dispersion modeling estimated off-site transport and deposition of PFAS-bearing particulate matter. These analyses provided a scientifically supported mechanism linking historical industrial activities with atmospheric deposition observed in surrounding environmental media.
Finally, the investigation recognized that environmental contamination reflected the combined occurrence of multiple PFAS compounds exhibiting differing environmental behavior, transformation pathways, mobility, and persistence. Accordingly, the investigation integrated analytical chemistry, PFAS fingerprinting, atmospheric dispersion modeling, hydrogeology, contaminant fate and transport, statistical analyses, environmental monitoring, and source attribution methodologies to evaluate cumulative environmental contamination rather than relying upon individual PFAS compounds in isolation. This multidisciplinary approach provides a scientifically reliable framework for evaluating complex PFAS contamination and demonstrates the importance of integrating environmental chemistry, atmospheric science, hydrogeology, and statistical fingerprinting when reconstructing historical environmental releases and identifying contaminant sources.
Methods
The investigation was conducted using accepted principles of environmental chemistry, atmospheric dispersion modeling, contaminant fate and transport, hydrogeology, soil science, analytical chemistry, statistical analysis, environmental forensics, exposure assessment, and quantitative human health risk assessment. Because PFAS contamination resulted from multiple historical release mechanisms operating over several decades, the investigation integrated historical operational records, engineering documentation, environmental sampling, air dispersion modeling, PFAS fingerprinting, hydrogeologic investigations, statistical analyses, and regulatory guidance to reconstruct historical contaminant releases and evaluate environmental transport pathways. Rather than relying upon a single environmental dataset or analytical technique, the investigation employed a multidisciplinary weight-of-evidence approach that combined atmospheric science, environmental chemistry, hydrogeology, statistics, and engineering analyses to evaluate historical PFAS contamination and source attribution.
A major component of the investigation involved reconstruction of historical PFAS release mechanisms associated with industrial operations. Historical facility records, engineering documents, aerial photographs, historical satellite imagery, waste management practices, production histories, environmental investigations, and operational timelines were reviewed to characterize changes in facility operations through time and identify activities capable of releasing PFAS into surrounding environmental media. Historical reconstruction included evaluation of disposal practices, contaminated material handling, dust suppression activities, particulate generation, transportation routes, and changes in facility boundaries that could influence environmental transport. These engineering evaluations established representative source terms for subsequent atmospheric dispersion modeling and environmental transport analyses.
Atmospheric dispersion modeling represented one of the principal analytical components of the investigation. Historical PFAS emissions associated with contaminated particulate matter were reconstructed using engineering information, particulate emission inventories, vehicle traffic estimates, aggregate handling activities, historical site configurations, and meteorological observations. EPA-approved AERMOD air dispersion modeling estimated long-term atmospheric transport and deposition of PFAS-containing particulate matter under multiple historical operating scenarios. Sensitivity analyses evaluated alternative historical facility layouts, emission assumptions, meteorological datasets, and source geometries to characterize uncertainty associated with historical operations. Comparison of multiple modeling scenarios demonstrated consistent deposition patterns despite variations in historical source assumptions, strengthening confidence in the reconstructed atmospheric transport evaluation.
The investigation also incorporated PFAS fingerprinting and multivariate statistical analyses to evaluate environmental source attribution. Chemical fingerprints obtained from onsite soils, groundwater, off-site environmental media, and background datasets were compared using multiple independent statistical similarity techniques, including compositional fingerprint analysis, cosine similarity, Bray-Curtis similarity, Pearson correlation, and detection-based Jaccard similarity. Rather than relying solely on individual PFAS concentrations, statistical analyses evaluated the overall distribution of PFAS compounds to determine whether environmental samples exhibited consistent chemical signatures indicative of a common historical source. Integration of multiple statistical methodologies provided independent confirmation of source attribution while minimizing reliance upon any single analytical approach.
Hydrogeologic and environmental chemistry evaluations were further integrated with atmospheric deposition modeling to characterize contaminant migration following atmospheric release. Soil sampling, groundwater monitoring, contaminant fate and transport analyses, PFAS transformation pathways, soil-to-groundwater evaluations, and groundwater investigations were collectively evaluated to determine whether modeled atmospheric deposition was consistent with independently measured environmental concentrations. Geographic Information Systems (GIS) were used to compare modeled deposition patterns with observed soil and groundwater contamination while accounting for historical land use, surface conditions, and environmental transport pathways. Integration of atmospheric science with hydrogeology and analytical chemistry substantially strengthened interpretation of environmental monitoring results by linking predicted deposition with independently measured contamination.
Finally, the investigation employed accepted principles of uncertainty evaluation fundamental to environmental forensics and PFAS source attribution. Uncertainty associated with historical operational practices, emissions estimates, particulate generation, atmospheric dispersion, meteorological variability, PFAS transformation, groundwater migration, statistical analyses, and environmental sampling was addressed through integration of multiple independent engineering records, environmental datasets, atmospheric modeling scenarios, hydrogeologic investigations, fingerprinting analyses, statistical evaluations, and published scientific literature. Rather than relying upon any single model, environmental sample, or statistical comparison, the investigation synthesized engineering analyses, atmospheric science, hydrogeology, environmental chemistry, PFAS fingerprinting, analytical chemistry, and exposure science into a comprehensive multidisciplinary framework. This methodology provides a scientifically reliable basis for reconstructing historical PFAS releases, evaluating environmental transport pathways, and identifying contaminant sources while remaining consistent with accepted principles of environmental chemistry, atmospheric dispersion modeling, hydrogeology, environmental forensics, and quantitative exposure assessment.
Results
Review of the available engineering records, environmental investigations, analytical chemistry, hydrogeologic data, atmospheric dispersion modeling, and statistical evaluations demonstrated that characterization of long-term PFAS contamination requires integration of multiple independent scientific disciplines rather than reliance upon any single line of evidence. Historical operational records documented potential PFAS release mechanisms, while environmental sampling identified PFAS within soil, groundwater, and other environmental media. Atmospheric dispersion modeling reconstructed historical transport and deposition of PFAS-containing particulate matter, and statistical fingerprinting compared chemical signatures among onsite materials, off-site samples, and regional background data. Collectively, these complementary analyses provided a comprehensive scientific framework for evaluating contaminant source attribution, environmental transport, and long-term environmental persistence.
One of the principal findings of the investigation was the strong agreement between historical operational reconstruction, atmospheric dispersion modeling, PFAS fingerprinting, and environmental sampling. Historical engineering records documented multiple activities capable of generating and redistributing PFAS-containing particulate matter, including waste management practices, contaminated material handling, dust suppression operations, and vehicle traffic over contaminated surfaces. Independent AERMOD simulations predicted off-site atmospheric transport and deposition consistent with the observed spatial distribution of PFAS detected in environmental samples. Multiple historical facility configurations and sensitivity analyses produced similar deposition patterns, demonstrating that the overall conclusions remained robust despite variations in historical source assumptions.
The investigation further demonstrated the value of PFAS fingerprinting and multivariate statistical analyses for evaluating environmental source attribution. Rather than relying solely upon individual PFAS concentrations, multiple statistical similarity techniques compared the relative distribution of numerous PFAS compounds among onsite soils, groundwater, environmental samples, and regional background datasets. Independent fingerprinting methods—including cosine similarity, Bray-Curtis similarity, Pearson correlation, and detection-based Jaccard similarity—produced consistent results indicating that environmental samples shared chemical characteristics more closely associated with the historical industrial source than with regional background conditions. Agreement among several independent statistical approaches substantially strengthened confidence in the overall source attribution analysis.
The investigation also demonstrated the importance of integrating atmospheric deposition with hydrogeologic and environmental chemistry evaluations. Air dispersion modeling estimated long-term deposition of PFAS-containing particulate matter across surrounding properties, while soil sampling, groundwater investigations, and contaminant fate and transport evaluations assessed whether modeled deposition was consistent with independently measured environmental concentrations. Geographic Information Systems (GIS) were used to compare modeled deposition contours with sampling locations and observed PFAS occurrence, allowing atmospheric transport, soil contamination, and groundwater observations to be evaluated within a unified spatial framework. Integration of atmospheric science, hydrogeology, and analytical chemistry therefore provided a more scientifically representative assessment than evaluation of any single environmental medium alone.
Engineering evaluations further demonstrated that particulate generation and historical site activities represented plausible mechanisms for environmental redistribution of PFAS. Historical records documented contaminated material handling, aggregate processing, vehicle traffic, dust suppression practices, and other activities capable of generating PFAS-bearing particulate matter. Particulate emission inventories quantified emissions associated with vehicle movement, aggregate handling, and material transfer operations, while atmospheric modeling estimated off-site transport and deposition of contaminated particles. Integration of engineering analyses with environmental chemistry and air dispersion modeling provided a technically supported explanation for the environmental distribution of PFAS observed throughout the study area.
Another important finding involved the successful integration of air dispersion modeling, PFAS fingerprinting, environmental chemistry, hydrogeology, GIS analysis, statistical evaluation, engineering reconstruction, analytical chemistry, and environmental forensics into a unified scientific framework. No individual soil sample, groundwater result, air model, historical record, or statistical comparison independently characterized the complexity of decades of PFAS releases and environmental transport. However, when historical operational records, engineering documentation, atmospheric dispersion modeling, PFAS fingerprinting, environmental monitoring, hydrogeologic characterization, GIS analyses, and statistical evaluations were collectively reviewed, they provided a scientifically supported assessment of historical PFAS releases, environmental migration pathways, and contaminant source attribution. This multidisciplinary, weight-of-evidence approach represents a fundamental principle of modern environmental forensics and provides a technically reliable framework for evaluating complex PFAS contamination involving multiple environmental media, multiple release mechanisms, and long-term industrial operations.
Conclusions
The available scientific and technical documentation provides a comprehensive foundation for evaluating long-term PFAS contamination resulting from historical industrial operations using accepted principles of environmental chemistry, atmospheric dispersion modeling, hydrogeology, contaminant fate and transport, analytical chemistry, environmental forensics, statistical analysis, and quantitative exposure assessment. Although PFAS contamination develops through multiple environmental pathways operating over decades, integration of historical operational records, engineering documentation, atmospheric deposition modeling, environmental sampling, PFAS fingerprinting, hydrogeologic characterization, and statistical evaluation provides a scientifically reliable framework for reconstructing contaminant releases, identifying transport mechanisms, and evaluating environmental source attribution. This multidisciplinary methodology is consistent with accepted scientific practice within the fields of environmental engineering, atmospheric science, hydrogeology, and environmental chemistry.
The investigation demonstrated that evaluation of historical PFAS contamination is most scientifically reliable when engineering analyses, atmospheric dispersion modeling, PFAS fingerprinting, environmental chemistry, hydrogeology, statistical analyses, and environmental monitoring are considered collectively rather than independently. This weight-of-evidence approach reduces uncertainty by integrating complementary sources of scientific information and provides a technically supported basis for reconstructing historical releases, evaluating atmospheric transport, identifying environmental migration pathways, and determining contaminant source attribution. Independent agreement among historical operational records, engineering documentation, atmospheric modeling, fingerprinting analyses, environmental sampling, and statistical similarity evaluations substantially strengthens confidence in the overall scientific assessment while recognizing the complexity of long-term PFAS contamination.
The investigation further demonstrated the importance of evaluating multiple environmental transport pathways rather than relying upon a single release mechanism. Historical engineering evaluations identified several activities capable of redistributing PFAS-containing materials, while particulate emission analyses, atmospheric dispersion modeling, soil investigations, groundwater monitoring, and contaminant fate and transport evaluations demonstrated that PFAS may migrate through interconnected atmospheric, terrestrial, and subsurface pathways. Comprehensive investigations integrating atmospheric science, hydrogeology, soil chemistry, engineering analyses, environmental chemistry, and analytical monitoring therefore provide a more technically accurate understanding of PFAS contamination than evaluations based solely upon groundwater sampling, soil analyses, or air modeling independently. Consideration of these multiple environmental processes is essential for developing scientifically defensible evaluations of long-term PFAS contamination.
The investigation also demonstrated the value of integrating PFAS fingerprinting with atmospheric dispersion modeling and environmental monitoring. Chemical fingerprinting compared the relative distribution of multiple PFAS compounds using several independent statistical similarity methods, while atmospheric dispersion modeling reconstructed historical deposition patterns based upon engineering source terms and historical operational conditions. Soil sampling, groundwater investigations, and environmental monitoring provided independent analytical measurements that complemented both the fingerprinting and atmospheric modeling evaluations. Integration of these independent scientific disciplines substantially strengthened source attribution by demonstrating consistency among chemical composition, environmental transport, and observed contaminant occurrence rather than relying upon any single analytical technique.
More broadly, this investigation demonstrates how modern environmental consulting integrates air dispersion modeling, PFAS fingerprinting, environmental chemistry, contaminant fate and transport, hydrogeology, soil science, analytical chemistry, GIS analysis, multivariate statistical analysis, environmental forensics, and quantitative exposure assessment to evaluate complex PFAS contamination investigations. These multidisciplinary evaluations provide scientifically supported assessments of historical contaminant releases while remaining grounded in accepted engineering principles, atmospheric science, peer-reviewed scientific literature, environmental monitoring, regulatory guidance, and objective technical evaluation. By combining historical operational reconstruction, atmospheric deposition modeling, environmental sampling, PFAS fingerprinting, hydrogeologic characterization, statistical analyses, and environmental forensics, comprehensive investigations are able to develop reliable assessments of PFAS contamination that are consistent with recognized scientific practice and contemporary environmental health methodologies.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist, air dispersion modeler, environmental forensic expert, and exposure assessment specialist with more than twenty-five years of experience evaluating PFAS contamination, atmospheric deposition, groundwater quality, environmental chemistry, contaminant fate and transport, hydrogeology, analytical chemistry, environmental forensics, statistical source attribution, and quantitative human health risk assessment. Throughout his career, Dr. Rosenfeld has conducted investigations involving PFAS, volatile organic compounds, petroleum hydrocarbons, hazardous air pollutants, metals, combustion byproducts, chlorinated solvents, radionuclides, and numerous other environmental contaminants affecting industrial facilities, residential communities, groundwater resources, and public drinking water systems. His professional experience includes historical emissions reconstruction, EPA AERMOD modeling, PFAS fingerprinting, environmental site investigations, hydrogeologic characterization, contaminant fate and transport analysis, regulatory review, and expert witness testimony involving complex environmental contamination, toxic tort litigation, and environmental exposure assessment.
References
Agency for Toxic Substances and Disease Registry (ATSDR). (2024). Toxicological Profile for Per- and Polyfluoroalkyl Substances (PFAS).
Interstate Technology & Regulatory Council (ITRC). (2025). PFAS Technical and Regulatory Guidance.
U.S. Environmental Protection Agency (EPA). (2024). Integrated Risk Information System (IRIS): Perfluorooctanoic Acid (PFOA).
U.S. Environmental Protection Agency (EPA). (2024). National Primary Drinking Water Regulations for PFAS.
U.S. Environmental Protection Agency (EPA). (2024). Guideline on Air Quality Models (40 CFR Part 51, Appendix W).
U.S. Environmental Protection Agency (EPA). (2024). AERMOD Implementation Guide.
U.S. Environmental Protection Agency (EPA). (2024). Regional Screening Levels (RSLs): Soil-to-Groundwater Migration.
U.S. Geological Survey (USGS). (2024). Groundwater Hydrology and Contaminant Transport.
National Academies of Sciences, Engineering, and Medicine. (2022). Guidance on PFAS Exposure, Environmental Transport, and Human Health.