Soil retention of trifluoroacetate

The phase out of chlorofluorocarbons (CFCs) has resulted in the use of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) as environmentally acceptable alternative chemicals. Trifluoroacetic acid (TFA) has been identified as a degradation byproduct of these compounds, which largely returns to Earth's surface via precipitation. Little is known about the environmental and ecological fate of TFA. Soil retention studies were conducted to evaluate the potential accumulation of TFA in soil of terrestrial ecosystems. Batch equilibrium studies showed that detectable TFA was retained by 34 of 54 soils collected from diverse locations. Retention ranged from a high of 260 to 25 μmol kg^-1 (0-60% of added TFA). Most soils (43 of 54) did not retain TFA strongly (>25%), but soils high in organic matter and some mineral soils with high iron and aluminum content exhibited strong retention. Trifluoroacetate retention was correlated (r = 0.60) with % organic matter content. Organic soils from wetlands, peatlands, and a boreal forest showed the greatest retention. The retention of TFA increased with decreasing pH. The magnitude of TFA retention was similar to Cl^- and Br^-. Trifluoroacetate retention decreased with increasing concentrations of F^-, Cl^-, and SO₄^2-. The ultimate fate of TFA retained in soils is uncertain.