Quaternary ammonium salts (QAS), including ionic liquids (ILs), constitute a huge group of substances, which due to their desirable physical and chemical properties still attracts great interest in ...many industrial sectors. An increased concentration of this compound in the environment may lead to the contamination of the natural environment and may pose a potential threat to all organisms, including terrestrial higher plants. The present study demonstrates the interaction of three QAS with PF6− anions – tetramethylammonium TMAPF6, tetrabutylammonium TBAPF6, and tetrahexylammonium THAPF6 hexafluorophosphates – and its impact on the physiological and biochemical changes in spring barley seedlings and common radish plants. A similar study was also carried out by introducing the inorganic salt – ammonium hexafluorophosphate APF6 to the soil; the results showed the soil became highly toxic to both plants. All the salts used led to significant changes in the metabolism of both spring barley and common radish which can be evidenced, for example, by a decrease in the content of chlorophyll a (Chla), chlorophyll b (Chlb), and total chlorophyll (Chla + b), as well as carotenoids (Car). The decrease in assimilation pigments was linearly correlated with an increasing concentration of QAS in the soil. QAS and APF6 led to the formation of oxidative stress in both experimental plants, as evidenced by an increase in malondialdehyde (MDA) content in their cells and the changes in H2O2 level. In response to stress, the plants synthesized enzymatic free radicals (ROS) scavengers that lead to changes in the activity of superoxide dismutase (SOD) and catalase (CAT), as well as significantly increased peroxidase (POD) activity. A decrease in the content of assimilation pigments and an increased POD activity are the most reliable indices of oxidative stress, and concurrently the signs of premature plants aging. Common radish proved to be more resistant to the presence of QAS in the soil compared to spring barley.
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•The level of oxidative stress in plants as a result of QAS in the soil was defined.•The common radish revealed the higher tolerance to the QAS as compared to barley.•The increased level of QAS in soil causes a decrease in content of plant pigments.•The increased concentration of QAS in the soil increases the activity of POD.
Ionic liquids have attracted considerable interest in various areas as new, nonvolatile and nonflammable organic solvents, catalysts, reaction additives, ligands, drugs, and other dedicated ...materials. Ionic liquids exhibit solubility both in organic solvents and in water. They also constitute very good solvents for many inorganic, organic, and organometallic compounds. Yet, the most important feature of ionic liquids is that they provide the possibility of obtaining substances of optimal properties for a given process through modification of the cation structure and selection of the appropriate anion. Therefore, the term designer solvents has been invented for these salts. The above characteristics and relatively low production cost may soon lead to the situation, in which huge amounts of these chemicals will be brought into environment via industry, agriculture, and commercial trading. Their general use, sometimes in bulky quantities, requires determination of their potential ecotoxicity on selected plant and animal organisms. Other biological tests, are also very important.
Abstract Ionic liquids have attracted considerable interest in various areas as new, non-volatile and non-flammable organic solvents, catalysts, reaction additives, ligands, drugs and other dedicated ...materials etc. Their general use, sometimes in bulky quantities, requires determination of their potential ecotoxicity on selected organisms. In the present work, influence of triphenylmethylphosphonium iodide (1) and triphenylhexadecylphosphonium iodide (2), introduced to soil, on germination and early stages of growth and development of superior plants was investigated using the plant growth test based on the OECD/OCDE 208/2006. In this test, the seeds of selected species, i.e. land superior plants - spring barley ( Hordeum vulgare ) and common radish ( Raphanus sativus L. subvar. radicula Pers.) were planted in pots containing soil to which a test chemical compound had been added and in pots with control soil. To evaluate the phytotoxicity of ionic liquids 1 and 2 germination and weight (dry and fresh) of control plant seedlings were determined and compared with the germination and weight (dry and fresh) of the seedlings of plants grown in the soil watered with appropriate amounts of the test chemicals. The visual assessment of any types of damage to the test species, such as growth inhibition, chlorosis and necrosis, was also carried out and documented by digital photographs. Based on the obtained results, magnitudes of the LOEC - the lowest concentration causing observable effects in the form of reduction in growth and germination compared with the control and the NOEC - the highest concentration not causing observable, toxic effects - were also determined.
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