The science of the fate, transport and toxicity of per- and polyfluoroalkyl substances (PFAS) has progressed to the point that water quality guidelines have been promulgated in Canada for some of these compounds and more are being developed or considered. This will likely result in the identification of more PFAS-contaminated sites. Sampling and analytical tools to reliably measure PFAS in water and other environmental media have improved in the last few years; however, many grab sampling techniques are time-consuming, cause disturbance of the water column and generate volumes of contaminated water that need disposal. Furthermore, grab sampling approaches only provide a snapshot of PFAS concentrations. Passive samplers overcome many of these issues and can be valuable in site investigation, risk assessment and management. Passive samplers are a valued tool for evaluating other hydrophobic contaminants, such as polychlorinated biphenyls and polyaromatic hydrocarbons. A passive sampler is a physical medium such as a polymer with a predictable affinity for the analyte of interest. This physical medium is loaded into a device suitable for deployment (e.g., down a groundwater well or embedded in sediment). Because the uptake of hydrophobic contaminants is rather slow (on the order of weeks or months), the results represent time-integrated concentrations and provide better long-term site characterization. Additionally, accumulation of the analyte by the passive sampler medium allows improved detection limits when compared to traditional water sampling. Furthermore, passive samplers accumulate only the freely dissolved (most bioavailable) fraction of the contaminant, providing better insights into the ecological risk than the total concentrations which tend to overestimate the magnitude of risk. With these benefits in mind, a passive sampler for PFAS has been designed. The research process involved preliminary trials to identify a suitable physical medium. Adsorption experiments were then conducted for 15 PFAS analytes ranging from anionic carboxylic acids and sulfonates of different chain lengths to PFAS precursors to determine their uptake kinetics and adsorption isotherms. The equilibrium between passive sampler and the sampled water was achieved in less than seven days for most of the analytes. The adsorption behaviour varied significantly between the analytes. The longer chain compounds demonstrated higher sorption than the shorter chains, and the sulfonates showed higher sorption compared to carboxylates. Sorption of PFAS onto the passive sampler was also affected by the water pH, ionic strength, and dissolved organic matter, which indicates the importance of considering these variables in PFAS site investigation and risk management planning. This presentation will include the details on the PFAS passive sampler development as well as a discussion on how passive samplers can benefit PFAS site investigations and why results from passive samplers are an important line of evidence for ecological risk assessments. If available in time for the presentation, the results from a field demonstration to be conducted will also be presented. The field data will be discussed in terms of the benefits, limitations, and future refinement needs of the technology and its applicability in site investigation and risk assessment. Eliza Kaltenberg, Research Scientist, Environmental Assessment Group, Battelle Memorial Institute Dr. Eliza Kaltenberg is a Research Scientist with Battelle's Environmental Assessment Group. The majority of her current work focuses on assessments of hydrophobic organic compounds in sediments and water. She has been also a part of Battelle's research group working on advancement of PFAS sampling methods. Eliza’s research interests include aqueous and sediment geochemistry, hydrophobic contaminant partitioning and bioavailability, the influence of bioturbation of early diagenesis processes, and the role of sediments in nutrient retention. She worked on several projects regarding development of new analytical methods for aqueous and sediment samples, where she utilized a combination of passive sampling, colorimetry, and fluorescent tracers to answer the emerging questions and needs in an innovative way.
Stefano Marconetto, Global PFAS Practice Leader, Golder Stefano Marconetto is Golder’s global PFAS practice leader with 10 years of experience with the characterization and remediation of PFAS impacted sites. Mr. Marconetto’s technical focus is primarily on detailed site characterization, fate&transport assessment and conceptual site model development, but his expertise also includes remedial options evaluation, feasibility assessment, remedial action plan development and implementation at military bases, firefighting training facilities, airports, manufacturing plants, power plants and waste disposal sites in North America and abroad. He has also provided technical training as well as support to clients in their liaison with project stakeholders on PFAS related issues. He authored presentations and guidance documents on PFAS, is currently an active member of the ITRC PFAS team and is involved in several research projects in collaboration with prestigious universities and industrial partners on PFAS fate&transport and remediation.