Production of perflourinated acids from colloid and particle associated precursors in urban runoff

Perfluoroalkyl carboxylic and sulfonic acids are persistent, fully fluorinated organic pollutants that are stable in the environment, tend to bioaccumulate, and cause deleterious health effects. We hypothesize that precursors to the perfluoroalkyl acids are present as freely dissolved species and as species sorbed to colloidal particles in aqueous environmental samples; over time, these compounds are microbially transformed to the perfluoroalkyl acids. This slowly released source poses a long-term threat to the presence of perflourinated acids in the environment. The purpose of this investigation is to quantify the freely dissolved and colloidally-associated fractions of precursors in aqueous runoff samples. Particles and colloidal content will be isolated by filtration and centrifugation. Precursor concentrations will be measured indirectly by oxidizing potential precursors to their corresponding perfluoroalkyl acids and measuring the concentrations that evolve. The anticipated results are that a large fraction of precursors present in aqueous samples are not in dissolved form, but associated with particles and colloidal material. The binding of precursors to organic matter and particles might inhibit their accessibility to biotransformation. The results of this study have implications for the long-term release and presence of perfluoroalkyl acids in the environment.