Fate of nonylphenol-ethoxylates in soil/biosolids systems planted with crested wheatgrass

Microcosm experiments, 150 days in duration, were conducted to evaluate the fate of 14C-labeled nonylphenol (NP), nonylphenol tetraethoxylate (NPE4), and nonylphenol nonylethoxylate (NPE9) in a soil/biosolids (99.5:0.5% w/w) environment planted with crested wheatgrass (Agropyron cristatum). Three concentrations (6, 24, and 47 mg/kg dry weight) of NP, NPE4, and NPE9 were examined along with unplanted and poisoned controls. Phenol at 22 mg/kg was also evaluated as a reference compound. The biosolids were obtained from a municipal wastewater treatment plant receiving mixed use wastewater, and the loamy sand soil was collected from an agricultural plot. Mineralization was quantified by collecting the 14CO2 produced during the study. The extent of mineralization at the end of the study ranged from 7% (NP) to 53% (phenol) with phenol > NPE9 > NPE4 > NP. 14C concentrations in the foliar tissues were proportional to the exposure concentration but much lower than the root concentrations.