Domene X., Chelinho S., Sousa J.P. (2010) Effects of nonylphenol on a soil community using microcosms. Journal of Soils and Sediments. 10: 556-567.EnllaçDoi: 10.1007/s11368-009-0167-9
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.
Domene X., Colón J., Uras M.V., Izquierdo R., Àvila A., Alcañiz J.M. (2010) Role of soil properties in sewage sludge toxicity to soil collembolans. Soil Biology and Biochemistry. 42: 1982-1990.EnllaçDoi: 10.1016/j.soilbio.2010.07.019
Soil properties are one of the most important factors explaining the different toxicity results found in different soils. Although there is knowledge about the role of soil properties on the toxicity of individual chemicals, not much is known about its relevance for sewage sludge amendments. In particular little is known about the effect of soil properties on the toxicity modulation of these complex wastes. In addition, in most studies on sewage sludges the identity of the main substances linked to the toxicity and the influence of soil properties on their bioavailability remains unknown.In this study, the toxicity of a sewage sludge to the soil collembolan Folsomia candida was assessed in nine natural soils from agricultural, grassland and woodland sites, together with the OECD soil. Correlations between the relative toxicity of sludge for collembolans in the different soils and their physical and chemical soil properties were assessed in order to identify the main compounds responsible for the effects observed. Furthermore, the relationships between the toxic effects to collembolans and water-soluble ions released by sludge, pH and electric conductivity were also assessed, together with the modulating effects of soil properties.Sludge toxicity was directly linked to the water extractable ammonium, which explained most of the mortality of the collembolans, and part of the inhibition of reproduction. For the last endpoint, nitrite also contributed significantly to the inhibition observed. The varied levels in water extractable ammonium in the different soils at equal dosages seem to be, in turn, modulated by some soil properties. Higher organic carbon contents were associated with lower toxicity of sludge, both for survival and reproduction, probably related to its higher ammonium sorption capacity. In addition, for reproduction, increasing the C/N ratio and pH appeared to increase the toxicity, probably due to both the greater difficultly in nitrification and the known unsuitability of alkaline soils for this species. © 2010 Elsevier Ltd.
Domene X, Mattana S, Ramírez W, Colón J, Jiménez P, Balanyà T, Alcañiz JM, Bonmatí M (2010) Bioassays prove the suitability of mining debris mixed with sewage sludge for land reclamation purposes. Journal of Soils Sediments 10: 30-44. doi 10.1007/s11368-009-0073-1.
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