Mineralization and plant uptake of 14C-labeled nonylphenol, nonylphenol tetraethoxylate, and nonylphenol nonylethoxylate in biosolids/soil systems planted with crested wheatgrass

Microcosm experiments (duration, 150 d) were conducted to evaluate the mineralization and plant uptake of [C-14]nonylphenol (NP), [C-14]nonylphenol tetraethoxylate (NPE4), and [C-14]nonylphenol nonylethoxylate (NPE9) in a soil/biosolids (99.5:0.5 w/w) environment planted with crested wheatgrass (Agropyron cristatum). Three initial nominal concentrations (6, 24, and 47 mg/kg dry wt) each of NP, NPE4, and NPE9 were examined along with unplanted and unplanted poisoned controls. Phenol (22 mg/kg) also was evaluated as a more degradable reference compound. The biosolids were obtained from a municipal treatment plant. and the loamy sand soil was freshly collected. Mineralization ranged from 7% for NP to 53% for phenol, and no enhancement was observed in the planted systems. For NP, NPE4, and NPE9, C-14 foliar tissues concentrations were proportional to exposure concentrations but were 10-fold lower than the root concentrations and two- to threefold lower than the soil concentrations. Bioconcentration factors (BCFs) based on C-14 Measurements ranged from 0.31 (mg compound/kg dry plant/mg compound/kg dry soil) for systems spiked with NP to 0.52 for systems spiked with NPE9. Results of the NP analysis (initial concentration, 47 mg/kg) showed a 90% decrease in the soil concentration and an average BCF of 1.0. The lower BCF calculated from the C-14 analysis likely resulted from the presence of NP transformation products in the soil that are less available or are translocated by the plants but quantified by the combustion/liquid scintillation counting procedure.