1,500 research outputs found

    New direct contact approach to evaluate soil genotoxicity using the Vicia faba micronucleus test.

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    A method to assess micronucleus (MN) induction in Vicia faba roots by direct contact exposure to a solid matrix was developed. The procedure comprised a 5-d germination period, as in the well-known method using aqueous extracts. However, the seeds were here sown directly into the test soil whereas a culture period is necessary before exposing seedlings to a liquid medium. One soil under forest and two contaminated soils from areas affected by industrial installations and a coke works were used. Three durations of direct exposure were tested: 2, 5 and 7 d. The optimal duration was evaluated at 2 d to observe maximal MN induction without observing toxicity symptoms. The methodology using aqueous extracts was applied to the same three soils: MN frequency was higher than in the direct contact assay but the ratios of MN frequencies from tested soils in comparison to the negative control were lower. However, for each soil, both the direct contact method and the aqueous extract exposure led to the same risk assessment diagnosis. The evaluation of a concentration range of a polycyclic aromatic hydrocarbons (PAH)-contaminated soil showed a dose-dependent MN frequency when the seeds were allowed to germinate before sowing in the soil: the soil genotoxicity was the highest at intermediate doses. The direct contact method was found to be rapid, sensitive and well suited to the evaluation of soil qualit

    Ökotoxikologische Untersuchungen zur Gefährdung der Lebensraumfunktion des Bodens durch sprengstofftypische Verbindungen

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    Titel Tables Abbreviations Zusammenfassung der Arbeit 1 Directory 2 Introduction 3 Materials and methods 3.1 Determination of soil parameters 3.2 Test organisms 3.3 Tests 4 Pure substances 4.1 Abstract 4.2 Theoretical background 4.3 Materials and methods 4.4 Results 4.5 Discussion 5 Toxicity of TNT in different reference soil materials 5.1 Abstract 5.2 Theoretical background 5.3 Materials and methods 5.4 Results 5.5 Discussion 6 Ageing of TNT-contaminated soil materials 6.1 Abstract 6.2 Theoretical background 6.3 Materials and methods 6.4 Results 6.5 Discussion 7 Contaminated soil materials 7.1 Abstract 7.2 Theoretical background 7.3 Materials and methods 7.4 Results 7.5 Discussion 8 Remediation 8.1 Abstract 8.2 Theoretical background 8.3 Materials and methods 8.4 Results 8.5 Discussion 9 Summary 10 Future research 11 References Appendix A Data sheets of the reference soil materials B Analysis of aged soil materials C Data sheets of the reference soil materials D Original data E Personal dataThis thesis is a contribution to the environmental risk assessment of explosives for the soil fauna. As typical representatives the collembola F. candida and the enchytraeid E. crypticus were chosen. For both test organisms standardised tests have been established. With the mortality, the reproduction and the choice test the following issues have been investigated: -Toxicity in the standard soil Lufa 2.2 of the explosives TNT, Hexyl, Hexogen (RDX) and Octogen (HMX) as well as of Triaminotoluene (TAT), the end product of reductive microbial degradation of TNT -Influence of the soil type on the toxicity of TNT in four uncontaminated soil materials with different contents of clay and organic carbon -Influence of ageing on TNT with the collembola-biotest in the standard soil Lufa 2.2 -Toxicity of contaminated soils on both test organisms -Success of different remediation processes. The toxicity of the pure substances decreases from TNT to Hexyl for both test organisms. TAT is toxic for E. crypticus, but has no effect on F. candida. Hexogen and Octogen are not toxic. The reproduction test is generally more sensitive than the mortality test. In the choice test only the enchytraeid reacts at even lower concentrations than in the reproduction test. The reference soils differ in their content of clay and organic carbon from the standard soil Lufa 2.2. The toxicity of TNT in the soil materials is correlated with their contents of clay and organic matter. Both species show soil specific reproduction rates in the uncontaminated reference soils. The investigation of the ageing process reveals a time dependent decrease of the toxicity of TNT. The decrease is greater at higher temperatures than at lower. This is probably the result of the temperature dependence of the microbial activity. The toxicity of TNT in contaminated soil materials was investigated for six soils from four different sites. It varies with the content of clay and organic matter of the soil materials. With the biotests it could be shown that remediation processes can improve the habitat function of soil materials. Processes which use autochthon microorganisms, improve it. However, it was observed that the the habitat function became worse with white rot fungi, even though TNT was completely transformed.Diese Arbeit untersucht die ökotoxikologischen Auswirkungen von sprengstofftypischen Verbindungen auf die Lebensraumfunktion des Bodens. Als typische Vertreter für die Bodenfauna wurden die Collembole F. candida und die Enchytraee E. crypticus ausgewählt, für die standardisierte Testverfahren entwickelt sind. Mit Hilfe von Mortalitäts-, Reproduktions- und Verhaltenstests wurden die folgenden Fragestellungen untersucht: -Toxizität der Sprengstoffe TNT, Hexyl, Hexogen (RDX) und Octogen (HMX), sowie von Triaminotoluol (TAT), dem Endprodukt des reduktiven mikrobiellen Abbaus von TNT, im Standardboden Lufa 2.2 -Einfluß der Bodenart auf die Toxizität von TNT mit vier unbelasteten Referenzböden unterschiedlichen Ton- und organischen Kohlenstoffgehalts -Einfluß der Alterung von TNT im Standardboden Lufa 2.2 im Collembolen-Test -Toxizität von nutzungsbedingt belasteten Böden auf beide Testorganismen -Erfolg verschiedener Sanierungsverfahren. Von den Reinsubstanzen nimmt die Toxizität für beide Testorganismen in der Reihenfolge TNT zu Hexyl ab. TAT ist für E. crypticus noch toxisch, wirkt dagegen auf F. candida nicht. Hexogen und Octogen sind untoxisch. Der Reproduktionstest ist generell sensitiver als der Mortalitätstest. Im Verhaltenstest reagiert nur die Enchytraee und zwar schon bei niederen Konzentrationen als im Reproduktionstest. Die Referenzböden unterscheiden sich in ihren Gehalten an Ton und organischen Kohlenstoff von dem Standardboden Lufa 2.2. Die Toxizität für TNT in den Bodenmaterialen korreliert mit ihrem Gehalt an Ton und organischer Materie. Beide Arten zeigen in den unbelasteten Referenzböden bodenspezifische Reproduktionsraten. In den Versuchen zur Alterung wurde eine zeitabhängige Abnahme der Toxizität von TNT nachgewiesen. Die Toxizitätsabnahme ist bei höheren Temperaturen größer als bei niedrigen. Dies ist vermutlich auf die Temperaturabhängigkeit der mikrobiellen Aktivität zurückzuführen. Die Toxizität von TNT in nutzungsbedingt belasteten Böden wurde für sechs Böden von vier verschiedenen Standorten untersucht. Sie variiert mit dem Gehalt der Böden an Ton und organischer Materie. Mit diesen Biotests konnte gezeigt werden, daß Sanierungsverfahren die Habitatqualität des Bodenmaterials verbessern. Verfahren, die auf autochthone Mikroorganismen zurückgreifen, verbessern sie nachhaltig. Bei einem Verfahren mit Weißfäulnispilzen, daß zu einer vollständigen Transformierung von TNT führte, wurde sie jedoch verschlechtert. Dagegen reduzierte eine Bodenwäsche sowohl die Toxizität der Sand- als auch der Feinkornfraktion

    Assessment of the genotoxicity of quinolone and fluoroquinolones contaminated soil with the Vicia faba micronucleus test

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    The genotoxicity of quinolone and fluroquinolones was assessed using the micronucleus (MN) test on Viciafaba roots by direct contact exposure to a solid matrix. Plants were exposed to quinolones (nalidixic acid) and fluoroquinolones (ciprofloxacin and enrofloxacin) alone or mixed with artificially contaminatedsoils. Four different concentrations of each of these antibiotics were tested (0.01, 0.1, 1 and 10 mg/Kg) for nalidixic acid and (0.005, 0.05, 0.5 and 5 mg/Kg) for ciprofloxacin and enrofloxacin. These antibiotics were also used in mixture. Exposure of Vicia faba plants to each antibiotic at the highest two concentrations showed significant MN induction. The lowest two concentrations had no significant genotoxic effect. The mixture of the three compounds induced a significant MN induction whatever the mixture tested, from 0.02 to 20 mg/Kg. The results indicated that a similar genotoxic effect was obtained with the mixture at 0.2 mg/Kg in comparison with each molecule alone at 5–10 mg/Kg. Data revealed a clear synergism of these molecules on Vicia faba genotoxicity

    Intercomparison of soil pore water extraction methods for stable isotope analysis

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    Funded by NSERC Discovery Grant U.S. Forest Service U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies OfficePeer reviewedPostprin

    Joint effects of chlorpyrifos and mancozeb to the terrestrial isopod Porcellionides pruinosus: a multiple biomarker approach

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    The exposure to pesticides by non-target soil biota has long been regarded as a serious downside of modern agriculture regimes and subject of heated debate. Of utmost relevance is the exposure to pesticide mixtures since their effects have shown not to necessarily reflect the individual toxicity of its components and even the simple addition of effects may lead to consequences not clearly anticipated. In this work, a multiple biomarker approach was employed to identify the mechanistic and time-effects underlying several single and mixture treatments of chlorpyrifos and mancozeb in juveniles and adults of the terrestrial isopod Porcellionides pruinosus. The effects of both pesticides and mixture at recommended doses were mostly transitory under these controlled conditions and one-pulse exposure. While imbalances were identified on detoxification and oxidative stress-related enzymes, isopods generally showed the ability to recover until the end of the experiment. Juveniles showed, however, higher vulnerability than adults. The most notorious differences between life stages occurred in energy-related parameters where distinct performances and stress-handling behaviours were observed, suggesting higher metabolic costs in juveniles. Our results stress that understanding the time-dependence of the underlying mechanisms governing the joint-effects of pesticides can help assessing and anticipating mixtures’ effects. Moreover, it is also emphasized the importance taking life stage-related differences in consideration when evaluating the environmental risks of pesticides and pesticide mixtures

    Composites of biopolymers and ZnO NPs for controlled release of zinc in agricultural soils and timed delivery for maize

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    Zinc deficiency is a widespread micronutrient deficiency problem affecting crops worldwide. Unlike conventional ionic fertilizers (Zn as salt or chelated forms), Zn-based engineered nanomaterials (ENMs) have the potential to release Zn in a controlled manner, reducing Zn losses through leaching upon application to soil. In this work, composites made of biopolymers (microcrystalline cellulose, chitosan and alginate) and ZnO nanoparticles (4-65% Zn w/w) were prepared. Their potential for Zn controlled release was tested in four agricultural soils of distinct pH and organic matter content over 30 days. While conventionally used Zn salts leached from the soil resulting in very low CaCl2-extractable Zn concentration, Zn in ZnO NPs was less labile, and ZnO-biopolymers maintained a better constant supply of CaCl2-extractable Zn than all other treatments. ZnO NPs/alginate beads prepared by crosslinking with CaCl2 presented the slowest Zn release kinetics. As assessed with maize plants grown in poor Zn acidic soil (LUFA 2.1, pH=5.2), this constant Zn release from ZnO NPs/alginate beads resulted in a steadier Zn concentration in the soil pore water over time. These results further indicate that ZnO NPs/alginate beads could meet the maize Zn needs while avoiding the early stage Zn toxicity induced by conventional Zn supplies, demonstrating that these ENMs are a sustainable way to supply Zn in a controlled manner in acidic soils. The impact of plant exudates on Zn bioavailability in the soil under maize-root influence (rhizosphere) is also discussed, underlying the need to study the fate of micronutrients in the rhizosphere to better predict its long-term bioavailability in bulk soils.publishe

    Effects of three pesticides on the avoidance behavior of earthworms in laboratory tests performed under temperate and tropical conditions.

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    Little research has been performed on the impact of pesticides on earthworms under tropical conditions. Taking into consideration the oftenlimited resources in tropical countries, simple screening tests are needed. Therefore, it was investigated whether three pesticides relevant for the Brazilian Amazon (benomyl, carbendazim, lambda-cyhalothrin) affect the avoidance behavior of the earthworm Eisenia fetida. The tests were performed for two days according to ISO guideline 17512 but were adapted to tropical conditions (i.e. test substrate, test organism and temperature). The results indicate that this test gives reproducible and reliable results. Toxicity values (NOEC, EC50) are lower than those determined in 14 day-acute mortality tests and are approximately in the same range such as those found in 56 day-chronic reproduction tests with the same earthworm species, which were performed in parallel. Therefore, the use of the earthworm avoidance tests is recommended as a screening tool for the risk assessment of pesticides

    Assessing the acute and chronic toxicity of exposure to naturally occurring oil sands deposits to aquatic organisms using Daphnia magna

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    In the Athabasca region, the oil sands are located at or near the surface making open-pit mining viable. In addition, the Athabasca River and its tributaries flow through these oil sands deposits, thereby receiving bitumen-associated contaminants through natural fluvial erosional and weathering processes. A key knowledge gap has been related to understanding both the magnitude and significance of the toxicological and ecological effects on aquatic organisms exposed to naturally occurring bitumen entering fluvial systems. Using the Daphnia magna model system, this study assessed the ecotoxicological effects of exposure to bitumen-elutriate treatments that simulated the early stages of fluvial/erosional exposure conditions. No significant among-site differences were observed in the survival of D. magna after 48 h exposure to elutriates produced from a 24 h extraction cycle, and chemical analysis indicated low concentration of a complex mixture of hydrocarbon and metal contaminants. In contrast, the same elutriates impaired reproduction and growth after a 21-day chronic exposure. F1 neonates from the chronic tests were tested for sensitivity to the reference substance potassium dichromate, revealing a decrease in their sensitivity. Inter-generational effects were also observed, with a significant decrease in subsequent neonate production, when daphnids were moved to a clean medium. Supplemental acute toxicity assays using 48 and 72 h bitumen extraction cycles progressively increased daphnid mortality after a 48-h exposure to the respective elutriates. This indicates that bitumen-associated contaminants are being liberated after initial input and fluvial washing (24 h), highlighting the need for future work to assess toxicity responses and associated elutriate water chemistry of a longer fluvial exposure time-series. This work contributes to our understanding of the possible effects of natural bitumen exposure on riverine aquatic ecosystems, providing new information to inform the delineation of baseline conditions to assess environmental change and the design of future regional effects-based monitoring programs.publishe

    Effect of soil properties on Pb bioavailability and toxicity to the soil invertebrate Enchytraeus crypticus

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    The present study investigated the bioavailability and toxicity of lead to the potworm Enchytraeus crypticus in six soils with different properties. Pb partitioning between the soil solution and solid phase was affected by soil organic matter (OM) content, cation exchange capacity (CEC) and water holding capacity (WHC). After 21 d exposure, Pb bioaccumulation in the enchytraeids was positively correlated with total soil Pb concentration. Bioaccumulation was best predicted by Pb availability (CaCl2-extractable and porewater Pb concentrations), and by the Ca concentration in pore water and the CEC of the soils. Toxicity varied greatly among soils, with LC50s and EC50reproductions based on total Pb concentrations ranging from 246 to >3092 and from 81 to 1008 mg Pb/kg dry soil, respectively. The variation in LC50s among soils was explained by differences in CaCl2-extractable Pb concentrations in soil and internal Pb concentrations in the animals. The differences in EC50reproductions could be explained from the CaCl2-extractable Pb concentrations in the soils. Although it was also correlated with CEC and porewater Ca concentration, pHCaCl2 was the dominating factor for predicting Pb toxicity based on total soil concentrations. This study demonstrates that soil properties, such as pH, CEC and Ca concentration in pore water, significantly affected the bioavailability and toxicity of Pb and therefore should be taken into account when assessing the ecological risk of metals in contaminated soils
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