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  • 11
    Language: English
    In: Aquatic Toxicology, Jan 15, 2013, Vol.126, p.163(6)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.aquatox.2012.10.015 Byline: Frank Seitz (a), Mirco Bundschuh (a)(b), Ricki R. Rosenfeldt (a), Ralf Schulz (a) Keywords: Inorganic nanoparticles; Reproduction; Growth; Flow-through; Crustacea Abstract: a* nTiO.sub.2 concentrations one order of magnitude above the PEC caused adverse chronic effects. a* Particle size and product composition, i.e. crystalline structure, trigger differences in nTiO.sub.2 toxicity. a* nTiO.sub.2 accumulation at the bottom of the test vessel is an important effect pathway. a* Dissolved organic carbon influences fate and finally nTiO.sub.2 toxicity. Author Affiliation: (a) Institute for Environmental Sciences, University of Koblenz-Landau, Germany (b) Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden Article History: Received 23 August 2012; Revised 15 October 2012; Accepted 31 October 2012
    Keywords: Crystal Structure
    ISSN: 0166-445X
    Source: Cengage Learning, Inc.
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  • 12
    Language: English
    In: PLoS ONE, 01 January 2013, Vol.8(11), p.e80960
    Description: Due to their surface characteristics, nanosized titanium dioxide particles (nTiO2) tend to adhere to biological surfaces and we thus hypothesize that they may alter the swimming performance and behavior of motile aquatic organisms. However, no suitable approaches to address these impairments...
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 13
    Language: English
    In: Environmental Pollution, January 2015, Vol.196, pp.276-283
    Description: Interactions with environmental parameters may alter the ecotoxicity of nanoparticles. The present study therefore assessed the (in)direct effects of nanoparticulate titanium dioxide (nano-TiO ) towards , considering nano-TiO 's photocatalytic properties at ambient UV-intensities. Gammarids' habitat selection was investigated using its feeding preference on leaf discs either exposed to or protected from UV-irradiation in presence of nano-TiO as proxy (  = 49). UV-irradiation alone induced a significant preference for UV-protected habitats, which was more pronounced in simultaneous presence of nano-TiO . This behaviour may be mainly explained by the UV-induced formation of reactive oxygen species (ROS) by nano-TiO . Besides their direct toxicity, ROS may have lowered the leaf-quality in UV-exposed areas contributing (approximately 30%) to the observed behavioural pattern. Since the predicted no effect concentration of nano-TiO in combination with UV-irradiation falls below the predicted environmental concentration this study underpins the importance of considering environmental parameters during the risk assessment of nanoparticles. Results revealed for the first time a PNEC of nano-TiO falling below the PEC indicating a substantial risk for aquatic ecosystems already nowadays.
    Keywords: Gammarus ; Uv-Irradiation ; Interaction Effect ; Reactive Oxygen Species ; Behavioural Response ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 14
    Language: English
    In: Environmental Pollution, Jan, 2015, Vol.196, p.276(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envpol.2014.09.022 Byline: Alexander Feckler, Ricki R. Rosenfeldt, Frank Seitz, Ralf Schulz, Mirco Bundschuh Abstract: Interactions with environmental parameters may alter the ecotoxicity of nanoparticles. The present study therefore assessed the (in)direct effects of nanoparticulate titanium dioxide (nano-TiO.sub.2) towards Gammarus fossarum, considering nano-TiO.sub.2's photocatalytic properties at ambient UV-intensities. Gammarids' habitat selection was investigated using its feeding preference on leaf discs either exposed to or protected from UV-irradiation in presence of nano-TiO.sub.2 as proxy (n = 49). UV-irradiation alone induced a significant preference for UV-protected habitats, which was more pronounced in simultaneous presence of nano-TiO.sub.2. This behaviour may be mainly explained by the UV-induced formation of reactive oxygen species (ROS) by nano-TiO.sub.2. Besides their direct toxicity, ROS may have lowered the leaf-quality in UV-exposed areas contributing (approximately 30%) to the observed behavioural pattern. Since the predicted no effect concentration of nano-TiO.sub.2 in combination with UV-irradiation falls below the predicted environmental concentration this study underpins the importance of considering environmental parameters during the risk assessment of nanoparticles. Author Affiliation: (a) Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany (b) Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Lennart Hjelms vag 9, 75007 Uppsala, Sweden Article History: Received 26 June 2014; Revised 16 September 2014; Accepted 22 September 2014
    Keywords: Nanoparticles -- Analysis ; Habitat Conservation -- Analysis ; Titanium Dioxide -- Analysis
    ISSN: 0269-7491
    Source: Cengage Learning, Inc.
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  • 15
    In: Journal of Applied Ecology, April 2015, Vol.52(2), pp.310-322
    Description: The application of fungicides is considered an indispensable measure to secure crop production. These substances, however, may unintentionally enter surface waters via run‐off, potentially affecting the microbial community. To assess such risks adequately, authorities recently called for suitable test designs involving relevant aquatic micro‐organisms. We assessed the structural and functional responses of leaf‐associated microbial communities, which play a key role in the breakdown of allochthonous leaf material in streams, towards the inorganic fungicides copper (Cu) and elemental sulphur (S). These substances are of particular interest as they are authorized for both conventional and organic farming in many countries of the world. We used the food choice of the amphipod shredder Gammarus fossarum (indicative for micro‐organism‐mediated leaf palatability) as well as microbial leaf decomposition as functional endpoints. Moreover, the leaf‐associated microbial communities were characterized by means of bacterial density, fungal biomass and community composition facilitating mechanistic understanding of the observed functional effects. While Gammarus preferred Cu‐exposed leaves over unexposed ones, microbial leaf decomposition was reduced by both Cu and S (up to 30%). Furthermore, Cu exposure decreased bacterial densities (up to 60%), stimulated the growth of leaf‐associated fungi (up to 100%) and altered fungal community composition, while S did not affect any of the assessed structural endpoints. Synthesis and applications. We observed both structural and functional changes in leaf‐associated microbial communities at inorganic fungicide concentrations realistic for surface water bodies influenced by conventional and organic farming. Our data hence justify a careful re‐evaluation of the environmental safety of the agricultural use of these compounds. Moreover, inclusion of an experimental design similar to the one used in this study in lower tier environmental risk assessments of antimicrobial compounds may aid to safeguard the integrity of aquatic microbial communities and the functions they provide. We observed both structural and functional changes in leaf‐associated microbial communities at inorganic fungicide concentrations realistic for surface water bodies influenced by conventional and organic farming. Our data hence justify a careful re‐evaluation of the environmental safety of the agricultural use of these compounds. Moreover, inclusion of an experimental design similar to the one used in this study in lower tier environmental risk assessments of antimicrobial compounds may aid to safeguard the integrity of aquatic microbial communities and the functions they provide.
    Keywords: Antagonistic Effect ; Antimicrobial ; Aquatic Hyphomycetes ; Bacteria ; Biofilm ; Ecosystem Functioning ; Environmental Risk Assessment ; Heavy Metal ; Leaf Litter Breakdown ; Mixture Toxicity
    ISSN: 0021-8901
    E-ISSN: 1365-2664
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  • 16
    Language: English
    In: Environmental Pollution, March 2014, Vol.186, pp.136-140
    Description: Although nanoparticle production and application increases continuously, their implications in species interactions, especially in combination with other environmental stressors, are rarely assessed. Therefore, the present study investigated the influence of 2 mg/L titanium dioxide nanoparticles (nTiO ; 〈100 nm) on the interaction between the prey (Ephemeroptera) and the predator (Amphipoda) over 96 h considering UV-irradiation at field relevant levels (approximately 11.4 W/m ) as an additional environmental factor (  = 16). At the same time, gammarid's consumption of an alternative food source, i.e. leaf discs, was assessed. All endpoints covered were not affected by nTiO alone, while the combination of nTiO and UV caused a reduction in gammarid's predation (68%), leaf consumption (60%) and body weight (22%). These effects were most likely triggered by the UV-induced formation of reactive oxygen species by nTiO . The present study, hence, highlights the importance to cover UV-irradiation during the risk assessment of nanoparticles. UV-irradiation influences nanoparticles' ecotoxicity rising concerns about adverse effects in trophic interactions and ecosystem functions.
    Keywords: Gammarid ; Mayfly ; Energy Transfer ; Ecosystem Functioning ; Sunlight ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 17
    Language: English
    In: Journal of Cleaner Production, 20 October 2018, Vol.199, pp.112-120
    Description: Only little information is available on combined effects of abiotic environmental factors on algal arsenate ( ) metabolic biokinetics. Using the Taguchi statistical method, we investigated four environmental factors including , nitrate (N), orthophosphate (P) and pH for their combined effects on algal growth and arsenic ( ) uptake but also extracellular adsorption of as well as release from dead algal cells. Results showed that an increase of N facilitated growth and thus was the principal factor for the algal maximum specific growth rate ( ). P was vital to bioconcentration factor (BCF) and partition coefficients (Log ) released from deal algal cells. impacted the extracellular adsorption onto the algal cells, which thereby increased with increasing initial level. The initial pH had an imperative effect on the uptake ( ) and release rate ( ) from the dead cells. The optimum conditions on metabolic biokinetics were N at 10.0 mg L for , P at 0.02 mg L for Log and BCF, at 10.0 μM for extracellular adsorption, and pH at 10 for , BCF and extracellular adsorption, but pH at 6 for . Collectively, the condition of low P, high N and alkaline pH level was favorable to accumulation rate of living cells and restrictive to release rate from dead cells of . The obtained information can pave a road for extensive understanding on efficient utilization of bioremediation of algae in practical environment.
    Keywords: Algal Bioremediation ; Accumulation ; Release ; Dead Algae ; Taguchi ; Engineering
    ISSN: 0959-6526
    E-ISSN: 1879-1786
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  • 18
    Language: English
    In: Environmental Pollution, 2015, Vol.205, pp.16-22
    Description: Copper (Cu) exposure can increase leaf-associated fungal biomass, an important food component for leaf-shredding macroinvertebrates. To test if this positive nutritional effect supports the physiological fitness of these animals and to assess its importance compared to waterborne toxicity, we performed...
    Keywords: Other Biological Topics ; Annan Biologi
    ISSN: 0269-7491
    E-ISSN: 18736424
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  • 19
    Language: English
    In: Environmental science & technology, 17 June 2014, Vol.48(12), pp.6965-72
    Description: Unintentionally released titanium dioxide nanoparticles (nTiO2) may co-occur in aquatic environments together with other stressors, such as, metal ions. The effects of P25-nTiO2 on the toxicity and uptake of the elements silver (Ag), arsenic (As) and copper (Cu) were assessed by applying a factorial test design. The test design consisted of two developmental stages of Daphnia magna, two levels of nTiO2 (0 versus 2 mg/L) as well as seven nominal test concentrations of the respective element. The presence of nTiO2 increased Ag toxicity for juveniles as indicated by a 40% lower 72-h EC50, while the toxicities of As and Cu were reduced by up to 80%. This reduction was even more pronounced for Cu in the presence of dissolved organic carbon (i.e., seaweed extract) and nTiO2. This outcome coincides with the body burden of the elements, which was elevated 2-fold for Ag and decreased 14-fold for Cu in the presence of nTiO2. Although the underlying mechanisms could not be uncovered, the data suggest that the carrier function of nTiO2 plays a central role. However, to understand the processes and mechanisms occurring in the field due to the presence of nTiO2 further systematic investigations considering environmental variables and nanoparticle characteristics are required.
    Keywords: Toxicity Tests ; Daphnia -- Drug Effects ; Metals, Heavy -- Toxicity ; Nanoparticles -- Chemistry ; Titanium -- Chemistry
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 20
    Language: English
    In: Aquatic toxicology, 2013, Vol.126, pp.163-168
    Description: The increasing use of titanium dioxide nanoparticles (nTiO₂) 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 nTiO₂ among others to Daphnia magna. 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 nTiO₂ products with varying crystalline structure (A-100; P25) to D. magna. 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 0.06mg/L A-100 (∼330nm) 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 (∼140nm). Likewise, P25 (∼130nm) 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 nTiO₂ 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 nTiO₂ toxicity to D. magna. Hence, these factors should be considered to improve environmental risk assessment of nanoparticles. ; p. 163-168.
    Keywords: Particle Size ; Progeny ; Titanium Dioxide ; Dissolved Organic Carbon ; Exposure Scenario ; Wildlife ; Crystal Structure ; Reproduction ; Daphnia Magna ; Risk ; Ecotoxicology ; Toxicity ; Adverse Effects ; Nanoparticles
    ISSN: 0166-445X
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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