Abstract. Production and wide application of nanomaterials have led to nanotechnology development but their release to environment and the induction of toxic reactions, affects the natural microbial communities. Therefore, studies on the impact of nanoparticles on microorganisms and environment are required and needed. The aim of this study was to assess the impact of aluminium oxide nanoparticles on the growth of Pseudomonas putida. To compare the harmfulness of different forms of aluminium oxide, the ecotoxicity of its macro-forms was also evaluated in the study. Research showed that the exposure to nanoparticles can negatively influence microorganisms. The EC 50 -16h determined in this study was 0.5 mg/l, and NOEC equaled 0.19 mg/l. Nano-Al 2 O 3 proved to be more toxic to P. putida than aluminium oxide. This indicates that the nano-form of a given substance demonstrates different properties and may constitute a far greater danger for the environment than the same substance in the large form. According to EU and US EPA criteria, nano-Al 2 O 3 proved to be very toxic and highly toxic, respectively. Changes in bacterial communities caused by nanoparticles may affect the normal biological, chemical and nutrient cycle in the ecosystem and the effect triggered by nanomaterials in relation to other organisms is unpredictable.
The aim of this research was to observe the relationship between zeta potential, morphology, surface area, porosity, chemical composition, and ecotoxicity of nanocomposite powders such as were exhibiting good antimicrobial properties. It was observed, that nanomaterials characterized by similar morphology and zeta potential revealed the similar toxic behavior. The samples of higher agglomeration and higher zeta potential, especially Ag/TiO 2 /SiO 2 xerogel and TiO 2 /SiO 2 aerogel were generally less ecotoxic to water organisms and plants. They were also not genotoxic in concentrations up to 500 and 250 mg/L, respectively.where g = 8.90 9 10 À4 [Pa s] is the viscosity of the electrolyte solution (water at 25°C), l is the particle velocity [m/s], and e 0 = 8.85 [pF/m] is the vacuum permittivity, e r = 78.54 is the relative permittivity of the *agsolgala@gmail.com
The goal of this work was to assess the risk posed by the presence of ciprofloxacin, 17α-ethinylestradiol and 5-fluorouracil in aquatic ecosystems based on chronic single-species ecotoxicological tests. There were 23 species used in this study: one cyanobacterium, three green algae, one higher plant, one protozoan, two crustaceans, two fish, 12 bacteria and one fungus (yeast). The risk assessment was performed on the basis of the PEC/PNEC ratio (PEC - predicted environmental concentration, PNEC - predicted no-effect concentration). PNEC was calculated using an assessment factor and statistical extrapolation models. The risk in relation to aquatic organisms proved to be high. The potentially affected fraction of aquatic species in the presence of pharmaceutical active ingredients, depending on the calculation method and the selected concentration in surface waters (predicted or measured), ranged from 6.26 to 27.84% for ciprofloxacin, 2.13 to 18.74% for 17α-ethinylestradiol and 4.96 to 39.28% for 5-fluorouracil. The study indicates several gaps in the existing guidelines, which may be considered within the guideline-revision process.
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