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  • 1
    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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  • 2
    Language: English
    In: Environmental science & technology, 03 February 2015, Vol.49(3), pp.1815-22
    Description: Titanium dioxide nanoparticles (nTiO2) are expected to interact with natural substances and other chemicals in the environment, however little is known about their combined effects. Therefore, this study assessed the toxicity of copper (Cu) in combination with varying crystalline phases (anatase, rutile, and the mixture) of nTiO2 and differing organic materials on Daphnia magna. The nanoparticles reduced the Cu-toxicity depending on the product (0.3- to 2-fold higher 48-h EC50). This decrease in toxicity coincided with a lowered Cu-concentration in the water column, which was driven by the adsorption of Cu to nTiO2-depending on available surface area and structure-and their subsequent sedimentation. In the presence of organic material and nTiO2, the Cu-toxicity was further reduced (up to 7-fold higher 48-h EC50). This observation can be explained by a reduced Cu-bioavailability as a result of complexation and adsorption by the organic material and nTiO2, respectively. Thus, the crystalline phase composition, which is determining the surface area and structure of nTiO2, seems to be of major importance for the toxicity reduction of heavy metals, while the influence of the organic materials was mainly driven by the quantity and quality of humic substances.
    Keywords: Humic Substances ; Copper -- Toxicity ; Nanoparticles -- Chemistry ; Titanium -- Chemistry ; Water Pollutants, Chemical -- Toxicity
    ISSN: 0013936X
    E-ISSN: 1520-5851
    Library Location Call Number Volume/Issue/Year Availability
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