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  • 1
    Language: English
    In: Aquatic Toxicology, 15 January 2013, Vol.126, pp.163-168
    Description: ► nTiO concentrations one order of magnitude above the PEC caused adverse chronic effects. ► Particle size and product composition, i.e. crystalline structure, trigger differences in nTiO toxicity. ► nTiO accumulation at the bottom of the test vessel is an important effect pathway. ► Dissolved organic carbon influences fate and finally nTiO toxicity. The increasing use of titanium dioxide nanoparticles (nTiO ) inevitably results in their release into the environment, raising concerns about potential adverse effects in wildlife. By following standard test protocols, several studies investigated the ecotoxicity of nTiO among others to . These studies indicated a large variability – several orders of magnitude – in the response variables. However, other factors, like nanoparticle characteristics and test design, potentially triggering these differences, were largely ignored. Therefore, the present study assessed the chronic ecotoxicity of two nTiO products with varying crystalline structure (A-100; P25) to . A semi-static and a flow-through exposure scenario were compared, ensuring that both contained environmentally relevant concentrations of dissolved organic carbon. Utilizing the semi-static test design, a concentration as low as 0.06 mg/L A-100 (∼330 nm) significantly reduced the reproduction of daphnia indicating environmental risk. In contrast, no implication in the number of released offspring was observed during the flow-through experiment with A-100 (∼140 nm). Likewise, P25 (∼130 nm) did not adversely affect reproduction irrespective of the test design utilized. Given the present study's results, the particle size, the product composition, i.e. the crystalline structure, and the accumulation of nTiO at the bottom of the test vessel – the latter is relevant for a semi-static test design – may be suggested as factors potentially triggering differences in nTiO toxicity to . Hence, these factors should be considered to improve environmental risk assessment of nanoparticles.
    Keywords: Inorganic Nanoparticles ; Reproduction ; Growth ; Flow-through ; Crustacea ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 2
    Language: English
    In: Aquatic Toxicology, 2014, Vol.150, pp.133-143
    Description: Fungicides are frequently applied in agriculture and are subsequently detected in surface waters in total concentrations of up to several tens of micrograms per liter. These concentrations imply potential effects on aquatic communities and fundamental ecosystem functions such as leaf litter breakdown....
    Keywords: Other Biological Topics ; Annan Biologi
    ISSN: 0166-445X
    E-ISSN: 18791514
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  • 3
    Language: English
    In: Aquatic Toxicology, February 2017, Vol.183, pp.46-53
    Description: Selection of appropriate test species is a critical issue when assessing effects of environmental contamination on fish because the ecological relevance of commonly used test species might be restricted due to their exotic origin. In the present study, a European freshwater fish with frequent occurrence in agricultural areas is suggested as a potential alternative: the European weatherfish ( ). Its suitability for acute embryo toxicity tests (FET) was investigated with regard to practical implementation, sensitivity to contaminants and tolerance against environmental conditions of concern. For this purpose, weatherfish embryos were exposed (72 h) to the reference substance 3,4-dichloroaniline (DCA) in three independent tests. Furthermore, the effects of dissolved oxygen (DO) deficiency on weatherfish embryos were studied to evaluate their suitability e.g. for sediment bioassays. Obtained results revealed that the sensitivity of weatherfish embryos towards DCA (72 h-EC = 0.52 mg/l; 72 h-LC = 0.71 mg/l) was highest compared to other species and three times higher than that reported for the commonly used zebrafish ( ). Even though knowledge of DO requirements during the embryonic period of European fish species is scarce, weatherfish can be stated as one of the most tolerant native species (LC for DO = 0.53 mg/l after 48 h exposure plus 72 h post-exposure). Its high ecological relevance for Europe, the particular sensitivity towards DCA and high tolerance against DO depletion highlight the potential of weatherfish as additional species for toxicity testing.
    Keywords: Fish Embryo Toxicity Test ; 3,4-Dichloroaniline ; Dissolved Oxygen Requirements ; Alternative Test Method ; Early Life Stages ; Sediment Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 4
    Language: English
    In: Aquatic Toxicology, 2011, Vol.104(1), pp.32-37
    Description: The energy stored in coarse particulate organic matter, e.g. leaf litter, is released to aquatic ecosystems by breakdown processes involving microorganisms and leaf shredding invertebrates. The palatability of leaves and thus the feeding of shredders on leaf material are highly influenced by microorganisms. However, implications in the colonization of leaves by microorganisms (=conditioning) caused by chemical stressors are rarely studied. Our laboratory experiments, therefore, investigated for the first time effects of a fungicide on the conditioning process of leaf material by means of food-choice experiments using (Crustacea: Amphipoda). Additionally, microbial analyses were conducted to facilitate the mechanistic understanding of the observed behavior. Gammarids significantly preferred control leaf discs over those conditioned in presence of the fungicide tebuconazole at concentrations of 50 and 500 μg/L. Besides the decrease of fungal biomass with increasing fungicide concentration, also the leaf associated fungal community composition showed that species preferred by gammarids, such as , , or , were more frequent in the control. , however, which is rejected by gammarids, was abundant in all treatments suggesting an increasing importance of this species for the lower leaf palatability – as other more palatable fungal species were almost absent – in the fungicide treatments. Hence, the food-choice behavior of seems to be a suitable indicator for alterations in leaf associated microbial communities, especially fungal species composition, caused by chemical stressors. Finally, this or similar test systems may be a reasonable supplement to the environmental risk assessment of chemicals in order to achieve its protection goals, as on the one hand, indirect effects may occur far below concentrations known to affect gammarids directly, and on the other hand, the observed shifts in leaf associated microbial communities may have perpetuating implications in leaf shredding invertebrates.
    Keywords: Fungal Community ; Leaf Litter Decomposition ; Confidence Interval Testing ; Aquatic Hyphomycetes ; Azole Fungicide ; Bacteria ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 5
    Language: English
    In: Aquatic Toxicology, December 2016, Vol.181, pp.94-103
    Description: For in situ remediation of groundwater contaminated by halogenated hydrocarbons Carbo-Iron , a composite of microscale activated carbon and nano Fe , was developed. Against the background of intended release of Carbo-Iron into the environment in concentrations in the g/L-range, potential ecotoxicological consequences were evaluated in the present study. The nano Fei in Carbo-Iron acts as reducing agent and is oxidized in aqueous systems by chlorinated solvents, groundwater constituents (e.g. dissolved oxygen) and anaerobic corrosion. As Carbo-Iron is generally oxidized rapidly after application into the environment, the oxidized state is environmentally most relevant, and Carbo-Iron was used in its oxidized form in the ecotoxicological tests. The amphipod was selected as a surrogate test species for functionally important groundwater crustaceans. Effects of Carbo-Iron on were determined in a 10-d acute test, a 7-d feeding activity test and a 42-d chronic test. Additionally, a 56-d life cycle test was performed with a modified design to further evaluate effects of Carbo-Iron on adult and their offspring. The size of Carbo-Iron particles in stock and test suspensions was determined via dynamic light scattering. Potential uptake of particles into test organisms was investigated using transmission and scanning electron microscopy. At the termination of the feeding and acute toxicity test (i.e. after 7 and 10 d of exposure, respectively), Carbo-Iron had a significant effect on the weight, length and feeding rate of at the highest test concentration of 100 mg/L. While an uptake of Carbo-Iron into the gut was observed, no passage into the surrounding tissue was detected. In both chronic tests, the number of offspring was the most sensitive endpoint and significant effects were recorded at concentrations ≥50 mg/L (42-d experiment) and ≥12.5 mg/L (56-d experiment). Parental exposure to oxidized Carbo-Iron significantly exacerbated the acute effects of the nanocomposite on the subsequent generation of by a factor 〉10. The present study indicates risks for groundwater species at concentrations in the mg/L range. Carbo-Iron may exceed these effect concentrations in treated aquifers, but the presence of the pollutant has most likely impaired the quality of this habitat already. The benefit of remediation has to be regarded against the risk of ecological consequences with special consideration of the observed increasing sensitivity of juvenile .
    Keywords: Iron-Based Nanomaterial ; Nanocomposite ; Groundwater Remediation ; Environmental Risk ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 6
    Language: English
    In: Aquatic Toxicology, August 2015, Vol.165, pp.154-159
    Description: In aquatic ecosystems, titanium dioxide nanoparticles (nano-TiO ) may adsorb co-occurring chemical stressors, such as copper (Cu). This interaction has the potential to reduce the concentration of dissolved Cu due to surface binding to the nanoparticles. The subsequent sedimentation of nano-TiO agglomerates may increase the exposure of benthic species towards the associated Cu. This scenario was assessed by employing the amphipod as model species and taking advantage of a 2 × 2-factorial design investigating absence and presence of 2 mg nano-TiO /L and 40 μg Cu/L ( = 45; = 24 d) in darkness, respectively. Nano-TiO alone did not affect mortality and leaf consumption, whereas Cu alone caused high mortality (〉70%), reduced leaf consumption (25%) and feces production (30%) relative to the control. In presence of nano-TiO , Cu-induced toxicity was largely eliminated. However, independent of Cu, nano-TiO decreased the gammarids’ assimilation and weight. Hence, nano-TiO may be applicable as Cu-remediation agent, while its potential long-term effects need further attention.
    Keywords: Heavy Metal ; Benthic Invertebrates ; Energy Processing ; Remediation ; Combined Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 7
    Language: English
    In: Aquatic Toxicology, 2015, Vol.169, pp.105-112
    Description: Animals involved in leaf litter breakdown (i.e., shredders) play a central role in detritus-based stream food webs, while their fitness and functioning can be impaired by anthropogenic stressors. Particularly fungicides can affect shredders via both waterborne exposure and their diet, namely due to co-ingestion...
    Keywords: Other Biological Topics ; Annan Biologi
    ISSN: 0166-445X
    E-ISSN: 18791514
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  • 8
    Language: English
    In: Aquatic Toxicology, July 2019, Vol.212, pp.47-53
    Description: The increasing production of engineered inorganic nanoparticles (EINPs) elevates their release into aquatic ecosystems raising concerns about associated environmental risks. Numerous investigations indicate sediments as the final sink, facilitating the exposure of benthic species to EINPs. Although reports of sub-lethal EINP effects on benthic species are increasing, the importance of exposure pathways (either waterborne or dietary) is poorly understood. This study investigates the influence of two EINPs, namely titanium dioxide (nTiO ) and silver (nAg), on the benthic model organism specifically addressing the relative relevance of these pathways. For each type of EINP an individual 30-day long bioassay was conducted, applying a two-factorial test design. The factors include the presence or absence of the EINPs (nTiO : ∼80 nm, 4 mg/L or nAg: ∼30 nm, 0.125 mg/L;  = 30) in the water phase (waterborne), combined with a preceding 6-day long aging of their diet (black alder leaves) also in presence or absence of the EINPs (dietary). Response variables were mortality, food consumption, feces production and energy assimilation. Additionally, the physiological fitness was examined using lipid content and dry weight of the organisms as measures. Results revealed a significantly reduced energy assimilation (up to ∼30%) in induced by waterborne exposure towards nTiO . In contrast, the dietary exposure towards nAg significantly increased the organisms’ energy assimilation (up to ∼50%). Hence, exposure pathway dependent effects of EINPs cannot be generalized and remain particle specific resting upon their intrinsic properties affecting their potential to interact with the surrounding environment. As a result of the different properties of the EINPs used in this study, we clearly demonstrated variations in type and direction of observed effects in . The results of the present study are thus supporting current approaches for nano-specific grouping that might enable an enhanced accuracy in predicting EINP effects facilitating their environmental risk assessment.
    Keywords: Nanomaterial ; Titanium Dioxide ; Silver ; Exposure Pathway ; Chronic Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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