Juliane Filser

Environmental behavior and ecotoxicity of engineered nanoparticles to algae, plants, and fungi

Developments in nanotechnology are leading to a rapid proliferation of new materials that are likely to become a source of engineered nanoparticles (ENPs) to the environment, where their possible ecotoxicological impacts remain unknown. The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi. Interactions of ENPs with natural organic matter have to be considered as well, as those will alter the ENPs aggregation behavior in surface waters or in soils. Cells of plants, algae, and fungi possess cell walls that constitute a primary site for interaction and a barrier for the entrance of ENPs. Mechanisms allowing ENPs to pass through cell walls and membranes are as yet poorly understood. Inside cells, ENPs might directly provoke alterations of membranes and other cell structures and molecules, as well as protective mechanisms. Indirect effects of ENPs depend on their chemical and physical properties and may include physical restraints (clogging effects), solubilization of toxic ENP compounds, or production of reactive oxygen species. Many questions regarding the bioavailability of ENPs, their uptake by algae, plants, and fungi and the toxicity mechanisms remain to be elucidated.

Biological effects of imidazolium ionic liquids with varying chain lengths in acute Vibrio fischeri and WST-1 cell viability assays

Detailed biological studies of methyl- and some ethylimidazolium ionic liquids in luminescent bacteria as well as in the IPC-81 (leukemia cells) and C6 (glioma cells) rat cell lines are presented. Effective concentrations in these test systems are generally some orders of magnitude lower than effective concentrations [corrected] of the conventional solvents acetone, acetonitrile, methanol, and methyl t-butyl ether. No general influence of the anionic compound in the ionic liquids on toxicity could be found, although they seem to modulate toxicity in some cases. The clear influence of the alkyl chain length on toxicity was quantified by linear regression analysis. Alkyl chain length of the longer alkyl chain was varied from 3 to 10 carbon atoms. Consequences for a design of sustainable alternative solvents are briefly sketched.

How hazardous are ionic liquids? Structure–activity relationships and biological testing as important elements for sustainability evaluationThis work was presented at the Green Solvents for Catalysis Meeting held in Bruchsal, Germany, 13–16th October 2002.

For ionic liquids only few toxicological and/or ecotoxicological data are available until now. A strategy is presented which aims at an environmental risk assessment of chemicals, using a combination of structure–activity relationships (SAR), toxicological and ecotoxicological tests and modelling. The parts “test-kit-concept” and “multidimensional risk analysis” are described in detail by means of selected imidazolium ionic liquids. The iterative process of this strategy offers a tool for sustainable product design.

The role of Collembola in carbon and nitrogen cycling in soil

The article reviews recent publications dealing with relationships between Collembola, carbon and nitrogen turnover. Under field conditions, correlations between Collembola, total C and N are usually weak. More pronouncedinterdependences can be found with microbial parameters, especially when using multivariate statistics and sampling at high temporal resolution. Many manipulation experiments have revealed strong and usually positive impacts of Collembola on N mineralisation, soil respiration, leaching of dissolved organic carbon and plant growth. The effects are mostly indirect and depend on temperature, water content, substrate quality, population density, Collembola species, plant species and in particular on interactions with other soil biota. Key mechanisms are fungal feeding, distribution of fungal propagules, root herbivory and predation on nematodes. Omnivory is probably the prevailing feeding strategy in Collembola. Finally, a tentative conceptual model for arable soils is given, explaining the differing effects of Collembola on C and N turnover by switching feeding strategies according to environmental conditions.

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.

The influence of soil type and cultivation system on the spatial distributions of the soil fauna and microorganisms and their interactions

Abstract The aim of the FAM research network (Forschungsverbund Agrarokosysteme Munchen) is to investigate the ecological effects resulting from two different agricultural cultivation systems. This long-term experiment takes place on a landscape scale of a 143 ha farm which is situated in a hilly landscape derived from tertiary sediments. In April 1991 405 soil samples were taken along a 50 m by 50 m grid. One approach taken was to use geostastistical methods. Semivariograms were calculated, punctual kriging was performed and maps of the spatial distribution of the microbial biomass, soil carbon content and the Collembola were drawn. It was shown that management practice and type of cultivation had more influence on soil biota than different soil types. The higher amounts of organic matter in the top soil of grassland areas were reflected both in higher microbial biomass and in larger individual numbers of Collembola. On the whole experimental farm a high correlation ( r = 0.79) was found between carbon content ( C t ) and microbial biomass, whereas a value of r of 0.36 was found between Collembola and C t .

Imidazolium based ionic liquids in soils: effects of the side chain length on wheat (Triticum aestivum) and cress (Lepidium sativum) as affected by different clays and organic matter

This study provides data on the behaviour and toxicity of selected imidazolium based ionic liquids in the terrestrial environment with the aim to contribute to a prospective hazard assessment. Using the plant growth inhibition assay with wheat (Triticum aestivum) and cress (Lepidium sativum) we investigated the influence of two different clay minerals (kaolinite and smectite) in varying concentrations and clay mineral mixtures as well as the influence of organic matter in varying concentrations on the toxicity of three imidazolium based ionic liquids differing in the alkyl side chain length. The obtained results were compared to the German standard soil Lufa 2.2. Overall the influence of the 2:1 layer mineral smectite on toxicity was stronger than for the 1:1 layer mineral kaolinite resulting in lower toxicities when smectite was present. Comparable results were achieved in the tests with different clay mineral mixtures. The influence of the clay minerals was substance concentration dependent and the side chain effect could not consistently be confirmed for the different soil mixtures. The 1:1 clay mineral kaolinite caused in some cases an increase in toxicity. The obtained results for the influence of organic matter on the toxicity proved to be much more consistent than for the clay minerals: here an increase in organic matter concentration always resulted in a decrease of the toxicity. Differences in plant species sensitivity could be shown, but not in a consistent manner. A site specific hazard assessment of ionic liquids should therefore take into account organic matter content, quantity and especially quality of clay minerals.

Ecological and evolutionary consequences of biological invasion and habitat fragmentation

There is substantial evidence that environmental changes on a landscape level can have dramatic consequences for the species richness and structure of food webs as well as on trophic interactions within such food webs. Thus far, the consequences of environmental change, and particularly the effects of invasive species and the fragmentation and isolation of natural habitats, have most often been studied in a purely ecological context, with the main emphasis on the description of alterations in species abundance and diversity and trophic links within food webs. Here, we argue that the study of evolutionary processes that may be affected by such changes is urgently needed to enhance our understanding of the consequences of environmental change. This requires an approach that treats species as dynamic systems with plastic responses to change rather than as static entities. As such, phenotypic plasticity on an individual level and genotypic change as a population level response should be taken into account when studying the consequences of a changing world. Using a multidisciplinary approach, we report on recent advances in our understanding, identify some major gaps in our current knowledge, and point towards rewarding approaches to enhance our understanding of how environmental change alters trophic interactions and ecosystems.

Ionic liquids in soils: effects of different anion species of imidazolium based ionic liquids on wheat (Triticum aestivum) as affected by different clay minerals and clay concentrations.

This study contributes to a prospective hazard assessment of ionic liquids, focusing on the terrestrial environment. The influence of differently composed soils—varying contents of the clay minerals smectite and kaolinite—on the toxicity of different anion species of imidazolium based ionic liquids was studied for growth inhibition of wheat (Triticum aestivum). IM14 (CF3SO2)2N appeared the most toxic, independently of the investigated soil type. The toxicity of IM14 Cl, IM14 BF4 and IM14 HSO4 was mainly dominated by the cationic moiety. The observed effects varied in dependence of the added clay type and clay concentration. An increase of clay content resulted in less pronounced effects of these substances. In contrast, for IM14 (CF3SO2)2N the addition of clay minerals caused higher toxic effects in comparison to the reference soil. Our results give first hints for the assumption, that ionic liquids whose toxic action is based on the anionic moiety are especially hazardous for soils, particular for soils with high clay contents.

Long-term dynamics and interrelationships of soil Collembola and microorganisms in an arable landscape following land use change

Abstract An arable landscape (150 ha) comprising a broad variety of soil types had been cultivated conventionally for many years. A small section had been intensively managed (hops), while another had been used as grassland. For 2 years at the beginning of our study, all arable land was cultivated with cereals only. After that, management was changed to integrated or organic farming, grassland or fallow land. Within a group of sites representing the variety of soil types and management systems, the development of soil microorganisms and Collembola was monitored every spring during an 8-year period. The microbial biomass compared to initial conditions under uniform management increased, particularly in land that had been set aside. General Collembola abundance slightly decreased, except for areas that had been converted to integrated farming. Protaphorura armata and Lepidocyrtus cyaneus decreased over the entire area, whereas the Isotoma viridis group was positively affected by conversion to integrated farming. Although recorded only once per year, the main results were comparable to data recorded in this area at higher temporal or spatial resolution. Nevertheless, site conditions may influence the reactions of soil organisms to land use change, and should be taken into account for evaluation. Biota resident in the upper 0–10 cm of the soil reflected current management practice, whereas those at greater soil depth reflected instead management history and soil properties. The microbial biomass and abundance of selected Collembola taxa were modeled using artificial intelligence methods (regression trees). Land management type was the most important factor determining soil biota performance. The variation of Collembola abundance depended additionally on microbial biomass. When supported by a sufficiently large data set, regression trees are powerful tools for explaining complex non-linear relationships. Finally, suggestions for the sampling design in future long-term studies at the landscape scale are given.