Purpose: Nonylphenol polyethoxylates (NPEOs) are a group of surfactants known to be toxic and able to mimic estrogen compounds and thus interfere with the action of an animal's endogenous hormones. NPEOs are easily biodegraded in the environment, but the last end product, nonylphenol (NP), is the most toxic and recalcitrant form and hence can have a longer half-life in the environment. Despite the fact that most NP is finally degraded, a small fraction may remain in soil for longer periods. In soils, the application of sewage sludge is the main source of NPEOs. The aim of this study is to provide data on the effects of NP on a simplified soil invertebrate community since only a few studies using single-species bioassays are available for terrestrial ecosystems in comparison with aquatic ecosystems. Materials and methods: In our study, we assessed the effect of increasing NP concentrations (0, 10, 30, 90, and 270 mg NP kg-1) in soil microcosms containing a simplified soil community consisting of natural microorganisms, a primary producer (an oat seedling of Avena sativa), several consumers (the isopod Porcellionides sexfasciatus, the enchytraeid Enchytraeus crypticus, and the collembolans Folsomia candida, Ceratophysella (Hypogastrura) denticulata, and Proisotoma minuta), and a predator species (the mite Hypoaspis aculeifer). The effects on the different taxa of the different NP concentrations were assessed over three sampling dates (28, 56, and 112 days) using the principal response curves method. Results and discussion: The soil community did not change significantly at concentrations below 90 mg NP kg-1, which was selected as the nonobserved effect concentration (NOEC). The highest concentration (270 mg NP kg-1) changed the community significantly after 28 and 56 days, but this effect disappeared after 112 days, in accordance with the known rapid biodegradation of this compound in soil. Conclusions: Taking into account the usual NP concentrations in soils with repeated applications of sludge, the environmental risk of NP to soils seems to be limited because the derived NOEC was clearly above the usual concentrations in soil reported in the literature. However, the use of highly polluted sludges or accidental spillages, together with the possible pollution exportation by runoff to aquatic ecosystems, which are highly sensitive to NP pollution, recommend the careful monitoring of this chemical in the environment. © Springer-Verlag 2010.
- Invertebrate community