Occurrence of a Nitro Metabolite of a Defined Nonylphenol Isomer in Soil/Sewage Sludge Mixtures

摘要

Uniformly [~(14)C]-ring-labeled 4-(3,5-dimethyl-3-heptyl)phenol (353-nonylphenol) is a highly relevant isomer of the technical nonylphenol mixture.We studied the sorption,desorption,and degradation of the synthesized isomer in an agricultural sandy loam at various soil/sewage sludge ratios.Sorption of 353-nonylphenol was high and differed with the amount of suspended soil in water,log /C_(oc) values,which are used to assess the risk of nonylphenol,ranged from 3.80 to 5.75.Desorption was slow and low and resulted in constant concentrations of about 15 ng/L 353-nonylphenol in water after several desorption steps.In degradation studies up to 6% of the applied 353-nonylphenol in soil was volatilized;we consider this an important source of nonylphenol in the environment.With increasing amounts of sewage sludge in the soil/sewage sludge mixtures,353-nonylphenol was stabilized,probably because of the lack of oxygen in sludge aggregates even under oxic conditions in flow-through systems.Unexpectedly,a less-polar metabolite was detected in amounts up to 40% of the applied nonylphenol after 135 days of incubation.This novel metabolite was identified as 4-(3,5-dimethyl-3-heptyl)-2-nitrophenol.This product formation might indicate the existence of novel metabolic pathways of nonylphenol in the environment.