Different commercial, industrial, and military applications use many subcategories of fluorinated compounds all covered under Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS). The main molecular characteristic of PFAS is their strong carbon-fluorine bonds which make them ideal as water repellents, surfactants, and aqueous film-forming foams (AFFF). Also, the same characteristic makes them persistent in the environment. PFAS compounds with different chain-lengths pose different toxicity levels and PFAS with longer chain-lengths can undergo biotic and abiotic transformation to shorter chain-lengths or transformed to other subcategories of PFAS. The transformation of PFAS over time creates long term problems for contaminated sites. All above-mentioned factors need to be taken into account for site remediation. Governing bodies are looking for effective remediation solutions to limit exposure to PFAS. As such, containment of PFAS in landfill is a commonly used remediation practice so far. However, a better understanding of the fate of PFAS in the environment and their leaching characteristics when disposed in landfills is desirable to evaluate the containment efficiency. Here, we designed a set of experiments to identify the relationship of PFAS-contaminated soil and its potential impact on landfill leachate using Health Canada’s drinking water screening values as guidance in the absence of any landfill PFAS guidelines. The experiments include spiking of soil with 2 two different AFFF products (a fluorotelomer-based and a legacy, PFOS-based), characterisation of spiked and unspiked soil, identification of leachability of PFAS from soil using two different leaching procedures (Toxicity Characteristic Leaching Procedure TCLP and Synthetic Precipitation Leaching Procedure SPLP), and determination of transformation patterns of PFAS before and after leaching. The results indicate that PFAS concentrations in leachate depend not only on the leaching procedures used, but also on soil characteristics that could potentially be utilized to estimate leachate concentrations. Further testing is required to identify possible transformation of PFAS before and after leaching from contaminated sited and landfills. This study will help to evaluate site specific leaching characteristics of PFAS and possible PFAS contamination of water resources around contaminated sites, and landfills. Thus enabling risk assessors to estimate the risks associated with PFAS-contaminated soils originating from sites where AFFF has been applied for years, and for site remediation stakeholders to better understand the options available to them when removing impacted soil from sites undergoing remediation.

 

Egemen Aydin Bio:
Egemen Aydin holds a Ph.D. in environmental sciences and engineering. He has an extensive experience in environmental analytical chemistry particularly in method development for quantitative analysis of organic contaminants in various environmental matrices as well as identification of transformation products and unknown contaminants in the environment. He published more than 20 scientific papers in highly acclaimed journals and has been a frequent presenter at international scientific conferences. He conducted research at different universities in the USA, Italy and Turkey. Currently, he works for AGAT Laboratories and he is responsible for developing and directing R&D projects.