Nanotechnology offers manufacturing and use of structures in which at least one dimension is expressed in nanometers. An increasing number of everyday products contain some ingredients in molecules size. One of them – Ag-nanoparticles (nanosilver) – is commonly used due to its biocidal properties. There is a serious risk of nanoparticles being released into the environment, especially to the soil or surface water. Because of low selectivity of silver-nanoparticles in water it is not an environmentally-friendly product (destroying aquatic microflora and fauna).
The aim of this study was to determine the effect of Ag-nanoparticles on the growth and survivability of three water plants: Oedogonium sp., Versicularia dubyana, and Lagarosyphon madagascariensis.
Plants were treated with silver nanoparticle solutions of concentrations ranging from 0.0 to 10.0 mg·dm^-3 Ag (NANO SILVER product by NANOCO Corp.). Light conditions were controlled through 16-hour light cycle using a 15W Tungsram lamp. The whole experiment was carried out over 10 days. Changes in plant morphology and growth in various Ag-nanoparticle concentrations were observed.
Ag-nanoparticles showed biocidal activity for Oedogonium sp. after 24 hours of incubation in solutions with a concentration of 1.0-10.0 mg·dm^-3 Ag. Plants were dark, destroyed, and sank to the bottom. In samples with higher plants, nano silver caused blackening and some plant deaths at concentrations of 5.0 and 10.0 mg·dm^-3 Ag, or inhibited their growth in lower concentrations.
Selective activity of nano silver may be useful for eliminating unwanted plants. However, its uncontrolled release into the environment may be harmful to aquatic organisms and devastating for entire ecosystems.