Maike Schaefer

Progress in evaluation of risk potential of ionic liquids—basis for an eco-design of sustainable products

Motivated by the prevailing need for a sustainable development and taking the principles of Green Chemistry as a starting point, the present paper describes new and updated findings regarding a sustainable product design for ionic liquids. The focus is on environmental risk. Nevertheless, cytotoxicity testing and first indicative results from a genotoxicity study extend present knowledge also with regard to possible effects on humans. The structural variability of commercially available ionic liquids as well as the abundance of theoretically accessible ionic liquids is illustrated and the consequences for an integrated risk assessment accompanying the development process are discussed. The side chain effect on toxicity for imidazolium type ionic liquids was confounded by more complex biological testing. Also, an influence of an anion on cytotoxicity is shown for the first time. Testing of presumed metabolites of the imidazolium type cations showed a significantly lower biological activity in cytotoxicity studies than their parent compounds. The importance of a purity assessment for ionic liquids is pointed out and a collection of methods that is believed to be adequate is presented. In addition to risk analysis, the use of life cycle analysis for the multi-objective problem of designing ionic liquids is sketched and an eco-design scheme for ionic liquids is proposed. In conclusion, the paper illustrates the complex nature of the development processes ionic liquids are currently undergoing and provides guidance on which aspects have to be kept in mind.

Behavioural Endpoints in Earthworm Ecotoxicology Evaluation of Different Test Systems in Soil Toxicity Assessment

Background, Aims and ScopeEndpoints in earthworm ecotoxicology scheduled in guidelines are mortality and reproduction rates. However, not only the direct influence of pollutants on population parameters but also changes in behaviour such as substrate avoidance can have an important impact on soil ecosystems. In practice two different avoidance response tests are applied in earthworm ecotoxicology: (i) a six-chamber test system and (ii) a two-chamber test system. Both avoidance response-test systems were compared to establish their respective advantages and disadvantages in order to advance the standardisation of behavioural tests. The earthworm avoidance-response tests were applied in addition to the standard acute and chronic earthworm toxicity tests (ISO 11268) in order to compare the sensitivity of the test endpoints.MethodsTest substrates were contaminated with crude oil and 2,4,6-Trinitrotoluene (TNT), respectively. The test species wasEisenia fetida. The earthworms were exposed to the contaminated substrates and their mortality (14 d), reproduction rates (number of cocoons after 28 d, juvenile hatching after 56 d), and substrate preference (48 h) determined.Results and DiscussionWhereas 1000 mg/kg TPH (Total Petroleum Hydrocarbons) did not show any lethal effects, 100% mortality occurred in soil with comparable TNT concentration. The acute tests consistently produced the highest effect concentrations whereas reproduction and substrate avoidance were the more sensitive test parameters. Both behavioural test systems, when compared, showed similar substrate avoidance after an incubation time of 48 h. The six-chamber test system provides the potential to test six different substrates/concentrations at one time. It was observed, however, that earthworms did not migrate among all test chambers within a test unit in order to select the most appropriate substrate. Orientation was observed only between directly neighbouring test compartments, which complicates the interpretation of the test results.ConclusionSubstrate avoidance and reproduction variables were clearly more sensitive test endpoints than mortality. Therefore avoidance-response tests proved to be useful test methods in detecting effects of sublethal concentrations of pollutants on earthworms. The test duration of the avoidance tests is much shorter compared to the standard acute and chronic earthworm toxicity tests, which makes them a quick screening tool for identifying potential soil toxicity. Both avoidance-response test systems showed comparable results regarding the test sensitivity. Nonetheless, the incomplete substrate use in the six-chamber avoidance test due to the reduced migration possibilities (orientation only to neighbouring chambers) might reduce the distinctness of test results as it allows only reliable information on the most avoided and therefore most toxic substrate but not on 1 a clear dose-response pattern. Thus, to gain valid results, the number of replicates and the arrangement of the different substrates must be adopted. The two-chamber test system is less time-consuming due to easy handling and test results can be quantified more easily.Recommendations and OutlookIn consequence of the better validity of test results, lower expenses for test containers and less time for handling, the use of the two-chamber system is preferred over the six-chamber test system to assess the toxicity of polluted soil. Because of the ecosystem consequences of behavioural effects and the fact that avoidance response tests can reveal the toxic potential of pollutants in low concentrations, such tests should be included into ecotoxicological test protocols.

Erprobung und Erfolgskontrolle eines Phytoremediations-verfahrens zur Sanierung Sprengstoff-kontaminierter Böden

ZusammenfassungDie Befunde des in seiner Konzeption in Teil I dargestellten Freilandexperimentes dokumentieren die TNT-Abreicherung und Erholung des Standortes im Laufe der Phytoremediation. Das Monitoring umfasst Erhebungen im Feld (Nitroaromatengehalte in Boden, Sickerwasser und Pflanzen; Erfassung von Bodenorganismen und Streuabbau) und den Einsatz einer Biotestbatterie mit 6 Einzeltests. Die Daten belegen die hohe Heterogenität der TNT-Kontamination, eine rasche initiale Abreicherung und eine geringe Verlagerung von Nitroaromaten in Pflanzen und Sickerwasser. Die anfänglich rasche Transformation des TNT zu Aminodinitrotoluolen lässt nach 3 Monaten deutlich nach. Mit Hilfe der Biotestbatterie wird die Toxizität des Bodens differenziert beurteilbar; die boden-biologischen Befunde lassen Langzeitwirkungen der TNT-Belastung wahrscheinlich werden. Eine Gesamtbeurteilung des Projekts wird im dritten Teil der Artikelserie erfolgen.AbstractResults of a field experiment (please refer to Warrelmann et al. 2000a) document TNT-degradation and regeneration after the establishment of a phytoremediation. Various approaches are included in a complex monitoring system, which are conducted in the field (nitroaromatics in soil, seepage water, and plants; soil fauna; soil fungi; decomposition) as well as in the lab (a battery of 6 biotests). The data document a high heterogeneity of the TNT-contamination, a rapid initial decrease and a mediocre displacement of nitroaromatics in plants and seepage water. The initial rapid transformation of TNT to aminodinitrotoluenes ceases significantly after 3 months. Results of the biotest battery allow a sophisticated assessment of soil toxicity; the results from the soil ecological field investigations make the long-term effects of TNT-contamination likely. In a third part of the series of articles, a synopsis and judgement of the project will be delivered.