Selection of relevant ecotoxicity tests to assess the effects of biosolids used in agriculture

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Huguier, Pierre | Manier, Nicolas | Chancerelle, Laure | Pandard, Pascal | Bauda, Pascale

Edité par CCSD -

In modern agriculture and in accordance with environmental sustainability, biosolids are applied on fields. These materials are used as fertilizers, to maintain a high production rate of plants. But if they are a source of nutrients, they can also be potentially a source of pollutants. As a consequence they can affect plants, soil fauna and finally humans. In this study, environmental effects of different biosolids (sewage sludge, manure, composted materials...) were studied using ecotoxicity tests on soil and aquatic organisms. The aim of this work was to establish a test battery to assess the effects of biosolids, by comparing their respective sensitivities towards these materials. Organisms composing the biotest battery and their respective acute and/or chronic endpoints are the followings : algal growth inhibition of Pseudokirchneriella subcapitata (NF EN ISO 8692) ; inhibition of growth and reproduction of the nematode Caenorhabditis elegans for solid and liquid media (ISO 10872) ; inhibition of the mobility of the crustacean Daphnia magna (NF EN ISO 6341) ; inhibition of population growth of the rotifer Brachionus calyciflorus (NF ISO 20666) ; inhibition of light emission of the bacteria Vibrio fischeri (NF EN ISO 11348-3) ; inhibition of root growth, emergence and growth of higher plants (ISO 11269-1 and ISO 11269-2) ; avoidance and reproduction inhibition of the earthworm Eisenia fetida (ISO 17512-and ISO 111268-2). All of these bioassays were conducted using their respective standardized protocol, excepted for C. elegans soil tests which were carried out using the method detailed in another work (in Huguier et al., Applicability of the C. elegans survival, growth and reproduction test to assess the effect of solid wastes; same conference topic). Concerning samples preparation, standard soils (ISO and/or LUFA) were mixed with biosolids at defined doses (application rate, and e.g. 2 times, 5 times, 10 times, 20 times the application rate) to determine toxicity thresholds. For liquid samples, water extracts of the mixtures were obtained following the standard EN 14735. Results of a limed sludge, a cow manure, ashes and a compost obtained from domestic wastes will be presented and discussed in details.

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