Progressing eutrophication of waterbodies requires measures to be undertaken that aim at halting or reversing negative changes in the environment. Chemical restoration is one of the most common methods used for lake treatment, where iron or aluminium phosphate coagulants are applied. However, their chemical qualities pose the risk of acidification and aluminium ion release, which become toxic in acidic conditions. The influence of coagulants on aquatic plants, including charophytes that are very valuable from the ecological perspective, is little recognised. For this reason, the aim of the research was to define changes in the growth pattern of the charophyte Chara hispida under the influence of an aluminium coagulant. The research was carried out in mesocosms (0.8 m3) located in situ in a lake. Polyaluminium chloride was applied once to each chamber in doses of 50.0, 100.0 and 200.0 ml m−3. Coagulant concentrations reflected aggressive restoration aimed at precipitation of phosphates, suspension and water colour at the same time. It was proved that the coagulant had inhibited the growth and slightly reduced the length of branchlets, and simultaneously elongated internode cells. Changes in the total length as well as the length of branchlets were caused by a strong pH decrease of the environment which simultaneously induced higher aluminium solubility and toxicity. Elongation of internode cells was caused by reduced light availability, resulting from high water turbidity in the first stage of coagulant’s application, and then from the charophytes’ thallus being covered by a coagulated suspension precipitated from water.
Małgorzata Osękowska, Ewa Karuga-Kuźniewska, Damian Wojcieszak, Michał Mazur, Agata Poniedziałek, Danuta Kaczmarek, Maria Szymonowicz and Zbigniew Rybak
In this work the physicochemical and biological properties of nanocrystalline TiO2 thin films were investigated. Thin films were prepared by magnetron sputtering method. Their properties were examined by X-ray diffraction, photoelectron spectroscopy, atomic force microscopy, optical transmission method and optical profiler. Moreover, surface wettability and scratch resistance were determined. It was found that as-deposited coatings were nanocrystalline and had TiO2-anatase structure, built from crystallites in size of 24 nm. The surface of the films was homogenous, composed of closely packed grains and hydrophilic. Due to nanocrystalline structure thin films exhibited good scratch resistance. The results were correlated to the biological activity (in vitro) of thin films. Morphological changes of mouse fibroblasts (L929 cell line) after contact with the surface of TiO2 films were evaluated with the use of a contrast-phase microscope, while their viability was tested by MTT colorimetric assay. The viability of cell line upon contact with the surface of nanocrystalline TiO2 film was comparable to the control sample. L929 cells had homogenous cytoplasm and were forming a confluent monofilm, while lysis and inhibition of cell growth was not observed. Moreover, the viability in contact with surface of examined films was high. This confirms non-cytotoxic effect of TiO2 film surface on mouse fibroblasts.