TRICHLOROETHYLENE SORPTION TO SEDIMENTARY ROCKS OF THE NEW JERSEY BASIN INDICATE MATURE ORGANIC MATTER

The former Naval Air Warfare Center (NAWC) in Trenton, New Jersey, has legacy trichloroethylene (TCE) contamination that persists at high dissolved concentrations in spite of decades of pump-and-treat control. The geology at NAWC consists of fractured, low permeability mudstones of the New Jersey basin. The four primarily lithologies exhibit more than an order of magnitude in fraction organic carbon (f_oc) content. Representative samples of each of the lithologies, reflecting the f_oc range, were chosen for this study. Batch sorption experiments were used to generate sorption isotherms spanning approximately four orders of magnitude in aqueous concentration. The isotherms for all of the samples were very nonlinear, as characterized by Freundlich slopes less than 0.75. The isotherms showed mostly similar slopes (similar Freundlich exponents). Overall the samples with the highest f_oc were able to sorb a greater amount of TCE. However, at moderate to low aqueous concentrations, the sorbed to solution concentration ratios for all samples (i.e. Kd) were at least an order of magnitude greater than predicted from the empirical approach using a literature average for the carbon-normalized TCE Kd (Koc). Our results are consistent with literature reports of TCE sorption to mature organic matter or to organic matter containing black carbon. Ongoing work will compare the isotherms to the properties of the organic matter. The sorption data gathered will be used to model retarded pore diffusion from the low permeability matrix rock to high permeability zones.